rust/src/libsyntax/parse/parser.rs

import print::pprust::expr_to_str;

import result::result;
import either::{either, left, right};
import std::map::{hashmap, str_hash};
import token::{can_begin_expr, is_ident, is_plain_ident, INTERPOLATED};
import codemap::{span,fss_none};
import util::interner;
import ast_util::{spanned, respan, mk_sp, ident_to_path, operator_prec};
import lexer::{reader, tt_reader_as_reader};
import prec::{as_prec, token_to_binop};
import attr::parser_attr;
import common::{seq_sep_trailing_disallowed, seq_sep_trailing_allowed,
                seq_sep_none, token_to_str};
import dvec::{dvec, extensions};
import vec::{push};
import ast::{_mod, add, alt_check, alt_exhaustive, arg, arm, attribute,
             bitand, bitor, bitxor, blk, blk_check_mode, bound_const,
             bound_copy, bound_send, bound_trait, bound_owned,
             box, by_copy, by_move,
             by_mutbl_ref, by_ref, by_val, capture_clause, capture_item,
             cdir_dir_mod, cdir_src_mod,
             cdir_view_item, class_immutable,
             class_member, class_method, class_mutable,
             crate, crate_cfg, crate_directive, decl,
             decl_item, decl_local, default_blk, deref, div, expl, expr,
             expr_, expr_addr_of, expr_alt, expr_again, expr_assert,
             expr_assign, expr_assign_op, expr_binary, expr_block, expr_break,
             expr_call, expr_cast, expr_copy, expr_do_body,
             expr_fail, expr_field, expr_fn, expr_fn_block, expr_if,
             expr_index, expr_lit, expr_log, expr_loop,
             expr_loop_body, expr_mac, expr_move, expr_new, expr_path,
             expr_rec, expr_ret, expr_swap, expr_struct, expr_tup, expr_unary,
             expr_vec, expr_vstore, expr_while, extern_fn, field, fn_decl,
             foreign_item, foreign_item_fn, foreign_mod, ident, impure_fn,
             infer, init_assign, init_move, initializer, instance_var, item,
             item_, item_class, item_const, item_enum, item_fn,
             item_foreign_mod, item_impl, item_mac, item_mod, item_trait,
             item_ty, lit, lit_, lit_bool, lit_float, lit_int,
             lit_int_unsuffixed, lit_nil, lit_str, lit_uint, local, m_const,
             m_imm, m_mutbl, mac_, mac_aq, mac_ellipsis,
             mac_invoc, mac_invoc_tt, mac_var, matcher, match_nonterminal,
             match_seq, match_tok, method, mode, mt, mul, mutability, neg,
             noreturn, not, pat, pat_box, pat_enum, pat_ident, pat_lit,
             pat_range, pat_rec, pat_tup, pat_uniq, pat_wild, path, private,
             proto, proto_any, proto_bare, proto_block, proto_box, proto_uniq,
             provided, public, pure_fn, purity, re_anon, re_named, region,
             rem, required, ret_style, return_val, shl, shr, stmt, stmt_decl,
             stmt_expr, stmt_semi, subtract, token_tree, trait_method,
             trait_ref, tt_delim, tt_seq, tt_tok, tt_nonterminal, ty,
             ty_, ty_bot, ty_box, ty_field, ty_fn, ty_infer, ty_mac,
             ty_method, ty_nil, ty_param, ty_path, ty_ptr, ty_rec, ty_rptr,
             ty_tup, ty_u32, ty_uniq, ty_vec, ty_fixed_length, unchecked_blk,
             uniq, unsafe_blk, unsafe_fn, variant, view_item, view_item_,
             view_item_export, view_item_import, view_item_use, view_path,
             view_path_glob, view_path_list, view_path_simple, visibility,
             vstore, vstore_box, vstore_fixed, vstore_slice, vstore_uniq};

export file_type;
export parser;
export CRATE_FILE;
export SOURCE_FILE;

// FIXME (#1893): #ast expects to find this here but it's actually
// defined in `parse` Fixing this will be easier when we have export
// decls on individual items -- then parse can export this publicly, and
// everything else crate-visibly.
import parse_from_source_str;
export parse_from_source_str;

enum restriction {
    UNRESTRICTED,
    RESTRICT_STMT_EXPR,
    RESTRICT_NO_CALL_EXPRS,
    RESTRICT_NO_BAR_OP,
    RESTRICT_NO_BAR_OR_DOUBLEBAR_OP,
}

enum file_type { CRATE_FILE, SOURCE_FILE, }


// We don't allow single-entry tuples in the true AST; that indicates a
// parenthesized expression.  However, we preserve them temporarily while
// parsing because `(while{...})+3` parses differently from `while{...}+3`.
//
// To reflect the fact that the @expr is not a true expr that should be
// part of the AST, we wrap such expressions in the pexpr enum.  They
// can then be converted to true expressions by a call to `to_expr()`.
enum pexpr {
    pexpr(@expr),
}

/*
  So that we can distinguish a class ctor or dtor
  from other class members
 */
enum class_contents { ctor_decl(fn_decl, ~[attribute], blk, codemap::span),
                      dtor_decl(blk, ~[attribute], codemap::span),
                      members(~[@class_member]) }

type arg_or_capture_item = either<arg, capture_item>;
type item_info = (ident, item_, option<~[attribute]>);


/* The expr situation is not as complex as I thought it would be.
The important thing is to make sure that lookahead doesn't balk
at INTERPOLATED tokens */
macro_rules! maybe_whole_expr {
    {$p:expr} => { alt copy $p.token {
      INTERPOLATED(token::nt_expr(e)) {
        $p.bump();
        ret pexpr(e);
      }
      INTERPOLATED(token::nt_path(pt)) {
        $p.bump();
        ret $p.mk_pexpr($p.span.lo, $p.span.lo,
                       expr_path(pt));
      }
      _ {}
    }}
}

macro_rules! maybe_whole {
    {$p:expr, $constructor:path} => { alt copy $p.token {
      INTERPOLATED($constructor(x)) { $p.bump(); ret x; }
      _ {}
    }}
}

/* ident is handled by common.rs */

fn dummy() {
    /* we will need this to bootstrap maybe_whole! */
    #macro[[#maybe_whole_path[p],
            alt p.token {
                INTERPOLATED(token::nt_path(pt)) { p.bump(); ret pt; }
                _ {} }]];
}


class parser {
    let sess: parse_sess;
    let cfg: crate_cfg;
    let file_type: file_type;
    let mut token: token::token;
    let mut span: span;
    let mut last_span: span;
    let mut buffer: [mut {tok: token::token, sp: span}]/4;
    let mut buffer_start: int;
    let mut buffer_end: int;
    let mut restriction: restriction;
    let mut quote_depth: uint; // not (yet) related to the quasiquoter
    let reader: reader;
    let keywords: hashmap<~str, ()>;
    let restricted_keywords: hashmap<~str, ()>;

    new(sess: parse_sess, cfg: ast::crate_cfg, +rdr: reader, ftype: file_type)
    {
        self.reader <- rdr;
        let tok0 = self.reader.next_token();
        let span0 = tok0.sp;
        self.sess = sess;
        self.cfg = cfg;
        self.file_type = ftype;
        self.token = tok0.tok;
        self.span = span0;
        self.last_span = span0;
        self.buffer = [mut
            {tok: tok0.tok, sp: span0},
            {tok: tok0.tok, sp: span0},
            {tok: tok0.tok, sp: span0},
            {tok: tok0.tok, sp: span0}
        ]/4;
        self.buffer_start = 0;
        self.buffer_end = 0;
        self.restriction = UNRESTRICTED;
        self.quote_depth = 0u;
        self.keywords = token::keyword_table();
        self.restricted_keywords = token::restricted_keyword_table();
    }

    drop {} /* do not copy the parser; its state is tied to outside state */

    fn bump() {
        self.last_span = self.span;
        let next = if self.buffer_start == self.buffer_end {
            self.reader.next_token()
        } else {
            let next = self.buffer[self.buffer_start];
            self.buffer_start = (self.buffer_start + 1) & 3;
            next
        };
        self.token = next.tok;
        self.span = next.sp;
    }
    fn swap(next: token::token, lo: uint, hi: uint) {
        self.token = next;
        self.span = mk_sp(lo, hi);
    }
    fn buffer_length() -> int {
        if self.buffer_start <= self.buffer_end {
            ret self.buffer_end - self.buffer_start;
        }
        ret (4 - self.buffer_start) + self.buffer_end;
    }
    fn look_ahead(distance: uint) -> token::token {
        let dist = distance as int;
        while self.buffer_length() < dist {
            self.buffer[self.buffer_end] = self.reader.next_token();
            self.buffer_end = (self.buffer_end + 1) & 3;
        }
        ret copy self.buffer[(self.buffer_start + dist - 1) & 3].tok;
    }
    fn fatal(m: ~str) -> ! {
        self.sess.span_diagnostic.span_fatal(copy self.span, m)
    }
    fn span_fatal(sp: span, m: ~str) -> ! {
        self.sess.span_diagnostic.span_fatal(sp, m)
    }
    fn bug(m: ~str) -> ! {
        self.sess.span_diagnostic.span_bug(copy self.span, m)
    }
    fn warn(m: ~str) {
        self.sess.span_diagnostic.span_warn(copy self.span, m)
    }
    pure fn get_str(i: token::str_num) -> @~str {
        (*self.reader.interner()).get(i)
    }
    fn get_id() -> node_id { next_node_id(self.sess) }

    fn parse_ty_fn(purity: ast::purity) -> ty_ {
        let proto = if self.eat_keyword(~"extern") {
            self.expect_keyword(~"fn");
            ast::proto_bare
        } else {
            self.expect_keyword(~"fn");
            self.parse_fn_ty_proto()
        };
        ty_fn(proto, self.parse_ty_fn_decl(purity))
    }

    fn parse_ty_fn_decl(purity: ast::purity) -> fn_decl {
        let inputs = do self.parse_unspanned_seq(
            token::LPAREN, token::RPAREN,
            seq_sep_trailing_disallowed(token::COMMA)) |p| {
            let mode = p.parse_arg_mode();
            let name = if is_plain_ident(p.token)
                && p.look_ahead(1u) == token::COLON {

                let name = self.parse_value_ident();
                p.bump();
                name
            } else { @~"" };

            {mode: mode, ty: p.parse_ty(false), ident: name,
             id: p.get_id()}
        };
        let (ret_style, ret_ty) = self.parse_ret_ty();
        ret {inputs: inputs, output: ret_ty,
             purity: purity, cf: ret_style};
    }

    fn parse_trait_methods() -> ~[trait_method] {
        do self.parse_unspanned_seq(token::LBRACE, token::RBRACE,
                                    seq_sep_none()) |p| {
            let attrs = p.parse_outer_attributes();
            let lo = p.span.lo;
            let pur = p.parse_fn_purity();
            // NB: at the moment, trait methods are public by default; this
            // could change.
            let vis = p.parse_visibility(public);
            let ident = p.parse_method_name();
            let tps = p.parse_ty_params();
            let d = p.parse_ty_fn_decl(pur);
            let hi = p.last_span.hi;
            #debug["parse_trait_methods(): trait method signature ends in \
                    `%s`",
                   token_to_str(p.reader, p.token)];
            alt p.token {
              token::SEMI {
                p.bump();
                #debug["parse_trait_methods(): parsing required method"];
                // NB: at the moment, visibility annotations on required
                // methods are ignored; this could change.
                required({ident: ident, attrs: attrs,
                          decl: {purity: pur with d}, tps: tps,
                          span: mk_sp(lo, hi)})
              }
              token::LBRACE {
                #debug["parse_trait_methods(): parsing provided method"];
                let (inner_attrs, body) =
                    p.parse_inner_attrs_and_block(true);
                let attrs = vec::append(attrs, inner_attrs);
                provided(@{ident: ident,
                           attrs: attrs,
                           tps: tps,
                           decl: d,
                           body: body,
                           id: p.get_id(),
                           span: mk_sp(lo, hi),
                           self_id: p.get_id(),
                           vis: vis})
              }

