src/libsyntax/attr.rs

   1 // Copyright 2012-2014 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 // Functions dealing with attributes and meta items
  12
  13 pub use self::StabilityLevel::*;
  14 pub use self::ReprAttr::*;
  15 pub use self::IntType::*;
  16
  17 use ast;
  18 use ast::{AttrId, Attribute, Attribute_, MetaItem, MetaWord, MetaNameValue, MetaList};
  19 use codemap::{Span, Spanned, spanned, dummy_spanned};
  20 use codemap::BytePos;
  21 use diagnostic::SpanHandler;
  22 use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
  23 use parse::token::{InternedString, intern_and_get_ident};
  24 use parse::token;
  25 use ptr::P;
  26
  27 use std::cell::{RefCell, Cell};
  28 use std::collections::BitSet;
  29 use std::collections::HashSet;
  30 use std::fmt;
  31
  32 thread_local! { static USED_ATTRS: RefCell<BitSet> = RefCell::new(BitSet::new()) }
  33
  34 pub fn mark_used(attr: &Attribute) {
  35     let AttrId(id) = attr.node.id;
  36     USED_ATTRS.with(|slot| slot.borrow_mut().insert(id));
  37 }
  38
  39 pub fn is_used(attr: &Attribute) -> bool {
  40     let AttrId(id) = attr.node.id;
  41     USED_ATTRS.with(|slot| slot.borrow().contains(&id))
  42 }
  43
  44 pub trait AttrMetaMethods {
  45     fn check_name(&self, name: &str) -> bool {
  46         name == &self.name()[..]
  47     }
  48
  49     /// Retrieve the name of the meta item, e.g. `foo` in `#[foo]`,
  50     /// `#[foo="bar"]` and `#[foo(bar)]`
  51     fn name(&self) -> InternedString;
  52
  53     /// Gets the string value if self is a MetaNameValue variant
  54     /// containing a string, otherwise None.
  55     fn value_str(&self) -> Option<InternedString>;
  56     /// Gets a list of inner meta items from a list MetaItem type.
  57     fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]>;
  58
  59     fn span(&self) -> Span;
  60 }
  61
  62 impl AttrMetaMethods for Attribute {
  63     fn check_name(&self, name: &str) -> bool {
  64         let matches = name == &self.name()[..];
  65         if matches {
  66             mark_used(self);
  67         }
  68         matches
  69     }
  70     fn name(&self) -> InternedString { self.meta().name() }
  71     fn value_str(&self) -> Option<InternedString> {
  72         self.meta().value_str()
  73     }
  74     fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]> {
  75         self.node.value.meta_item_list()
  76     }
  77     fn span(&self) -> Span { self.meta().span }
  78 }
  79
  80 impl AttrMetaMethods for MetaItem {
  81     fn name(&self) -> InternedString {
  82         match self.node {
  83             MetaWord(ref n) => (*n).clone(),
  84             MetaNameValue(ref n, _) => (*n).clone(),
  85             MetaList(ref n, _) => (*n).clone(),
  86         }
  87     }
  88
  89     fn value_str(&self) -> Option<InternedString> {
  90         match self.node {
  91             MetaNameValue(_, ref v) => {
  92                 match v.node {
  93                     ast::LitStr(ref s, _) => Some((*s).clone()),
  94                     _ => None,
  95                 }
  96             },
  97             _ => None
  98         }
  99     }
 100
 101     fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]> {
 102         match self.node {
 103             MetaList(_, ref l) => Some(&l[..]),
 104             _ => None
 105         }
 106     }
 107     fn span(&self) -> Span { self.span }
 108 }
 109
 110 // Annoying, but required to get test_cfg to work
 111 impl AttrMetaMethods for P<MetaItem> {
 112     fn name(&self) -> InternedString { (**self).name() }
 113     fn value_str(&self) -> Option<InternedString> { (**self).value_str() }
 114     fn meta_item_list<'a>(&'a self) -> Option<&'a [P<MetaItem>]> {
 115         (**self).meta_item_list()
 116     }
 117     fn span(&self) -> Span { (**self).span() }
 118 }
 119
 120
 121 pub trait AttributeMethods {
 122     fn meta<'a>(&'a self) -> &'a MetaItem;
 123     fn with_desugared_doc<T, F>(&self, f: F) -> T where
 124         F: FnOnce(&Attribute) -> T;
 125 }
 126
 127 impl AttributeMethods for Attribute {
 128     /// Extract the MetaItem from inside this Attribute.
