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Diffstat (limited to 'third_party/rust/regex/src/compile.rs')
| -rw-r--r-- | third_party/rust/regex/src/compile.rs | 1264 |
1 files changed, 1264 insertions, 0 deletions
diff --git a/third_party/rust/regex/src/compile.rs b/third_party/rust/regex/src/compile.rs new file mode 100644 index 0000000000..90ca25015f --- /dev/null +++ b/third_party/rust/regex/src/compile.rs @@ -0,0 +1,1264 @@ +use std::collections::HashMap; +use std::fmt; +use std::iter; +use std::result; +use std::sync::Arc; + +use regex_syntax::hir::{self, Hir}; +use regex_syntax::is_word_byte; +use regex_syntax::utf8::{Utf8Range, Utf8Sequence, Utf8Sequences}; + +use crate::prog::{ + EmptyLook, Inst, InstBytes, InstChar, InstEmptyLook, InstPtr, InstRanges, + InstSave, InstSplit, Program, +}; + +use crate::Error; + +type Result = result::Result<Patch, Error>; +type ResultOrEmpty = result::Result<Option<Patch>, Error>; + +#[derive(Debug)] +struct Patch { + hole: Hole, + entry: InstPtr, +} + +/// A compiler translates a regular expression AST to a sequence of +/// instructions. The sequence of instructions represents an NFA. +// `Compiler` is only public via the `internal` module, so avoid deriving +// `Debug`. +#[allow(missing_debug_implementations)] +pub struct Compiler { + insts: Vec<MaybeInst>, + compiled: Program, + capture_name_idx: HashMap<String, usize>, + num_exprs: usize, + size_limit: usize, + suffix_cache: SuffixCache, + utf8_seqs: Option<Utf8Sequences>, + byte_classes: ByteClassSet, + // This keeps track of extra bytes allocated while compiling the regex + // program. Currently, this corresponds to two things. First is the heap + // memory allocated by Unicode character classes ('InstRanges'). Second is + // a "fake" amount of memory used by empty sub-expressions, so that enough + // empty sub-expressions will ultimately trigger the compiler to bail + // because of a size limit restriction. (That empty sub-expressions don't + // add to heap memory usage is more-or-less an implementation detail.) In + // the second case, if we don't bail, then an excessively large repetition + // on an empty sub-expression can result in the compiler using a very large + // amount of CPU time. + extra_inst_bytes: usize, +} + +impl Compiler { + /// Create a new regular expression compiler. + /// + /// Various options can be set before calling `compile` on an expression. + pub fn new() -> Self { + Compiler { + insts: vec![], + compiled: Program::new(), + capture_name_idx: HashMap::new(), + num_exprs: 0, + size_limit: 10 * (1 << 20), + suffix_cache: SuffixCache::new(1000), + utf8_seqs: Some(Utf8Sequences::new('\x00', '\x00')), + byte_classes: ByteClassSet::new(), + extra_inst_bytes: 0, + } + } + + /// The size of the resulting program is limited by size_limit. If + /// the program approximately exceeds the given size (in bytes), then + /// compilation will stop and return an error. + pub fn size_limit(mut self, size_limit: usize) -> Self { + self.size_limit = size_limit; + self + } + + /// If bytes is true, then the program is compiled as a byte based + /// automaton, which incorporates UTF-8 decoding into the machine. If it's + /// false, then the automaton is Unicode scalar value based, e.g., an + /// engine utilizing such an automaton is responsible for UTF-8 decoding. + /// + /// The specific invariant is that when returning a byte based machine, + /// the neither the `Char` nor `Ranges` instructions are produced. + /// Conversely, when producing a Unicode scalar value machine, the `Bytes` + /// instruction is never produced. + /// + /// Note that `dfa(true)` implies `bytes(true)`. + pub fn bytes(mut self, yes: bool) -> Self { + self.compiled.is_bytes = yes; + self + } + + /// When disabled, the program compiled may match arbitrary bytes. + /// + /// When enabled (the default), all compiled programs exclusively match + /// valid UTF-8 bytes. + pub fn only_utf8(mut self, yes: bool) -> Self { + self.compiled.only_utf8 = yes; + self + } + + /// When set, the machine returned is suitable for use in the DFA matching + /// engine. + /// + /// In particular, this ensures that if the regex is not anchored in the + /// beginning, then a preceding `.*?` is included in the program. (The NFA + /// based engines handle the preceding `.*?