              _ { p.fatal(~"expected `;` or `}` but found `" +
                          token_to_str(p.reader, p.token) + ~"`");
                }
            }
        }
    }


    fn parse_mt() -> mt {
        let mutbl = self.parse_mutability();
        let t = self.parse_ty(false);
        ret {ty: t, mutbl: mutbl};
    }

    fn parse_ty_field() -> ty_field {
        let lo = self.span.lo;
        let mutbl = self.parse_mutability();
        let id = self.parse_ident();
        self.expect(token::COLON);
        let ty = self.parse_ty(false);
        ret spanned(lo, ty.span.hi, {ident: id, mt: {ty: ty, mutbl: mutbl}});
    }

    fn parse_ret_ty() -> (ret_style, @ty) {
        ret if self.eat(token::RARROW) {
            let lo = self.span.lo;
            if self.eat(token::NOT) {
                (noreturn, @{id: self.get_id(),
                             node: ty_bot,
                             span: mk_sp(lo, self.last_span.hi)})
            } else {
                (return_val, self.parse_ty(false))
            }
        } else {
            let pos = self.span.lo;
            (return_val, @{id: self.get_id(),
                           node: ty_nil,
                           span: mk_sp(pos, pos)})
        }
    }

    fn region_from_name(s: option<@~str>) -> @region {
        let r = alt s {
          some (string) { re_named(string) }
          none { re_anon }
        };

        @{id: self.get_id(), node: r}
    }

    // Parses something like "&x"
    fn parse_region() -> @region {
        self.expect(token::BINOP(token::AND));
        alt copy self.token {
          token::IDENT(sid, _) {
            self.bump();
            let n = self.get_str(sid);
            self.region_from_name(some(n))
          }
          _ {
            self.region_from_name(none)
          }
        }
    }

    // Parses something like "&x/" (note the trailing slash)
    fn parse_region_with_sep() -> @region {
        let name =
            alt copy self.token {
              token::IDENT(sid, _) => {
                if self.look_ahead(1u) == token::BINOP(token::SLASH) {
                    self.bump(); self.bump();
                    some(self.get_str(sid))
                } else {
                    none
                }
              }
              _ => { none }
            };
        self.region_from_name(name)
    }

    fn parse_ty(colons_before_params: bool) -> @ty {
        let lo = self.span.lo;

        alt self.maybe_parse_dollar_mac() {
          some(e) {
            ret @{id: self.get_id(),
                  node: ty_mac(spanned(lo, self.span.hi, e)),
                  span: mk_sp(lo, self.span.hi)};
          }
          none {}
        }

        let t = if self.token == token::LPAREN {
            self.bump();
            if self.token == token::RPAREN {
                self.bump();
                ty_nil
            } else {
                let mut ts = ~[self.parse_ty(false)];
                while self.token == token::COMMA {
                    self.bump();
                    vec::push(ts, self.parse_ty(false));
                }
                let t = if vec::len(ts) == 1u { ts[0].node }
                else { ty_tup(ts) };
                self.expect(token::RPAREN);
                t
            }
        } else if self.token == token::AT {
            self.bump();
            ty_box(self.parse_mt())
        } else if self.token == token::TILDE {
            self.bump();
            ty_uniq(self.parse_mt())
        } else if self.token == token::BINOP(token::STAR) {
            self.bump();
            ty_ptr(self.parse_mt())
        } else if self.token == token::LBRACE {
            let elems = self.parse_unspanned_seq(
                token::LBRACE, token::RBRACE,
                seq_sep_trailing_allowed(token::COMMA),
                |p| p.parse_ty_field());
            if vec::len(elems) == 0u {
                self.unexpected_last(token::RBRACE);
            }
            ty_rec(elems)
        } else if self.token == token::LBRACKET {
            self.expect(token::LBRACKET);
            let t = ty_vec(self.parse_mt());
            self.expect(token::RBRACKET);
            t
        } else if self.token == token::BINOP(token::AND) {
            self.bump();
            let region = self.parse_region_with_sep();
            let mt = self.parse_mt();
            ty_rptr(region, mt)
        } else if self.eat_keyword(~"pure") {
            self.parse_ty_fn(ast::pure_fn)
        } else if self.eat_keyword(~"unsafe") {
            self.parse_ty_fn(ast::unsafe_fn)
        } else if self.is_keyword(~"fn") {
            self.parse_ty_fn(ast::impure_fn)
        } else if self.eat_keyword(~"extern") {
            self.expect_keyword(~"fn");
            ty_fn(proto_bare, self.parse_ty_fn_decl(ast::impure_fn))
        } else if self.token == token::MOD_SEP || is_ident(self.token) {
            let path = self.parse_path_with_tps(colons_before_params);
            ty_path(path, self.get_id())
        } else { self.fatal(~"expected type"); };

        let sp = mk_sp(lo, self.last_span.hi);
        ret @{id: self.get_id(),
              node: alt self.maybe_parse_fixed_vstore() {
                // Consider a fixed vstore suffix (/N or /_)
                none { t }
                some(v) {
                  ty_fixed_length(@{id: self.get_id(), node:t, span: sp}, v)
                } },
              span: sp}
    }

    fn parse_arg_mode() -> mode {
        if self.eat(token::BINOP(token::AND)) {
            expl(by_mutbl_ref)
        } else if self.eat(token::BINOP(token::MINUS)) {
            expl(by_move)
        } else if self.eat(token::ANDAND) {
            expl(by_ref)
        } else if self.eat(token::BINOP(token::PLUS)) {
            if self.eat(token::BINOP(token::PLUS)) {
                expl(by_val)
            } else {
                expl(by_copy)
            }
        } else { infer(self.get_id()) }
    }

    fn parse_capture_item_or(parse_arg_fn: fn(parser) -> arg_or_capture_item)
        -> arg_or_capture_item {

        fn parse_capture_item(p:parser, is_move: bool) -> capture_item {
            let sp = mk_sp(p.span.lo, p.span.hi);
            let ident = p.parse_ident();
            @{id: p.get_id(), is_move: is_move, name: ident, span: sp}
        }

        if self.eat_keyword(~"move") {
            either::right(parse_capture_item(self, true))
        } else if self.eat_keyword(~"copy") {
            either::right(parse_capture_item(self, false))
        } else {
            parse_arg_fn(self)
        }
    }

    fn parse_arg() -> arg_or_capture_item {
        let m = self.parse_arg_mode();
        let i = self.parse_value_ident();
        self.expect(token::COLON);
        let t = self.parse_ty(false);
        either::left({mode: m, ty: t, ident: i, id: self.get_id()})
    }

    fn parse_arg_or_capture_item() -> arg_or_capture_item {
        self.parse_capture_item_or(|p| p.parse_arg())
    }

    fn parse_fn_block_arg() -> arg_or_capture_item {
        do self.parse_capture_item_or |p| {
            let m = p.parse_arg_mode();
            let i = p.parse_value_ident();
            let t = if p.eat(token::COLON) {
                p.parse_ty(false)
            } else {
                @{id: p.get_id(),
                  node: ty_infer,
                  span: mk_sp(p.span.lo, p.span.hi)}
            };
            either::left({mode: m, ty: t, ident: i, id: p.get_id()})
        }
    }

    fn maybe_parse_dollar_mac() -> option<mac_> {
        alt copy self.token {
          token::DOLLAR {
            let lo = self.span.lo;
            self.bump();
            alt copy self.token {
              token::LIT_INT_UNSUFFIXED(num) {
                self.bump();
                some(mac_var(num as uint))
              }
              token::LPAREN {
                self.bump();
                let e = self.parse_expr();
                self.expect(token::RPAREN);
                let hi = self.last_span.hi;
                some(mac_aq(mk_sp(lo,hi), e))
              }
              _ {
                self.fatal(~"expected `(` or unsuffixed integer literal");
              }
            }
          }
          _ {none}
        }
    }

    fn maybe_parse_fixed_vstore() -> option<option<uint>> {
        if self.token == token::BINOP(token::SLASH) {
            self.bump();
            alt copy self.token {
              token::UNDERSCORE {
                self.bump(); some(none)
              }
              token::LIT_INT_UNSUFFIXED(i) if i >= 0i64 {
                self.bump(); some(some(i as uint))
              }
              _ {
                none
              }
            }
        } else {
            none
        }
    }

    fn lit_from_token(tok: token::token) -> lit_ {
        alt tok {
          token::LIT_INT(i, it) { lit_int(i, it) }
          token::LIT_UINT(u, ut) { lit_uint(u, ut) }
          token::LIT_INT_UNSUFFIXED(i) { lit_int_unsuffixed(i) }
          token::LIT_FLOAT(s, ft) { lit_float(self.get_str(s), ft) }
          token::LIT_STR(s) { lit_str(self.get_str(s)) }
          token::LPAREN { self.expect(token::RPAREN); lit_nil }
          _ { self.unexpected_last(tok); }
        }
    }

    fn parse_lit() -> lit {
        let lo = self.span.lo;
        let lit = if self.eat_keyword(~"true") {
            lit_bool(true)
        } else if self.eat_keyword(~"false") {
            lit_bool(false)
        } else {
            let tok = self.token;
            self.bump();
            self.lit_from_token(tok)
        };
        ret {node: lit, span: mk_sp(lo, self.last_span.hi)};
    }

    fn parse_path_without_tps() -> @path {
        self.parse_path_without_tps_(|p| p.parse_ident(),
                                     |p| p.parse_ident())
    }

    fn parse_path_without_tps_(
        parse_ident: fn(parser) -> ident,
        parse_last_ident: fn(parser) -> ident) -> @path {

        let lo = self.span.lo;
        let global = self.eat(token::MOD_SEP);
        let mut ids = ~[];
        loop {
            let is_not_last =
                self.look_ahead(2u) != token::LT
                && self.look_ahead(1u) == token::MOD_SEP;

            if is_not_last {
                vec::push(ids, parse_ident(self));
                self.expect(token::MOD_SEP);
            } else {
                vec::push(ids, parse_last_ident(self));
                break;
            }
        }
        @{span: mk_sp(lo, self.last_span.hi), global: global,
          idents: ids, rp: none, types: ~[]}
    }

    fn parse_value_path() -> @path {
        self.parse_path_without_tps_(|p| p.parse_ident(),
                                     |p| p.parse_value_ident())
    }

    fn parse_path_with_tps(colons: bool) -> @path {
        #debug["parse_path_with_tps(colons=%b)", colons];

        let lo = self.span.lo;
        let path = self.parse_path_without_tps();
        if colons && !self.eat(token::MOD_SEP) {
            ret path;
        }

        // Parse the region parameter, if any, which will
        // be written "foo/&x"
        let rp = {
            // Hack: avoid parsing vstores like /@ and /~.  This is painful
            // because the notation for region bounds and the notation for
            // vstores is... um... the same.  I guess that's my fault.  This
            // is still not ideal as for &str we end up parsing more than we
            // ought to and have to sort it out later.
            if self.token == token::BINOP(token::SLASH)
                && self.look_ahead(1u) == token::BINOP(token::AND) {

                self.expect(token::BINOP(token::SLASH));
                some(self.parse_region())
            } else {
                none
            }
        };

