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, TtDelimited, TtSequence, TtToken};
13 use codemap::{Span, DUMMY_SP};
14 use ext::base::{ExtCtxt, MacResult, MacroDef};
15 use ext::base::{NormalTT, TTMacroExpander};
16 use ext::tt::macro_parser::{Success, Error, Failure};
17 use ext::tt::macro_parser::{NamedMatch, MatchedSeq, MatchedNonterminal};
18 use ext::tt::macro_parser::{parse, parse_or_else};
19 use parse::lexer::new_tt_reader;
20 use parse::parser::Parser;
21 use parse::attr::ParserAttr;
22 use parse::token::{special_idents, gensym_ident};
23 use parse::token::{MatchNt, NtTT};
28 use util::small_vector::SmallVector;
30 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 /// panic!(); } )` 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 == token::Semi {
49 if parser.token != 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[]);
60 impl<'a> MacResult for ParserAnyMacro<'a> {
61 fn make_expr(self: Box<ParserAnyMacro<'a>>) -> Option<P<ast::Expr>> {
62 let ret = self.parser.borrow_mut().parse_expr();
63 self.ensure_complete_parse(true);
66 fn make_pat(self: Box<ParserAnyMacro<'a>>) -> Option<P<ast::Pat>> {
67 let ret = self.parser.borrow_mut().parse_pat();
68 self.ensure_complete_parse(false);
71 fn make_items(self: Box<ParserAnyMacro<'a>>) -> Option<SmallVector<P<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: Box<ParserAnyMacro<'a>>) -> Option<SmallVector<P<ast::Method>>> {
88 let mut ret = SmallVector::zero();
90 let mut parser = self.parser.borrow_mut();
94 let attrs = parser.parse_outer_attributes();
95 ret.push(parser.parse_method(attrs, ast::Inherited))
99 self.ensure_complete_parse(false);
103 fn make_stmt(self: Box<ParserAnyMacro<'a>>) -> Option<P<ast::Stmt>> {
104 let attrs = self.parser.borrow_mut().parse_outer_attributes();
105 let ret = self.parser.borrow_mut().parse_stmt(attrs);
106 self.ensure_complete_parse(true);
111 struct MacroRulesMacroExpander {
113 lhses: Vec<Rc<NamedMatch>>,
114 rhses: Vec<Rc<NamedMatch>>,
117 impl TTMacroExpander for MacroRulesMacroExpander {
118 fn expand<'cx>(&self,
119 cx: &'cx mut ExtCtxt,
121 arg: &[ast::TokenTree])
122 -> Box<MacResult+'cx> {
123 generic_extension(cx,
132 struct MacroRulesDefiner {
133 def: Option<MacroDef>
135 impl MacResult for MacroRulesDefiner {
136 fn make_def(&mut self) -> Option<MacroDef> {
137 Some(self.def.take().expect("empty MacroRulesDefiner"))
141 /// Given `lhses` and `rhses`, this is the new macro we create
142 fn generic_extension<'cx>(cx: &'cx ExtCtxt,
145 arg: &[ast::TokenTree],
146 lhses: &[Rc<NamedMatch>],
147 rhses: &[Rc<NamedMatch>])
148 -> Box<MacResult+'cx> {
149 if cx.trace_macros() {
150 println!("{}! {{ {} }}",
151 token::get_ident(name),
152 print::pprust::tts_to_string(arg));
155 // Which arm's failure should we report? (the one furthest along)
156 let mut best_fail_spot = DUMMY_SP;
157 let mut best_fail_msg = "internal error: ran no matchers".to_string();
159 for (i, lhs) in lhses.iter().enumerate() { // try each arm's matchers
161 MatchedNonterminal(NtTT(ref lhs_tt)) => {
162 let lhs_tt = match **lhs_tt {
163 TtDelimited(_, ref delim) => delim.tts[],
164 _ => cx.span_fatal(sp, "malformed macro lhs")
166 // `None` is because we're not interpolating
167 let mut arg_rdr = new_tt_reader(&cx.parse_sess().span_diagnostic,
170 .map(|x| (*x).clone())
172 arg_rdr.desugar_doc_comments = true;
173 match parse(cx.parse_sess(), cx.cfg(), arg_rdr, lhs_tt) {
174 Success(named_matches) => {
175 let rhs = match *rhses[i] {
176 // okay, what's your transcriber?
