We had a really naive and simplistic implementation, which lead to
various issues where the optimiser incorrectly rewrote the regex to use
atomic groups; this commit fixes that.
ECMA-262 defines \s as:
Return the CharSet containing all characters corresponding to a code
point on the right-hand side of the WhiteSpace or LineTerminator
productions.
The LineTerminator production is simply: U+000A, U+000D, U+2028, or
U+2029. Unfortunately there isn't a Unicode property that covers just
those code points.
The WhiteSpace production is: U+0009, U+000B, U+000C, U+FEFF, or any
code point with the Space_Separator general category.
If the Unicode generators are disabled, this will fall back to ASCII
space code points.
As ECMA262 regex allows `[^]` and literal newlines to match newlines in
the input string, we shouldn't split the input string into lines, rather
simply make boundaries and catchall patterns capable of checking for
these conditions specifically.
Instead of leaking all capture groups and selectively clearing some,
simply avoid leaking things and only "define" the ones that need to
exist.
This *actually* implements the capture groups ECMA262 quirk.
Also adds the test removed in the previous commit (to avoid messing up
test runs across bisects).
Generate a sorted, compressed series of ranges in a match table for
character classes, and use a binary search to find the matches.
This is about a 3-4x speedup for character class match performance. :^)
It's very common to encounter single-character strings in JavaScript on
the web. We can make such strings significantly lighter by having a
1-character inline capacity on the Vectors.
Doing so would increase memory consumption by quite a bit, since many
useless copies of the checkpoints hashmap would be created and later
thrown away.
- Make sure that all the Repeat ops are reset (otherwise the operation
would not be correct when going over the Repeat op a second time)
- Make sure that all matches that are allowed to fail are backed by a
fork, otherwise the last failing fork would not have anywhere to
return to.
Fixes#9707.
Currently, when we need to repeat an instruction N times, we simply add
that instruction N times in a for-loop. This doesn't scale well with
extremely large values of N, and ECMA-262 allows up to N = 2^53 - 1.
Instead, add a new REPEAT bytecode operation to defer this loop from the
parser to the runtime executor. This allows the parser to complete sans
any loops (for this instruction), and allows the executor to bail early
if the repeated bytecode fails.
Note: The templated ByteCode methods are to allow the Posix parsers to
continue using u32 because they are limited to N = 2^20.
This struct holds a counter for the number of executed operations, and
vectors for matches, captures groups, and named capture groups. Each of
the vectors is unused. Remove the struct and just keep a separate
counter for the executed operations.
Combining these into one list helps reduce the size of MatchState, and
as a result, reduces the amount of memory consumed during execution of
very large regex matches.
Doing this also allows us to remove a few regex byte code instructions:
ClearNamedCaptureGroup, SaveLeftNamedCaptureGroup, and NamedReference.
Named groups now behave the same as unnamed groups for these operations.
Note that SaveRightNamedCaptureGroup still exists to cache the matched
group name.
This also removes the recursion level from the MatchState, as it can
exist as a local variable in Matcher::execute instead.
In non-Unicode mode, the existing MatchState::string_position is tracked
in code units; in Unicode mode, it is tracked in code points.
In order for some RegexStringView operations to be performant, it is
useful for the MatchState to have a field to always track the position
in code units. This will allow RegexStringView methods (e.g. operator[])
to perform lookups based on code unit offsets, rather than needing to
iterate over the entire string to find a code point offset.
This changes LibRegex to parse the property escape as a Variant of
Unicode Property & General Category values. A byte code instruction is
added to perform matching based on General Category values.
This supports some binary property matching. It does not support any
properties not yet parsed by LibUnicode, nor does it support value
matching (such as Script_Extensions=Latin).
When the Unicode option is not set, regular expressions should match
based on code units; when it is set, they should match based on code
points. To do so, the regex parser must combine surrogate pairs when
the Unicode option is set. Further, RegexStringView needs to know if
the flag is set in order to return code point vs. code unit based
string lengths and substrings.
ECMA262 requires that the capture groups only contain the values from
the last iteration, e.g. `((c)(a)?(b))` should _not_ contain 'a' in the
second capture group when matching "cabcb".
This commit makes LibRegex (mostly) capable of operating on any of
the three main string views:
- StringView for raw strings
- Utf8View for utf-8 encoded strings
- Utf32View for raw unicode strings
As a result, regexps with unicode strings should be able to properly
handle utf-8 and not stop in the middle of a code point.
A future commit will update LibJS to use the correct type of string
depending on the flags.
When REGEX_DEBUG is enabled, LibRegex dumps a table of information
regarding the state of the regex bytecode execution. The Compare opcode
manipulates state.string_position directly, so the string_position value
cannot be used to display where the comparison started; therefore, this
patch introduces a new variable to keep track of where we were before
the comparison happened.
Previously this would return a pointer which could be null if the
requested opcode was invalid. This should never be the case though
so let's VERIFY() that instead.
This replaces ctype.h with CharacterType.h everywhere I could find
issues with narrowing conversions. While using it will probably make
sense almost everywhere in the future, the most critical places should
have been addressed.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
This only applies to the ECMA262 parser.
This behaviour is an ECMA262-specific quirk, such references always
generate zero-length matches (even on subsequent passes).
Also adds a test in LibJS's test suite.
Fixes#6039.