        // Parse any type parameters which may appear:
        let tps = {
            if self.token == token::LT {
                self.parse_seq_lt_gt(some(token::COMMA),
                                     |p| p.parse_ty(false))
            } else {
                {node: ~[], span: path.span}
            }
        };

        ret @{span: mk_sp(lo, tps.span.hi),
              rp: rp,
              types: tps.node with *path};
    }

    fn parse_mutability() -> mutability {
        if self.eat_keyword(~"mut") {
            m_mutbl
        } else if self.eat_keyword(~"const") {
            m_const
        } else {
            m_imm
        }
    }

    fn parse_field(sep: token::token) -> field {
        let lo = self.span.lo;
        let m = self.parse_mutability();
        let i = self.parse_ident();
        self.expect(sep);
        let e = self.parse_expr();
        ret spanned(lo, e.span.hi, {mutbl: m, ident: i, expr: e});
    }

    fn mk_expr(lo: uint, hi: uint, +node: expr_) -> @expr {
        ret @{id: self.get_id(), callee_id: self.get_id(),
              node: node, span: mk_sp(lo, hi)};
    }

    fn mk_mac_expr(lo: uint, hi: uint, m: mac_) -> @expr {
        ret @{id: self.get_id(),
              callee_id: self.get_id(),
              node: expr_mac({node: m, span: mk_sp(lo, hi)}),
              span: mk_sp(lo, hi)};
    }

    fn mk_lit_u32(i: u32) -> @expr {
        let span = self.span;
        let lv_lit = @{node: lit_uint(i as u64, ty_u32),
                       span: span};

        ret @{id: self.get_id(), callee_id: self.get_id(),
              node: expr_lit(lv_lit), span: span};
    }

    fn mk_pexpr(lo: uint, hi: uint, node: expr_) -> pexpr {
        ret pexpr(self.mk_expr(lo, hi, node));
    }

    fn to_expr(e: pexpr) -> @expr {
        alt e.node {
          expr_tup(es) if vec::len(es) == 1u { es[0u] }
          _ { *e }
        }
    }

    fn parse_bottom_expr() -> pexpr {
        maybe_whole_expr!{self};
        let lo = self.span.lo;
        let mut hi = self.span.hi;

        let mut ex: expr_;

        alt self.maybe_parse_dollar_mac() {
          some(x) {ret pexpr(self.mk_mac_expr(lo, self.span.hi, x));}
          _ {}
        }

        if self.token == token::LPAREN {
            self.bump();
            if self.token == token::RPAREN {
                hi = self.span.hi;
                self.bump();
                let lit = @spanned(lo, hi, lit_nil);
                ret self.mk_pexpr(lo, hi, expr_lit(lit));
            }
            let mut es = ~[self.parse_expr()];
            while self.token == token::COMMA {
                self.bump(); vec::push(es, self.parse_expr());
            }
            hi = self.span.hi;
            self.expect(token::RPAREN);

            // Note: we retain the expr_tup() even for simple
            // parenthesized expressions, but only for a "little while".
            // This is so that wrappers around parse_bottom_expr()
            // can tell whether the expression was parenthesized or not,
            // which affects expr_is_complete().
            ret self.mk_pexpr(lo, hi, expr_tup(es));
        } else if self.token == token::LBRACE {
            self.bump();
            if self.is_keyword(~"mut") ||
                is_plain_ident(self.token)
                && self.look_ahead(1u) == token::COLON {
                let mut fields = ~[self.parse_field(token::COLON)];
                let mut base = none;
                while self.token != token::RBRACE {
                    // optional comma before "with"
                    if self.token == token::COMMA
                        && self.token_is_keyword(~"with",
                                                 self.look_ahead(1u)) {
                        self.bump();
                    }
                    if self.eat_keyword(~"with") {
                        base = some(self.parse_expr()); break;
                    }
                    self.expect(token::COMMA);
                    if self.token == token::RBRACE {
                        // record ends by an optional trailing comma
                        break;
                    }
                    vec::push(fields, self.parse_field(token::COLON));
                }
                hi = self.span.hi;
                self.expect(token::RBRACE);
                ex = expr_rec(fields, base);
            } else {
                let blk = self.parse_block_tail(lo, default_blk);
                ret self.mk_pexpr(blk.span.lo, blk.span.hi, expr_block(blk));
            }
        } else if token::is_bar(self.token) {
            ret pexpr(self.parse_lambda_expr());
        } else if self.eat_keyword(~"new") {
            self.expect(token::LPAREN);
            let r = self.parse_expr();
            self.expect(token::RPAREN);
            let v = self.parse_expr();
            ret self.mk_pexpr(lo, self.span.hi,
                              expr_new(r, self.get_id(), v));
        } else if self.eat_keyword(~"if") {
            ret pexpr(self.parse_if_expr());
        } else if self.eat_keyword(~"for") {
            ret pexpr(self.parse_sugary_call_expr(~"for", expr_loop_body));
        } else if self.eat_keyword(~"do") {
            ret pexpr(self.parse_sugary_call_expr(~"do", expr_do_body));
        } else if self.eat_keyword(~"while") {
            ret pexpr(self.parse_while_expr());
        } else if self.eat_keyword(~"loop") {
            ret pexpr(self.parse_loop_expr());
        } else if self.eat_keyword(~"alt") {
            ret pexpr(self.parse_alt_expr());
        } else if self.eat_keyword(~"fn") {
            let proto = self.parse_fn_ty_proto();
            alt proto {
              proto_bare { self.fatal(~"fn expr are deprecated, use fn@"); }
              proto_any {
                self.fatal(~"fn* cannot be used in an expression");
              }
              _ { /* fallthrough */ }
            }
            ret pexpr(self.parse_fn_expr(proto));
        } else if self.eat_keyword(~"unchecked") {
            ret pexpr(self.parse_block_expr(lo, unchecked_blk));
        } else if self.eat_keyword(~"unsafe") {
            ret pexpr(self.parse_block_expr(lo, unsafe_blk));
        } else if self.token == token::LBRACKET {
            self.bump();
            let mutbl = self.parse_mutability();
            let es = self.parse_seq_to_end(
                token::RBRACKET, seq_sep_trailing_allowed(token::COMMA),
                |p| p.parse_expr());
            hi = self.span.hi;
            ex = expr_vec(es, mutbl);
        } else if self.token == token::ELLIPSIS {
            self.bump();
            ret pexpr(self.mk_mac_expr(lo, self.span.hi, mac_ellipsis));
        } else if self.token == token::POUND {
            let ex_ext = self.parse_syntax_ext();
            hi = ex_ext.span.hi;
            ex = ex_ext.node;
        } else if self.eat_keyword(~"fail") {
            if can_begin_expr(self.token) {
                let e = self.parse_expr();
                hi = e.span.hi;
                ex = expr_fail(some(e));
            } else { ex = expr_fail(none); }
        } else if self.eat_keyword(~"log") {
            self.expect(token::LPAREN);
            let lvl = self.parse_expr();
            self.expect(token::COMMA);
            let e = self.parse_expr();
            ex = expr_log(2, lvl, e);
            hi = self.span.hi;
            self.expect(token::RPAREN);
        } else if self.eat_keyword(~"assert") {
            let e = self.parse_expr();
            ex = expr_assert(e);
            hi = e.span.hi;
        } else if self.eat_keyword(~"ret") {
            if can_begin_expr(self.token) {
                let e = self.parse_expr();
                hi = e.span.hi;
                ex = expr_ret(some(e));
            } else { ex = expr_ret(none); }
        } else if self.eat_keyword(~"break") {
            ex = expr_break;
            hi = self.span.hi;
        } else if self.eat_keyword(~"again") {
            ex = expr_again;
            hi = self.span.hi;
        } else if self.eat_keyword(~"copy") {
            let e = self.parse_expr();
            ex = expr_copy(e);
            hi = e.span.hi;
        } else if self.token == token::MOD_SEP ||
            is_ident(self.token) && !self.is_keyword(~"true") &&
            !self.is_keyword(~"false") {
            let pth = self.parse_path_with_tps(true);

            /* `!`, as an operator, is prefix, so we know this isn't that */
            if self.token == token::NOT {
                self.bump();
                let tts = self.parse_unspanned_seq(
                    token::LBRACE, token::RBRACE, seq_sep_none(),
                    |p| p.parse_token_tree());
                let hi = self.span.hi;

                ret pexpr(self.mk_mac_expr(lo, hi, mac_invoc_tt(pth, tts)));
            } else if self.token == token::LBRACE {
                // This might be a struct literal.
                let lookahead = self.look_ahead(1);
                if self.token_is_keyword(~"mut", lookahead) ||
                        (is_plain_ident(lookahead) &&
                         self.look_ahead(2) == token::COLON) {

                    // It's a struct literal.
                    self.bump();
                    let mut fields = ~[];
                    if self.is_keyword(~"mut") || is_plain_ident(self.token)
                            && self.look_ahead(1) == token::COLON {
                        vec::push(fields, self.parse_field(token::COLON));
                        while self.token != token::RBRACE {
                            self.expect(token::COMMA);
                            if self.token == token::RBRACE {
                                // Accept an optional trailing comma.
                                break;
                            }
                            vec::push(fields, self.parse_field(token::COLON));
                        }
                    }

                    hi = pth.span.hi;
                    self.expect(token::RBRACE);
                    ex = expr_struct(pth, fields);
                    ret self.mk_pexpr(lo, hi, ex);
                }
            }

            hi = pth.span.hi;
            ex = expr_path(pth);
        } else {
            let lit = self.parse_lit();
            hi = lit.span.hi;
            ex = expr_lit(@lit);
        }

        // Vstore is legal following expr_lit(lit_str(...)) and expr_vec(...)
        // only.
        alt ex {
          expr_lit(@{node: lit_str(_), span: _}) |
          expr_vec(_, _)  {
            alt self.maybe_parse_fixed_vstore() {
              none { }
              some(v) {
                hi = self.span.hi;
                ex = expr_vstore(self.mk_expr(lo, hi, ex), vstore_fixed(v));
              }
            }
          }
          _ { }
        }

        ret self.mk_pexpr(lo, hi, ex);
    }

    fn parse_block_expr(lo: uint, blk_mode: blk_check_mode) -> @expr {
        self.expect(token::LBRACE);
        let blk = self.parse_block_tail(lo, blk_mode);
        ret self.mk_expr(blk.span.lo, blk.span.hi, expr_block(blk));
    }

    fn parse_syntax_ext() -> @expr {
        let lo = self.span.lo;
        self.expect(token::POUND);
        ret self.parse_syntax_ext_naked(lo);
    }

    fn parse_syntax_ext_naked(lo: uint) -> @expr {
        alt self.token {
          token::IDENT(_, _) {}
          _ { self.fatal(~"expected a syntax expander name"); }
        }
        let pth = self.parse_path_without_tps();
        //temporary for a backwards-compatible cycle:
        let sep = seq_sep_trailing_disallowed(token::COMMA);
        let mut e = none;
        if (self.token == token::LPAREN || self.token == token::LBRACKET) {
            let lo = self.span.lo;
            let es =
                if self.token == token::LPAREN {
                    self.parse_unspanned_seq(token::LPAREN, token::RPAREN,
                                             sep, |p| p.parse_expr())
                } else {
                    self.parse_unspanned_seq(token::LBRACKET, token::RBRACKET,
                                             sep, |p| p.parse_expr())
                };
            let hi = self.span.hi;
            e = some(self.mk_expr(lo, hi, expr_vec(es, m_imm)));
        }
        let mut b = none;
        if self.token == token::LBRACE {
            self.bump();
            let lo = self.span.lo;
            let mut depth = 1u;
            while (depth > 0u) {
                alt (self.token) {
                  token::LBRACE {depth += 1u;}
                  token::RBRACE {depth -= 1u;}
                  token::EOF {self.fatal(~"unexpected EOF in macro body");}
                  _ {}
                }
                self.bump();
            }
            let hi = self.last_span.lo;
            b = some({span: mk_sp(lo,hi)});
        }
        ret self.mk_mac_expr(lo, self.span.hi, mac_invoc(pth, e, b));
    }

    fn parse_dot_or_call_expr() -> pexpr {
        let b = self.parse_bottom_expr();
        self.parse_dot_or_call_expr_with(b)
    }

    fn permits_call() -> bool {
        ret self.restriction != RESTRICT_NO_CALL_EXPRS;
    }

    fn parse_dot_or_call_expr_with(e0: pexpr) -> pexpr {
        let mut e = e0;
        let lo = e.span.lo;
        let mut hi;
        loop {
            // expr.f
            if self.eat(token::DOT) {
                alt copy self.token {
                  token::IDENT(i, _) {
                    hi = self.span.hi;
                    self.bump();
                    let tys = if self.eat(token::MOD_SEP) {
                        self.expect(token::LT);
                        self.parse_seq_to_gt(some(token::COMMA),
                                             |p| p.parse_ty(false))
                    } else { ~[] };
                    e = self.mk_pexpr(lo, hi, expr_field(self.to_expr(e),
                                                         self.get_str(i),
                                                         tys));
                  }
                  _ { self.unexpected(); }
                }
                again;
            }
            if self.expr_is_complete(e) { break; }
            alt copy self.token {
              // expr(...)
              token::LPAREN if self.permits_call() {
                let es = self.parse_unspanned_seq(
                    token::LPAREN, token::RPAREN,
                    seq_sep_trailing_disallowed(token::COMMA),
                    |p| p.parse_expr());
                hi = self.span.hi;

                let nd = expr_call(self.to_expr(e), es, false);
                e = self.mk_pexpr(lo, hi, nd);
              }

