proc_macro_api/msg/
flat.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
//! Serialization-friendly representation of `tt::Subtree`.
//!
//! It is possible to serialize `Subtree` as is, as a tree, but using
//! arbitrary-nested trees in JSON is problematic, as they can cause the JSON
//! parser to overflow the stack.
//!
//! Additionally, such implementation would be pretty verbose, and we do care
//! about performance here a bit.
//!
//! So what this module does is dumping a `tt::Subtree` into a bunch of flat
//! array of numbers. See the test in the parent module to get an example
//! output.
//!
//! ```json
//!  {
//!    // Array of subtrees, each subtree is represented by 4 numbers:
//!    // id of delimiter, delimiter kind, index of first child in `token_tree`,
//!    // index of last child in `token_tree`
//!    "subtree":[4294967295,0,0,5,2,2,5,5],
//!    // 2 ints per literal: [token id, index into `text`]
//!    "literal":[4294967295,1],
//!    // 3 ints per punct: [token id, char, spacing]
//!    "punct":[4294967295,64,1],
//!    // 2 ints per ident: [token id, index into `text`]
//!    "ident":   [0,0,1,1],
//!    // children of all subtrees, concatenated. Each child is represented as `index << 2 | tag`
//!    // where tag denotes one of subtree, literal, punct or ident.
//!    "token_tree":[3,7,1,4],
//!    // Strings shared by idents and literals
//!    "text": ["struct","Foo"]
//!  }
//! ```
//!
//! We probably should replace most of the code here with bincode someday, but,
//! as we don't have bincode in Cargo.toml yet, lets stick with serde_json for
//! the time being.

use std::collections::VecDeque;

use intern::Symbol;
use rustc_hash::FxHashMap;
use serde::{Deserialize, Serialize};
use span::{EditionedFileId, ErasedFileAstId, Span, SpanAnchor, SyntaxContextId, TextRange};

use crate::msg::EXTENDED_LEAF_DATA;

pub type SpanDataIndexMap =
    indexmap::IndexSet<Span, std::hash::BuildHasherDefault<rustc_hash::FxHasher>>;

pub fn serialize_span_data_index_map(map: &SpanDataIndexMap) -> Vec<u32> {
    map.iter()
        .flat_map(|span| {
            [
                span.anchor.file_id.as_u32(),
                span.anchor.ast_id.into_raw(),
                span.range.start().into(),
                span.range.end().into(),
                span.ctx.into_u32(),
            ]
        })
        .collect()
}

pub fn deserialize_span_data_index_map(map: &[u32]) -> SpanDataIndexMap {
    debug_assert!(map.len() % 5 == 0);
    map.chunks_exact(5)
        .map(|span| {
            let &[file_id, ast_id, start, end, e] = span else { unreachable!() };
            Span {
                anchor: SpanAnchor {
                    file_id: EditionedFileId::from_raw(file_id),
                    ast_id: ErasedFileAstId::from_raw(ast_id),
                },
                range: TextRange::new(start.into(), end.into()),
                ctx: SyntaxContextId::from_u32(e),
            }
        })
        .collect()
}

#[derive(Clone, Copy, PartialEq, Eq, Hash)]
pub struct TokenId(pub u32);

impl std::fmt::Debug for TokenId {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        self.0.fmt(f)
    }
}

#[derive(Serialize, Deserialize, Debug)]
pub struct FlatTree {
    subtree: Vec<u32>,
    literal: Vec<u32>,
    punct: Vec<u32>,
    ident: Vec<u32>,
    token_tree: Vec<u32>,
    text: Vec<String>,
}

struct SubtreeRepr {
    open: TokenId,
    close: TokenId,
    kind: tt::DelimiterKind,
    tt: [u32; 2],
}

struct LiteralRepr {
    id: TokenId,
    text: u32,
    suffix: u32,
    kind: u16,
}

struct PunctRepr {
    id: TokenId,
    char: char,
    spacing: tt::Spacing,
}

struct IdentRepr {
    id: TokenId,
    text: u32,
    is_raw: bool,
}

impl FlatTree {
    pub fn new(
        subtree: &tt::Subtree<Span>,
        version: u32,
        span_data_table: &mut SpanDataIndexMap,
    ) -> FlatTree {
        let mut w = Writer {
            string_table: FxHashMap::default(),
            work: VecDeque::new(),
            span_data_table,

            subtree: Vec::new(),
            literal: Vec::new(),
            punct: Vec::new(),
            ident: Vec::new(),
            token_tree: Vec::new(),
            text: Vec::new(),
            version,
        };
        w.write(subtree);

