rust/src/libsyntax/ext/source_util.rs

// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use ast;
use codemap::{Pos, Span};
use codemap;
use ext::base::*;
use ext::base;
use ext::build::AstBuilder;
use parse::token;
use parse;
use print::pprust;
use ptr::P;
use util::small_vector::SmallVector;

use std::old_io::File;
use std::rc::Rc;

// These macros all relate to the file system; they either return
// the column/row/filename of the expression, or they include
// a given file into the current one.

/// line!(): expands to the current line number
pub fn expand_line(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
                   -> Box<base::MacResult+'static> {
    base::check_zero_tts(cx, sp, tts, "line!");

    let topmost = cx.original_span_in_file();
    let loc = cx.codemap().lookup_char_pos(topmost.lo);

    base::MacExpr::new(cx.expr_u32(topmost, loc.line as u32))
}

/* column!(): expands to the current column number */
pub fn expand_column(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
                  -> Box<base::MacResult+'static> {
    base::check_zero_tts(cx, sp, tts, "column!");

    let topmost = cx.original_span_in_file();
    let loc = cx.codemap().lookup_char_pos(topmost.lo);

    base::MacExpr::new(cx.expr_u32(topmost, loc.col.to_usize() as u32))
}

/// file!(): expands to the current filename */
/// The filemap (`loc.file`) contains a bunch more information we could spit
/// out if we wanted.
pub fn expand_file(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
                   -> Box<base::MacResult+'static> {
    base::check_zero_tts(cx, sp, tts, "file!");

    let topmost = cx.original_span_in_file();
    let loc = cx.codemap().lookup_char_pos(topmost.lo);
    let filename = token::intern_and_get_ident(&loc.file.name);
    base::MacExpr::new(cx.expr_str(topmost, filename))
}

pub fn expand_stringify(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
                        -> Box<base::MacResult+'static> {
    let s = pprust::tts_to_string(tts);
    base::MacExpr::new(cx.expr_str(sp,
                                   token::intern_and_get_ident(&s[..])))
}

pub fn expand_mod(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
                  -> Box<base::MacResult+'static> {
    base::check_zero_tts(cx, sp, tts, "module_path!");
    let string = cx.mod_path()
                   .iter()
                   .map(|x| token::get_ident(*x).to_string())
                   .collect::<Vec<String>>()
                   .connect("::");
    base::MacExpr::new(cx.expr_str(
            sp,
            token::intern_and_get_ident(&string[..])))
}

/// include! : parse the given file as an expr
/// This is generally a bad idea because it's going to behave
/// unhygienically.
pub fn expand_include<'cx>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
                           -> Box<base::MacResult+'cx> {
    let file = match get_single_str_from_tts(cx, sp, tts, "include!") {
        Some(f) => f,
        None => return DummyResult::expr(sp),
    };
    // The file will be added to the code map by the parser
    let p =
        parse::new_sub_parser_from_file(cx.parse_sess(),
                                        cx.cfg(),
                                        &res_rel_file(cx,
                                                      sp,
                                                      &Path::new(file)),
                                        true,
                                        None,
                                        sp);

    struct ExpandResult<'a> {
        p: parse::parser::Parser<'a>,
    }
    impl<'a> base::MacResult for ExpandResult<'a> {
        fn make_expr(mut self: Box<ExpandResult<'a>>) -> Option<P<ast::Expr>> {
            Some(self.p.parse_expr())
        }
        fn make_items(mut self: Box<ExpandResult<'a>>)
                      -> Option<SmallVector<P<ast::Item>>> {
            let mut ret = SmallVector::zero();
            while self.p.token != token::Eof {
                match self.p.parse_item_with_outer_attributes() {
                    Some(item) => ret.push(item),
                    None => self.p.span_fatal(
                        self.p.span,
                        &format!("expected item, found `{}`",
                                 self.p.this_token_to_string())
                    )
                }
            }
            Some(ret)
        }
    }

    box ExpandResult { p: p }
}

// include_str! : read the given file, insert it as a literal string expr
pub fn expand_include_str(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
                          -> Box<base::MacResult+'static> {
    let file = match get_single_str_from_tts(cx, sp, tts, "include_str!") {
        Some(f) => f,
        None => return DummyResult::expr(sp)
    };
    let file = res_rel_file(cx, sp, &Path::new(file));
    let bytes = match File::open(&file).read_to_end() {
        Err(e) => {
            cx.span_err(sp,
                        &format!("couldn't read {}: {}",
                                file.display(),
                                e));
            return DummyResult::expr(sp);
        }
        Ok(bytes) => bytes,
    };
    match String::from_utf8(bytes) {
        Ok(src) => {
            // Add this input file to the code map to make it available as
            // dependency information
            let filename = format!("{}", file.display());
            let interned = token::intern_and_get_ident(&src[..]);
            cx.codemap().new_filemap(filename, src);

            base::MacExpr::new(cx.expr_str(sp, interned))
        }
        Err(_) => {
            cx.span_err(sp,
                        &format!("{} wasn't a utf-8 file",
                                file.display()));
            return DummyResult::expr(sp);
        }
    }
}

pub fn expand_include_bytes(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
                            -> Box<base::MacResult+'static> {
    let file = match get_single_str_from_tts(cx, sp, tts, "include_bytes!") {
        Some(f) => f,
        None => return DummyResult::expr(sp)
    };
    let file = res_rel_file(cx, sp, &Path::new(file));
    match File::open(&file).read_to_end() {
        Err(e) => {
            cx.span_err(sp,
                        &format!("couldn't read {}: {}", file.display(), e));
            return DummyResult::expr(sp);
        }
        Ok(bytes) => {
            let bytes = bytes.iter().cloned().collect();
            base::MacExpr::new(cx.expr_lit(sp, ast::LitBinary(Rc::new(bytes))))
        }
    }
}

// resolve a file-system path to an absolute file-system path (if it
// isn't already)
fn res_rel_file(cx: &mut ExtCtxt, sp: codemap::Span, arg: &Path) -> Path {
    // NB: relative paths are resolved relative to the compilation unit
    if !arg.is_absolute() {
        let mut cu = Path::new(cx.codemap().span_to_filename(sp));
        cu.pop();
        cu.push(arg);
        cu
    } else {
        arg.clone()
    }
}