 129     fn meta<'a>(&'a self) -> &'a MetaItem {
 130         &*self.node.value
 131     }
 132
 133     /// Convert self to a normal #[doc="foo"] comment, if it is a
 134     /// comment like `///` or `/** */`. (Returns self unchanged for
 135     /// non-sugared doc attributes.)
 136     fn with_desugared_doc<T, F>(&self, f: F) -> T where
 137         F: FnOnce(&Attribute) -> T,
 138     {
 139         if self.node.is_sugared_doc {
 140             let comment = self.value_str().unwrap();
 141             let meta = mk_name_value_item_str(
 142                 InternedString::new("doc"),
 143                 token::intern_and_get_ident(&strip_doc_comment_decoration(
 144                         &comment)));
 145             if self.node.style == ast::AttrOuter {
 146                 f(&mk_attr_outer(self.node.id, meta))
 147             } else {
 148                 f(&mk_attr_inner(self.node.id, meta))
 149             }
 150         } else {
 151             f(self)
 152         }
 153     }
 154 }
 155
 156 /* Constructors */
 157
 158 pub fn mk_name_value_item_str(name: InternedString, value: InternedString)
 159                               -> P<MetaItem> {
 160     let value_lit = dummy_spanned(ast::LitStr(value, ast::CookedStr));
 161     mk_name_value_item(name, value_lit)
 162 }
 163
 164 pub fn mk_name_value_item(name: InternedString, value: ast::Lit)
 165                           -> P<MetaItem> {
 166     P(dummy_spanned(MetaNameValue(name, value)))
 167 }
 168
 169 pub fn mk_list_item(name: InternedString, items: Vec<P<MetaItem>>) -> P<MetaItem> {
 170     P(dummy_spanned(MetaList(name, items)))
 171 }
 172
 173 pub fn mk_word_item(name: InternedString) -> P<MetaItem> {
 174     P(dummy_spanned(MetaWord(name)))
 175 }
 176
 177 thread_local! { static NEXT_ATTR_ID: Cell<usize> = Cell::new(0) }
 178
 179 pub fn mk_attr_id() -> AttrId {
 180     let id = NEXT_ATTR_ID.with(|slot| {
 181         let r = slot.get();
 182         slot.set(r + 1);
 183         r
 184     });
 185     AttrId(id)
 186 }
 187
 188 /// Returns an inner attribute with the given value.
 189 pub fn mk_attr_inner(id: AttrId, item: P<MetaItem>) -> Attribute {
 190     dummy_spanned(Attribute_ {
 191         id: id,
 192         style: ast::AttrInner,
 193         value: item,
 194         is_sugared_doc: false,
 195     })
 196 }
 197
 198 /// Returns an outer attribute with the given value.
 199 pub fn mk_attr_outer(id: AttrId, item: P<MetaItem>) -> Attribute {
 200     dummy_spanned(Attribute_ {
 201         id: id,
 202         style: ast::AttrOuter,
 203         value: item,
 204         is_sugared_doc: false,
 205     })
 206 }
 207
 208 pub fn mk_sugared_doc_attr(id: AttrId, text: InternedString, lo: BytePos,
 209                            hi: BytePos)
 210                            -> Attribute {
 211     let style = doc_comment_style(&text);
 212     let lit = spanned(lo, hi, ast::LitStr(text, ast::CookedStr));
 213     let attr = Attribute_ {
 214         id: id,
 215         style: style,
 216         value: P(spanned(lo, hi, MetaNameValue(InternedString::new("doc"),
 217                                                lit))),
 218         is_sugared_doc: true
 219     };
 220     spanned(lo, hi, attr)
 221 }
 222
 223 /* Searching */
 224 /// Check if `needle` occurs in `haystack` by a structural
 225 /// comparison. This is slightly subtle, and relies on ignoring the
 226 /// span included in the `==` comparison a plain MetaItem.