        FlatTree {
            subtree: write_vec(w.subtree, SubtreeRepr::write),
            literal: if version >= EXTENDED_LEAF_DATA {
                write_vec(w.literal, LiteralRepr::write_with_kind)
            } else {
                write_vec(w.literal, LiteralRepr::write)
            },
            punct: write_vec(w.punct, PunctRepr::write),
            ident: if version >= EXTENDED_LEAF_DATA {
                write_vec(w.ident, IdentRepr::write_with_rawness)
            } else {
                write_vec(w.ident, IdentRepr::write)
            },
            token_tree: w.token_tree,
            text: w.text,
        }
    }

    pub fn new_raw(subtree: &tt::Subtree<TokenId>, version: u32) -> FlatTree {
        let mut w = Writer {
            string_table: FxHashMap::default(),
            work: VecDeque::new(),
            span_data_table: &mut (),

            subtree: Vec::new(),
            literal: Vec::new(),
            punct: Vec::new(),
            ident: Vec::new(),
            token_tree: Vec::new(),
            text: Vec::new(),
            version,
        };
        w.write(subtree);

        FlatTree {
            subtree: write_vec(w.subtree, SubtreeRepr::write),
            literal: if version >= EXTENDED_LEAF_DATA {
                write_vec(w.literal, LiteralRepr::write_with_kind)
            } else {
                write_vec(w.literal, LiteralRepr::write)
            },
            punct: write_vec(w.punct, PunctRepr::write),
            ident: if version >= EXTENDED_LEAF_DATA {
                write_vec(w.ident, IdentRepr::write_with_rawness)
            } else {
                write_vec(w.ident, IdentRepr::write)
            },
            token_tree: w.token_tree,
            text: w.text,
        }
    }

    pub fn to_subtree_resolved(
        self,
        version: u32,
        span_data_table: &SpanDataIndexMap,
    ) -> tt::Subtree<Span> {
        Reader {
            subtree: read_vec(self.subtree, SubtreeRepr::read),
            literal: if version >= EXTENDED_LEAF_DATA {
                read_vec(self.literal, LiteralRepr::read_with_kind)
            } else {
                read_vec(self.literal, LiteralRepr::read)
            },
            punct: read_vec(self.punct, PunctRepr::read),
            ident: if version >= EXTENDED_LEAF_DATA {
                read_vec(self.ident, IdentRepr::read_with_rawness)
            } else {
                read_vec(self.ident, IdentRepr::read)
            },
            token_tree: self.token_tree,
            text: self.text,
            span_data_table,
            version,
        }
        .read()
    }

    pub fn to_subtree_unresolved(self, version: u32) -> tt::Subtree<TokenId> {
        Reader {
            subtree: read_vec(self.subtree, SubtreeRepr::read),
            literal: if version >= EXTENDED_LEAF_DATA {
                read_vec(self.literal, LiteralRepr::read_with_kind)
            } else {
                read_vec(self.literal, LiteralRepr::read)
            },
            punct: read_vec(self.punct, PunctRepr::read),
            ident: if version >= EXTENDED_LEAF_DATA {
                read_vec(self.ident, IdentRepr::read_with_rawness)
            } else {
                read_vec(self.ident, IdentRepr::read)
            },
            token_tree: self.token_tree,
            text: self.text,
            span_data_table: &(),
            version,
        }
        .read()
    }
}

fn read_vec<T, F: Fn([u32; N]) -> T, const N: usize>(xs: Vec<u32>, f: F) -> Vec<T> {
    let mut chunks = xs.chunks_exact(N);
    let res = chunks.by_ref().map(|chunk| f(chunk.try_into().unwrap())).collect();
    assert!(chunks.remainder().is_empty());
    res
}

