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.
10 use self::LockstepIterSize::*;
13 use ast::{TokenTree, TtDelimited, TtToken, TtSequence, Ident};
14 use codemap::{Span, DUMMY_SP};
15 use diagnostic::SpanHandler;
16 use ext::tt::macro_parser::{NamedMatch, MatchedSeq, MatchedNonterminal};
17 use parse::token::{Eof, DocComment, Interpolated, MatchNt, SubstNt};
18 use parse::token::{Token, NtIdent, SpecialMacroVar};
20 use parse::lexer::TokenAndSpan;
24 use std::collections::HashMap;
26 ///an unzipping of `TokenTree`s
36 pub struct TtReader<'a> {
37 pub sp_diag: &'a SpanHandler,
38 /// the unzipped tree:
40 /* for MBE-style macro transcription */
41 interpolations: HashMap<Ident, Rc<NamedMatch>>,
42 imported_from: Option<Ident>,
44 // Some => return imported_from as the next token
45 crate_name_next: Option<Span>,
46 repeat_idx: Vec<usize>,
47 repeat_len: Vec<usize>,
51 /// Transform doc comments. Only useful in macro invocations
52 pub desugar_doc_comments: bool,
55 /// This can do Macro-By-Example transcription. On the other hand, if
56 /// `src` contains no `TtSequence`s, `MatchNt`s or `SubstNt`s, `interp` can
57 /// (and should) be None.
58 pub fn new_tt_reader<'a>(sp_diag: &'a SpanHandler,
59 interp: Option<HashMap<Ident, Rc<NamedMatch>>>,
60 imported_from: Option<Ident>,
61 src: Vec<ast::TokenTree>)
63 new_tt_reader_with_doc_flag(sp_diag, interp, imported_from, src, false)
66 /// The extra `desugar_doc_comments` flag enables reading doc comments
67 /// like any other attribute which consists of `meta` and surrounding #[ ] tokens.
69 /// This can do Macro-By-Example transcription. On the other hand, if
70 /// `src` contains no `TtSequence`s, `MatchNt`s or `SubstNt`s, `interp` can
71 /// (and should) be None.
72 pub fn new_tt_reader_with_doc_flag<'a>(sp_diag: &'a SpanHandler,
73 interp: Option<HashMap<Ident, Rc<NamedMatch>>>,
74 imported_from: Option<Ident>,
75 src: Vec<ast::TokenTree>,
76 desugar_doc_comments: bool)
78 let mut r = TtReader {
81 forest: TtSequence(DUMMY_SP, Rc::new(ast::SequenceRepetition {
83 // doesn't matter. This merely holds the root unzipping.
84 separator: None, op: ast::ZeroOrMore, num_captures: 0
90 interpolations: match interp { /* just a convenience */
91 None => HashMap::new(),
94 imported_from: imported_from,
95 crate_name_next: None,
96 repeat_idx: Vec::new(),
97 repeat_len: Vec::new(),
98 desugar_doc_comments: desugar_doc_comments,
99 /* dummy values, never read: */
103 tt_next_token(&mut r); /* get cur_tok and cur_span set up */
107 fn lookup_cur_matched_by_matched(r: &TtReader, start: Rc<NamedMatch>) -> Rc<NamedMatch> {
108 r.repeat_idx.iter().fold(start, |ad, idx| {
110 MatchedNonterminal(_) => {
111 // end of the line; duplicate henceforth
114 MatchedSeq(ref ads, _) => ads[*idx].clone()
119 fn lookup_cur_matched(r: &TtReader, name: Ident) -> Option<Rc<NamedMatch>> {
120 let matched_opt = r.interpolations.get(&name).cloned();
121 matched_opt.map(|s| lookup_cur_matched_by_matched(r, s))
125 enum LockstepIterSize {
127 LisConstraint(usize, Ident),
128 LisContradiction(String),
131 impl Add for LockstepIterSize {
132 type Output = LockstepIterSize;
134 fn add(self, other: LockstepIterSize) -> LockstepIterSize {
136 LisUnconstrained => other,
137 LisContradiction(_) => self,
138 LisConstraint(l_len, ref l_id) => match other {
139 LisUnconstrained => self.clone(),
140 LisContradiction(_) => other,
141 LisConstraint(r_len, _) if l_len == r_len => self.clone(),
142 LisConstraint(r_len, r_id) => {
143 let l_n = token::get_ident(l_id.clone());
144 let r_n = token::get_ident(r_id);
145 LisContradiction(format!("inconsistent lockstep iteration: \
146 '{:?}' has {} items, but '{:?}' has {}",
147 l_n, l_len, r_n, r_len).to_string())
154 fn lockstep_iter_size(t: &TokenTree, r: &TtReader) -> LockstepIterSize {
156 TtDelimited(_, ref delimed) => {
157 delimed.tts.iter().fold(LisUnconstrained, |size, tt| {
158 size + lockstep_iter_size(tt, r)
161 TtSequence(_, ref seq) => {
162 seq.tts.iter().fold(LisUnconstrained, |size, tt| {
163 size + lockstep_iter_size(tt, r)
166 TtToken(_, SubstNt(name, _)) | TtToken(_, MatchNt(name, _, _, _)) =>
167 match lookup_cur_matched(r, name) {
168 Some(matched) => match *matched {
169 MatchedNonterminal(_) => LisUnconstrained,
170 MatchedSeq(ref ads, _) => LisConstraint(ads.len(), name),
172 _ => LisUnconstrained
174 TtToken(..) => LisUnconstrained,
178 /// Return the next token from the TtReader.
