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Correct Regular Expressions Behavior Related to Annex B #58320

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Merged
rbuckton merged 12 commits into from
May 29, 2024
Merged

Correct Regular Expressions Behavior Related to Annex B #58320

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e049438
Correct RegExp Behavior Related to Annex B
graphemecluster Apr 25, 2024
358eb30
Fix Comment
graphemecluster Apr 25, 2024
8facb0a
Correct Quantifiability of `{1` in Annex B
graphemecluster Apr 27, 2024
f5c0b60
`\c` is an Annex B thing
graphemecluster Apr 27, 2024
cff993f
Add Tests
graphemecluster Apr 27, 2024
603c3cf
Merge from main
rbuckton May 16, 2024
2e62d25
Apply Suggested Changes
graphemecluster May 21, 2024
ed08ef7
Apply Suggested Changes
graphemecluster May 24, 2024
8b67d77
Merge branch 'main' into regex-syntax-check-annexB
graphemecluster May 24, 2024
b48f0d0
Provide User-Friendly Errors for Decimal Escapes Inside Character Cla…
graphemecluster May 24, 2024
c72f92f
Fix Behavior Related to `namedCaptureGroups`
graphemecluster May 28, 2024
70a3214
Clarify why nested character classes should not be considered in the …
graphemecluster May 28, 2024
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Merge from main
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@rbuckton
rbuckton committed May 16, 2024
commit 603c3cf18ce89adab5c35a3275934f3ae9324a2c
262 changes: 60 additions & 202 deletions src/compiler/scanner.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2675,215 +2675,46 @@ export function createScanner(languageVersion: ScriptTarget, skipTrivia: boolean
const digitsStart = pos;
scanDigits();
const min = tokenValue;
if (annexB && !min) {
isPreviousTermQuantifiable = true;
break;
}
if (charCodeChecked(pos) === CharacterCodes.comma) {
pos++;
scanDigits();
const min = tokenValue;
if (annexB && !min) {
isPreviousTermQuantifiable = true;
break;
}
if (text.charCodeAt(pos) === CharacterCodes.comma) {
pos++;
scanDigits();
const max = tokenValue;
if (!min) {
if (max || text.charCodeAt(pos) === CharacterCodes.closeBrace) {
error(Diagnostics.Incomplete_quantifier_Digit_expected, digitsStart, 0);
}
else {
error(Diagnostics.Unexpected_0_Did_you_mean_to_escape_it_with_backslash, start, 1, String.fromCharCode(ch));
isPreviousTermQuantifiable = true;
break;
}
const max = tokenValue;
if (!min) {
if (max || charCodeChecked(pos) === CharacterCodes.closeBrace) {
error(Diagnostics.Incomplete_quantifier_Digit_expected, digitsStart, 0);
}
else if (max && Number.parseInt(min) > Number.parseInt(max) && (!annexB || text.charCodeAt(pos) === CharacterCodes.closeBrace)) {
error(Diagnostics.Numbers_out_of_order_in_quantifier, digitsStart, pos - digitsStart);
}
}
else if (!min) {
if (!annexB) {
else {
error(Diagnostics.Unexpected_0_Did_you_mean_to_escape_it_with_backslash, start, 1, String.fromCharCode(ch));
}
isPreviousTermQuantifiable = true;
break;
}
if (text.charCodeAt(pos) !== CharacterCodes.closeBrace) {
if (annexB) {
isPreviousTermQuantifiable = true;
break;
}
else {
error(Diagnostics._0_expected, pos, 0, String.fromCharCode(CharacterCodes.closeBrace));
pos--;
}
}
// falls through
case CharacterCodes.asterisk:
case CharacterCodes.plus:
case CharacterCodes.question:
pos++;
if (text.charCodeAt(pos) === CharacterCodes.question) {
// Non-greedy
pos++;
else if (max && Number.parseInt(min) > Number.parseInt(max) && (!annexB || text.charCodeAt(pos) === CharacterCodes.closeBrace)) {
error(Diagnostics.Numbers_out_of_order_in_quantifier, digitsStart, pos - digitsStart);
}
isPreviousTermQuantifiable = true;
break;
case CharacterCodes.openBracket:
pos++;
if (unicodeSetsMode) {
scanClassSetExpression();
}
else {
scanClassRanges();
}
else if (!min) {
if (!annexB) {
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@rbuckton rbuckton May 16, 2024 •
edited
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Though it may be redundant, I think it might be better to still indicate unicodeMode here so that someone editing this code in the future doesn't mistakenly think this only applies to non-Annex B code. It may be better to use unicodeMode || !annexB and remove the if (unicodeMode) { annexB = false; } at the top of scanRegularExpressionWorker.

The same would go for other uses of annexB as well.

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@graphemecluster graphemecluster May 20, 2024

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Are you sure you are really fine with a dozen of occurrences of unicodeMode || !annexB?