fn write_vec<T, F: Fn(T) -> [u32; N], const N: usize>(xs: Vec<T>, f: F) -> Vec<u32> {
    xs.into_iter().flat_map(f).collect()
}

impl SubtreeRepr {
    fn write(self) -> [u32; 5] {
        let kind = match self.kind {
            tt::DelimiterKind::Invisible => 0,
            tt::DelimiterKind::Parenthesis => 1,
            tt::DelimiterKind::Brace => 2,
            tt::DelimiterKind::Bracket => 3,
        };
        [self.open.0, self.close.0, kind, self.tt[0], self.tt[1]]
    }
    fn read([open, close, kind, lo, len]: [u32; 5]) -> SubtreeRepr {
        let kind = match kind {
            0 => tt::DelimiterKind::Invisible,
            1 => tt::DelimiterKind::Parenthesis,
            2 => tt::DelimiterKind::Brace,
            3 => tt::DelimiterKind::Bracket,
            other => panic!("bad kind {other}"),
        };
        SubtreeRepr { open: TokenId(open), close: TokenId(close), kind, tt: [lo, len] }
    }
}

impl LiteralRepr {
    fn write(self) -> [u32; 2] {
        [self.id.0, self.text]
    }
    fn read([id, text]: [u32; 2]) -> LiteralRepr {
        LiteralRepr { id: TokenId(id), text, kind: 0, suffix: !0 }
    }
    fn write_with_kind(self) -> [u32; 4] {
        [self.id.0, self.text, self.kind as u32, self.suffix]
    }
    fn read_with_kind([id, text, kind, suffix]: [u32; 4]) -> LiteralRepr {
        LiteralRepr { id: TokenId(id), text, kind: kind as u16, suffix }
    }
}

impl PunctRepr {
    fn write(self) -> [u32; 3] {
        let spacing = match self.spacing {
            tt::Spacing::Alone | tt::Spacing::JointHidden => 0,
            tt::Spacing::Joint => 1,
        };
        [self.id.0, self.char as u32, spacing]
    }
    fn read([id, char, spacing]: [u32; 3]) -> PunctRepr {
        let spacing = match spacing {
            0 => tt::Spacing::Alone,
            1 => tt::Spacing::Joint,
            other => panic!("bad spacing {other}"),
        };
        PunctRepr { id: TokenId(id), char: char.try_into().unwrap(), spacing }
    }
}

impl IdentRepr {
    fn write(self) -> [u32; 2] {
        [self.id.0, self.text]
    }
    fn read(data: [u32; 2]) -> IdentRepr {
        IdentRepr { id: TokenId(data[0]), text: data[1], is_raw: false }
    }
    fn write_with_rawness(self) -> [u32; 3] {
        [self.id.0, self.text, self.is_raw as u32]
    }
    fn read_with_rawness([id, text, is_raw]: [u32; 3]) -> IdentRepr {
        IdentRepr { id: TokenId(id), text, is_raw: is_raw == 1 }
    }
}

trait InternableSpan: Copy {
    type Table;
    fn token_id_of(table: &mut Self::Table, s: Self) -> TokenId;
    fn span_for_token_id(table: &Self::Table, id: TokenId) -> Self;
}

impl InternableSpan for TokenId {
    type Table = ();
    fn token_id_of((): &mut Self::Table, token_id: Self) -> TokenId {
        token_id
    }

    fn span_for_token_id((): &Self::Table, id: TokenId) -> Self {
        id
    }
}
impl InternableSpan for Span {
    type Table = SpanDataIndexMap;
    fn token_id_of(table: &mut Self::Table, span: Self) -> TokenId {
        TokenId(table.insert_full(span).0 as u32)
    }
    fn span_for_token_id(table: &Self::Table, id: TokenId) -> Self {
        *table.get_index(id.0 as usize).unwrap_or_else(|| &table[0])
    }
}

struct Writer<'a, 'span, S: InternableSpan> {
    work: VecDeque<(usize, &'a tt::Subtree<S>)>,
    string_table: FxHashMap<std::borrow::Cow<'a, str>, u32>,
    span_data_table: &'span mut S::Table,
    version: u32,