              // expr[...]
              token::LBRACKET {
                self.bump();
                let ix = self.parse_expr();
                hi = ix.span.hi;
                self.expect(token::RBRACKET);
                e = self.mk_pexpr(lo, hi, expr_index(self.to_expr(e), ix));
              }

              _ { ret e; }
            }
        }
        ret e;
    }

    fn parse_sep_and_zerok() -> (option<token::token>, bool) {
        if self.token == token::BINOP(token::STAR)
            || self.token == token::BINOP(token::PLUS) {
            let zerok = self.token == token::BINOP(token::STAR);
            self.bump();
            ret (none, zerok);
        } else {
            let sep = self.token;
            self.bump();
            if self.token == token::BINOP(token::STAR)
                || self.token == token::BINOP(token::PLUS) {
                let zerok = self.token == token::BINOP(token::STAR);
                self.bump();
                ret (some(sep), zerok);
            } else {
                self.fatal(~"expected `*` or `+`");
            }
        }
    }

    fn parse_token_tree() -> token_tree {
        /// what's the opposite delimiter?
        fn flip(&t: token::token) -> token::token {
            alt t {
              token::LPAREN { token::RPAREN }
              token::LBRACE { token::RBRACE }
              token::LBRACKET { token::RBRACKET }
              _ { fail }
            }
        }

        fn parse_tt_tok(p: parser, delim_ok: bool) -> token_tree {
            alt p.token {
              token::RPAREN | token::RBRACE | token::RBRACKET
              if !delim_ok {
                p.fatal(~"incorrect close delimiter: `"
                           + token_to_str(p.reader, p.token) + ~"`");
              }
              token::EOF {
                p.fatal(~"file ended in the middle of a macro invocation");
              }
              /* we ought to allow different depths of unquotation */
              token::DOLLAR if p.quote_depth > 0u {
                p.bump();
                let sp = p.span;

                if p.token == token::LPAREN {
                    let seq = p.parse_seq(token::LPAREN, token::RPAREN,
                                          seq_sep_none(),
                                          |p| p.parse_token_tree());
                    let (s, z) = p.parse_sep_and_zerok();
                    ret tt_seq(mk_sp(sp.lo ,p.span.hi), seq.node, s, z);
                } else {
                    ret tt_nonterminal(sp, p.parse_ident());
                }
              }
              _ { /* ok */ }
            }
            let res = tt_tok(p.span, p.token);
            p.bump();
            ret res;
        }

        ret alt self.token {
          token::LPAREN | token::LBRACE | token::LBRACKET {
            let ket = flip(self.token);
            tt_delim(vec::append(
                ~[parse_tt_tok(self, true)],
                vec::append(
                    self.parse_seq_to_before_end(
                        ket, seq_sep_none(),
                        |p| p.parse_token_tree()),
                    ~[parse_tt_tok(self, true)])))
          }
          _ { parse_tt_tok(self, false) }
        };
    }

    fn parse_matchers() -> ~[matcher] {
        let name_idx = @mut 0u;
        ret self.parse_matcher_subseq(name_idx, token::LBRACE, token::RBRACE);
    }


    // This goofy function is necessary to correctly match parens in matchers.
    // Otherwise, `$( ( )` would be a valid matcher, and `$( () )` would be
    // invalid. It's similar to common::parse_seq.
    fn parse_matcher_subseq(name_idx: @mut uint, bra: token::token,
                            ket: token::token) -> ~[matcher] {
        let mut ret_val = ~[];
        let mut lparens = 0u;

        self.expect(bra);

        while self.token != ket || lparens > 0u {
            if self.token == token::LPAREN { lparens += 1u; }
            if self.token == token::RPAREN { lparens -= 1u; }
            vec::push(ret_val, self.parse_matcher(name_idx));
        }

        self.bump();

        ret ret_val;
    }

    fn parse_matcher(name_idx: @mut uint) -> matcher {
        let lo = self.span.lo;

        let m = if self.token == token::DOLLAR {
            self.bump();
            if self.token == token::LPAREN {
                let name_idx_lo = *name_idx;
                let ms = self.parse_matcher_subseq(name_idx, token::LPAREN,
                                                   token::RPAREN);
                if ms.len() == 0u {
                    self.fatal(~"repetition body must be nonempty");
                }
                let (sep, zerok) = self.parse_sep_and_zerok();
                match_seq(ms, sep, zerok, name_idx_lo, *name_idx)
            } else {
                let bound_to = self.parse_ident();
                self.expect(token::COLON);
                let nt_name = self.parse_ident();
                let m = match_nonterminal(bound_to, nt_name, *name_idx);
                *name_idx += 1u;
                m
            }
        } else {
            let m = match_tok(self.token);
            self.bump();
            m
        };

        ret spanned(lo, self.span.hi, m);
    }


    fn parse_prefix_expr() -> pexpr {
        let lo = self.span.lo;
        let mut hi;

        let mut ex;
        alt copy self.token {
          token::NOT {
            self.bump();
            let e = self.to_expr(self.parse_prefix_expr());
            hi = e.span.hi;
            self.get_id(); // see ast_util::op_expr_callee_id
            ex = expr_unary(not, e);
          }
          token::BINOP(b) {
            alt b {
              token::MINUS {
                self.bump();
                let e = self.to_expr(self.parse_prefix_expr());
                hi = e.span.hi;
                self.get_id(); // see ast_util::op_expr_callee_id
                ex = expr_unary(neg, e);
              }
              token::STAR {
                self.bump();
                let e = self.to_expr(self.parse_prefix_expr());
                hi = e.span.hi;
                ex = expr_unary(deref, e);
              }
              token::AND {
                self.bump();
                let m = self.parse_mutability();
                let e = self.to_expr(self.parse_prefix_expr());
                hi = e.span.hi;
                // HACK: turn &[...] into a &-evec
                ex = alt e.node {
                  expr_vec(*) | expr_lit(@{node: lit_str(_), span: _})
                  if m == m_imm {
                    expr_vstore(e, vstore_slice(self.region_from_name(none)))
                  }
                  _ { expr_addr_of(m, e) }
                };
              }
              _ { ret self.parse_dot_or_call_expr(); }
            }
          }
          token::AT {
            self.bump();
            let m = self.parse_mutability();
            let e = self.to_expr(self.parse_prefix_expr());
            hi = e.span.hi;
            // HACK: turn @[...] into a @-evec
            ex = alt e.node {
              expr_vec(*) | expr_lit(@{node: lit_str(_), span: _})
              if m == m_imm { expr_vstore(e, vstore_box) }
              _ { expr_unary(box(m), e) }
            };
          }
          token::TILDE {
            self.bump();
            let m = self.parse_mutability();
            let e = self.to_expr(self.parse_prefix_expr());
            hi = e.span.hi;
            // HACK: turn ~[...] into a ~-evec
            ex = alt e.node {
              expr_vec(*) | expr_lit(@{node: lit_str(_), span: _})
              if m == m_imm { expr_vstore(e, vstore_uniq) }
              _ { expr_unary(uniq(m), e) }
            };
          }
          _ { ret self.parse_dot_or_call_expr(); }
        }
        ret self.mk_pexpr(lo, hi, ex);
    }


    fn parse_binops() -> @expr {
        ret self.parse_more_binops(self.parse_prefix_expr(), 0u);
    }

    fn parse_more_binops(plhs: pexpr, min_prec: uint) ->
        @expr {
        let lhs = self.to_expr(plhs);
        if self.expr_is_complete(plhs) { ret lhs; }
        let peeked = self.token;
        if peeked == token::BINOP(token::OR) &&
            (self.restriction == RESTRICT_NO_BAR_OP ||
             self.restriction == RESTRICT_NO_BAR_OR_DOUBLEBAR_OP) {
            ret lhs;
        }
        if peeked == token::OROR &&
            self.restriction == RESTRICT_NO_BAR_OR_DOUBLEBAR_OP {
            ret lhs;
        }
        let cur_opt   = token_to_binop(peeked);
        alt cur_opt {
          some(cur_op) {
            let cur_prec = operator_prec(cur_op);
            if cur_prec > min_prec {
                self.bump();
                let expr = self.parse_prefix_expr();
                let rhs = self.parse_more_binops(expr, cur_prec);
                self.get_id(); // see ast_util::op_expr_callee_id
                let bin = self.mk_pexpr(lhs.span.lo, rhs.span.hi,
                                        expr_binary(cur_op, lhs, rhs));
                ret self.parse_more_binops(bin, min_prec);
            }
          }
          _ {}
        }
        if as_prec > min_prec && self.eat_keyword(~"as") {
            let rhs = self.parse_ty(true);
            let _as =
                self.mk_pexpr(lhs.span.lo, rhs.span.hi, expr_cast(lhs, rhs));
            ret self.parse_more_binops(_as, min_prec);
        }
        ret lhs;
    }

    fn parse_assign_expr() -> @expr {
        let lo = self.span.lo;
        let lhs = self.parse_binops();
        alt copy self.token {
          token::EQ {
            self.bump();
            let rhs = self.parse_expr();
            ret self.mk_expr(lo, rhs.span.hi, expr_assign(lhs, rhs));
          }
          token::BINOPEQ(op) {
            self.bump();
            let rhs = self.parse_expr();
            let mut aop;
            alt op {
              token::PLUS { aop = add; }
              token::MINUS { aop = subtract; }
              token::STAR { aop = mul; }
              token::SLASH { aop = div; }
              token::PERCENT { aop = rem; }
              token::CARET { aop = bitxor; }
              token::AND { aop = bitand; }
              token::OR { aop = bitor; }
              token::SHL { aop = shl; }
              token::SHR { aop = shr; }
            }
            self.get_id(); // see ast_util::op_expr_callee_id
            ret self.mk_expr(lo, rhs.span.hi, expr_assign_op(aop, lhs, rhs));
          }
          token::LARROW {
            self.bump();
            let rhs = self.parse_expr();
            ret self.mk_expr(lo, rhs.span.hi, expr_move(lhs, rhs));
          }
          token::DARROW {
            self.bump();
            let rhs = self.parse_expr();
            ret self.mk_expr(lo, rhs.span.hi, expr_swap(lhs, rhs));
          }
          _ {/* fall through */ }
        }
        ret lhs;
    }

    fn parse_if_expr() -> @expr {
        let lo = self.last_span.lo;
        let cond = self.parse_expr();
        let thn = self.parse_block();
        let mut els: option<@expr> = none;
        let mut hi = thn.span.hi;
        if self.eat_keyword(~"else") {
            let elexpr = self.parse_else_expr();
            els = some(elexpr);
            hi = elexpr.span.hi;
        }
        let q = {cond: cond, then: thn, els: els, lo: lo, hi: hi};
        ret self.mk_expr(q.lo, q.hi, expr_if(q.cond, q.then, q.els));
    }

    fn parse_fn_expr(proto: proto) -> @expr {
        let lo = self.last_span.lo;