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@rbuckton rbuckton May 20, 2024 •
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No, but

const anyUnicodeModeOrNonAnnexB = unicodeMode || !annexB;

would work.

error(Diagnostics.Unexpected_0_Did_you_mean_to_escape_it_with_backslash, start, 1, String.fromCharCode(ch));
}
scanExpectedChar(CharacterCodes.closeBracket);
isPreviousTermQuantifiable = true;
break;
case CharacterCodes.closeParen:
if (isInGroup) {
return;
}
// falls through
case CharacterCodes.closeBracket:
case CharacterCodes.closeBrace:
if (isUnterminated && !isInGroup) {
// Assume what starting from the character to be outside of the regex
return;
}
if (charCodeChecked(pos) !== CharacterCodes.closeBrace) {
if (annexB) {
isPreviousTermQuantifiable = true;
break;
}
if (!annexB || ch === CharacterCodes.closeParen) {
error(Diagnostics.Unexpected_0_Did_you_mean_to_escape_it_with_backslash, pos, 1, String.fromCharCode(ch));
else {
error(Diagnostics._0_expected, pos, 0, String.fromCharCode(CharacterCodes.closeBrace));
pos--;
}
pos++;
isPreviousTermQuantifiable = true;
break;
case CharacterCodes.slash:
case CharacterCodes.bar:
return;
default:
scanSourceCharacter();
isPreviousTermQuantifiable = true;
break;
}
}
}

function scanPatternModifiers(currFlags: RegularExpressionFlags): RegularExpressionFlags {
while (pos < end) {
const ch = text.charCodeAt(pos);
if (!isIdentifierPart(ch, languageVersion)) {
break;
}
const flag = characterToRegularExpressionFlag(String.fromCharCode(ch));
if (flag === undefined) {
error(Diagnostics.Unknown_regular_expression_flag, pos, 1);
}
else if (currFlags & flag) {
error(Diagnostics.Duplicate_regular_expression_flag, pos, 1);
}
else if (!(flag & RegularExpressionFlags.Modifiers)) {
error(Diagnostics.This_regular_expression_flag_cannot_be_toggled_within_a_subpattern, pos, 1);
}
else {
currFlags |= flag;
const availableFrom = regExpFlagToFirstAvailableLanguageVersion.get(flag)!;
if (languageVersion < availableFrom) {
error(Diagnostics.This_regular_expression_flag_is_only_available_when_targeting_0_or_later, pos, 1, getNameOfScriptTarget(availableFrom));
}
}
pos++;
}
return currFlags;
}

// AtomEscape ::=
// | DecimalEscape
// | CharacterClassEscape
// | CharacterEscape
// | 'k<' RegExpIdentifierName '>'
function scanAtomEscape() {
Debug.assertEqual(text.charCodeAt(pos - 1), CharacterCodes.backslash);
switch (text.charCodeAt(pos)) {
case CharacterCodes.k:
pos++;
if (text.charCodeAt(pos) === CharacterCodes.lessThan) {
pos++;
scanGroupName(/*isReference*/ true);
scanExpectedChar(CharacterCodes.greaterThan);
}
else {
// This is actually allowed in Annex B if there are no named capturing groups in the regex,
// but if we were going to suppress these errors, we would have to record the positions of all '\k's
// and defer the errors until after the scanning to know if the regex has any named capturing groups.
error(Diagnostics.k_must_be_followed_by_a_capturing_group_name_enclosed_in_angle_brackets, pos - 2, 2);
}
break;
case CharacterCodes.q:
if (unicodeSetsMode) {
pos++;
error(Diagnostics.q_is_only_available_inside_character_class, pos - 2, 2);
break;
}
scanExpectedChar(CharacterCodes.closeBrace);
pos--;
// falls through
default:
// The scanEscapeSequence call in scanCharacterEscape must return non-empty strings
// since there must not be line breaks in a regex literal
Debug.assert(scanCharacterClassEscape() || scanDecimalEscape() || scanCharacterEscape(/*atomEscape*/ true));
break;
}
}

// DecimalEscape ::= [1-9] [0-9]*
function scanDecimalEscape(): boolean {
Debug.assertEqual(text.charCodeAt(pos - 1), CharacterCodes.backslash);
const ch = text.charCodeAt(pos);
if (ch >= CharacterCodes._1 && ch <= CharacterCodes._9) {
const start = pos;
scanDigits();
decimalEscapes.push({ pos: start, end: pos, value: +tokenValue });
return true;
}
return false;
}