 227 pub fn contains(haystack: &[P<MetaItem>], needle: &MetaItem) -> bool {
 228     debug!("attr::contains (name={})", needle.name());
 229     haystack.iter().any(|item| {
 230         debug!("  testing: {}", item.name());
 231         item.node == needle.node
 232     })
 233 }
 234
 235 pub fn contains_name<AM: AttrMetaMethods>(metas: &[AM], name: &str) -> bool {
 236     debug!("attr::contains_name (name={})", name);
 237     metas.iter().any(|item| {
 238         debug!("  testing: {}", item.name());
 239         item.check_name(name)
 240     })
 241 }
 242
 243 pub fn first_attr_value_str_by_name(attrs: &[Attribute], name: &str)
 244                                  -> Option<InternedString> {
 245     attrs.iter()
 246         .find(|at| at.check_name(name))
 247         .and_then(|at| at.value_str())
 248 }
 249
 250 pub fn last_meta_item_value_str_by_name(items: &[P<MetaItem>], name: &str)
 251                                      -> Option<InternedString> {
 252     items.iter()
 253          .rev()
 254          .find(|mi| mi.check_name(name))
 255          .and_then(|i| i.value_str())
 256 }
 257
 258 /* Higher-level applications */
 259
 260 pub fn sort_meta_items(items: Vec<P<MetaItem>>) -> Vec<P<MetaItem>> {
 261     // This is sort of stupid here, but we need to sort by
 262     // human-readable strings.
 263     let mut v = items.into_iter()
 264         .map(|mi| (mi.name(), mi))
 265         .collect::<Vec<(InternedString, P<MetaItem>)>>();
 266
 267     v.sort_by(|&(ref a, _), &(ref b, _)| a.cmp(b));
 268
 269     // There doesn't seem to be a more optimal way to do this
 270     v.into_iter().map(|(_, m)| m.map(|Spanned {node, span}| {
 271         Spanned {
 272             node: match node {
 273                 MetaList(n, mis) => MetaList(n, sort_meta_items(mis)),
 274                 _ => node
 275             },
 276             span: span
 277         }
 278     })).collect()
 279 }
 280
 281 pub fn find_crate_name(attrs: &[Attribute]) -> Option<InternedString> {
 282     first_attr_value_str_by_name(attrs, "crate_name")
 283 }
 284
 285 #[derive(Copy, Clone, PartialEq)]
 286 pub enum InlineAttr {
 287     None,
 288     Hint,
 289     Always,
 290     Never,
 291 }
 292
 293 /// Determine what `#[inline]` attribute is present in `attrs`, if any.
 294 pub fn find_inline_attr(diagnostic: Option<&SpanHandler>, attrs: &[Attribute]) -> InlineAttr {
 295     // FIXME (#2809)---validate the usage of #[inline] and #[inline]
 296     attrs.iter().fold(InlineAttr::None, |ia,attr| {
 297         match attr.node.value.node {
 298             MetaWord(ref n) if *n == "inline" => {
 299                 mark_used(attr);
 300                 InlineAttr::Hint
 301             }
 302             MetaList(ref n, ref items) if *n == "inline" => {
 303                 mark_used(attr);
 304                 if items.len() != 1 {
 305                     diagnostic.map(|d|{ d.span_err(attr.span, "expected one argument"); });
 306                     InlineAttr::None
 307                 } else if contains_name(&items[..], "always") {
 308                     InlineAttr::Always
 309                 } else if contains_name(&items[..], "never") {
 310                     InlineAttr::Never
 311                 } else {
 312                     diagnostic.map(|d|{ d.span_err((*items[0]).span, "invalid argument"); });
 313                     InlineAttr::None
 314                 }
 315             }
 316             _ => ia
 317         }
 318     })
 319 }
 320
 321 /// True if `#[inline]` or `#[inline(always)]` is present in `attrs`.