` explicitly, which is difficult + /// or impossible in the DFA engine.) + pub fn dfa(mut self, yes: bool) -> Self { + self.compiled.is_dfa = yes; + self + } + + /// When set, the machine returned is suitable for matching text in + /// reverse. In particular, all concatenations are flipped. + pub fn reverse(mut self, yes: bool) -> Self { + self.compiled.is_reverse = yes; + self + } + + /// Compile a regular expression given its AST. + /// + /// The compiler is guaranteed to succeed unless the program exceeds the + /// specified size limit. If the size limit is exceeded, then compilation + /// stops and returns an error. + pub fn compile(mut self, exprs: &[Hir]) -> result::Result<Program, Error> { + debug_assert!(!exprs.is_empty()); + self.num_exprs = exprs.len(); + if exprs.len() == 1 { + self.compile_one(&exprs[0]) + } else { + self.compile_many(exprs) + } + } + + fn compile_one(mut self, expr: &Hir) -> result::Result<Program, Error> { + // If we're compiling a forward DFA and we aren't anchored, then + // add a `.*?` before the first capture group. + // Other matching engines handle this by baking the logic into the + // matching engine itself. + let mut dotstar_patch = Patch { hole: Hole::None, entry: 0 }; + self.compiled.is_anchored_start = expr.is_anchored_start(); + self.compiled.is_anchored_end = expr.is_anchored_end(); + if self.compiled.needs_dotstar() { + dotstar_patch = self.c_dotstar()?; + self.compiled.start = dotstar_patch.entry; + } + self.compiled.captures = vec![None]; + let patch = + self.c_capture(0, expr)?.unwrap_or_else(|| self.next_inst()); + if self.compiled.needs_dotstar() { + self.fill(dotstar_patch.hole, patch.entry); + } else { + self.compiled.start = patch.entry; + } + self.fill_to_next(patch.hole); + self.compiled.matches = vec![self.insts.len()]; + self.push_compiled(Inst::Match(0)); + self.compile_finish() + } + + fn compile_many( + mut self, + exprs: &[Hir], + ) -> result::Result<Program, Error> { + debug_assert!(exprs.len() > 1); + + self.compiled.is_anchored_start = + exprs.iter().all(|e| e.is_anchored_start()); + self.compiled.is_anchored_end = + exprs.iter().all(|e| e.is_anchored_end()); + let mut dotstar_patch = Patch { hole: Hole::None, entry: 0 }; + if self.compiled.needs_dotstar() { + dotstar_patch = self.c_dotstar()?; + self.compiled.start = dotstar_patch.entry; + } else { + self.compiled.start = 0; // first instruction is always split + } + self.fill_to_next(dotstar_patch.hole); + + let mut prev_hole = Hole::None; + for (i, expr) in exprs[0..exprs.len() - 1].iter().enumerate() { + self.fill_to_next(prev_hole); + let split = self.push_split_hole(); + let Patch { hole, entry } = + self.c_capture(0, expr)?.unwrap_or_else(|| self.next_inst()); + self.fill_to_next(hole); + self.compiled.matches.push(self.insts.len()); + self.push_compiled(Inst::Match(i)); + prev_hole = self.fill_split(split, Some(entry), None); + } + let i = exprs.len() - 1; + let Patch { hole, entry } = + self.c_capture(0, &exprs[i])?.unwrap_or_else(|| self.next_inst()); + self.fill(prev_hole, entry); + self.fill_to_next(hole); + self.compiled.matches.push(self.insts.len()); + self.push_compiled(Inst::Match(i)); + self.compile_finish() + } + + fn compile_finish(mut self) -> result::Result<Program, Error> { + self.compiled.insts = + self.insts.into_iter().map(|inst| inst.unwrap()).collect(); + self.compiled.byte_classes = self.byte_classes.byte_classes(); + self.compiled.capture_name_idx = Arc::new(self.capture_name_idx); + Ok(self.compiled) + } + + /// Compile expr into self.insts, returning a patch on success, + /// or an error if we run out of memory. + /// + /// All of the c_* methods of the compiler share the contract outlined + /// here. + /// + /// The main thing that a c_* method does is mutate `self.insts` + /// to add a list of mostly compiled instructions required to execute + /// the given expression. `self.insts` contains MaybeInsts rather than + /// Insts because there is some backpatching required. + /// + /// The `Patch` value returned by each c_* method provides metadata + /// about the compiled instructions emitted to `self.insts`. The + /// `entry` member of the patch refers to the first instruction + /// (the entry point), while the `hole` member contains zero or + /// more offsets to partial instructions that need to be backpatched. + /// The c_* routine can't know where its list of instructions are going to + /// jump to after execution, so it is up to the caller to patch + /// these jumps to point to the right place. So compiling some + /// expression, e, we would end up with a situation that looked like: + /// + /// ```text + /// self.insts = [ ..., i1, i2, ..., iexit1, ..., iexitn, ...] + /// ^ ^ ^ + /// | \ / + /// entry \ / + /// hole + /// ``` + /// + /// To compile two expressions, e1 and e2, concatenated together we + /// would do: + /// + /// ```ignore + /// let patch1 = self.c(e1); + /// let patch2 = self.c(e2); + /// ``` + /// + /// while leaves us with a