177 MatchedNonterminal(NtTT(ref tt)) => {
180 TtDelimited(_, ref delimed) => delimed.tts.clone(),
181 _ => cx.span_fatal(sp, "macro rhs must be delimited"),
184 _ => cx.span_bug(sp, "bad thing in rhs")
186 // rhs has holes ( `$id` and `$(...)` that need filled)
187 let trncbr = new_tt_reader(&cx.parse_sess().span_diagnostic,
190 let p = Parser::new(cx.parse_sess(), cx.cfg(), box trncbr);
191 // Let the context choose how to interpret the result.
192 // Weird, but useful for X-macros.
193 return box ParserAnyMacro {
194 parser: RefCell::new(p),
195 } as Box<MacResult+'cx>
197 Failure(sp, ref msg) => if sp.lo >= best_fail_spot.lo {
199 best_fail_msg = (*msg).clone();
201 Error(sp, ref msg) => cx.span_fatal(sp, msg[])
204 _ => cx.bug("non-matcher found in parsed lhses")
207 cx.span_fatal(best_fail_spot, best_fail_msg[]);
210 // Note that macro-by-example's input is also matched against a token tree:
211 // $( $lhs:tt => $rhs:tt );+
213 // Holy self-referential!
215 /// This procedure performs the expansion of the
216 /// macro_rules! macro. It parses the RHS and adds
217 /// an extension to the current context.
218 pub fn add_new_extension<'cx>(cx: &'cx mut ExtCtxt,
221 arg: Vec<ast::TokenTree> )
222 -> Box<MacResult+'cx> {
224 let lhs_nm = gensym_ident("lhs");
225 let rhs_nm = gensym_ident("rhs");
227 // The pattern that macro_rules matches.
228 // The grammar for macro_rules! is:
229 // $( $lhs:tt => $rhs:tt );+
230 // ...quasiquoting this would be nice.
231 // These spans won't matter, anyways
232 let match_lhs_tok = MatchNt(lhs_nm, special_idents::tt, token::Plain, token::Plain);
233 let match_rhs_tok = MatchNt(rhs_nm, special_idents::tt, token::Plain, token::Plain);
234 let argument_gram = vec!(
236 Rc::new(ast::SequenceRepetition {
238 TtToken(DUMMY_SP, match_lhs_tok),
239 TtToken(DUMMY_SP, token::FatArrow),
240 TtToken(DUMMY_SP, match_rhs_tok)],
241 separator: Some(token::Semi),
245 //to phase into semicolon-termination instead of
246 //semicolon-separation
248 Rc::new(ast::SequenceRepetition {
249 tts: vec![TtToken(DUMMY_SP, token::Semi)],
256 // Parse the macro_rules! invocation (`none` is for no interpolations):
257 let arg_reader = new_tt_reader(&cx.parse_sess().span_diagnostic,
260 let argument_map = parse_or_else(cx.parse_sess(),
265 // Extract the arguments:
266 let lhses = match *argument_map[lhs_nm] {
267 MatchedSeq(ref s, _) => /* FIXME (#2543) */ (*s).clone(),
268 _ => cx.span_bug(sp, "wrong-structured lhs")
271 let rhses = match *argument_map[rhs_nm] {
272 MatchedSeq(ref s, _) => /* FIXME (#2543) */ (*s).clone(),
273 _ => cx.span_bug(sp, "wrong-structured rhs")
276 let exp = box MacroRulesMacroExpander {
282 box MacroRulesDefiner {
284 name: token::get_ident(name).to_string(),
285 ext: NormalTT(exp, Some(sp))
287 } as Box<MacResult+'cx>