 322 pub fn requests_inline(attrs: &[Attribute]) -> bool {
 323     match find_inline_attr(None, attrs) {
 324         InlineAttr::Hint | InlineAttr::Always => true,
 325         InlineAttr::None | InlineAttr::Never => false,
 326     }
 327 }
 328
 329 /// Tests if a cfg-pattern matches the cfg set
 330 pub fn cfg_matches(diagnostic: &SpanHandler, cfgs: &[P<MetaItem>], cfg: &ast::MetaItem) -> bool {
 331     match cfg.node {
 332         ast::MetaList(ref pred, ref mis) if &pred[..] == "any" =>
 333             mis.iter().any(|mi| cfg_matches(diagnostic, cfgs, &**mi)),
 334         ast::MetaList(ref pred, ref mis) if &pred[..] == "all" =>
 335             mis.iter().all(|mi| cfg_matches(diagnostic, cfgs, &**mi)),
 336         ast::MetaList(ref pred, ref mis) if &pred[..] == "not" => {
 337             if mis.len() != 1 {
 338                 diagnostic.span_err(cfg.span, "expected 1 cfg-pattern");
 339                 return false;
 340             }
 341             !cfg_matches(diagnostic, cfgs, &*mis[0])
 342         }
 343         ast::MetaList(ref pred, _) => {
 344             diagnostic.span_err(cfg.span, &format!("invalid predicate `{}`", pred));
 345             false
 346         },
 347         ast::MetaWord(_) | ast::MetaNameValue(..) => contains(cfgs, cfg),
 348     }
 349 }
 350
 351 /// Represents the #[deprecated] and friends attributes.
 352 #[derive(RustcEncodable,RustcDecodable,Clone,Debug)]
 353 pub struct Stability {
 354     pub level: StabilityLevel,
 355     pub feature: InternedString,
 356     pub since: Option<InternedString>,
 357     pub deprecated_since: Option<InternedString>,
 358     // The reason for the current stability level. If deprecated, the
 359     // reason for deprecation.
 360     pub reason: Option<InternedString>,
 361 }
 362
 363 /// The available stability levels.
 364 #[derive(RustcEncodable,RustcDecodable,PartialEq,PartialOrd,Clone,Debug,Copy)]
 365 pub enum StabilityLevel {
 366     Unstable,
 367     Stable,
 368 }
 369
 370 impl fmt::Display for StabilityLevel {
 371     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 372         fmt::Debug::fmt(self, f)
 373     }
 374 }
 375
 376 fn find_stability_generic<'a,
 377                               AM: AttrMetaMethods,
 378                               I: Iterator<Item=&'a AM>>
 379                              (diagnostic: &SpanHandler, attrs: I, item_sp: Span)
 380                              -> (Option<Stability>, Vec<&'a AM>) {
 381
 382     let mut stab: Option<Stability> = None;
 383     let mut deprecated: Option<(InternedString, Option<InternedString>)> = None;
 384     let mut used_attrs: Vec<&'a AM> = vec![];
 385
 386     'outer: for attr in attrs {
 387         let tag = attr.name();
 388         let tag = &tag[..];
 389         if tag != "deprecated" && tag != "unstable" && tag != "stable" {
 390             continue // not a stability level
 391         }
 392
 393         used_attrs.push(attr);
 394
 395         let (feature, since, reason) = match attr.meta_item_list() {
 396             Some(metas) => {
 397                 let mut feature = None;
 398                 let mut since = None;
 399                 let mut reason = None;
 400                 for meta in metas.iter() {
 401                     if meta.name() == "feature" {
 402                         match meta.value_str() {
 403                             Some(v) => feature = Some(v),
 404                             None => {
 405                                 diagnostic.span_err(meta.span, "incorrect meta item");
 406                                 continue 'outer;
 407                             }
 408                         }
 409                     }
 410                     if &meta.name()[..] == "since" {
 411                         match meta.value_str() {
 412                             Some(v) => since = Some(v),
