src/librustc/front/std_inject.rs

   1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use driver::config;
  12 use driver::session::Session;
  13
  14 use syntax::ast;
  15 use syntax::attr;
  16 use syntax::codemap::DUMMY_SP;
  17 use syntax::codemap;
  18 use syntax::fold::Folder;
  19 use syntax::fold;
  20 use syntax::owned_slice::OwnedSlice;
  21 use syntax::parse::token::InternedString;
  22 use syntax::parse::token::special_idents;
  23 use syntax::parse::token;
  24 use syntax::ptr::P;
  25 use syntax::util::small_vector::SmallVector;
  26
  27 use std::mem;
  28
  29 pub fn maybe_inject_crates_ref(sess: &Session, krate: ast::Crate)
  30                                -> ast::Crate {
  31     if use_std(&krate) {
  32         inject_crates_ref(sess, krate)
  33     } else {
  34         krate
  35     }
  36 }
  37
  38 pub fn maybe_inject_prelude(sess: &Session, krate: ast::Crate) -> ast::Crate {
  39     if use_std(&krate) {
  40         inject_prelude(sess, krate)
  41     } else {
  42         krate
  43     }
  44 }
  45
  46 fn use_std(krate: &ast::Crate) -> bool {
  47     !attr::contains_name(krate.attrs.as_slice(), "no_std")
  48 }
  49
  50 fn use_start(krate: &ast::Crate) -> bool {
  51     !attr::contains_name(krate.attrs.as_slice(), "no_start")
  52 }
  53
  54 fn no_prelude(attrs: &[ast::Attribute]) -> bool {
  55     attr::contains_name(attrs, "no_implicit_prelude")
  56 }
  57
  58 struct StandardLibraryInjector<'a> {
  59     sess: &'a Session,
  60 }
  61
  62 impl<'a> fold::Folder for StandardLibraryInjector<'a> {
  63     fn fold_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
  64
  65         // The name to use in `extern crate "name" as std;`
  66         let actual_crate_name = match self.sess.opts.alt_std_name {
  67             Some(ref s) => token::intern_and_get_ident(s.as_slice()),
  68             None => token::intern_and_get_ident("std"),
  69         };
  70
  71         let mut vis = vec!(ast::ViewItem {
  72             node: ast::ViewItemExternCrate(token::str_to_ident("std"),
  73                                            Some((actual_crate_name, ast::CookedStr)),
  74                                            ast::DUMMY_NODE_ID),
  75             attrs: vec!(
  76                 attr::mk_attr_outer(attr::mk_attr_id(), attr::mk_list_item(
  77                         InternedString::new("phase"),
  78                         vec!(
  79                             attr::mk_word_item(InternedString::new("plugin")),
  80                             attr::mk_word_item(InternedString::new("link")
  81                         ))))),
  82             vis: ast::Inherited,
  83             span: DUMMY_SP
  84         });
  85
  86         let any_exe = self.sess.crate_types.borrow().iter().any(|ty| {
  87             *ty == config::CrateTypeExecutable
  88         });
  89         if use_start(&krate) && any_exe {
  90             let visible_rt_name = "rt";
  91             let actual_rt_name = "native";
  92             // Gensym the ident so it can't be named
  93             let visible_rt_name = token::gensym_ident(visible_rt_name);
  94             let actual_rt_name = token::intern_and_get_ident(actual_rt_name);
  95
  96             vis.push(ast::ViewItem {
  97                 node: ast::ViewItemExternCrate(visible_rt_name,
  98                                                Some((actual_rt_name, ast::CookedStr)),
  99                                                ast::DUMMY_NODE_ID),
 100                 attrs: Vec::new(),
 101                 vis: ast::Inherited,
 102                 span: DUMMY_SP
 103             });
 104         }
 105
 106         // `extern crate` must be precede `use` items
 107         mem::swap(&mut vis, &mut krate.module.view_items);
 108         krate.module.view_items.push_all_move(vis);
 109
 110         // don't add #![no_std] here, that will block the prelude injection later.
 111         // Add it during the prelude injection instead.
 112
 113         // Add #![feature(phase)] here, because we use #[phase] on extern crate std.