situation that looks like + /// + /// ```text + /// self.insts = [ ..., i1, ..., iexit1, ..., i2, ..., iexit2 ] + /// ^ ^ ^ ^ + /// | | | | + /// entry1 hole1 entry2 hole2 + /// ``` + /// + /// Then to merge the two patches together into one we would backpatch + /// hole1 with entry2 and return a new patch that enters at entry1 + /// and has hole2 for a hole. In fact, if you look at the c_concat + /// method you will see that it does exactly this, though it handles + /// a list of expressions rather than just the two that we use for + /// an example. + /// + /// Ok(None) is returned when an expression is compiled to no + /// instruction, and so no patch.entry value makes sense. + fn c(&mut self, expr: &Hir) -> ResultOrEmpty { + use crate::prog; + use regex_syntax::hir::HirKind::*; + + self.check_size()?; + match *expr.kind() { + Empty => self.c_empty(), + Literal(hir::Literal::Unicode(c)) => self.c_char(c), + Literal(hir::Literal::Byte(b)) => { + assert!(self.compiled.uses_bytes()); + self.c_byte(b) + } + Class(hir::Class::Unicode(ref cls)) => self.c_class(cls.ranges()), + Class(hir::Class::Bytes(ref cls)) => { + if self.compiled.uses_bytes() { + self.c_class_bytes(cls.ranges()) + } else { + assert!(cls.is_all_ascii()); + let mut char_ranges = vec![]; + for r in cls.iter() { + let (s, e) = (r.start() as char, r.end() as char); + char_ranges.push(hir::ClassUnicodeRange::new(s, e)); + } + self.c_class(&char_ranges) + } + } + Anchor(hir::Anchor::StartLine) if self.compiled.is_reverse => { + self.byte_classes.set_range(b'\n', b'\n'); + self.c_empty_look(prog::EmptyLook::EndLine) + } + Anchor(hir::Anchor::StartLine) => { + self.byte_classes.set_range(b'\n', b'\n'); + self.c_empty_look(prog::EmptyLook::StartLine) + } + Anchor(hir::Anchor::EndLine) if self.compiled.is_reverse => { + self.byte_classes.set_range(b'\n', b'\n'); + self.c_empty_look(prog::EmptyLook::StartLine) + } + Anchor(hir::Anchor::EndLine) => { + self.byte_classes.set_range(b'\n', b'\n'); + self.c_empty_look(prog::EmptyLook::EndLine) + } + Anchor(hir::Anchor::StartText) if self.compiled.is_reverse => { + self.c_empty_look(prog::EmptyLook::EndText) + } + Anchor(hir::Anchor::StartText) => { + self.c_empty_look(prog::EmptyLook::StartText) + } + Anchor(hir::Anchor::EndText) if self.compiled.is_reverse => { + self.c_empty_look(prog::EmptyLook::StartText) + } + Anchor(hir::Anchor::EndText) => { + self.c_empty_look(prog::EmptyLook::EndText) + } + WordBoundary(hir::WordBoundary::Unicode) => { + if !cfg!(feature = "unicode-perl") { + return Err(Error::Syntax( + "Unicode word boundaries are unavailable when \ + the unicode-perl feature is disabled" + .to_string(), + )); + } + self.compiled.has_unicode_word_boundary = true; + self.byte_classes.set_word_boundary(); + // We also make sure that all ASCII bytes are in a different + // class from non-ASCII bytes. Otherwise, it's possible for + // ASCII bytes to get lumped into the same class as non-ASCII + // bytes. This in turn may cause the lazy DFA to falsely start + // when it sees an ASCII byte that maps to a byte class with + // non-ASCII bytes. This ensures that never happens. + self.byte_classes.set_range(0, 0x7F); + self.c_empty_look(prog::EmptyLook::WordBoundary) + } + WordBoundary(hir::WordBoundary::UnicodeNegate) => { + if !cfg!(feature = "unicode-perl") { + return Err(Error::Syntax( + "Unicode word boundaries are unavailable when \ + the unicode-perl feature is disabled" + .to_string(), + )); + } + self.compiled.has_unicode_word_boundary = true; + self.byte_classes.set_word_boundary(); + // See comments above for why we set the ASCII range here. + self.byte_classes.set_range(0, 0x7F); + self.c_empty_look(prog::EmptyLook::NotWordBoundary) + } + WordBoundary(hir::WordBoundary::Ascii) => { + self.byte_classes.set_word_boundary(); + self.c_empty_look(prog::EmptyLook::WordBoundaryAscii) + } + WordBoundary(hir::WordBoundary::AsciiNegate) => { + self.byte_classes.set_word_boundary(); + self.c_empty_look(prog::EmptyLook::NotWordBoundaryAscii) + } + Group(ref g) => match g.kind { + hir::GroupKind::NonCapturing => self.c(&g.hir), + hir::GroupKind::CaptureIndex(index) => { + if index as usize >= self.compiled.captures.len() { + self.compiled.captures.push(None); + } + self.c_capture(2 * index as usize, &g.hir) + } + hir::GroupKind::CaptureName { index, ref name } => { + if index as usize >= self.compiled.captures.len() { + let n = name.to_string(); + self.compiled.captures.push(Some(n.clone())); + self.capture_name_idx.insert(n, index as usize); + } + self.c_capture(2 * index as usize, &g.hir) + } + }, + Concat(ref es) => { + if self.compiled.is_reverse { + self.c_concat(es.iter().rev()) + } else { + self.c_concat(es) + } + } + Alternation(ref es) => self.c_alternate(&**es), + Repetition(ref rep) => self.c_repeat(rep), + } + } + + fn c_empty(&mut self) -> ResultOrEmpty { + // See: https://github.com/rust-lang/regex/security/advisories/GHSA-m5pq-gvj9-9vr8 + // See: CVE-2022-24713 + // + // Since 'empty' sub-expressions don't increase the size of + // the actual compiled object, we "fake" an increase in its + // size so that our 'check_size_limit' routine will eventually + // stop compilation if there are too many empty sub-expressions + // (e.g., via a large repetition). + self.extra_inst_bytes += std::mem::size_of::<Inst>(); + Ok(None) + } + + fn c_capture(&mut self, first_slot: usize, expr: &Hir) -> ResultOrEmpty { + if self.num_exprs > 1 || self.compiled.is_dfa { + // Don't ever compile Save instructions for regex sets because + // they are never used. They are also never used in DFA programs + // because DFAs can't handle captures. + self.c(expr) + } else { + let entry = self.insts.len(); + let hole = self.push_hole(InstHole::Save { slot: first_slot }); + let patch = self.c(expr)?.unwrap_or_else(|| self.next_inst()); + self.fill(hole, patch.entry); + self.fill_to_next(patch.hole); + let hole = self.push_hole(InstHole::Save { slot: first_slot + 1 }); + Ok(Some(Patch { hole, entry })) + } + } + + fn c_dotstar(&mut self) -> Result { + Ok(if !self.compiled.only_utf8() { + self.c(&Hir::repetition(hir::Repetition { + kind: hir::RepetitionKind::ZeroOrMore, + greedy: false, + hir: Box::new(Hir::any(true)), + }))? + .unwrap() + } else { + self.c(&Hir::repetition(hir::Repetition { + kind: hir::RepetitionKind::ZeroOrMore, + greedy: false, + hir: Box::new(Hir::any(false)), + }))? + .unwrap() + }) + } + + fn c_char(&mut self, c: char) -> ResultOrEmpty { + if self.compiled.uses_bytes() { + if c.is_ascii() { + let b = c as u8; + let hole = + self.push_hole(InstHole::Bytes { start: b, end: b }); + self.byte_classes.set_range(b, b); + Ok(Some(Patch { hole, entry: self.insts.len() - 1 })) + } else { + self.c_class(&[hir::ClassUnicodeRange::new(c, c)]) + } + } else { + let hole = self.push_hole(InstHole::Char { c }); + Ok(Some(Patch { hole, entry: self.insts.len() - 1 })) + } + } + + fn c_class(&mut self, ranges: &[hir::ClassUnicodeRange]) -> ResultOrEmpty { + use std::mem::size_of; + + assert!(!ranges.is_empty()); + if self.compiled.uses_bytes() { + Ok(Some(CompileClass { c: self, ranges }.compile()?)) + } else { + let ranges: Vec<(char, char)> = + ranges.iter().map(|r| (r.start(), r.end())).collect(); + let hole = if ranges.len() == 1 && ranges[0].0 == ranges[0].1 { + self.push_hole(InstHole::Char { c: ranges[0].0 }) + } else { + self.extra_inst_bytes += + ranges.len() * (size_of::<char>() * 2); + self.push_hole(InstHole::Ranges { ranges }) + }; + Ok(Some(Patch { hole, entry: self.insts.len() - 1 })) + } + } + + fn c_byte(&mut self, b: u8) -> ResultOrEmpty { + self.c_class_bytes(&[hir::ClassBytesRange::new(b, b)]) + } + + fn c_class_bytes( + &mut self, + ranges: &[hir::ClassBytesRange], + ) -> ResultOrEmpty { + debug_assert!(!ranges.is_empty()); + + let first_split_entry = self.insts.len(); + let mut holes = vec![]; + let mut prev_hole = Hole::None; + for r in &ranges[0..ranges.len() - 1] { + self.fill_to_next(prev_hole); + let split = self.push_split_hole(); + let next = self.insts.len(); + self.byte_classes.set_range(r.start(), r.end()); + holes.push(self.push_hole(InstHole::Bytes { + start: r.start(), + end: r.end(), + })); + prev_hole = self.fill_split(split, Some(next), None); + } + let next = self.insts.len(); + let r = &ranges[ranges.len() - 1]; + self.byte_classes.set_range(r.start(), r.end()); + holes.push( + self.push_hole(InstHole::Bytes { start: r.start(), end: r.end() }), + ); + self.fill(prev_hole, next); + Ok(Some(Patch { hole: Hole::Many(holes), entry: first_split_entry })) + } + + fn c_empty_look(&mut self, look: EmptyLook) -> ResultOrEmpty { + let hole = self.push_hole(InstHole::EmptyLook { look }); + Ok(Some(Patch { hole, entry: self.insts.len() - 1 })) + } + + fn c_concat<'a, I>(&mut self, exprs: I) -> ResultOrEmpty + where + I: IntoIterator<Item = &'a Hir>, + { + let mut exprs = exprs.into_iter(); + let Patch { mut hole, entry } = loop { + match exprs.next() { + None => return self.c_empty(), + Some(e) => { + if let Some(p) = self.c(e)? { + break p; + } + } + } + }; + for e in exprs { + if let Some(p) = self.c(e)? { + self.fill(hole, p.entry); + hole = p.hole; + } + } + Ok(Some(Patch { hole, entry })) + } + + fn c_alternate(&mut self, exprs: &[Hir]) -> ResultOrEmpty { + debug_assert!