        // if we want to allow fn expression argument types to be inferred in
        // the future, just have to change parse_arg to parse_fn_block_arg.
        let (decl, capture_clause) =
            self.parse_fn_decl(impure_fn,
                               |p| p.parse_arg_or_capture_item());

        let body = self.parse_block();
        ret self.mk_expr(lo, body.span.hi,
                         expr_fn(proto, decl, body, capture_clause));
    }

    // `|args| { ... }` like in `do` expressions
    fn parse_lambda_block_expr() -> @expr {
        self.parse_lambda_expr_(
            || {
                alt self.token {
                  token::BINOP(token::OR) | token::OROR {
                    self.parse_fn_block_decl()
                  }
                  _ {
                    // No argument list - `do foo {`
                    ({
                        {
                            inputs: ~[],
                            output: @{
                                id: self.get_id(),
                                node: ty_infer,
                                span: self.span
                            },
                            purity: impure_fn,
                            cf: return_val
                        }
                    },
                    @~[])
                  }
                }
            },
            || {
                let blk = self.parse_block();
                self.mk_expr(blk.span.lo, blk.span.hi, expr_block(blk))
            })
    }

    // `|args| expr`
    fn parse_lambda_expr() -> @expr {
        self.parse_lambda_expr_(|| self.parse_fn_block_decl(),
                                || self.parse_expr())
    }

    fn parse_lambda_expr_(parse_decl: fn&() -> (fn_decl, capture_clause),
                          parse_body: fn&() -> @expr) -> @expr {
        let lo = self.last_span.lo;
        let (decl, captures) = parse_decl();
        let body = parse_body();
        let fakeblock = {view_items: ~[], stmts: ~[], expr: some(body),
                         id: self.get_id(), rules: default_blk};
        let fakeblock = spanned(body.span.lo, body.span.hi,
                                fakeblock);
        ret self.mk_expr(lo, body.span.hi,
                         expr_fn_block(decl, fakeblock, captures));
    }

    fn parse_else_expr() -> @expr {
        if self.eat_keyword(~"if") {
            ret self.parse_if_expr();
        } else {
            let blk = self.parse_block();
            ret self.mk_expr(blk.span.lo, blk.span.hi, expr_block(blk));
        }
    }

    fn parse_sugary_call_expr(keyword: ~str,
                              ctor: fn(+@expr) -> expr_) -> @expr {
        let lo = self.last_span;
        // Parse the callee `foo` in
        //    for foo || {
        //    for foo.bar || {
        // etc, or the portion of the call expression before the lambda in
        //    for foo() || {
        // or
        //    for foo.bar(a) || {
        // Turn on the restriction to stop at | or || so we can parse
        // them as the lambda arguments
        let e = self.parse_expr_res(RESTRICT_NO_BAR_OR_DOUBLEBAR_OP);
        alt e.node {
          expr_call(f, args, false) {
            let block = self.parse_lambda_block_expr();
            let last_arg = self.mk_expr(block.span.lo, block.span.hi,
                                    ctor(block));
            let args = vec::append(args, ~[last_arg]);
            @{node: expr_call(f, args, true)
              with *e}
          }
          expr_path(*) | expr_field(*) | expr_call(*) {
            let block = self.parse_lambda_block_expr();
            let last_arg = self.mk_expr(block.span.lo, block.span.hi,
                                    ctor(block));
            self.mk_expr(lo.lo, last_arg.span.hi,
                         expr_call(e, ~[last_arg], true))
          }
          _ {
            // There may be other types of expressions that can
            // represent the callee in `for` and `do` expressions
            // but they aren't represented by tests
            #debug("sugary call on %?", e.node);
            self.span_fatal(
                lo, #fmt("`%s` must be followed by a block call", keyword));
          }
        }
    }

    fn parse_while_expr() -> @expr {
        let lo = self.last_span.lo;
        let cond = self.parse_expr();
        let body = self.parse_block_no_value();
        let mut hi = body.span.hi;
        ret self.mk_expr(lo, hi, expr_while(cond, body));
    }

    fn parse_loop_expr() -> @expr {
        let lo = self.last_span.lo;
        let body = self.parse_block_no_value();
        let mut hi = body.span.hi;
        ret self.mk_expr(lo, hi, expr_loop(body));
    }

    fn parse_alt_expr() -> @expr {
        let lo = self.last_span.lo;
        let mode = if self.eat_keyword(~"check") { alt_check }
        else { alt_exhaustive };
        let discriminant = self.parse_expr();
        self.expect(token::LBRACE);
        let mut arms: ~[arm] = ~[];
        while self.token != token::RBRACE {
            let pats = self.parse_pats();
            let mut guard = none;
            if self.eat_keyword(~"if") { guard = some(self.parse_expr()); }
            if self.token == token::FAT_ARROW { self.bump(); }
            let blk = self.parse_block();
            vec::push(arms, {pats: pats, guard: guard, body: blk});
        }
        let mut hi = self.span.hi;
        self.bump();
        ret self.mk_expr(lo, hi, expr_alt(discriminant, arms, mode));
    }

    fn parse_expr() -> @expr {
        ret self.parse_expr_res(UNRESTRICTED);
    }

    fn parse_expr_res(r: restriction) -> @expr {
        let old = self.restriction;
        self.restriction = r;
        let e = self.parse_assign_expr();
        self.restriction = old;
        ret e;
    }

    fn parse_initializer() -> option<initializer> {
        alt self.token {
          token::EQ {
            self.bump();
            ret some({op: init_assign, expr: self.parse_expr()});
          }
          token::LARROW {
            self.bump();
            ret some({op: init_move, expr: self.parse_expr()});
          }
          // Now that the the channel is the first argument to receive,
          // combining it with an initializer doesn't really make sense.
          // case (token::RECV) {
          //     self.bump();
          //     ret some(rec(op = init_recv,
          //                  expr = self.parse_expr()));
          // }
          _ {
            ret none;
          }
        }
    }

    fn parse_pats() -> ~[@pat] {
        let mut pats = ~[];
        loop {
            vec::push(pats, self.parse_pat());
            if self.token == token::BINOP(token::OR) { self.bump(); }
            else { ret pats; }
        };
    }

    fn parse_pat() -> @pat {
        let lo = self.span.lo;
        let mut hi = self.span.hi;
        let mut pat;
        alt self.token {
          token::UNDERSCORE { self.bump(); pat = pat_wild; }
          token::AT {
            self.bump();
            let sub = self.parse_pat();
            hi = sub.span.hi;
            // HACK: parse @"..." as a literal of a vstore @str
            pat = alt sub.node {
              pat_lit(e@@{node: expr_lit(@{node: lit_str(_), span: _}), _}) {
                let vst = @{id: self.get_id(), callee_id: self.get_id(),
                            node: expr_vstore(e, vstore_box),
                            span: mk_sp(lo, hi)};
                pat_lit(vst)
              }
              _ { pat_box(sub) }
            };
          }
          token::TILDE {
            self.bump();
            let sub = self.parse_pat();
            hi = sub.span.hi;
            // HACK: parse ~"..." as a literal of a vstore ~str
            pat = alt sub.node {
              pat_lit(e@@{node: expr_lit(@{node: lit_str(_), span: _}), _}) {
                let vst = @{id: self.get_id(), callee_id: self.get_id(),
                            node: expr_vstore(e, vstore_uniq),
                            span: mk_sp(lo, hi)};
                pat_lit(vst)
              }
              _ { pat_uniq(sub) }
            };

          }
          token::LBRACE {
            self.bump();
            let mut fields = ~[];
            let mut etc = false;
            let mut first = true;
            while self.token != token::RBRACE {
                if first { first = false; }
                else { self.expect(token::COMMA); }

                if self.token == token::UNDERSCORE {
                    self.bump();
                    if self.token != token::RBRACE {
                        self.fatal(~"expected `}`, found `" +
                                   token_to_str(self.reader, self.token) +
                                   ~"`");
                    }
                    etc = true;
                    break;
                }

                let lo1 = self.last_span.lo;
                let fieldname = if self.look_ahead(1u) == token::COLON {
                    self.parse_ident()
                } else {
                    self.parse_value_ident()
                };
                let hi1 = self.last_span.lo;
                let fieldpath = ast_util::ident_to_path(mk_sp(lo1, hi1),
                                                        fieldname);
                let mut subpat;
                if self.token == token::COLON {
                    self.bump();
                    subpat = self.parse_pat();
                } else {
                    subpat = @{id: self.get_id(),
                               node: pat_ident(fieldpath, none),
                               span: mk_sp(lo, hi)};
                }
                vec::push(fields, {ident: fieldname, pat: subpat});
            }
            hi = self.span.hi;
            self.bump();
            pat = pat_rec(fields, etc);
          }
          token::LPAREN {
            self.bump();
            if self.token == token::RPAREN {
                hi = self.span.hi;
                self.bump();
                let lit = @{node: lit_nil, span: mk_sp(lo, hi)};
                let expr = self.mk_expr(lo, hi, expr_lit(lit));
                pat = pat_lit(expr);
            } else {
                let mut fields = ~[self.parse_pat()];
                while self.token == token::COMMA {
                    self.bump();
                    vec::push(fields, self.parse_pat());
                }
                if vec::len(fields) == 1u { self.expect(token::COMMA); }
                hi = self.span.hi;
                self.expect(token::RPAREN);
                pat = pat_tup(fields);
            }
          }
          tok {
            if !is_ident(tok) || self.is_keyword(~"true")
                || self.is_keyword(~"false") {
                let val = self.parse_expr_res(RESTRICT_NO_BAR_OP);
                if self.eat_keyword(~"to") {
                    let end = self.parse_expr_res(RESTRICT_NO_BAR_OP);
                    hi = end.span.hi;
                    pat = pat_range(val, end);
                } else {
                    hi = val.span.hi;
                    pat = pat_lit(val);
                }
            } else if is_plain_ident(self.token) &&
                alt self.look_ahead(1u) {
                  token::LPAREN | token::LBRACKET | token::LT { false }
                  _ { true }
                } {
                let name = self.parse_value_path();
                let sub = if self.eat(token::AT) { some(self.parse_pat()) }
                else { none };
                pat = pat_ident(name, sub);
            } else {
                let enum_path = self.parse_path_with_tps(true);
                hi = enum_path.span.hi;
                let mut args: ~[@pat] = ~[];
                let mut star_pat = false;
                alt self.token {
                  token::LPAREN {
                    alt self.look_ahead(1u) {
                      token::BINOP(token::STAR) {
                        // This is a "top constructor only" pat
                        self.bump(); self.bump();
                        star_pat = true;
                        self.expect(token::RPAREN);
                      }
                      _ {
                        args = self.parse_unspanned_seq(
                            token::LPAREN, token::RPAREN,
                            seq_sep_trailing_disallowed(token::COMMA),
                            |p| p.parse_pat());
                        hi = self.span.hi;
                      }
                    }
                  }
                  _ { }
                }
                // at this point, we're not sure whether it's a enum or a bind
                if star_pat {
                    pat = pat_enum(enum_path, none);
                }
                else if vec::is_empty(args) &&
                    vec::len(enum_path.idents) == 1u {
                    pat = pat_ident(enum_path, none);
                }
                else {
                    pat = pat_enum(enum_path, some(args));
                }
            }
          }
        }
        ret @{id: self.get_id(), node: pat, span: mk_sp(lo, hi)};
    }

    fn parse_local(is_mutbl: bool,
                   allow_init: bool) -> @local {
        let lo = self.span.lo;
        let pat = self.parse_pat();
        let mut ty = @{id: self.get_id(),
                       node: ty_infer,
                       span: mk_sp(lo, lo)};
        if self.eat(token::COLON) { ty = self.parse_ty(false); }
        let init = if allow_init { self.parse_initializer() } else { none };
        ret @spanned(lo, self.last_span.hi,
                     {is_mutbl: is_mutbl, ty: ty, pat: pat,
                      init: init, id: self.get_id()});
    }

    fn parse_let() -> @decl {
        let is_mutbl = self.eat_keyword(~"mut");
        let lo = self.span.lo;
        let mut locals = ~[self.parse_local(is_mutbl, true)];
        while self.eat(token::COMMA) {
            vec::push(locals, self.parse_local(is_mutbl, true));
        }
        ret @spanned(lo, self.last_span.hi, decl_local(locals));
    }