 413                             None => {
 414                                 diagnostic.span_err(meta.span, "incorrect meta item");
 415                                 continue 'outer;
 416                             }
 417                         }
 418                     }
 419                     if &meta.name()[..] == "reason" {
 420                         match meta.value_str() {
 421                             Some(v) => reason = Some(v),
 422                             None => {
 423                                 diagnostic.span_err(meta.span, "incorrect meta item");
 424                                 continue 'outer;
 425                             }
 426                         }
 427                     }
 428                 }
 429                 (feature, since, reason)
 430             }
 431             None => {
 432                 diagnostic.span_err(attr.span(), "incorrect stability attribute type");
 433                 continue
 434             }
 435         };
 436
 437         // Deprecated tags don't require feature names
 438         if feature == None && tag != "deprecated" {
 439             diagnostic.span_err(attr.span(), "missing 'feature'");
 440         }
 441
 442         // Unstable tags don't require a version
 443         if since == None && tag != "unstable" {
 444             diagnostic.span_err(attr.span(), "missing 'since'");
 445         }
 446
 447         if tag == "unstable" || tag == "stable" {
 448             if stab.is_some() {
 449                 diagnostic.span_err(item_sp, "multiple stability levels");
 450             }
 451
 452             let level = match tag {
 453                 "unstable" => Unstable,
 454                 "stable" => Stable,
 455                 _ => unreachable!()
 456             };
 457
 458             stab = Some(Stability {
 459                 level: level,
 460                 feature: feature.unwrap_or(intern_and_get_ident("bogus")),
 461                 since: since,
 462                 deprecated_since: None,
 463                 reason: reason
 464             });
 465         } else { // "deprecated"
 466             if deprecated.is_some() {
 467                 diagnostic.span_err(item_sp, "multiple deprecated attributes");
 468             }
 469
 470             deprecated = Some((since.unwrap_or(intern_and_get_ident("bogus")), reason));
 471         }
 472     }
 473
 474     // Merge the deprecation info into the stability info
 475     if deprecated.is_some() {
 476         match stab {
 477             Some(ref mut s) => {
 478                 let (since, reason) = deprecated.unwrap();
 479                 s.deprecated_since = Some(since);
 480                 s.reason = reason;
 481             }
 482             None => {
 483                 diagnostic.span_err(item_sp, "deprecated attribute must be paired with \
 484                                               either stable or unstable attribute");
 485             }
 486         }
 487     }
 488
 489     (stab, used_attrs)
 490 }
 491
 492 /// Find the first stability attribute. `None` if none exists.
 493 pub fn find_stability(diagnostic: &SpanHandler, attrs: &[Attribute],
 494                       item_sp: Span) -> Option<Stability> {
 495     let (s, used) = find_stability_generic(diagnostic, attrs.iter(), item_sp);
 496     for used in used { mark_used(used) }
 497     return s;
 498 }
 499
 500 pub fn require_unique_names(diagnostic: &SpanHandler, metas: &[P<MetaItem>]) {
 501     let mut set = HashSet::new();
 502     for meta in metas {
 503         let name = meta.name();
 504
 505         if !set.insert(name.clone()) {
 506             diagnostic.span_fatal(meta.span,
 507                                   &format!("duplicate meta item `{}`", name));
 508         }
 509     }
 510 }
 511
 512
 513 /// Parse #[repr(...)] forms.