179 /// EFFECT: advances the reader's token field
180 pub fn tt_next_token(r: &mut TtReader) -> TokenAndSpan {
181 // FIXME(pcwalton): Bad copy?
182 let ret_val = TokenAndSpan {
183 tok: r.cur_tok.clone(),
184 sp: r.cur_span.clone(),
187 match r.crate_name_next.take() {
191 r.cur_tok = token::Ident(r.imported_from.unwrap(), token::Plain);
195 let should_pop = match r.stack.last() {
197 assert_eq!(ret_val.tok, token::Eof);
201 if frame.idx < frame.forest.len() {
204 !frame.dotdotdoted ||
205 *r.repeat_idx.last().unwrap() == *r.repeat_len.last().unwrap() - 1
209 /* done with this set; pop or repeat? */
211 let prev = r.stack.pop().unwrap();
212 match r.stack.last_mut() {
214 r.cur_tok = token::Eof;
221 if prev.dotdotdoted {
225 } else { /* repeat */
226 *r.repeat_idx.last_mut().unwrap() += 1;
227 r.stack.last_mut().unwrap().idx = 0;
228 match r.stack.last().unwrap().sep.clone() {
230 r.cur_tok = tk; /* repeat same span, I guess */
237 loop { /* because it's easiest, this handles `TtDelimited` not starting
238 with a `TtToken`, even though it won't happen */
240 let frame = r.stack.last().unwrap();
241 // FIXME(pcwalton): Bad copy.
242 frame.forest.get_tt(frame.idx)
245 TtSequence(sp, seq) => {
246 // FIXME(pcwalton): Bad copy.
247 match lockstep_iter_size(&TtSequence(sp, seq.clone()),
249 LisUnconstrained => {
250 r.sp_diag.span_fatal(
251 sp.clone(), /* blame macro writer */
252 "attempted to repeat an expression \
253 containing no syntax \
254 variables matched as repeating at this depth");
256 LisContradiction(ref msg) => {
257 // FIXME #2887 blame macro invoker instead
258 r.sp_diag.span_fatal(sp.clone(), &msg[..]);
260 LisConstraint(len, _) => {
262 if seq.op == ast::OneOrMore {
263 // FIXME #2887 blame invoker
264 r.sp_diag.span_fatal(sp.clone(),
265 "this must repeat at least once");
268 r.stack.last_mut().unwrap().idx += 1;
269 return tt_next_token(r);
271 r.repeat_len.push(len);
272 r.repeat_idx.push(0);
273 r.stack.push(TtFrame {
276 sep: seq.separator.clone(),
277 forest: TtSequence(sp, seq),
282 // FIXME #2887: think about span stuff here
283 TtToken(sp, SubstNt(ident, namep)) => {
284 r.stack.last_mut().unwrap().idx += 1;
285 match lookup_cur_matched(r, ident) {
288 r.cur_tok = SubstNt(ident, namep);
290 // this can't be 0 length, just like TtDelimited
292 Some(cur_matched) => {
294 // sidestep the interpolation tricks for ident because
295 // (a) idents can be in lots of places, so it'd be a pain
296 // (b) we actually can, since it's a token.
297 MatchedNonterminal(NtIdent(box sn, b)) => {
299 r.cur_tok = token::Ident(sn, b);
302 MatchedNonterminal(ref other_whole_nt) => {
303 // FIXME(pcwalton): Bad copy.
305 r.cur_tok = token::Interpolated((*other_whole_nt).clone());
309 r.sp_diag.span_fatal(
310 r.cur_span, /* blame the macro writer */
311 &format!("variable '{:?}' is still repeating at this depth",
312 token::get_ident(ident)));
318 // TtDelimited or any token that can be unzipped
319 seq @ TtDelimited(..) | seq @ TtToken(_, MatchNt(..)) => {
320 // do not advance the idx yet
321 r.stack.push(TtFrame {
327 // if this could be 0-length, we'd need to potentially recur here
329 TtToken(sp, DocComment(name)) if r.desugar_doc_comments => {
330 r.stack.push(TtFrame {
331 forest: TtToken(sp, DocComment(name)),
337 TtToken(sp, token::SpecialVarNt(SpecialMacroVar::CrateMacroVar)) => {
338 r.stack.last_mut().unwrap().idx += 1;
340 if r.imported_from.is_some() {
342 r.cur_tok = token::ModSep;
343 r.crate_name_next = Some(sp);
347 // otherwise emit nothing and proceed to the next token
349 TtToken(sp, tok) => {
352 r.stack.last_mut().unwrap().idx += 1;