    /* assumes "let" token has already been consumed */
    fn parse_instance_var(pr: visibility) -> @class_member {
        let mut is_mutbl = class_immutable;
        let lo = self.span.lo;
        if self.eat_keyword(~"mut") {
            is_mutbl = class_mutable;
        }
        if !is_plain_ident(self.token) {
            self.fatal(~"expected ident");
        }
        let name = self.parse_ident();
        self.expect(token::COLON);
        let ty = self.parse_ty(false);
        ret @{node: instance_var(name, ty, is_mutbl, self.get_id(), pr),
              span: mk_sp(lo, self.last_span.hi)};
    }

    fn parse_stmt(+first_item_attrs: ~[attribute]) -> @stmt {
        fn check_expected_item(p: parser, current_attrs: ~[attribute]) {
            // If we have attributes then we should have an item
            if vec::is_not_empty(current_attrs) {
                p.fatal(~"expected item");
            }
        }

        let lo = self.span.lo;
        if self.is_keyword(~"let") {
            check_expected_item(self, first_item_attrs);
            self.expect_keyword(~"let");
            let decl = self.parse_let();
            ret @spanned(lo, decl.span.hi, stmt_decl(decl, self.get_id()));
        } else {
            let mut item_attrs;
            alt self.parse_outer_attrs_or_ext(first_item_attrs) {
              none { item_attrs = ~[]; }
              some(left(attrs)) { item_attrs = attrs; }
              some(right(ext)) {
                ret @spanned(lo, ext.span.hi, stmt_expr(ext, self.get_id()));
              }
            }

            let item_attrs = vec::append(first_item_attrs, item_attrs);

            alt self.parse_item(item_attrs, public) {
              some(i) {
                let mut hi = i.span.hi;
                let decl = @spanned(lo, hi, decl_item(i));
                ret @spanned(lo, hi, stmt_decl(decl, self.get_id()));
              }
              none() { /* fallthrough */ }
            }

            check_expected_item(self, item_attrs);

            // Remainder are line-expr stmts.
            let e = self.parse_expr_res(RESTRICT_STMT_EXPR);
            ret @spanned(lo, e.span.hi, stmt_expr(e, self.get_id()));
        }
    }

    fn expr_is_complete(e: pexpr) -> bool {
        log(debug, (~"expr_is_complete", self.restriction,
                    print::pprust::expr_to_str(*e),
                    classify::expr_requires_semi_to_be_stmt(*e)));
        ret self.restriction == RESTRICT_STMT_EXPR &&
            !classify::expr_requires_semi_to_be_stmt(*e);
    }

    fn parse_block() -> blk {
        let (attrs, blk) = self.parse_inner_attrs_and_block(false);
        assert vec::is_empty(attrs);
        ret blk;
    }

    fn parse_inner_attrs_and_block(parse_attrs: bool)
        -> (~[attribute], blk) {

        fn maybe_parse_inner_attrs_and_next(p: parser, parse_attrs: bool) ->
            {inner: ~[attribute], next: ~[attribute]} {
            if parse_attrs {
                p.parse_inner_attrs_and_next()
            } else {
                {inner: ~[], next: ~[]}
            }
        }

        let lo = self.span.lo;
        if self.eat_keyword(~"unchecked") {
            self.expect(token::LBRACE);
            let {inner, next} = maybe_parse_inner_attrs_and_next(self,
                                                                 parse_attrs);
            ret (inner, self.parse_block_tail_(lo, unchecked_blk, next));
        } else if self.eat_keyword(~"unsafe") {
            self.expect(token::LBRACE);
            let {inner, next} = maybe_parse_inner_attrs_and_next(self,
                                                                 parse_attrs);
            ret (inner, self.parse_block_tail_(lo, unsafe_blk, next));
        } else {
            self.expect(token::LBRACE);
            let {inner, next} = maybe_parse_inner_attrs_and_next(self,
                                                                 parse_attrs);
            ret (inner, self.parse_block_tail_(lo, default_blk, next));
        }
    }

    fn parse_block_no_value() -> blk {
        // We parse blocks that cannot have a value the same as any other
        // block; the type checker will make sure that the tail expression (if
        // any) has unit type.
        ret self.parse_block();
    }

    // Precondition: already parsed the '{' or '#{'
    // I guess that also means "already parsed the 'impure'" if
    // necessary, and this should take a qualifier.
    // some blocks start with "#{"...
    fn parse_block_tail(lo: uint, s: blk_check_mode) -> blk {
        self.parse_block_tail_(lo, s, ~[])
    }

    fn parse_block_tail_(lo: uint, s: blk_check_mode,
                         +first_item_attrs: ~[attribute]) -> blk {
        let mut stmts = ~[];
        let mut expr = none;
        let {attrs_remaining, view_items} =
            self.parse_view(first_item_attrs, true);
        let mut initial_attrs = attrs_remaining;

        if self.token == token::RBRACE && !vec::is_empty(initial_attrs) {
            self.fatal(~"expected item");
        }

        while self.token != token::RBRACE {
            alt self.token {
              token::SEMI {
                self.bump(); // empty
              }
              _ {
                let stmt = self.parse_stmt(initial_attrs);
                initial_attrs = ~[];
                alt stmt.node {
                  stmt_expr(e, stmt_id) { // Expression without semicolon:
                    alt self.token {
                      token::SEMI {
                        self.bump();
                        push(stmts,
                             @{node: stmt_semi(e, stmt_id) with *stmt});
                      }
                      token::RBRACE {
                        expr = some(e);
                      }
                      t {
                        if classify::stmt_ends_with_semi(*stmt) {
                            self.fatal(~"expected `;` or `}` after \
                                         expression but found `"
                                       + token_to_str(self.reader, t) + ~"`");
                        }
                        vec::push(stmts, stmt);
                      }
                    }
                  }

                  _ { // All other kinds of statements:
                    vec::push(stmts, stmt);

                    if classify::stmt_ends_with_semi(*stmt) {
                        self.expect(token::SEMI);
                    }
                  }
                }
              }
            }
        }
        let mut hi = self.span.hi;
        self.bump();
        let bloc = {view_items: view_items, stmts: stmts, expr: expr,
                    id: self.get_id(), rules: s};
        ret spanned(lo, hi, bloc);
    }

    fn parse_ty_param() -> ty_param {
        let mut bounds = ~[];
        let ident = self.parse_ident();
        if self.eat(token::COLON) {
            while self.token != token::COMMA && self.token != token::GT {
                if self.eat_keyword(~"send") {
                    push(bounds, bound_send); }
                else if self.eat_keyword(~"copy") {
                    push(bounds, bound_copy) }
                else if self.eat_keyword(~"const") {
                    push(bounds, bound_const);
                } else if self.eat_keyword(~"owned") {
                    push(bounds, bound_owned);
                } else {
                    push(bounds, bound_trait(self.parse_ty(false))); }
            }
        }
        ret {ident: ident, id: self.get_id(), bounds: @bounds};
    }

    fn parse_ty_params() -> ~[ty_param] {
        if self.eat(token::LT) {
            self.parse_seq_to_gt(some(token::COMMA), |p| p.parse_ty_param())
        } else { ~[] }
    }

    fn parse_fn_decl(purity: purity,
                     parse_arg_fn: fn(parser) -> arg_or_capture_item)
        -> (fn_decl, capture_clause) {

        let args_or_capture_items: ~[arg_or_capture_item] =
            self.parse_unspanned_seq(
                token::LPAREN, token::RPAREN,
                seq_sep_trailing_disallowed(token::COMMA), parse_arg_fn);

        let inputs = either::lefts(args_or_capture_items);
        let capture_clause = @either::rights(args_or_capture_items);

        let (ret_style, ret_ty) = self.parse_ret_ty();
        ret ({inputs: inputs,
              output: ret_ty,
              purity: purity,
              cf: ret_style}, capture_clause);
    }

    fn parse_fn_block_decl() -> (fn_decl, capture_clause) {
        let inputs_captures = {
            if self.eat(token::OROR) {
                ~[]
            } else {
                self.parse_unspanned_seq(
                    token::BINOP(token::OR), token::BINOP(token::OR),
                    seq_sep_trailing_disallowed(token::COMMA),
                    |p| p.parse_fn_block_arg())
            }
        };
        let output = if self.eat(token::RARROW) {
            self.parse_ty(false)
        } else {
            @{id: self.get_id(), node: ty_infer, span: self.span}
        };
        ret ({inputs: either::lefts(inputs_captures),
              output: output,
              purity: impure_fn,
              cf: return_val},
             @either::rights(inputs_captures));
    }

    fn parse_fn_header() -> {ident: ident, tps: ~[ty_param]} {
        let id = self.parse_value_ident();
        let ty_params = self.parse_ty_params();
        ret {ident: id, tps: ty_params};
    }

    fn mk_item(lo: uint, hi: uint, +ident: ident,
               +node: item_, vis: visibility,
               +attrs: ~[attribute]) -> @item {
        ret @{ident: ident,
              attrs: attrs,
              id: self.get_id(),
              node: node,
              vis: vis,
              span: mk_sp(lo, hi)};
    }

    fn parse_item_fn(purity: purity) -> item_info {
        let t = self.parse_fn_header();
        let (decl, _) = self.parse_fn_decl(purity, |p| p.parse_arg());
        let (inner_attrs, body) = self.parse_inner_attrs_and_block(true);
        (t.ident, item_fn(decl, t.tps, body), some(inner_attrs))
    }

    fn parse_method_name() -> ident {
        alt copy self.token {
          token::BINOP(op) { self.bump(); @token::binop_to_str(op) }
          token::NOT { self.bump(); @~"!" }
          token::LBRACKET {
            self.bump();
            self.expect(token::RBRACKET);
            @~"[]"
          }
          _ {
            let id = self.parse_value_ident();
            if id == @~"unary" && self.eat(token::BINOP(token::MINUS)) {
                @~"unary-"
            }
            else { id }
          }
        }
    }

    fn parse_method(pr: visibility) -> @method {
        let attrs = self.parse_outer_attributes();
        let lo = self.span.lo, pur = self.parse_fn_purity();
        let ident = self.parse_method_name();
        let tps = self.parse_ty_params();
        let (decl, _) = self.parse_fn_decl(pur, |p| p.parse_arg());
        let (inner_attrs, body) = self.parse_inner_attrs_and_block(true);
        let attrs = vec::append(attrs, inner_attrs);
        @{ident: ident, attrs: attrs, tps: tps, decl: decl, body: body,
          id: self.get_id(), span: mk_sp(lo, body.span.hi),
          self_id: self.get_id(), vis: pr}
    }

    fn parse_item_trait() -> item_info {
        let ident = self.parse_ident();
        self.parse_region_param();
        let tps = self.parse_ty_params();
        let meths = self.parse_trait_methods();
        (ident, item_trait(tps, meths), none)
    }

    // Parses four variants (with the region/type params always optional):
    //    impl /&<T: copy> of to_str for ~[T] { ... }
    //    impl name/&<T> of to_str for ~[T] { ... }
    //    impl name/&<T> for ~[T] { ... }
    //    impl<T> ~[T] : to_str { ... }
    fn parse_item_impl() -> item_info {
        fn wrap_path(p: parser, pt: @path) -> @ty {
            @{id: p.get_id(), node: ty_path(pt, p.get_id()), span: pt.span}
        }

        // We do two separate paths here: old-style impls and new-style impls.