 514 ///
 515 /// Valid repr contents: any of the primitive integral type names (see
 516 /// `int_type_of_word`, below) to specify enum discriminant type; `C`, to use
 517 /// the same discriminant size that the corresponding C enum would or C
 518 /// structure layout, and `packed` to remove padding.
 519 pub fn find_repr_attrs(diagnostic: &SpanHandler, attr: &Attribute) -> Vec<ReprAttr> {
 520     let mut acc = Vec::new();
 521     match attr.node.value.node {
 522         ast::MetaList(ref s, ref items) if *s == "repr" => {
 523             mark_used(attr);
 524             for item in items {
 525                 match item.node {
 526                     ast::MetaWord(ref word) => {
 527                         let hint = match &word[..] {
 528                             // Can't use "extern" because it's not a lexical identifier.
 529                             "C" => Some(ReprExtern),
 530                             "packed" => Some(ReprPacked),
 531                             _ => match int_type_of_word(&word) {
 532                                 Some(ity) => Some(ReprInt(item.span, ity)),
 533                                 None => {
 534                                     // Not a word we recognize
 535                                     diagnostic.span_err(item.span,
 536                                                         "unrecognized representation hint");
 537                                     None
 538                                 }
 539                             }
 540                         };
 541
 542                         match hint {
 543                             Some(h) => acc.push(h),
 544                             None => { }
 545                         }
 546                     }
 547                     // Not a word:
 548                     _ => diagnostic.span_err(item.span, "unrecognized enum representation hint")
 549                 }
 550             }
 551         }
 552         // Not a "repr" hint: ignore.
 553         _ => { }
 554     }
 555     acc
 556 }
 557
 558 fn int_type_of_word(s: &str) -> Option<IntType> {
 559     match s {
 560         "i8" => Some(SignedInt(ast::TyI8)),
 561         "u8" => Some(UnsignedInt(ast::TyU8)),
 562         "i16" => Some(SignedInt(ast::TyI16)),
 563         "u16" => Some(UnsignedInt(ast::TyU16)),
 564         "i32" => Some(SignedInt(ast::TyI32)),
 565         "u32" => Some(UnsignedInt(ast::TyU32)),
 566         "i64" => Some(SignedInt(ast::TyI64)),
 567         "u64" => Some(UnsignedInt(ast::TyU64)),
 568         "isize" => Some(SignedInt(ast::TyIs)),
 569         "usize" => Some(UnsignedInt(ast::TyUs)),
 570         _ => None
 571     }
 572 }
 573
 574 #[derive(PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
 575 pub enum ReprAttr {
 576     ReprAny,
 577     ReprInt(Span, IntType),
 578     ReprExtern,
 579     ReprPacked,
 580 }
 581
 582 impl ReprAttr {
 583     pub fn is_ffi_safe(&self) -> bool {
 584         match *self {
 585             ReprAny => false,
 586             ReprInt(_sp, ity) => ity.is_ffi_safe(),
 587             ReprExtern => true,
 588             ReprPacked => false
 589         }
 590     }
 591 }
 592
 593 #[derive(Eq, Hash, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
 594 pub enum IntType {
 595     SignedInt(ast::IntTy),
 596     UnsignedInt(ast::UintTy)
 597 }
 598
 599 impl IntType {
 600     #[inline]
 601     pub fn is_signed(self) -> bool {
 602         match self {
 603             SignedInt(..) => true,
 604             UnsignedInt(..) => false
 605         }
 606     }
 607     fn is_ffi_safe(self) -> bool {
 608         match self {
 609             SignedInt(ast::TyI8) | UnsignedInt(ast::TyU8) |
 610             SignedInt(ast::TyI16) | UnsignedInt(ast::TyU16) |
 611             SignedInt(ast::TyI32) | UnsignedInt(ast::TyU32) |
 612             SignedInt(ast::TyI64) | UnsignedInt(ast::TyU64) => true,
 613             SignedInt(ast::TyIs) | UnsignedInt(ast::TyUs) => false
 614         }
 615     }
 616 }