The instructions can have dependencies (e.g. Repeat), so only unify
equal blocks instead of consecutive instructions.
Fixes#11247.
Also adds the minimal test case(s) from that issue.
The initial `ForkStay` is only needed if the looping block has a
following block, if there's no following block or the following block
does not attempt to match anything, we should not insert the ForkStay,
otherwise we would be rewriting `a+` as `a*` by allowing the 'end' to be
executed.
Fixes#10952.
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. :^)
Using a file(GLOB) to find all the test files in a directory is an easy
hack to get things started, but has some drawbacks. Namely, if you add
a test, it won't be found again without re-running CMake. `ninja` seems
to do this automatically, but it would be nice to one day stop seeing it
rechecking our globbed directories.
For example, consider the following pattern:
new RegExp('\ud834\udf06', 'u')
With this pattern, the regex parser should insert the UTF-8 encoded
bytes 0xf0, 0x9d, 0x8c, and 0x86. However, because these characters are
currently treated as normal char types, they have a negative value since
they are all > 0x7f. Then, due to sign extension, when these characters
are cast to u64, the sign bit is preserved. The result is that these
bytes are inserted as 0xfffffffffffffff0, 0xffffffffffffff9d, etc.
Fortunately, there are only a few places where we insert bytecode with
the raw characters. In these places, be sure to treat the bytes as u8
before they are cast to u64.
Unfortunately, this requires a slight divergence in the way the capture
group names are stored. Previously, the generated byte code would simply
store a view into the regex pattern string, so no string copying was
required.
Now, the escape sequences are decoded into a new string, and a vector
of all parsed capture group names are stored in a vector in the parser
result structure. The byte code then stores a view into the
corresponding string in that vector.
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.
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.
The grammar for the ECMA-262 CharacterEscape is:
CharacterEscape[U, N] ::
ControlEscape
c ControlLetter
0 [lookahead ∉ DecimalDigit]
HexEscapeSequence
RegExpUnicodeEscapeSequence[?U]
[~U]LegacyOctalEscapeSequence
IdentityEscape[?U, ?N]
It's important to parse the standalone "\0 [lookahead ∉ DecimalDigit]"
before parsing LegacyOctalEscapeSequence. Otherwise, all standalone "\0"
patterns are parsed as octal, which are disallowed in Unicode mode.
Further, LegacyOctalEscapeSequence should also be parsed while parsing
character classes.
A subsequent commit will add tests that require a string containing only
"\0". As a C-string, this will be interpreted as the null terminator. To
make the diff for that commit easier to grok, this commit converts all
tests to use StringView without any other functional changes.
* Only alphabetic (A-Z, a-z) characters may be escaped with \c. The loop
currently parsing \c includes code points between the upper/lower case
groups.
* In Unicode mode, all invalid identity escapes should cause a parser
error, even in browser-extended mode.
* Avoid an infinite loop when parsing the pattern "\c" on its own.
Before now, only binary properties could be parsed. Non-binary props are
of the form "Type=Value", where "Type" may be General_Category, Script,
or Script_Extension (or their aliases). Of these, LibUnicode currently
supports General_Category, so LibRegex can parse only that type.
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 flag is set, regular expressions may escape code points
by surrounding the hexadecimal code point with curly braces, e.g. \u{41}
is the character "A".
When the Unicode flag is not set, this should be considered a repetition
symbol - \u{41} is the character "u" repeated 41 times. This is left as
a TODO for now.
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.
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.
The C interface (posix interface?) for regexes has no "initialize"
function, only a free function. The comment in regcomp in
LibRegex/C/Regex.cpp notes that calling regcomp without a regfree is an
error, and will leak memory. Every single time regcomp is called on a
regex_t*, it will allocate new memory.
Make sure that all the regcomp calls are paired with a regfree in the
tests program