    subtree: Vec<SubtreeRepr>,
    literal: Vec<LiteralRepr>,
    punct: Vec<PunctRepr>,
    ident: Vec<IdentRepr>,
    token_tree: Vec<u32>,
    text: Vec<String>,
}

impl<'a, S: InternableSpan> Writer<'a, '_, S> {
    fn write(&mut self, root: &'a tt::Subtree<S>) {
        self.enqueue(root);
        while let Some((idx, subtree)) = self.work.pop_front() {
            self.subtree(idx, subtree);
        }
    }

    fn token_id_of(&mut self, span: S) -> TokenId {
        S::token_id_of(self.span_data_table, span)
    }

    fn subtree(&mut self, idx: usize, subtree: &'a tt::Subtree<S>) {
        let mut first_tt = self.token_tree.len();
        let n_tt = subtree.token_trees.len();
        self.token_tree.resize(first_tt + n_tt, !0);

        self.subtree[idx].tt = [first_tt as u32, (first_tt + n_tt) as u32];

        for child in subtree.token_trees.iter() {
            let idx_tag = match child {
                tt::TokenTree::Subtree(it) => {
                    let idx = self.enqueue(it);
                    idx << 2
                }
                tt::TokenTree::Leaf(leaf) => match leaf {
                    tt::Leaf::Literal(lit) => {
                        let idx = self.literal.len() as u32;
                        let id = self.token_id_of(lit.span);
                        let (text, suffix) = if self.version >= EXTENDED_LEAF_DATA {
                            (
                                self.intern(lit.symbol.as_str()),
                                lit.suffix.as_ref().map(|s| self.intern(s.as_str())).unwrap_or(!0),
                            )
                        } else {
                            (self.intern_owned(format!("{lit}")), !0)
                        };
                        self.literal.push(LiteralRepr {
                            id,
                            text,
                            kind: u16::from_le_bytes(match lit.kind {
                                tt::LitKind::Err(_) => [0, 0],
                                tt::LitKind::Byte => [1, 0],
                                tt::LitKind::Char => [2, 0],
                                tt::LitKind::Integer => [3, 0],
                                tt::LitKind::Float => [4, 0],
                                tt::LitKind::Str => [5, 0],
                                tt::LitKind::StrRaw(r) => [6, r],
                                tt::LitKind::ByteStr => [7, 0],
                                tt::LitKind::ByteStrRaw(r) => [8, r],
                                tt::LitKind::CStr => [9, 0],
                                tt::LitKind::CStrRaw(r) => [10, r],
                            }),
                            suffix,
                        });
                        idx << 2 | 0b01
                    }
                    tt::Leaf::Punct(punct) => {
                        let idx = self.punct.len() as u32;
                        let id = self.token_id_of(punct.span);
                        self.punct.push(PunctRepr { char: punct.char, spacing: punct.spacing, id });
                        idx << 2 | 0b10
                    }
                    tt::Leaf::Ident(ident) => {
                        let idx = self.ident.len() as u32;
                        let id = self.token_id_of(ident.span);
                        let text = if self.version >= EXTENDED_LEAF_DATA {
                            self.intern(ident.sym.as_str())
                        } else if ident.is_raw.yes() {
                            self.intern_owned(format!("r#{}", ident.sym.as_str(),))
                        } else {
                            self.intern(ident.sym.as_str())
                        };
                        self.ident.push(IdentRepr { id, text, is_raw: ident.is_raw.yes() });
                        idx << 2 | 0b11
                    }
                },
            };
            self.token_tree[first_tt] = idx_tag;
            first_tt += 1;
        }
    }

    fn enqueue(&mut self, subtree: &'a tt::Subtree<S>) -> u32 {
        let idx = self.subtree.len();
        let open = self.token_id_of(subtree.delimiter.open);
        let close = self.token_id_of(subtree.delimiter.close);
        let delimiter_kind = subtree.delimiter.kind;
        self.subtree.push(SubtreeRepr { open, close, kind: delimiter_kind, tt: [!0, !0] });
        self.work.push_back((idx, subtree));
        idx as u32
    }

