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syntax: Extract prec mod from parser mod

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This commit is contained in:
Brian Anderson 2012-04-17 20:41:04 -07:00
parent aa4278a3f5
commit 476d5a099d
4 changed files with 52 additions and 40 deletions
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40
src/librustsyntax/parse/parser.rs
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@ -7,8 +7,8 @@ import util::interner;
import ast::{node_id, spanned};
import ast_util::{mk_sp, ident_to_path};
import lexer::reader;
import prec::{op_spec, binop_prec_table, as_prec};
export as_prec;
export expr_requires_semi_to_be_stmt;
export file_type;
export mk_item;
@ -31,9 +31,7 @@ export parse_pat;
export parse_sess;
export parse_stmt;
export parse_ty;
export prec_table;
export stmt_ends_with_semi;
export unop_prec;
enum restriction {
UNRESTRICTED,
@ -71,7 +69,7 @@ type parser = @{
mut buffer: [{tok: token::token, span: span}],
mut restriction: restriction,
reader: reader,
precs: @[op_spec],
binop_precs: @[op_spec],
bad_expr_words: hashmap<str, ()>
};
@ -161,7 +159,7 @@ fn new_parser(sess: parse_sess, cfg: ast::crate_cfg, rdr: reader,
mut buffer: [],
mut restriction: UNRESTRICTED,
reader: rdr,
precs: prec_table(),
binop_precs: binop_prec_table(),
bad_expr_words: bad_expr_word_table()}
}
@ -1301,41 +1299,11 @@ fn parse_prefix_expr(p: parser) -> pexpr {
ret mk_pexpr(p, lo, hi, ex);
}
type op_spec = {tok: token::token, op: ast::binop, prec: int};
// FIXME make this a const, don't store it in parser state
fn prec_table() -> @[op_spec] {
ret @[{tok: token::BINOP(token::STAR), op: ast::mul, prec: 12},
{tok: token::BINOP(token::SLASH), op: ast::div, prec: 12},
{tok: token::BINOP(token::PERCENT), op: ast::rem, prec: 12},
// 'as' sits between here with 11
{tok: token::BINOP(token::PLUS), op: ast::add, prec: 10},
{tok: token::BINOP(token::MINUS), op: ast::subtract, prec: 10},
{tok: token::BINOP(token::LSL), op: ast::lsl, prec: 9},
{tok: token::BINOP(token::LSR), op: ast::lsr, prec: 9},
{tok: token::BINOP(token::ASR), op: ast::asr, prec: 9},
{tok: token::BINOP(token::AND), op: ast::bitand, prec: 8},
{tok: token::BINOP(token::CARET), op: ast::bitxor, prec: 7},
{tok: token::BINOP(token::OR), op: ast::bitor, prec: 6},
{tok: token::LT, op: ast::lt, prec: 4},
{tok: token::LE, op: ast::le, prec: 4},
{tok: token::GE, op: ast::ge, prec: 4},
{tok: token::GT, op: ast::gt, prec: 4},
{tok: token::EQEQ, op: ast::eq, prec: 3},
{tok: token::NE, op: ast::ne, prec: 3},
{tok: token::ANDAND, op: ast::and, prec: 2},
{tok: token::OROR, op: ast::or, prec: 1}];
}
fn parse_binops(p: parser) -> @ast::expr {
ret parse_more_binops(p, parse_prefix_expr(p), 0);
}
const unop_prec: int = 100;
const as_prec: int = 11;
fn parse_more_binops(p: parser, plhs: pexpr, min_prec: int) ->
@ast::expr {
let lhs = to_expr(plhs);
@ -1343,7 +1311,7 @@ fn parse_more_binops(p: parser, plhs: pexpr, min_prec: int) ->
let peeked = p.token;
if peeked == token::BINOP(token::OR) &&
p.restriction == RESTRICT_NO_BAR_OP { ret lhs; }
for vec::each(*p.precs) {|cur|
for vec::each(*p.binop_precs) {|cur|
if cur.prec > min_prec && cur.tok == peeked {
p.bump();
let expr = parse_prefix_expr(p);

