src/libsyntax/parse/obsolete.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 //! Support for parsing unsupported, old syntaxes, for the purpose of reporting errors. Parsing of
  12 //! these syntaxes is tested by compile-test/obsolete-syntax.rs.
  13 //!
  14 //! Obsolete syntax that becomes too hard to parse can be removed.
  15
  16 use ast::{Expr, ExprTup};
  17 use codemap::Span;
  18 use parse::parser;
  19 use parse::token;
  20 use ptr::P;
  21
  22 /// The specific types of unsupported syntax
  23 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
  24 pub enum ObsoleteSyntax {
  25     ClosureKind,
  26     ExternCrateString,
  27 }
  28
  29 pub trait ParserObsoleteMethods {
  30     /// Reports an obsolete syntax non-fatal error.
  31     fn obsolete(&mut self, sp: Span, kind: ObsoleteSyntax);
  32     /// Reports an obsolete syntax non-fatal error, and returns
  33     /// a placeholder expression
  34     fn obsolete_expr(&mut self, sp: Span, kind: ObsoleteSyntax) -> P<Expr>;
  35     fn report(&mut self,
  36               sp: Span,
  37               kind: ObsoleteSyntax,
  38               kind_str: &str,
  39               desc: &str,
  40               error: bool);
  41     fn is_obsolete_ident(&mut self, ident: &str) -> bool;
  42     fn eat_obsolete_ident(&mut self, ident: &str) -> bool;
  43 }
  44
  45 impl<'a> ParserObsoleteMethods for parser::Parser<'a> {
  46     /// Reports an obsolete syntax non-fatal error.
  47     fn obsolete(&mut self, sp: Span, kind: ObsoleteSyntax) {
  48         let (kind_str, desc, error) = match kind {
  49             ObsoleteSyntax::ClosureKind => (
  50                 "`:`, `&mut:`, or `&:`",
  51                 "rely on inference instead",
  52                 true,
  53             ),
  54             ObsoleteSyntax::ExternCrateString => (
  55                 "\"crate-name\"",
  56                 "use an identifier not in quotes instead",
  57                 false, // warning for now
  58             ),
  59         };
  60
  61         self.report(sp, kind, kind_str, desc, error);
  62     }
  63
  64     /// Reports an obsolete syntax non-fatal error, and returns
  65     /// a placeholder expression
  66     fn obsolete_expr(&mut self, sp: Span, kind: ObsoleteSyntax) -> P<Expr> {
  67         self.obsolete(sp, kind);
  68         self.mk_expr(sp.lo, sp.hi, ExprTup(vec![]))
  69     }
  70
  71     fn report(&mut self,
  72               sp: Span,
  73               kind: ObsoleteSyntax,
  74               kind_str: &str,
  75               desc: &str,
  76               error: bool) {
  77         if error {
  78             self.span_err(sp, &format!("obsolete syntax: {}", kind_str));
  79         } else {
  80             self.span_warn(sp, &format!("obsolete syntax: {}", kind_str));
  81         }
  82
  83         if !self.obsolete_set.contains(&kind) &&
  84             (error || self.sess.span_diagnostic.handler().can_emit_warnings) {
  85             self.sess
  86                 .span_diagnostic
  87                 .handler()
  88                 .note(&format!("{}", desc));
  89             self.obsolete_set.insert(kind);
  90         }
  91     }
  92
  93     fn is_obsolete_ident(&mut self, ident: &str) -> bool {
  94         match self.token {
  95             token::Ident(sid, _) => {
  96                 token::get_ident(sid) == ident
  97             }
  98             _ => false
  99         }
 100     }
 101
 102     fn eat_obsolete_ident(&mut self, ident: &str) -> bool {
 103         if self.is_obsolete_ident(ident) {
 104             panictry!(self.bump());
 105             true
 106         } else {
 107             false
 108         }
 109     }
 110 }