    pub(crate) fn intern(&mut self, text: &'a str) -> u32 {
        let table = &mut self.text;
        *self.string_table.entry(text.into()).or_insert_with(|| {
            let idx = table.len();
            table.push(text.to_owned());
            idx as u32
        })
    }

    pub(crate) fn intern_owned(&mut self, text: String) -> u32 {
        let table = &mut self.text;
        *self.string_table.entry(text.clone().into()).or_insert_with(|| {
            let idx = table.len();
            table.push(text);
            idx as u32
        })
    }
}

struct Reader<'span, S: InternableSpan> {
    version: u32,
    subtree: Vec<SubtreeRepr>,
    literal: Vec<LiteralRepr>,
    punct: Vec<PunctRepr>,
    ident: Vec<IdentRepr>,
    token_tree: Vec<u32>,
    text: Vec<String>,
    span_data_table: &'span S::Table,
}

impl<S: InternableSpan> Reader<'_, S> {
    pub(crate) fn read(self) -> tt::Subtree<S> {
        let mut res: Vec<Option<tt::Subtree<S>>> = vec![None; self.subtree.len()];
        let read_span = |id| S::span_for_token_id(self.span_data_table, id);
        for i in (0..self.subtree.len()).rev() {
            let repr = &self.subtree[i];
            let token_trees = &self.token_tree[repr.tt[0] as usize..repr.tt[1] as usize];
            let s = tt::Subtree {
                delimiter: tt::Delimiter {
                    open: read_span(repr.open),
                    close: read_span(repr.close),
                    kind: repr.kind,
                },
                token_trees: token_trees
                    .iter()
                    .copied()
                    .map(|idx_tag| {
                        let tag = idx_tag & 0b11;
                        let idx = (idx_tag >> 2) as usize;
                        match tag {
                            // XXX: we iterate subtrees in reverse to guarantee
                            // that this unwrap doesn't fire.
                            0b00 => res[idx].take().unwrap().into(),
                            0b01 => {
                                use tt::LitKind::*;
                                let repr = &self.literal[idx];
                                let text = self.text[repr.text as usize].as_str();
                                let span = read_span(repr.id);
                                tt::Leaf::Literal(if self.version >= EXTENDED_LEAF_DATA {
                                    tt::Literal {
                                        symbol: Symbol::intern(text),
                                        span,
                                        kind: match u16::to_le_bytes(repr.kind) {
                                            [0, _] => Err(()),
                                            [1, _] => Byte,
                                            [2, _] => Char,
                                            [3, _] => Integer,
                                            [4, _] => Float,
                                            [5, _] => Str,
                                            [6, r] => StrRaw(r),
                                            [7, _] => ByteStr,
                                            [8, r] => ByteStrRaw(r),
                                            [9, _] => CStr,
                                            [10, r] => CStrRaw(r),
                                            _ => unreachable!(),
                                        },
                                        suffix: if repr.suffix != !0 {
                                            Some(Symbol::intern(
                                                self.text[repr.suffix as usize].as_str(),
                                            ))
                                        } else {
                                            None
                                        },
                                    }
                                } else {
                                    tt::token_to_literal(text, span)
                                })
                                .into()
                            }
                            0b10 => {
                                let repr = &self.punct[idx];
                                tt::Leaf::Punct(tt::Punct {
                                    char: repr.char,
                                    spacing: repr.spacing,
                                    span: read_span(repr.id),
                                })
                                .into()
                            }
                            0b11 => {
                                let repr = &self.ident[idx];
                                let text = self.text[repr.text as usize].as_str();
                                let (is_raw, text) = if self.version >= EXTENDED_LEAF_DATA {
                                    (
                                        if repr.is_raw {
                                            tt::IdentIsRaw::Yes
                                        } else {
                                            tt::IdentIsRaw::No
                                        },
                                        text,
                                    )
                                } else {
                                    tt::IdentIsRaw::split_from_symbol(text)
                                };
                                tt::Leaf::Ident(tt::Ident {
                                    sym: Symbol::intern(text),
                                    span: read_span(repr.id),
                                    is_raw,
                                })
                                .into()
                            }
                            other => panic!("bad tag: {other}"),
                        }
                    })
                    .collect(),
            };
            res[i] = Some(s);
        }

        res[0].take().unwrap()
    }
}