rust/src/libsyntax/parse/eval.rs

import parser::{parser, SOURCE_FILE};
import attr::parser_attr;

export eval_crate_directives_to_mod;

type ctx =
    @{sess: parse::parse_sess,
      cfg: ast::crate_cfg};

fn eval_crate_directives(cx: ctx,
                         cdirs: ~[@ast::crate_directive],
                         prefix: str,
                         &view_items: ~[@ast::view_item],
                         &items: ~[@ast::item]) {
    for cdirs.each |sub_cdir| {
        eval_crate_directive(cx, sub_cdir, prefix, view_items, items);
    }
}

fn eval_crate_directives_to_mod(cx: ctx, cdirs: ~[@ast::crate_directive],
                                prefix: str, suffix: option<str>)
    -> (ast::_mod, ~[ast::attribute]) {
    #debug("eval crate prefix: %s", prefix);
    #debug("eval crate suffix: %s",
           option::get_default(suffix, "none"));
    let (cview_items, citems, cattrs)
        = parse_companion_mod(cx, prefix, suffix);
    let mut view_items: ~[@ast::view_item] = ~[];
    let mut items: ~[@ast::item] = ~[];
    eval_crate_directives(cx, cdirs, prefix, view_items, items);
    ret ({view_items: vec::append(view_items, cview_items),
          items: vec::append(items, citems)},
         cattrs);
}

/*
The 'companion mod'. So .rc crates and directory mod crate directives define
modules but not a .rs file to fill those mods with stuff. The companion mod is
a convention for location a .rs file to go with them.  For .rc files the
companion mod is a .rs file with the same name; for directory mods the
companion mod is a .rs file with the same name as the directory.

We build the path to the companion mod by combining the prefix and the
optional suffix then adding the .rs extension.
*/
fn parse_companion_mod(cx: ctx, prefix: str, suffix: option<str>)
    -> (~[@ast::view_item], ~[@ast::item], ~[ast::attribute]) {

    fn companion_file(+prefix: str, suffix: option<str>) -> str {
        ret alt suffix {
          option::some(s) { path::connect(prefix, s) }
          option::none { prefix }
        } + ".rs";
    }

    fn file_exists(path: str) -> bool {
        // Crude, but there's no lib function for this and I'm not
        // up to writing it just now
        alt io::file_reader(path) {
          result::ok(_) { true }
          result::err(_) { false }
        }
    }

    let modpath = companion_file(prefix, suffix);
    #debug("looking for companion mod %s", modpath);
    if file_exists(modpath) {
        #debug("found companion mod");
        let (p0, r0) = new_parser_etc_from_file(cx.sess, cx.cfg,
                                                modpath, SOURCE_FILE);
        let inner_attrs = p0.parse_inner_attrs_and_next();
        let m0 = p0.parse_mod_items(token::EOF, inner_attrs.next);
        cx.sess.chpos = r0.chpos;
        cx.sess.byte_pos = cx.sess.byte_pos + r0.pos;
        ret (m0.view_items, m0.items, inner_attrs.inner);
    } else {
        ret (~[], ~[], ~[]);
    }
}

fn cdir_path_opt(id: ast::ident, attrs: ~[ast::attribute]) -> @str {
    alt ::attr::first_attr_value_str_by_name(attrs, "path") {
      some(d) {
        ret d;
      }
      none { ret id; }
    }
}

fn eval_crate_directive(cx: ctx, cdir: @ast::crate_directive, prefix: str,
                        &view_items: ~[@ast::view_item],
                        &items: ~[@ast::item]) {
    alt cdir.node {
      ast::cdir_src_mod(id, attrs) {
        let file_path = cdir_path_opt(@(*id + ".rs"), attrs);
        let full_path =
            if path::path_is_absolute(*file_path) {
                *file_path
            } else { prefix + path::path_sep() + *file_path };
        let (p0, r0) =
            new_parser_etc_from_file(cx.sess, cx.cfg, full_path, SOURCE_FILE);
        let inner_attrs = p0.parse_inner_attrs_and_next();
        let mod_attrs = vec::append(attrs, inner_attrs.inner);
        let first_item_outer_attrs = inner_attrs.next;
        let m0 = p0.parse_mod_items(token::EOF, first_item_outer_attrs);

        let i = p0.mk_item(cdir.span.lo, cdir.span.hi,
                           /* FIXME (#2543) */ copy id,
                           ast::item_mod(m0), ast::public, mod_attrs);
        // Thread defids, chpos and byte_pos through the parsers
        cx.sess.chpos = r0.chpos;
        cx.sess.byte_pos = cx.sess.byte_pos + r0.pos;
        vec::push(items, i);
      }
      ast::cdir_dir_mod(id, cdirs, attrs) {
        let path = cdir_path_opt(id, attrs);
        let full_path =
            if path::path_is_absolute(*path) {
                *path
            } else { prefix + path::path_sep() + *path };
        let (m0, a0) = eval_crate_directives_to_mod(
            cx, cdirs, full_path, none);
        let i =
            @{ident: /* FIXME (#2543) */ copy id,
              attrs: vec::append(attrs, a0),
              id: cx.sess.next_id,
              node: ast::item_mod(m0),
              vis: ast::public,
              span: cdir.span};
        cx.sess.next_id += 1;
        vec::push(items, i);
      }
      ast::cdir_view_item(vi) { vec::push(view_items, vi); }
      ast::cdir_syntax(pth) { }
    }
}
//
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// mode: rust
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// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// End:
//