2 use crate::ext::base::ExtCtxt;
3 use crate::ext::expand::Marker;
4 use crate::ext::tt::macro_parser::{NamedMatch, MatchedSeq, MatchedNonterminal};
5 use crate::ext::tt::quoted;
6 use crate::mut_visit::noop_visit_tt;
7 use crate::parse::token::{self, Token, NtTT};
8 use crate::tokenstream::{DelimSpan, TokenStream, TokenTree, TreeAndJoint};
10 use smallvec::{smallvec, SmallVec};
11 use syntax_pos::DUMMY_SP;
13 use rustc_data_structures::fx::FxHashMap;
14 use rustc_data_structures::sync::Lrc;
19 // An iterator over the token trees in a delimited token tree (`{ ... }`) or a sequence (`$(...)`).
22 forest: Lrc<quoted::Delimited>,
27 forest: Lrc<quoted::SequenceRepetition>,
34 fn new(tts: Vec<quoted::TokenTree>) -> Frame {
35 let forest = Lrc::new(quoted::Delimited { delim: token::NoDelim, tts: tts });
36 Frame::Delimited { forest: forest, idx: 0, span: DelimSpan::dummy() }
40 impl Iterator for Frame {
41 type Item = quoted::TokenTree;
43 fn next(&mut self) -> Option<quoted::TokenTree> {
45 Frame::Delimited { ref forest, ref mut idx, .. } => {
47 forest.tts.get(*idx - 1).cloned()
49 Frame::Sequence { ref forest, ref mut idx, .. } => {
51 forest.tts.get(*idx - 1).cloned()
57 /// This can do Macro-By-Example transcription. On the other hand, if
58 /// `src` contains no `TokenTree::{Sequence, MetaVar, MetaVarDecl}`s, `interp` can
59 /// (and should) be None.
60 pub fn transcribe(cx: &ExtCtxt<'_>,
61 interp: Option<FxHashMap<Ident, Rc<NamedMatch>>>,
62 src: Vec<quoted::TokenTree>)
64 let mut stack: SmallVec<[Frame; 1]> = smallvec![Frame::new(src)];
65 let interpolations = interp.unwrap_or_else(FxHashMap::default); /* just a convenience */
66 let mut repeats = Vec::new();
67 let mut result: Vec<TreeAndJoint> = Vec::new();
68 let mut result_stack = Vec::new();
71 let tree = if let Some(tree) = stack.last_mut().unwrap().next() {
74 if let Frame::Sequence { ref mut idx, ref sep, .. } = *stack.last_mut().unwrap() {
75 let (ref mut repeat_idx, repeat_len) = *repeats.last_mut().unwrap();
77 if *repeat_idx < repeat_len {
79 if let Some(sep) = sep.clone() {
80 // repeat same span, I guess
81 let prev_span = match result.last() {
82 Some((tt, _)) => tt.span(),
85 result.push(TokenTree::Token(prev_span, sep).into());
91 match stack.pop().unwrap() {
92 Frame::Sequence { .. } => {
95 Frame::Delimited { forest, span, .. } => {
96 if result_stack.is_empty() {
97 return TokenStream::new(result);
99 let tree = TokenTree::Delimited(
102 TokenStream::new(result).into(),
104 result = result_stack.pop().unwrap();
105 result.push(tree.into());
112 quoted::TokenTree::Sequence(sp, seq) => {
113 // FIXME(pcwalton): Bad copy.
