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fix: align the CSS, HTML, XML and JavaScript tokenizers with their specs - #22872
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The "would start" checks took their code points as `f || charCodeAt`, so the `NaN` a caller passes past the end of the input fell back to re-reading the first code point: `1-` became a dimension and `@-` an at-keyword. The checks now default only an omitted code point, and the ident check takes all three from its callers. The tokenizer tests now reach every statement and branch: the escape and url branches no input could take are folded into the ones that are reachable, and `consumeAToken` no longer repeats the one-code-point arm that `readToken` fills first. Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
The tag-name state's last arm only ever sees NUL, a quoted value's quote memo is always behind a new value and never behind the scan inside one, and an XML name start always gives a name: the checks for the other cases go, so the tokenizer tests reach every statement and branch. Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
- `yield` in a generator read the regexp after it as a division when
only the tokenizer ran: the scope check that serves a parse was taken
whenever any scope existed, and the constructor always enters one.
A `parsing` flag, set by the parse entry points, now picks it.
- WebpackParser accepted regexp syntax newer than the requested
ecmaVersion (named groups, lookbehind, `\p{...}` before ES2018), since
V8 builds them whatever the edition; V8 now stands in for acorn's
validator only from the newest edition it gates on.
- Unterminated strings, templates and regexps raised with `pos` (and
so `raisedAt`) left where the token started.
The tokenizer tests now run their acorn comparisons through
WebpackParser's own tokenizer methods too, lazy and eager, and reach
every statement and branch of both classes; the `readNumber` checks and
the `validateRegExpPattern` override no input could reach are gone.
Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
🦋 Changeset detectedLatest commit: 9768e90 The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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This PR is packaged and the instant preview of its latest commit is available. Install it locally:
npm i -D webpack@https://pkg.pr.new/webpack@22872
yarn add -D webpack@https://pkg.pr.new/webpack@22872
pnpm add -D webpack@https://pkg.pr.new/webpack@22872 |
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.changeset/060-tokenizer-fixes.mdlib/css/syntax-parser.jslib/html/syntax-parser.jslib/javascript/syntax-parser.jstest/unitCases/css/tokenizer.unittest.jstest/unitCases/javascript/tokenizer.unittest.js
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Read No asset changed size. No runtime gained or lost a runtime module. Built |
`_readCustomAtRulesAhead` ran the tokenizer on the raw input, so a NUL in a custom media name (U+FFFD after CSS Syntax §3.3, an ident code point) split the name and its reference was never recorded. The lookahead now reads the preprocessed input, which keeps every offset. Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
- `<?…>` reports the processing-instruction errors the standard now defines (none for a well-formed one; invalid, disallowed or missing targets; EOF) instead of the retired unexpected-question-mark-instead-of-tag-name; it still reads as one bogus comment. - `<
alexander-akait
changed the title
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #22872 +/- ##
===========================================
+ Coverage 77.14% 96.56% +19.41%
===========================================
Files 601 778 +177
Lines 133120 141113 +7993
Branches 46082 48285 +2203
===========================================
+ Hits 102700 136262 +33562
+ Misses 30420 4851 -25569
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The tests' ParserOptions typedef went away in the unit-test split, after the SyntaxTree test that names it was written. Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
Merging this PR will improve performance by 37.74%1 warning, 1 note
Performance Changes
Tip Curious why performance improved? Comment Comparing 
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Each tokenizer's unit test file now covers 100% of its tokenizer's statements, branches and functions on its own, and each tokenizer was audited against its spec with differential testing against a conformant reference. Code no input can reach is removed or folded into the reachable path, not marked
istanbul ignore.SyntaxParser)WebpackParseroverrides)How it was checked
@csstools/css-tokenizerentitiesFixes
CSS
-at the end of the input was read as part of the token before it:1-became a dimension (spec: number, delim),@-an at-keyword. The "would start" checks defaulted code points withf || charCodeAt(...), so theNaNpast the end re-read the first code point.HTML
<?…>reports the processing-instruction errors the standard now defines (none for a well-formed one; invalid, disallowed or missing target; EOF) instead of the retiredunexpected-question-mark-instead-of-tag-name; it still reads as one bogus comment.<[CDATA[outside foreign content iscdata-in-html-content.eof-in-tagalone, not alsoend-tag-with-attributes.eof-in-script-html-comment-like-text.<title/>,<script/>,<style/>or<noframes/>now switches the content mode the tree builder already switched to:<title/><b></title>kept losing the<b>.JavaScript
Parser.tokenizer),function* g() { yield /re/g }read the regexp as division: the scope answer that serves a parse was taken whenever a scope existed, and the constructor always enters one. Aparsingflag set by the parse entry points now decides.WebpackParseraccepted regexp syntax newer than the requestedecmaVersion(named groups, lookbehind,\p{...}before ES2018): V8 builds them whatever the edition. V8 now stands in for acorn's validator only from the newest edition that validator gates on; webpack parses withlatest, so builds keep the fast path.raisedAtat the token start./=in expression position (await /=a/g,x\n{} /=a/g) is re-read as a regexp, as a lone/already was; acorn rejects these, the spec, V8, meriyah and Babel accept them.TypeErrorfor a${…}closed at the end of input; it raises acorn's "Unterminated template literal".Left as is (documented, deliberate)
url(kept in token ranges.eof-in-tag(the tree builder relies on it); NUL in a processing instruction stays reported (the tree builder replaces it from that error).tokenizeXmlstays lenient on documents that are not well-formed.yield /re/in a generator method reads a regexp during a parse (acorn rejects it);x\nof /a/gwith a variable namedofstill reads a regexp afterof, as acorn does.Unreachable code removed
consumeAToken's one-code-point arm.readNumber's "Invalid number" guard and non-digit arm,WebpackParser.validateRegExpPattern.Each fix has a test that fails without it.
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