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.
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.
11 use ast::{Ident, Matcher_, Matcher, MatchTok, MatchNonterminal, MatchSeq};
14 use codemap::{Span, Spanned, DUMMY_SP};
15 use ext::base::{ExtCtxt, MacResult, MacroDef};
16 use ext::base::{NormalTT, TTMacroExpander};
17 use ext::tt::macro_parser::{Success, Error, Failure};
18 use ext::tt::macro_parser::{NamedMatch, MatchedSeq, MatchedNonterminal};
19 use ext::tt::macro_parser::{parse, parse_or_else};
20 use parse::lexer::new_tt_reader;
21 use parse::parser::Parser;
22 use parse::attr::ParserAttr;
23 use parse::token::{special_idents, gensym_ident};
24 use parse::token::{FAT_ARROW, SEMI, NtMatchers, NtTT, EOF};
27 use util::small_vector::SmallVector;
29 use std::cell::RefCell;
33 struct ParserAnyMacro<'a> {
34 parser: RefCell<Parser<'a>>,
37 impl<'a> ParserAnyMacro<'a> {
38 /// Make sure we don't have any tokens left to parse, so we don't
39 /// silently drop anything. `allow_semi` is so that "optional"
40 /// semicolons at the end of normal expressions aren't complained
41 /// about e.g. the semicolon in `macro_rules! kapow( () => {
42 /// fail!(); } )` doesn't get picked up by .parse_expr(), but it's
43 /// allowed to be there.
44 fn ensure_complete_parse(&self, allow_semi: bool) {
45 let mut parser = self.parser.borrow_mut();
46 if allow_semi && parser.token == SEMI {
49 if parser.token != EOF {
50 let token_str = parser.this_token_to_string();
51 let msg = format!("macro expansion ignores token `{}` and any \
54 let span = parser.span;
55 parser.span_err(span, msg.as_slice());
60 impl<'a> MacResult for ParserAnyMacro<'a> {
61 fn make_expr(&self) -> Option<Gc<ast::Expr>> {
62 let ret = self.parser.borrow_mut().parse_expr();
63 self.ensure_complete_parse(true);
66 fn make_pat(&self) -> Option<Gc<ast::Pat>> {
67 let ret = self.parser.borrow_mut().parse_pat();
68 self.ensure_complete_parse(false);
71 fn make_items(&self) -> Option<SmallVector<Gc<ast::Item>>> {
72 let mut ret = SmallVector::zero();
74 let mut parser = self.parser.borrow_mut();
75 // so... do outer attributes attached to the macro invocation
76 // just disappear? This question applies to make_methods, as
78 match parser.parse_item_with_outer_attributes() {
79 Some(item) => ret.push(item),
83 self.ensure_complete_parse(false);
87 fn make_methods(&self) -> Option<SmallVector<Gc<ast::Method>>> {
88 let mut ret = SmallVector::zero();
90 let mut parser = self.parser.borrow_mut();
93 _ => ret.push(parser.parse_method(None))
96 self.ensure_complete_parse(false);
100 fn make_stmt(&self) -> Option<Gc<ast::Stmt>> {
101 let attrs = self.parser.borrow_mut().parse_outer_attributes();
102 let ret = self.parser.borrow_mut().parse_stmt(attrs);
103 self.ensure_complete_parse(true);
108 struct MacroRulesMacroExpander {
110 lhses: Vec<Rc<NamedMatch>>,
111 rhses: Vec<Rc<NamedMatch>>,
114 impl TTMacroExpander for MacroRulesMacroExpander {
115 fn expand<'cx>(&self,
116 cx: &'cx mut ExtCtxt,
118 arg: &[ast::TokenTree])
119 -> Box<MacResult+'cx> {
120 generic_extension(cx,
124 self.lhses.as_slice(),
125 self.rhses.as_slice())
129 struct MacroRulesDefiner {
130 def: RefCell<Option<MacroDef>>
132 impl MacResult for MacroRulesDefiner {
133 fn make_def(&self) -> Option<MacroDef> {
134 Some(self.def.borrow_mut().take().expect("MacroRulesDefiner expanded twice"))
138 /// Given `lhses` and `rhses`, this is the new macro we create
139 fn generic_extension<'cx>(cx: &'cx ExtCtxt,
142 arg: &[ast::TokenTree],
143 lhses: &[Rc<NamedMatch>],
144 rhses: &[Rc<NamedMatch>])
145 -> Box<MacResult+'cx> {
146 if cx.trace_macros() {
147 println!("{}! {} {} {}",
148 token::get_ident(name),
150 print::pprust::tt_to_string(&TTDelim(Rc::new(arg.iter()
151 .map(|x| (*x).clone())
156 // Which arm's failure should we report? (the one furthest along)
157 let mut best_fail_spot = DUMMY_SP;
158 let mut best_fail_msg = "internal error: ran no matchers".to_string();
160 for (i, lhs) in lhses.iter().enumerate() { // try each arm's matchers
162 MatchedNonterminal(NtMatchers(ref mtcs)) => {
163 // `None` is because we're not interpolating
164 let arg_rdr = new_tt_reader(&cx.parse_sess().span_diagnostic,
167 .map(|x| (*x).clone())
169 match parse(cx.parse_sess(), cx.cfg(), arg_rdr, mtcs.as_slice()) {
170 Success(named_matches) => {
171 let rhs = match *rhses[i] {
172 // okay, what's your transcriber?