( + exprs.len() >= 2, + "alternates must have at least 2 exprs" + ); + + // Initial entry point is always the first split. + let first_split_entry = self.insts.len(); + + // Save up all of the holes from each alternate. They will all get + // patched to point to the same location. + let mut holes = vec![]; + + // true indicates that the hole is a split where we want to fill + // the second branch. + let mut prev_hole = (Hole::None, false); + for e in &exprs[0..exprs.len() - 1] { + if prev_hole.1 { + let next = self.insts.len(); + self.fill_split(prev_hole.0, None, Some(next)); + } else { + self.fill_to_next(prev_hole.0); + } + let split = self.push_split_hole(); + if let Some(Patch { hole, entry }) = self.c(e)? { + holes.push(hole); + prev_hole = (self.fill_split(split, Some(entry), None), false); + } else { + let (split1, split2) = split.dup_one(); + holes.push(split1); + prev_hole = (split2, true); + } + } + if let Some(Patch { hole, entry }) = self.c(&exprs[exprs.len() - 1])? { + holes.push(hole); + if prev_hole.1 { + self.fill_split(prev_hole.0, None, Some(entry)); + } else { + self.fill(prev_hole.0, entry); + } + } else { + // We ignore prev_hole.1. When it's true, it means we have two + // empty branches both pushing prev_hole.0 into holes, so both + // branches will go to the same place anyway. + holes.push(prev_hole.0); + } + Ok(Some(Patch { hole: Hole::Many(holes), entry: first_split_entry })) + } + + fn c_repeat(&mut self, rep: &hir::Repetition) -> ResultOrEmpty { + use regex_syntax::hir::RepetitionKind::*; + match rep.kind { + ZeroOrOne => self.c_repeat_zero_or_one(&rep.hir, rep.greedy), + ZeroOrMore => self.c_repeat_zero_or_more(&rep.hir, rep.greedy), + OneOrMore => self.c_repeat_one_or_more(&rep.hir, rep.greedy), + Range(hir::RepetitionRange::Exactly(min_max)) => { + self.c_repeat_range(&rep.hir, rep.greedy, min_max, min_max) + } + Range(hir::RepetitionRange::AtLeast(min)) => { + self.c_repeat_range_min_or_more(&rep.hir, rep.greedy, min) + } + Range(hir::RepetitionRange::Bounded(min, max)) => { + self.c_repeat_range(&rep.hir, rep.greedy, min, max) + } + } + } + + fn c_repeat_zero_or_one( + &mut self, + expr: &Hir, + greedy: bool, + ) -> ResultOrEmpty { + let split_entry = self.insts.len(); + let split = self.push_split_hole(); + let Patch { hole: hole_rep, entry: entry_rep } = match self.c(expr)? { + Some(p) => p, + None => return self.pop_split_hole(), + }; + let split_hole = if greedy { + self.fill_split(split, Some(entry_rep), None) + } else { + self.fill_split(split, None, Some(entry_rep)) + }; + let holes = vec![hole_rep, split_hole]; + Ok(Some(Patch { hole: Hole::Many(holes), entry: split_entry })) + } + + fn c_repeat_zero_or_more( + &mut self, + expr: &Hir, + greedy: bool, + ) -> ResultOrEmpty { + let split_entry = self.insts.len(); + let split = self.push_split_hole(); + let Patch { hole: hole_rep, entry: entry_rep } = match self.c(expr)? { + Some(p) => p, + None => return self.pop_split_hole(), + }; + + self.fill(hole_rep, split_entry); + let split_hole = if greedy { + self.fill_split(split, Some(entry_rep), None) + } else { + self.fill_split(split, None, Some(entry_rep)) + }; + Ok(Some(Patch { hole: split_hole, entry: split_entry })) + } + + fn c_repeat_one_or_more( + &mut self, + expr: &Hir, + greedy: bool, + ) -> ResultOrEmpty { + let Patch { hole: hole_rep, entry: entry_rep } = match self.c(expr)? { + Some(p) => p, + None => return Ok(None), + }; + self.fill_to_next(hole_rep); + let split = self.push_split_hole(); + + let split_hole = if greedy { + self.fill_split(split, Some(entry_rep), None) + } else { + self.fill_split(split, None, Some(entry_rep)) + }; + Ok(Some(Patch { hole: split_hole, entry: entry_rep })) + } + + fn c_repeat_range_min_or_more( + &mut self, + expr: &Hir, + greedy: bool, + min: u32, + ) -> ResultOrEmpty { + let min = u32_to_usize(min); + // Using next_inst() is ok, because we can't return it (concat would + // have to return Some(_) while c_repeat_range_min_or_more returns + // None). + let patch_concat = self + .c_concat(iter::repeat(expr).take(min))? + .unwrap_or_else(|| self.next_inst()); + if let Some(patch_rep) = self.c_repeat_zero_or_more(expr, greedy)? { + self.fill(patch_concat.hole, patch_rep.entry); + Ok(Some(Patch { hole: patch_rep.hole, entry: patch_concat.entry })) + } else { + Ok(None) + } + } + + fn c_repeat_range( + &mut self, + expr: &Hir, + greedy: bool, + min: u32, + max: u32, + ) -> ResultOrEmpty { + let (min, max) = (u32_to_usize(min), u32_to_usize(max)); + debug_assert!