        // First, parse type parameters if necessary.
        let mut tps;
        if self.token == token::LT {
            tps = self.parse_ty_params();
        } else {
            tps = ~[];
        }

        let mut ident;
        let ty, traits;
        if !self.is_keyword(~"of") &&
                !self.token_is_keyword(~"of", self.look_ahead(1)) &&
                !self.token_is_keyword(~"for", self.look_ahead(1)) &&
                self.look_ahead(1) != token::BINOP(token::SLASH) &&
                self.look_ahead(1) != token::LT {

            // This is a new-style impl declaration.
            ident = @~"__extensions__";     // XXX: clownshoes

            // Parse the type.
            ty = self.parse_ty(false);

            // Parse traits, if necessary.
            if self.token == token::COLON {
                self.bump();
                traits = self.parse_trait_ref_list(token::LBRACE);
            } else {
                traits = ~[];
            }
        } else {
            let mut ident_old;
            if self.token == token::BINOP(token::SLASH) {
                self.parse_region_param();
                ident_old = none;
                tps = self.parse_ty_params();
            } else if self.is_keyword(~"of") {
                ident_old = none;
            } else {
                ident_old = some(self.parse_ident());
                self.parse_region_param();
                tps = self.parse_ty_params();
            }

            if self.eat_keyword(~"of") {
                let for_atom = (*self.reader.interner()).intern(@~"for");
                traits = self.parse_trait_ref_list
                    (token::IDENT(for_atom, false));
                if traits.len() >= 1 && option::is_none(ident_old) {
                    ident_old = some(vec::last(traits[0].path.idents));
                }
                if traits.len() == 0 {
                    self.fatal(~"BUG: 'of' but no trait");
                }
                if traits.len() > 1 {
                    self.fatal(~"BUG: multiple traits");
                }
            } else {
                traits = ~[];
            };
            ident = alt ident_old {
              some(name) { name }
              none { self.expect_keyword(~"of"); fail; }
            };
            self.expect_keyword(~"for");
            ty = self.parse_ty(false);
        }

        let mut meths = ~[];
        self.expect(token::LBRACE);
        while !self.eat(token::RBRACE) {
            vec::push(meths, self.parse_method(public));
        }
        (ident, item_impl(tps, traits, ty, meths), none)
    }

    // Instantiates ident <i> with references to <typarams> as arguments.
    // Used to create a path that refers to a class which will be defined as
    // the return type of the ctor function.
    fn ident_to_path_tys(i: ident,
                         typarams: ~[ty_param]) -> @path {
        let s = self.last_span;

        @{span: s, global: false, idents: ~[i],
          rp: none,
          types: vec::map(typarams, |tp| {
              @{id: self.get_id(),
                node: ty_path(ident_to_path(s, tp.ident), self.get_id()),
                span: s}})
         }
    }

    fn parse_trait_ref() -> @trait_ref {
        @{path: self.parse_path_with_tps(false),
          ref_id: self.get_id(), impl_id: self.get_id()}
    }

    fn parse_trait_ref_list(ket: token::token) -> ~[@trait_ref] {
        self.parse_seq_to_before_end(
            ket, seq_sep_trailing_disallowed(token::COMMA),
            |p| p.parse_trait_ref())
    }

    fn parse_item_class() -> item_info {
        let class_name = self.parse_value_ident();
        self.parse_region_param();
        let ty_params = self.parse_ty_params();
        let class_path = self.ident_to_path_tys(class_name, ty_params);
        let traits : ~[@trait_ref] = if self.eat(token::COLON)
            { self.parse_trait_ref_list(token::LBRACE) }
        else { ~[] };
        self.expect(token::LBRACE);
        let mut ms: ~[@class_member] = ~[];
        let ctor_id = self.get_id();
        let mut the_ctor : option<(fn_decl, ~[attribute], blk,
                                   codemap::span)> = none;
        let mut the_dtor : option<(blk, ~[attribute], codemap::span)> = none;
        while self.token != token::RBRACE {
            alt self.parse_class_item(class_path) {
              ctor_decl(a_fn_decl, attrs, blk, s) {
                the_ctor = some((a_fn_decl, attrs, blk, s));
              }
              dtor_decl(blk, attrs, s) {
                the_dtor = some((blk, attrs, s));
              }
              members(mms) { ms = vec::append(ms, mms); }
            }
        }
        let actual_dtor = do option::map(the_dtor) |dtor| {
            let (d_body, d_attrs, d_s) = dtor;
            {node: {id: self.get_id(),
                    attrs: d_attrs,
                    self_id: self.get_id(),
                    body: d_body},
             span: d_s}};
        self.bump();
        alt the_ctor {
          some((ct_d, ct_attrs, ct_b, ct_s)) {
            (class_name,
             item_class(ty_params, traits, ms, some({
                 node: {id: ctor_id,
                        attrs: ct_attrs,
                        self_id: self.get_id(),
                        dec: ct_d,
                        body: ct_b},
                 span: ct_s}), actual_dtor),
             none)
          }
          /*
          Is it strange for the parser to check this?
          */
          none {
            (class_name,
             item_class(ty_params, traits, ms, none, actual_dtor),
             none)
          }
        }
    }

    fn token_is_pound_or_doc_comment(++tok: token::token) -> bool {
        alt tok {
            token::POUND | token::DOC_COMMENT(_) { true }
            _ { false }
        }
    }

    fn parse_single_class_item(vis: visibility)
        -> @class_member {
        if (self.eat_keyword(~"let") ||
                self.token_is_keyword(~"mut", copy self.token) ||
                !self.is_any_keyword(copy self.token)) &&
                !self.token_is_pound_or_doc_comment(self.token) {
            let a_var = self.parse_instance_var(vis);
            self.expect(token::SEMI);
            ret a_var;
        } else {
            let m = self.parse_method(vis);
            ret @{node: class_method(m), span: m.span};
        }
    }

    fn parse_ctor(attrs: ~[attribute],
                  result_ty: ast::ty_) -> class_contents {
        let lo = self.last_span.lo;
        let (decl_, _) = self.parse_fn_decl(impure_fn, |p| p.parse_arg());
        let decl = {output: @{id: self.get_id(),
                              node: result_ty, span: decl_.output.span}
                    with decl_};
        let body = self.parse_block();
        ctor_decl(decl, attrs, body, mk_sp(lo, self.last_span.hi))
    }

    fn parse_dtor(attrs: ~[attribute]) -> class_contents {
        let lo = self.last_span.lo;
        let body = self.parse_block();
        dtor_decl(body, attrs, mk_sp(lo, self.last_span.hi))
    }

    fn parse_class_item(class_name_with_tps: @path)
        -> class_contents {

        if self.eat_keyword(~"priv") {
            self.expect(token::LBRACE);
            let mut results = ~[];
            while self.token != token::RBRACE {
                vec::push(results, self.parse_single_class_item(private));
            }
            self.bump();
            ret members(results);
        }

        let attrs = self.parse_outer_attributes();

        if self.eat_keyword(~"new") {
            // result type is always the type of the class
           ret self.parse_ctor(attrs, ty_path(class_name_with_tps,
                                        self.get_id()));
        }
        else if self.eat_keyword(~"drop") {
           ret self.parse_dtor(attrs);
        }
        else {
           ret members(~[self.parse_single_class_item(public)]);
        }
    }

    fn parse_visibility(def: visibility) -> visibility {
        if self.eat_keyword(~"pub") { public }
        else if self.eat_keyword(~"priv") { private }
        else { def }
    }

    fn parse_mod_items(term: token::token,
                       +first_item_attrs: ~[attribute]) -> _mod {
        // Shouldn't be any view items since we've already parsed an item attr
        let {attrs_remaining, view_items} =
            self.parse_view(first_item_attrs, false);
        let mut items: ~[@item] = ~[];
        let mut first = true;
        while self.token != term {
            let mut attrs = self.parse_outer_attributes();
            if first {
                attrs = vec::append(attrs_remaining, attrs);
                first = false;
            }
            #debug["parse_mod_items: parse_item(attrs=%?)", attrs];
            let vis = self.parse_visibility(private);
            alt self.parse_item(attrs, vis) {
              some(i) { vec::push(items, i); }
              _ {
                self.fatal(~"expected item but found `" +
                           token_to_str(self.reader, self.token) + ~"`");
              }
            }
            #debug["parse_mod_items: attrs=%?", attrs];
        }

        if first && attrs_remaining.len() > 0u {
            // We parsed attributes for the first item but didn't find it
            self.fatal(~"expected item");
        }

        ret {view_items: view_items, items: items};
    }

    fn parse_item_const() -> item_info {
        let id = self.parse_value_ident();
        self.expect(token::COLON);
        let ty = self.parse_ty(false);
        self.expect(token::EQ);
        let e = self.parse_expr();
        self.expect(token::SEMI);
        (id, item_const(ty, e), none)
    }

    fn parse_item_mod() -> item_info {
        let id = self.parse_ident();
        self.expect(token::LBRACE);
        let inner_attrs = self.parse_inner_attrs_and_next();
        let m = self.parse_mod_items(token::RBRACE, inner_attrs.next);
        self.expect(token::RBRACE);
        (id, item_mod(m), some(inner_attrs.inner))
    }

    fn parse_item_foreign_fn(+attrs: ~[attribute],
                             purity: purity) -> @foreign_item {
        let lo = self.last_span.lo;
        let t = self.parse_fn_header();
        let (decl, _) = self.parse_fn_decl(purity, |p| p.parse_arg());
        let mut hi = self.span.hi;
        self.expect(token::SEMI);
        ret @{ident: t.ident,
              attrs: attrs,
              node: foreign_item_fn(decl, t.tps),
              id: self.get_id(),
              span: mk_sp(lo, hi)};
    }

    fn parse_fn_purity() -> purity {
        if self.eat_keyword(~"fn") { impure_fn }
        else if self.eat_keyword(~"pure") {
            self.expect_keyword(~"fn");
            pure_fn
        } else if self.eat_keyword(~"unsafe") {
            self.expect_keyword(~"fn");
            unsafe_fn
        }
        else { self.unexpected(); }
    }

    fn parse_foreign_item(+attrs: ~[attribute]) ->
        @foreign_item {
        self.parse_item_foreign_fn(attrs, self.parse_fn_purity())
    }

    fn parse_foreign_mod_items(+first_item_attrs: ~[attribute]) ->
        foreign_mod {
        // Shouldn't be any view items since we've already parsed an item attr
        let {attrs_remaining, view_items} =
            self.parse_view(first_item_attrs, false);
        let mut items: ~[@foreign_item] = ~[];
        let mut initial_attrs = attrs_remaining;
        while self.token != token::RBRACE {
            let attrs = vec::append(initial_attrs,
                                    self.parse_outer_attributes());
            initial_attrs = ~[];
            vec::push(items, self.parse_foreign_item(attrs));
        }
        ret {view_items: view_items,
             items: items};
    }

    fn parse_item_foreign_mod() -> item_info {
        self.expect_keyword(~"mod");
        let id = self.parse_ident();
        self.expect(token::LBRACE);
        let more_attrs = self.parse_inner_attrs_and_next();
        let m = self.parse_foreign_mod_items(more_attrs.next);
        self.expect(token::RBRACE);
        (id, item_foreign_mod(m), some(more_attrs.inner))
    }

    fn parse_type_decl() -> {lo: uint, ident: ident} {
        let lo = self.last_span.lo;
        let id = self.parse_ident();
        ret {lo: lo, ident: id};
    }

    fn parse_item_type() -> item_info {
        let t = self.parse_type_decl();
        self.parse_region_param();
        let tps = self.parse_ty_params();
        self.expect(token::EQ);
        let ty = self.parse_ty(false);
        self.expect(token::SEMI);
        (t.ident, item_ty(ty, tps), none)
    }

    fn parse_region_param() {
        if self.eat(token::BINOP(token::SLASH)) {
            self.expect(token::BINOP(token::AND));
        }
    }