114 match lockstep_iter_size("ed::TokenTree::Sequence(sp, seq.clone()),
117 LockstepIterSize::Unconstrained => {
118 cx.span_fatal(sp.entire(), /* blame macro writer */
119 "attempted to repeat an expression \
120 containing no syntax \
121 variables matched as repeating at this depth");
123 LockstepIterSize::Contradiction(ref msg) => {
124 // FIXME #2887 blame macro invoker instead
125 cx.span_fatal(sp.entire(), &msg[..]);
127 LockstepIterSize::Constraint(len, _) => {
129 if seq.op == quoted::KleeneOp::OneOrMore {
130 // FIXME #2887 blame invoker
131 cx.span_fatal(sp.entire(), "this must repeat at least once");
134 repeats.push((0, len));
135 stack.push(Frame::Sequence {
137 sep: seq.separator.clone(),
144 // FIXME #2887: think about span stuff here
145 quoted::TokenTree::MetaVar(mut sp, ident) => {
146 if let Some(cur_matched) = lookup_cur_matched(ident, &interpolations, &repeats) {
147 if let MatchedNonterminal(ref nt) = *cur_matched {
148 if let NtTT(ref tt) = **nt {
149 result.push(tt.clone().into());
151 sp = sp.apply_mark(cx.current_expansion.mark);
152 let token = TokenTree::Token(sp, Token::interpolated((**nt).clone()));
153 result.push(token.into());
156 cx.span_fatal(sp, /* blame the macro writer */
157 &format!("variable '{}' is still repeating at this depth", ident));
161 Ident::new(ident.name, ident.span.apply_mark(cx.current_expansion.mark));
162 sp = sp.apply_mark(cx.current_expansion.mark);
163 result.push(TokenTree::Token(sp, token::Dollar).into());
164 result.push(TokenTree::Token(sp, token::Token::from_ast_ident(ident)).into());
167 quoted::TokenTree::Delimited(mut span, delimited) => {
168 span = span.apply_mark(cx.current_expansion.mark);
169 stack.push(Frame::Delimited { forest: delimited, idx: 0, span: span });
170 result_stack.push(mem::replace(&mut result, Vec::new()));
172 quoted::TokenTree::Token(sp, tok) => {
173 let mut marker = Marker(cx.current_expansion.mark);
174 let mut tt = TokenTree::Token(sp, tok);
175 noop_visit_tt(&mut tt, &mut marker);
176 result.push(tt.into());
178 quoted::TokenTree::MetaVarDecl(..) => panic!("unexpected `TokenTree::MetaVarDecl"),
183 fn lookup_cur_matched(ident: Ident,
184 interpolations: &FxHashMap<Ident, Rc<NamedMatch>>,
185 repeats: &[(usize, usize)])
186 -> Option<Rc<NamedMatch>> {
187 interpolations.get(&ident).map(|matched| {
188 let mut matched = matched.clone();
189 for &(idx, _) in repeats {
190 let m = matched.clone();
192 MatchedNonterminal(_) => break,
193 MatchedSeq(ref ads, _) => matched = Rc::new(ads[idx].clone()),
202 enum LockstepIterSize {
204 Constraint(usize, Ident),
205 Contradiction(String),
208 impl Add for LockstepIterSize {
209 type Output = LockstepIterSize;
211 fn add(self, other: LockstepIterSize) -> LockstepIterSize {
213 LockstepIterSize::Unconstrained => other,
214 LockstepIterSize::Contradiction(_) => self,
215 LockstepIterSize::Constraint(l_len, ref l_id) => match other {
216 LockstepIterSize::Unconstrained => self,
217 LockstepIterSize::Contradiction(_) => other,
218 LockstepIterSize::Constraint(r_len, _) if l_len == r_len => self,
219 LockstepIterSize::Constraint(r_len, r_id) => {
220 let msg = format!("inconsistent lockstep iteration: \
221 '{}' has {} items, but '{}' has {}",
222 l_id, l_len, r_id, r_len);
223 LockstepIterSize::Contradiction(msg)
230 fn lockstep_iter_size(tree: "ed::TokenTree,
231 interpolations: &FxHashMap<Ident, Rc<NamedMatch>>,
232 repeats: &[(usize, usize)])
233 -> LockstepIterSize {
234 use quoted::TokenTree;
236 TokenTree::Delimited(_, ref delimed) => {
237 delimed.tts.iter().fold(LockstepIterSize::Unconstrained, |size, tt| {
238 size + lockstep_iter_size(tt, interpolations, repeats)
241 TokenTree::Sequence(_, ref seq) => {
242 seq.tts.iter().fold(LockstepIterSize::Unconstrained, |size, tt| {
243 size + lockstep_iter_size(tt, interpolations, repeats)
246 TokenTree::MetaVar(_, name) | TokenTree::MetaVarDecl(_, name, _) =>
247 match lookup_cur_matched(name, interpolations, repeats) {
248 Some(matched) => match *matched {
249 MatchedNonterminal(_) => LockstepIterSize::Unconstrained,
250 MatchedSeq(ref ads, _) => LockstepIterSize::Constraint(ads.len(), name),
252 _ => LockstepIterSize::Unconstrained
254 TokenTree::Token(..) => LockstepIterSize::Unconstrained,