(min <= max); + let patch_concat = self.c_concat(iter::repeat(expr).take(min))?; + if min == max { + return Ok(patch_concat); + } + // Same reasoning as in c_repeat_range_min_or_more (we know that min < + // max at this point). + let patch_concat = patch_concat.unwrap_or_else(|| self.next_inst()); + let initial_entry = patch_concat.entry; + // It is much simpler to compile, e.g., `a{2,5}` as: + // + // aaa?a?a? + // + // But you end up with a sequence of instructions like this: + // + // 0: 'a' + // 1: 'a', + // 2: split(3, 4) + // 3: 'a' + // 4: split(5, 6) + // 5: 'a' + // 6: split(7, 8) + // 7: 'a' + // 8: MATCH + // + // This is *incredibly* inefficient because the splits end + // up forming a chain, which has to be resolved everything a + // transition is followed. + let mut holes = vec![]; + let mut prev_hole = patch_concat.hole; + for _ in min..max { + self.fill_to_next(prev_hole); + let split = self.push_split_hole(); + let Patch { hole, entry } = match self.c(expr)? { + Some(p) => p, + None => return self.pop_split_hole(), + }; + prev_hole = hole; + if greedy { + holes.push(self.fill_split(split, Some(entry), None)); + } else { + holes.push(self.fill_split(split, None, Some(entry))); + } + } + holes.push(prev_hole); + Ok(Some(Patch { hole: Hole::Many(holes), entry: initial_entry })) + } + + /// Can be used as a default value for the c_* functions when the call to + /// c_function is followed by inserting at least one instruction that is + /// always executed after the ones written by the c* function. + fn next_inst(&self) -> Patch { + Patch { hole: Hole::None, entry: self.insts.len() } + } + + fn fill(&mut self, hole: Hole, goto: InstPtr) { + match hole { + Hole::None => {} + Hole::One(pc) => { + self.insts[pc].fill(goto); + } + Hole::Many(holes) => { + for hole in holes { + self.fill(hole, goto); + } + } + } + } + + fn fill_to_next(&mut self, hole: Hole) { + let next = self.insts.len(); + self.fill(hole, next); + } + + fn fill_split( + &mut self, + hole: Hole, + goto1: Option<InstPtr>, + goto2: Option<InstPtr>, + ) -> Hole { + match hole { + Hole::None => Hole::None, + Hole::One(pc) => match (goto1, goto2) { + (Some(goto1), Some(goto2)) => { + self.insts[pc].fill_split(goto1, goto2); + Hole::None + } + (Some(goto1), None) => { + self.insts[pc].half_fill_split_goto1(goto1); + Hole::One(pc) + } + (None, Some(goto2)) => { + self.insts[pc].half_fill_split_goto2(goto2); + Hole::One(pc) + } + (None, None) => unreachable!( + "at least one of the split \ + holes must be filled" + ), + }, + Hole::Many(holes) => { + let mut new_holes = vec![]; + for hole in holes { + new_holes.push(self.fill_split(hole, goto1, goto2)); + } + if new_holes.is_empty() { + Hole::None + } else if new_holes.len() == 1 { + new_holes.pop().unwrap() + } else { + Hole::Many(new_holes) + } + } + } + } + + fn push_compiled(&mut self, inst: Inst) { + self.insts.push(MaybeInst::Compiled(inst)); + } + + fn push_hole(&mut self, inst: InstHole) -> Hole { + let hole = self.insts.len(); + self.insts.push(MaybeInst::Uncompiled(inst)); + Hole::One(hole) + } + + fn push_split_hole(&mut self) -> Hole { + let hole = self.insts.len(); + self.insts.push(MaybeInst::Split); + Hole::One(hole) + } + + fn pop_split_hole(&mut self) -> ResultOrEmpty { + self.insts.pop(); + Ok(None) + } + + fn check_size(&self) -> result::Result<(), Error> { + use std::mem::size_of; + + let size = + self.extra_inst_bytes + (self.insts.len() * size_of::<Inst>()); + if size > self.size_limit { + Err(Error::CompiledTooBig(self.size_limit)) + } else { + Ok(()) + } + } +} + +#[derive(Debug)] +enum Hole { + None, + One(InstPtr), + Many(Vec<Hole>), +} + +impl Hole { + fn dup_one(self) -> (Self, Self) { + match self { + Hole::One(pc) => (Hole::One(pc), Hole::One(pc)), + Hole::None | Hole::Many(_) => { + unreachable!("must be called on single hole") + } + } + } +} + +#[derive(Clone, Debug)] +enum MaybeInst { + Compiled(Inst), + Uncompiled(InstHole), + Split, + Split1(InstPtr), + Split2(InstPtr), +} + +impl MaybeInst { + fn fill(&mut self, goto: InstPtr) { + let maybeinst = match *self { + MaybeInst::Split => MaybeInst::Split1(goto), + MaybeInst::Uncompiled(ref inst) => { + MaybeInst::Compiled(inst.fill(goto)) + } + MaybeInst::Split1(goto1) => { + MaybeInst::Compiled(Inst::Split(InstSplit { + goto1, + goto2: goto, + })) + } + MaybeInst::Split2(goto2) => { + MaybeInst::Compiled(Inst::Split(InstSplit { + goto1: goto, + goto2, + })) + } + _ => unreachable!( + "not all instructions were compiled! \ + found uncompiled instruction: {:?}", + self + ), + }; + *self = maybeinst; + } + + fn fill_split(&mut self, goto1: InstPtr, goto2: InstPtr) { + let filled = match *self { + MaybeInst::Split => Inst::Split(InstSplit { goto1, goto2 }), + _ => unreachable!( + "must be called on Split instruction, \ + instead it was called on: {:?