 114         let feat_phase_attr = attr::mk_attr_inner(attr::mk_attr_id(),
 115                                                   attr::mk_list_item(
 116                                   InternedString::new("feature"),
 117                                   vec![attr::mk_word_item(InternedString::new("phase"))],
 118                               ));
 119         // std_inject runs after feature checking so manually mark this attr
 120         attr::mark_used(&feat_phase_attr);
 121         krate.attrs.push(feat_phase_attr);
 122
 123         krate
 124     }
 125 }
 126
 127 fn inject_crates_ref(sess: &Session, krate: ast::Crate) -> ast::Crate {
 128     let mut fold = StandardLibraryInjector {
 129         sess: sess,
 130     };
 131     fold.fold_crate(krate)
 132 }
 133
 134 struct PreludeInjector<'a>;
 135
 136
 137 impl<'a> fold::Folder for PreludeInjector<'a> {
 138     fn fold_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
 139         // Add #![no_std] here, so we don't re-inject when compiling pretty-printed source.
 140         // This must happen here and not in StandardLibraryInjector because this
 141         // fold happens second.
 142
 143         let no_std_attr = attr::mk_attr_inner(attr::mk_attr_id(),
 144                                               attr::mk_word_item(InternedString::new("no_std")));
 145         // std_inject runs after feature checking so manually mark this attr
 146         attr::mark_used(&no_std_attr);
 147         krate.attrs.push(no_std_attr);
 148
 149         if !no_prelude(krate.attrs.as_slice()) {
 150             // only add `use std::prelude::*;` if there wasn't a
 151             // `#![no_implicit_prelude]` at the crate level.
 152             // fold_mod() will insert glob path.
 153             let globs_attr = attr::mk_attr_inner(attr::mk_attr_id(),
 154                                                  attr::mk_list_item(
 155                 InternedString::new("feature"),
 156                 vec!(
 157                     attr::mk_word_item(InternedString::new("globs")),
 158                 )));
 159             // std_inject runs after feature checking so manually mark this attr
 160             attr::mark_used(&globs_attr);
 161             krate.attrs.push(globs_attr);
 162
 163             krate.module = self.fold_mod(krate.module);
 164         }
 165         krate
 166     }
 167
 168     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
 169         if !no_prelude(item.attrs.as_slice()) {
 170             // only recur if there wasn't `#![no_implicit_prelude]`
 171             // on this item, i.e. this means that the prelude is not
 172             // implicitly imported though the whole subtree
 173             fold::noop_fold_item(item, self)
 174         } else {
 175             SmallVector::one(item)
 176         }
 177     }
 178
 179     fn fold_mod(&mut self, ast::Mod {inner, view_items, items}: ast::Mod) -> ast::Mod {
 180         let prelude_path = ast::Path {
 181             span: DUMMY_SP,
 182             global: false,
 183             segments: vec!(
 184                 ast::PathSegment {
 185                     identifier: token::str_to_ident("std"),
 186                     lifetimes: Vec::new(),
 187                     types: OwnedSlice::empty(),
 188                 },
 189                 ast::PathSegment {
 190                     identifier: token::str_to_ident("prelude"),
 191                     lifetimes: Vec::new(),
 192                     types: OwnedSlice::empty(),
 193                 }),
 194         };
 195
 196         let (crates, uses) = view_items.partitioned(|x| {
 197             match x.node {
 198                 ast::ViewItemExternCrate(..) => true,
 199                 _ => false,
 200             }
 201         });
 202
 203         // add prelude after any `extern crate` but before any `use`
 204         let mut view_items = crates;
 205         let vp = P(codemap::dummy_spanned(ast::ViewPathGlob(prelude_path, ast::DUMMY_NODE_ID)));
 206         view_items.push(ast::ViewItem {
 207             node: ast::ViewItemUse(vp),
 208             attrs: vec![ast::Attribute {
 209                 span: DUMMY_SP,
 210                 node: ast::Attribute_ {
 211                     id: attr::mk_attr_id(),
 212                     style: ast::AttrOuter,
 213                     value: P(ast::MetaItem {
 214                         span: DUMMY_SP,
 215                         node: ast::MetaWord(token::get_name(
 216                                 special_idents::prelude_import.name)),
 217                     }),
 218                     is_sugared_doc: false,
 219                 },
 220             }],
 221             vis: ast::Inherited,
 222             span: DUMMY_SP,
 223         });
 224         view_items.push_all_move(uses);
 225
 226         fold::noop_fold_mod(ast::Mod {
 227             inner: inner,
 228             view_items: view_items,
 229             items: items
 230         }, self)
 231     }
 232 }
 233
 234 fn inject_prelude(_: &Session, krate: ast::Crate) -> ast::Crate {
 235     let mut fold = PreludeInjector;
 236     fold.fold_crate(krate)
 237 }