173 MatchedNonterminal(NtTT(tt)) => {
175 // cut off delimiters; don't parse 'em
176 TTDelim(ref tts) => {
177 (*tts).slice(1u,(*tts).len()-1u)
179 .map(|x| (*x).clone())
183 sp, "macro rhs must be delimited")
186 _ => cx.span_bug(sp, "bad thing in rhs")
188 // rhs has holes ( `$id` and `$(...)` that need filled)
189 let trncbr = new_tt_reader(&cx.parse_sess().span_diagnostic,
192 let p = Parser::new(cx.parse_sess(), cx.cfg(), box trncbr);
193 // Let the context choose how to interpret the result.
194 // Weird, but useful for X-macros.
195 return box ParserAnyMacro {
196 parser: RefCell::new(p),
197 } as Box<MacResult+'cx>
199 Failure(sp, ref msg) => if sp.lo >= best_fail_spot.lo {
201 best_fail_msg = (*msg).clone();
203 Error(sp, ref msg) => cx.span_fatal(sp, msg.as_slice())
206 _ => cx.bug("non-matcher found in parsed lhses")
209 cx.span_fatal(best_fail_spot, best_fail_msg.as_slice());
212 /// This procedure performs the expansion of the
213 /// macro_rules! macro. It parses the RHS and adds
214 /// an extension to the current context.
215 pub fn add_new_extension<'cx>(cx: &'cx mut ExtCtxt,
218 arg: Vec<ast::TokenTree> )
219 -> Box<MacResult+'cx> {
220 // these spans won't matter, anyways
221 fn ms(m: Matcher_) -> Matcher {
228 let lhs_nm = gensym_ident("lhs");
229 let rhs_nm = gensym_ident("rhs");
231 // The pattern that macro_rules matches.
232 // The grammar for macro_rules! is:
233 // $( $lhs:mtcs => $rhs:tt );+
234 // ...quasiquoting this would be nice.
235 let argument_gram = vec!(
237 ms(MatchNonterminal(lhs_nm, special_idents::matchers, 0u)),
238 ms(MatchTok(FAT_ARROW)),
239 ms(MatchNonterminal(rhs_nm, special_idents::tt, 1u))), Some(SEMI), false, 0u, 2u)),
240 //to phase into semicolon-termination instead of
241 //semicolon-separation
242 ms(MatchSeq(vec!(ms(MatchTok(SEMI))), None, true, 2u, 2u)));
245 // Parse the macro_rules! invocation (`none` is for no interpolations):
246 let arg_reader = new_tt_reader(&cx.parse_sess().span_diagnostic,
249 let argument_map = parse_or_else(cx.parse_sess(),
254 // Extract the arguments:
255 let lhses = match **argument_map.get(&lhs_nm) {
256 MatchedSeq(ref s, _) => /* FIXME (#2543) */ (*s).clone(),
257 _ => cx.span_bug(sp, "wrong-structured lhs")
260 let rhses = match **argument_map.get(&rhs_nm) {
261 MatchedSeq(ref s, _) => /* FIXME (#2543) */ (*s).clone(),
262 _ => cx.span_bug(sp, "wrong-structured rhs")
265 let exp = box MacroRulesMacroExpander {
271 box MacroRulesDefiner {
272 def: RefCell::new(Some(MacroDef {
273 name: token::get_ident(name).to_string(),
274 ext: NormalTT(exp, Some(sp))
276 } as Box<MacResult+'cx>