}", + self + ), + }; + *self = MaybeInst::Compiled(filled); + } + + fn half_fill_split_goto1(&mut self, goto1: InstPtr) { + let half_filled = match *self { + MaybeInst::Split => goto1, + _ => unreachable!( + "must be called on Split instruction, \ + instead it was called on: {:?}", + self + ), + }; + *self = MaybeInst::Split1(half_filled); + } + + fn half_fill_split_goto2(&mut self, goto2: InstPtr) { + let half_filled = match *self { + MaybeInst::Split => goto2, + _ => unreachable!( + "must be called on Split instruction, \ + instead it was called on: {:?}", + self + ), + }; + *self = MaybeInst::Split2(half_filled); + } + + fn unwrap(self) -> Inst { + match self { + MaybeInst::Compiled(inst) => inst, + _ => unreachable!( + "must be called on a compiled instruction, \ + instead it was called on: {:?}", + self + ), + } + } +} + +#[derive(Clone, Debug)] +enum InstHole { + Save { slot: usize }, + EmptyLook { look: EmptyLook }, + Char { c: char }, + Ranges { ranges: Vec<(char, char)> }, + Bytes { start: u8, end: u8 }, +} + +impl InstHole { + fn fill(&self, goto: InstPtr) -> Inst { + match *self { + InstHole::Save { slot } => Inst::Save(InstSave { goto, slot }), + InstHole::EmptyLook { look } => { + Inst::EmptyLook(InstEmptyLook { goto, look }) + } + InstHole::Char { c } => Inst::Char(InstChar { goto, c }), + InstHole::Ranges { ref ranges } => Inst::Ranges(InstRanges { + goto, + ranges: ranges.clone().into_boxed_slice(), + }), + InstHole::Bytes { start, end } => { + Inst::Bytes(InstBytes { goto, start, end }) + } + } + } +} + +struct CompileClass<'a, 'b> { + c: &'a mut Compiler, + ranges: &'b [hir::ClassUnicodeRange], +} + +impl<'a, 'b> CompileClass<'a, 'b> { + fn compile(mut self) -> Result { + let mut holes = vec![]; + let mut initial_entry = None; + let mut last_split = Hole::None; + let mut utf8_seqs = self.c.utf8_seqs.take().unwrap(); + self.c.suffix_cache.clear(); + + for (i, range) in self.ranges.iter().enumerate() { + let is_last_range = i + 1 == self.ranges.len(); + utf8_seqs.reset(range.start(), range.end()); + let mut it = (&mut utf8_seqs).peekable(); + loop { + let utf8_seq = match it.next() { + None => break, + Some(utf8_seq) => utf8_seq, + }; + if is_last_range && it.peek().is_none() { + let Patch { hole, entry } = self.c_utf8_seq(&utf8_seq)?; + holes.push(hole); + self.c.fill(last_split, entry); + last_split = Hole::None; + if initial_entry.is_none() { + initial_entry = Some(entry); + } + } else { + if initial_entry.is_none() { + initial_entry = Some(self.c.insts.len()); + } + self.c.fill_to_next(last_split); + last_split = self.c.push_split_hole(); + let Patch { hole, entry } = self.c_utf8_seq(&utf8_seq)?; + holes.push(hole); + last_split = + self.c.fill_split(last_split, Some(entry), None); + } + } + } + self.c.utf8_seqs = Some(utf8_seqs); + Ok(Patch { hole: Hole::Many(holes), entry: initial_entry.unwrap() }) + } + + fn c_utf8_seq(&mut self, seq: &Utf8Sequence) -> Result { + if self.c.compiled.is_reverse { + self.c_utf8_seq_(seq) + } else { + self.c_utf8_seq_(seq.into_iter().rev()) + } + } + + fn c_utf8_seq_<'r, I>(&mut self, seq: I) -> Result + where + I: IntoIterator<Item = &'r Utf8Range>, + { + // The initial instruction for each UTF-8 sequence should be the same. + let mut from_inst = ::std::usize::MAX; + let mut last_hole = Hole::None; + for byte_range in seq { + let key = SuffixCacheKey { + from_inst, + start: byte_range.start, + end: byte_range.end, + }; + { + let pc = self.c.insts.len(); + if let Some(cached_pc) = self.c.suffix_cache.get(key, pc) { + from_inst = cached_pc; + continue; + } + } + self.c.byte_classes.set_range(byte_range.start, byte_range.end); + if from_inst == ::std::usize::MAX { + last_hole = self.c.push_hole(InstHole::Bytes { + start: byte_range.start, + end: byte_range.end, + }); + } else { + self.c.push_compiled(Inst::Bytes(InstBytes { + goto: from_inst, + start: byte_range.start, + end: byte_range.end, + })); + } + from_inst = self.c.insts.len().checked_sub(1).unwrap(); + debug_assert!(from_inst < ::std::usize::MAX); + } + debug_assert!