    fn parse_item_enum(default_vis: visibility) -> item_info {
        let id = self.parse_ident();
        self.parse_region_param();
        let ty_params = self.parse_ty_params();
        let mut variants: ~[variant] = ~[];
        // Newtype syntax
        if self.token == token::EQ {
            self.check_restricted_keywords_(*id);
            self.bump();
            let ty = self.parse_ty(false);
            self.expect(token::SEMI);
            let variant =
                spanned(ty.span.lo, ty.span.hi,
                        {name: id,
                         attrs: ~[],
                         args: ~[{ty: ty, id: self.get_id()}],
                         id: self.get_id(),
                         disr_expr: none,
                         vis: public});
            ret (id, item_enum(~[variant], ty_params), none);
        }
        self.expect(token::LBRACE);

        let mut all_nullary = true, have_disr = false;

        while self.token != token::RBRACE {
            let variant_attrs = self.parse_outer_attributes();
            let vlo = self.span.lo;
            let vis = self.parse_visibility(default_vis);
            let ident = self.parse_value_ident();
            let mut args = ~[], disr_expr = none;
            if self.token == token::LPAREN {
                all_nullary = false;
                let arg_tys = self.parse_unspanned_seq(
                    token::LPAREN, token::RPAREN,
                    seq_sep_trailing_disallowed(token::COMMA),
                    |p| p.parse_ty(false));
                for arg_tys.each |ty| {
                    vec::push(args, {ty: ty, id: self.get_id()});
                }
            } else if self.eat(token::EQ) {
                have_disr = true;
                disr_expr = some(self.parse_expr());
            }

            let vr = {name: ident, attrs: variant_attrs,
                      args: args, id: self.get_id(),
                      disr_expr: disr_expr, vis: vis};
            vec::push(variants, spanned(vlo, self.last_span.hi, vr));

            if !self.eat(token::COMMA) { break; }
        }
        self.expect(token::RBRACE);
        if (have_disr && !all_nullary) {
            self.fatal(~"discriminator values can only be used with a c-like \
                        enum");
        }
        (id, item_enum(variants, ty_params), none)
    }

    fn parse_fn_ty_proto() -> proto {
        alt self.token {
          token::AT {
            self.bump();
            proto_box
          }
          token::TILDE {
            self.bump();
            proto_uniq
          }
          token::BINOP(token::AND) {
            self.bump();
            proto_block
          }
          _ {
            proto_any
          }
        }
    }

    fn fn_expr_lookahead(tok: token::token) -> bool {
        alt tok {
          token::LPAREN | token::AT | token::TILDE | token::BINOP(_) {
            true
          }
          _ {
            false
          }
        }
    }

    fn parse_item(+attrs: ~[attribute], vis: visibility)
        -> option<@item> {
        let lo = self.span.lo;
        let (ident, item_, extra_attrs) = if self.eat_keyword(~"const") {
            self.parse_item_const()
        } else if self.is_keyword(~"fn") &&
            !self.fn_expr_lookahead(self.look_ahead(1u)) {
            self.bump();
            self.parse_item_fn(impure_fn)
        } else if self.eat_keyword(~"pure") {
            self.expect_keyword(~"fn");
            self.parse_item_fn(pure_fn)
        } else if self.is_keyword(~"unsafe")
            && self.look_ahead(1u) != token::LBRACE {
            self.bump();
            self.expect_keyword(~"fn");
            self.parse_item_fn(unsafe_fn)
        } else if self.eat_keyword(~"extern") {
            if self.eat_keyword(~"fn") {
                self.parse_item_fn(extern_fn)
            } else {
                self.parse_item_foreign_mod()
            }
        } else if self.eat_keyword(~"mod") {
            self.parse_item_mod()
        } else if self.eat_keyword(~"type") {
            self.parse_item_type()
        } else if self.eat_keyword(~"enum") {
            self.parse_item_enum(vis)
        } else if self.eat_keyword(~"iface") {
            self.parse_item_trait()
        } else if self.eat_keyword(~"trait") {
            self.parse_item_trait()
        } else if self.eat_keyword(~"impl") {
            self.parse_item_impl()
        } else if self.eat_keyword(~"class") || self.eat_keyword(~"struct") {
            self.parse_item_class()
        } else if !self.is_any_keyword(copy self.token)
            && self.look_ahead(1) == token::NOT
            && is_plain_ident(self.look_ahead(2))
        {
            // item macro.
            let pth = self.parse_path_without_tps();
            self.expect(token::NOT);
            let id = self.parse_ident();
            let tts = self.parse_unspanned_seq(token::LBRACE, token::RBRACE,
                                               seq_sep_none(),
                                               |p| p.parse_token_tree());
            let m = ast::mac_invoc_tt(pth, tts);
            let m: ast::mac = {node: m,
                               span: {lo: self.span.lo,
                                      hi: self.span.hi,
                                      expn_info: none}};
            (id, item_mac(m), none)
        } else { ret none; };
        some(self.mk_item(lo, self.last_span.hi, ident, item_, vis,
                          alt extra_attrs {
                              some(as) { vec::append(attrs, as) }
                              none { attrs }
                          }))
    }

    fn parse_use() -> view_item_ {
        let ident = self.parse_ident();
        let metadata = self.parse_optional_meta();
        ret view_item_use(ident, metadata, self.get_id());
    }

    fn parse_view_path() -> @view_path {
        let lo = self.span.lo;
        let first_ident = self.parse_ident();
        let mut path = ~[first_ident];
        #debug("parsed view_path: %s", *first_ident);
        alt self.token {
          token::EQ {
            // x = foo::bar
            self.bump();
            path = ~[self.parse_ident()];
            while self.token == token::MOD_SEP {
                self.bump();
                let id = self.parse_ident();
                vec::push(path, id);
            }
            let path = @{span: mk_sp(lo, self.span.hi), global: false,
                         idents: path, rp: none, types: ~[]};
            ret @spanned(lo, self.span.hi,
                         view_path_simple(first_ident, path, self.get_id()));
          }

          token::MOD_SEP {
            // foo::bar or foo::{a,b,c} or foo::*
            while self.token == token::MOD_SEP {
                self.bump();

                alt copy self.token {

                  token::IDENT(i, _) {
                    self.bump();
                    vec::push(path, self.get_str(i));
                  }

                  // foo::bar::{a,b,c}
                  token::LBRACE {
                    let idents = self.parse_unspanned_seq(
                        token::LBRACE, token::RBRACE,
                        seq_sep_trailing_allowed(token::COMMA),
                        |p| p.parse_path_list_ident());
                    let path = @{span: mk_sp(lo, self.span.hi),
                                 global: false, idents: path,
                                 rp: none, types: ~[]};
                    ret @spanned(lo, self.span.hi,
                                 view_path_list(path, idents, self.get_id()));
                  }

                  // foo::bar::*
                  token::BINOP(token::STAR) {
                    self.bump();
                    let path = @{span: mk_sp(lo, self.span.hi),
                                 global: false, idents: path,
                                 rp: none, types: ~[]};
                    ret @spanned(lo, self.span.hi,
                                 view_path_glob(path, self.get_id()));
                  }

                  _ { break; }
                }
            }
          }
          _ { }
        }
        let last = path[vec::len(path) - 1u];
        let path = @{span: mk_sp(lo, self.span.hi), global: false,
                     idents: path, rp: none, types: ~[]};
        ret @spanned(lo, self.span.hi,
                     view_path_simple(last, path, self.get_id()));
    }

    fn parse_view_paths() -> ~[@view_path] {
        let mut vp = ~[self.parse_view_path()];
        while self.token == token::COMMA {
            self.bump();
            vec::push(vp, self.parse_view_path());
        }
        ret vp;
    }

    fn is_view_item() -> bool {
        let tok = if !self.is_keyword(~"pub") && !self.is_keyword(~"priv") {
            self.token
        } else { self.look_ahead(1u) };
        self.token_is_keyword(~"use", tok)
            || self.token_is_keyword(~"import", tok)
            || self.token_is_keyword(~"export", tok)
    }

    fn parse_view_item(+attrs: ~[attribute]) -> @view_item {
        let lo = self.span.lo, vis = self.parse_visibility(private);
        let node = if self.eat_keyword(~"use") {
            self.parse_use()
        } else if self.eat_keyword(~"import") {
            view_item_import(self.parse_view_paths())
        } else if self.eat_keyword(~"export") {
            view_item_export(self.parse_view_paths())
        } else { fail; };
        self.expect(token::SEMI);
        @{node: node, attrs: attrs,
          vis: vis, span: mk_sp(lo, self.last_span.hi)}
    }

    fn parse_view(+first_item_attrs: ~[attribute],
                  only_imports: bool) -> {attrs_remaining: ~[attribute],
                                          view_items: ~[@view_item]} {
        let mut attrs = vec::append(first_item_attrs,
                                    self.parse_outer_attributes());
        let mut items = ~[];
        while if only_imports { self.is_keyword(~"import") }
        else { self.is_view_item() } {
            vec::push(items, self.parse_view_item(attrs));
            attrs = self.parse_outer_attributes();
        }
        {attrs_remaining: attrs, view_items: items}
    }

    // Parses a source module as a crate
    fn parse_crate_mod(_cfg: crate_cfg) -> @crate {
        let lo = self.span.lo;
        let crate_attrs = self.parse_inner_attrs_and_next();
        let first_item_outer_attrs = crate_attrs.next;
        let m = self.parse_mod_items(token::EOF, first_item_outer_attrs);
        ret @spanned(lo, self.span.lo,
                     {directives: ~[],
                      module: m,
                      attrs: crate_attrs.inner,
                      config: self.cfg});
    }

    fn parse_str() -> @~str {
        alt copy self.token {
          token::LIT_STR(s) { self.bump(); self.get_str(s) }
          _ {
            self.fatal(~"expected string literal")
          }
        }
    }

    // Logic for parsing crate files (.rc)
    //
    // Each crate file is a sequence of directives.
    //
    // Each directive imperatively extends its environment with 0 or more
    // items.
    fn parse_crate_directive(first_outer_attr: ~[attribute]) ->
        crate_directive {

        // Collect the next attributes
        let outer_attrs = vec::append(first_outer_attr,
                                      self.parse_outer_attributes());
        // In a crate file outer attributes are only going to apply to mods
        let expect_mod = vec::len(outer_attrs) > 0u;

        let lo = self.span.lo;
        if expect_mod || self.is_keyword(~"mod") {
            self.expect_keyword(~"mod");
            let id = self.parse_ident();
            alt self.token {
              // mod x = "foo.rs";
              token::SEMI {
                let mut hi = self.span.hi;
                self.bump();
                ret spanned(lo, hi, cdir_src_mod(id, outer_attrs));
              }
              // mod x = "foo_dir" { ...directives... }
              token::LBRACE {
                self.bump();
                let inner_attrs = self.parse_inner_attrs_and_next();
                let mod_attrs = vec::append(outer_attrs, inner_attrs.inner);
                let next_outer_attr = inner_attrs.next;
                let cdirs = self.parse_crate_directives(token::RBRACE,
                                                        next_outer_attr);
                let mut hi = self.span.hi;
                self.expect(token::RBRACE);
                ret spanned(lo, hi,
                            cdir_dir_mod(id, cdirs, mod_attrs));
              }
              _ { self.unexpected(); }
            }
        } else if self.is_view_item() {
            let vi = self.parse_view_item(outer_attrs);
            ret spanned(lo, vi.span.hi, cdir_view_item(vi));
        } else { ret self.fatal(~"expected crate directive"); }
    }

    fn parse_crate_directives(term: token::token,
                              first_outer_attr: ~[attribute]) ->
        ~[@crate_directive] {

        // This is pretty ugly. If we have an outer attribute then we can't
        // accept seeing the terminator next, so if we do see it then fail the
        // same way parse_crate_directive would
        if vec::len(first_outer_attr) > 0u && self.token == term {
            self.expect_keyword(~"mod");
        }

        let mut cdirs: ~[@crate_directive] = ~[];
        let mut first_outer_attr = first_outer_attr;
        while self.token != term {
            let cdir = @self.parse_crate_directive(first_outer_attr);
            vec::push(cdirs, cdir);
            first_outer_attr = ~[];
        }
        ret cdirs;
    }
}
//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// End:
//