40
src/librustsyntax/parse/prec.rs Normal file
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@ -0,0 +1,40 @@
export as_prec;
export unop_prec;
export binop_prec_table;
export op_spec;
#[doc = "Unary operators have higher precedence than binary"]
const unop_prec: int = 100;
#[doc = "
Precedence of the `as` operator, which is a binary operator
but is not represented in the precedence table.
"]
const as_prec: int = 11;
type op_spec = {tok: token::token, op: ast::binop, prec: int};
// FIXME make this a const, don't store it in parser state
#[doc = "The precedence of binary operators"]
fn binop_prec_table() -> @[op_spec] {
ret @[{tok: token::BINOP(token::STAR), op: ast::mul, prec: 12},
{tok: token::BINOP(token::SLASH), op: ast::div, prec: 12},
{tok: token::BINOP(token::PERCENT), op: ast::rem, prec: 12},
// 'as' sits between here with 11
{tok: token::BINOP(token::PLUS), op: ast::add, prec: 10},
{tok: token::BINOP(token::MINUS), op: ast::subtract, prec: 10},
{tok: token::BINOP(token::LSL), op: ast::lsl, prec: 9},
{tok: token::BINOP(token::LSR), op: ast::lsr, prec: 9},
{tok: token::BINOP(token::ASR), op: ast::asr, prec: 9},
{tok: token::BINOP(token::AND), op: ast::bitand, prec: 8},
{tok: token::BINOP(token::CARET), op: ast::bitxor, prec: 7},
{tok: token::BINOP(token::OR), op: ast::bitor, prec: 6},
{tok: token::LT, op: ast::lt, prec: 4},
{tok: token::LE, op: ast::le, prec: 4},
{tok: token::GE, op: ast::ge, prec: 4},
{tok: token::GT, op: ast::gt, prec: 4},
{tok: token::EQEQ, op: ast::eq, prec: 3},
{tok: token::NE, op: ast::ne, prec: 3},
{tok: token::ANDAND, op: ast::and, prec: 2},
{tok: token::OROR, op: ast::or, prec: 1}];
}

8
src/librustsyntax/print/pprust.rs
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@ -934,7 +934,7 @@ fn print_expr(s: ps, &&expr: @ast::expr) {
}
ast::expr_unary(op, expr) {
word(s.s, ast_util::unop_to_str(op));
print_op_maybe_parens(s, expr, parse::parser::unop_prec);
print_op_maybe_parens(s, expr, parse::prec::unop_prec);
}
ast::expr_addr_of(m, expr) {
word(s.s, "&");
@ -943,7 +943,7 @@ fn print_expr(s: ps, &&expr: @ast::expr) {
}
ast::expr_lit(lit) { print_literal(s, lit); }
ast::expr_cast(expr, ty) {
print_op_maybe_parens(s, expr, parse::parser::as_prec);
print_op_maybe_parens(s, expr, parse::prec::as_prec);
space(s.s);
word_space(s, "as");
print_type(s, ty);
@ -1488,7 +1488,7 @@ fn print_view_item(s: ps, item: @ast::view_item) {
// FIXME: The fact that this builds up the table anew for every call is
// not good. Eventually, table should be a const.
fn operator_prec(op: ast::binop) -> int {
for vec::each(*parse::parser::prec_table()) {|spec|
for vec::each(*parse::prec::binop_prec_table()) {|spec|
if spec.op == op { ret spec.prec; }
}
core::unreachable();
@ -1497,7 +1497,7 @@ fn operator_prec(op: ast::binop) -> int {
fn need_parens(expr: @ast::expr, outer_prec: int) -> bool {
alt expr.node {
ast::expr_binary(op, _, _) { operator_prec(op) < outer_prec }
ast::expr_cast(_, _) { parse::parser::as_prec < outer_prec }
ast::expr_cast(_, _) { parse::prec::as_prec < outer_prec }
// This may be too conservative in some cases
ast::expr_assign(_, _) { true }
ast::expr_move(_, _) { true }

4
src/librustsyntax/rustsyntax.rc
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@ -26,12 +26,16 @@ mod parse {
export parser;
export lexer;
export comments;
export prec;
mod eval;
mod lexer;
mod parser;
mod token;
mod comments;
#[doc = "Functions dealing with operator precedence"]
mod prec;
}
mod print {