(from_inst < ::std::usize::MAX); + Ok(Patch { hole: last_hole, entry: from_inst }) + } +} + +/// `SuffixCache` is a simple bounded hash map for caching suffix entries in +/// UTF-8 automata. For example, consider the Unicode range \u{0}-\u{FFFF}. +/// The set of byte ranges looks like this: +/// +/// [0-7F] +/// [C2-DF][80-BF] +/// [E0][A0-BF][80-BF] +/// [E1-EC][80-BF][80-BF] +/// [ED][80-9F][80-BF] +/// [EE-EF][80-BF][80-BF] +/// +/// Each line above translates to one alternate in the compiled regex program. +/// However, all but one of the alternates end in the same suffix, which is +/// a waste of an instruction. The suffix cache facilitates reusing them across +/// alternates. +/// +/// Note that a HashMap could be trivially used for this, but we don't need its +/// overhead. Some small bounded space (LRU style) is more than enough. +/// +/// This uses similar idea to [`SparseSet`](../sparse/struct.SparseSet.html), +/// except it uses hashes as original indices and then compares full keys for +/// validation against `dense` array. +#[derive(Debug)] +struct SuffixCache { + sparse: Box<[usize]>, + dense: Vec<SuffixCacheEntry>, +} + +#[derive(Clone, Copy, Debug, Default, Eq, Hash, PartialEq)] +struct SuffixCacheEntry { + key: SuffixCacheKey, + pc: InstPtr, +} + +#[derive(Clone, Copy, Debug, Default, Eq, Hash, PartialEq)] +struct SuffixCacheKey { + from_inst: InstPtr, + start: u8, + end: u8, +} + +impl SuffixCache { + fn new(size: usize) -> Self { + SuffixCache { + sparse: vec![0usize; size].into(), + dense: Vec::with_capacity(size), + } + } + + fn get(&mut self, key: SuffixCacheKey, pc: InstPtr) -> Option<InstPtr> { + let hash = self.hash(&key); + let pos = &mut self.sparse[hash]; + if let Some(entry) = self.dense.get(*pos) { + if entry.key == key { + return Some(entry.pc); + } + } + *pos = self.dense.len(); + self.dense.push(SuffixCacheEntry { key, pc }); + None + } + + fn clear(&mut self) { + self.dense.clear(); + } + + fn hash(&self, suffix: &SuffixCacheKey) -> usize { + // Basic FNV-1a hash as described: + // https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function + const FNV_PRIME: u64 = 1_099_511_628_211; + let mut h = 14_695_981_039_346_656_037; + h = (h ^ (suffix.from_inst as u64)).wrapping_mul(FNV_PRIME); + h = (h ^ (suffix.start as u64)).wrapping_mul(FNV_PRIME); + h = (h ^ (suffix.end as u64)).wrapping_mul(FNV_PRIME); + (h as usize) % self.sparse.len() + } +} + +struct ByteClassSet([bool; 256]); + +impl ByteClassSet { + fn new() -> Self { + ByteClassSet([false; 256]) + } + + fn set_range(&mut self, start: u8, end: u8) { + debug_assert!(start <= end); + if start > 0 { + self.0[start as usize - 1] = true; + } + self.0[end as usize] = true; + } + + fn set_word_boundary(&mut self) { + // We need to mark all ranges of bytes whose pairs result in + // evaluating \b differently. + let iswb = is_word_byte; + let mut b1: u16 = 0; + let mut b2: u16; + while b1 <= 255 { + b2 = b1 + 1; + while b2 <= 255 && iswb(b1 as u8) == iswb(b2 as u8) { + b2 += 1; + } + self.set_range(b1 as u8, (b2 - 1) as u8); + b1 = b2; + } + } + + fn byte_classes(&self) -> Vec<u8> { + // N.B. If you're debugging the DFA, it's useful to simply return + // `(0..256).collect()`, which effectively removes the byte classes + // and makes the transitions easier to read. + // (0usize..256).map(|x| x as u8).collect() + let mut byte_classes = vec![0; 256]; + let mut class = 0u8; + let mut i = 0; + loop { + byte_classes[i] = class as u8; + if i >= 255 { + break; + } + if self.0[i] { + class = class.checked_add(1).unwrap(); + } + i += 1; + } + byte_classes + } +} + +impl fmt::Debug for ByteClassSet { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_tuple("ByteClassSet").field(&&self.0[..]).finish() + } +} + +fn u32_to_usize(n: u32) -> usize { + // In case usize is less than 32 bits, we need to guard against overflow. + // On most platforms this compiles to nothing. + // TODO Use `std::convert::TryFrom` once it's stable. + if (n as u64) > (::std::usize::MAX as u64) { + panic!("BUG: {} is too big to be pointer sized", n) + } + n as usize +} + +#[cfg(test)] +mod tests { + use super::ByteClassSet; + + #[test] + fn byte_classes() { + let mut set = ByteClassSet::new(); + set.set_range(b'a', b'z'); + let classes = set.byte_classes(); + assert_eq!(classes[0], 0); + assert_eq!(classes[1], 0); + assert_eq!(classes[2], 0); + assert_eq!(classes[b'a' as usize - 1], 0); + assert_eq!(classes[b'a' as usize], 1); + assert_eq!(classes[b'm' as usize], 1); + assert_eq!(classes[b'z' as usize], 1); + assert_eq!(classes[b'z' as usize + 1], 2); + assert_eq!(classes[254], 2); + assert_eq!(classes[255], 2); + + let mut set = ByteClassSet::new(); + set.set_range(0, 2); + set.set_range(4, 6); + let classes = set.byte_classes(); + assert_eq!(classes[0], 0); + assert_eq!(classes[1], 0); + assert_eq!(classes[2], 0); + assert_eq!(classes[3], 1); + assert_eq!(classes[4], 2); + assert_eq!(classes[5], 2); + assert_eq!(classes[6], 2); + assert_eq!(classes[7], 3); + assert_eq!(classes[255], 3); + } + + #[test] + fn full_byte_classes() { + let mut set = ByteClassSet::new(); + for i in 0..256u16 { + set.set_range(i as u8, i as u8); + } + assert_eq!(set.byte_classes().len(), 256); + } +} |