// CharacterEscape ::=
// | `c` ControlLetter
// | IdentityEscape
// | (Other sequences handled by `scanEscapeSequence`)
// IdentityEscape ::=
// | '^' | '$' | '/' | '\' | '.' | '*' | '+' | '?' | '(' | ')' | '[' | ']' | '{' | '}' | '|'
// | [~UnicodeMode] (any other non-identifier characters)
function scanCharacterEscape(atomEscape: boolean): string {
Debug.assertEqual(text.charCodeAt(pos - 1), CharacterCodes.backslash);
let ch = text.charCodeAt(pos);
switch (ch) {
case CharacterCodes.c:
pos++;
ch = text.charCodeAt(pos);
if (isASCIILetter(ch)) {
pos++;
return String.fromCharCode(ch & 0x1f);
}
if (!annexB) {
error(Diagnostics.c_must_be_followed_by_an_ASCII_letter, pos - 2, 2);
}
else if (atomEscape) {
// Annex B treats
//
// ExtendedAtom : `\` [lookahead = `c`]
//
// as the single character `\` when `c` isn't followed by a valid control character
pos--;
return "\\";
}
return String.fromCharCode(ch);
case CharacterCodes.caret:
case CharacterCodes.$:
case CharacterCodes.slash:
case CharacterCodes.backslash:
case CharacterCodes.dot:
case CharacterCodes.asterisk:
case CharacterCodes.plus:
case CharacterCodes.question:
Expand Down Expand Up @@ -2923,7 +2754,7 @@ export function createScanner(languageVersion: ScriptTarget, skipTrivia: boolean
// Assume what starting from the character to be outside of the regex
return;
}
if (unicodeMode || ch === CharacterCodes.closeParen) {
if (!annexB || ch === CharacterCodes.closeParen) {
error(Diagnostics.Unexpected_0_Did_you_mean_to_escape_it_with_backslash, pos, 1, String.fromCharCode(ch));
}
pos++;
Expand Down Expand Up @@ -2980,7 +2811,10 @@ export function createScanner(languageVersion: ScriptTarget, skipTrivia: boolean
scanGroupName(/*isReference*/ true);
scanExpectedChar(CharacterCodes.greaterThan);
}
else if (unicodeMode) {
else {
// This is actually allowed in Annex B if there are no named capturing groups in the regex,
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@rbuckton rbuckton May 16, 2024

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Could we keep track of whether we encountered a (?< during reScanSlashToken and add an entry to the RegularExpressionFlags enum? The spec passes NamedCaptureGroups as a production parameter just as it does for UnicodeMode and UnicodeSetsMode, but only ever passes it as ~NamedCaptureGroups in Annex B.

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@graphemecluster graphemecluster May 20, 2024

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Oh, didn’t think of this clever but dirty solution.
I can implement this but… the point is still about how much Annex B things we are going to respect. If we allow \k then should we allow \u and \x (and also \8 and \9 inside character classes) too? (#58320 (comment))

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I think it's better to error on \u, \x, \8, \9 because in those cases you are more likely to have actually meant something different. Writing \k when there are no named capture groups is far less ambiguous.

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@graphemecluster graphemecluster May 21, 2024

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If then I would personally lean towards linting also \1~\7 inside character classes to prevent this kind of mistakes. Or perhaps the opposite, only outside character classes. I don’t know. I understand that you don’t want the syntax checking to be too breaky, but someone must find this useful.

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Every decimal escape in a character class I've ever seen has been a bug, so it makes sense to error for that case.

// but if we were going to suppress these errors, we would have to record the positions of all '\k's
// and defer the errors until after the scanning to know if the regex has any named capturing groups.
error(Diagnostics.k_must_be_followed_by_a_capturing_group_name_enclosed_in_angle_brackets, pos - 2, 2);
}
break;
Expand Down Expand Up @@ -3030,10 +2864,10 @@ export function createScanner(languageVersion: ScriptTarget, skipTrivia: boolean
pos++;
return String.fromCharCode(ch & 0x1f);
}
if (unicodeMode) {
if (!annexB) {
error(Diagnostics.c_must_be_followed_by_an_ASCII_letter, pos - 2, 2);
}
else if (atomEscape && annexB) {
else if (atomEscape) {
// Annex B treats
//
// ExtendedAtom : `\` [lookahead = `c`]
Expand Down Expand Up @@ -3588,15 +3422,39 @@ export function createScanner(languageVersion: ScriptTarget, skipTrivia: boolean
}
}
}
else if (annexB) {
pos--;
return false;
}
else {
error(Diagnostics._0_must_be_followed_by_a_Unicode_property_value_expression_enclosed_in_braces, pos - 2, 2, String.fromCharCode(ch));
if (pos === propertyNameOrValueStart) {
error(Diagnostics.Expected_a_Unicode_property_name_or_value);
}
else if (binaryUnicodePropertiesOfStrings.has(propertyNameOrValue)) {
if (!unicodeSetsMode) {
error(Diagnostics.Any_Unicode_property_that_would_possibly_match_more_than_a_single_character_is_only_available_when_the_Unicode_Sets_v_flag_is_set, propertyNameOrValueStart, pos - propertyNameOrValueStart);
}
else if (isCharacterComplement) {
error(Diagnostics.Anything_that_would_possibly_match_more_than_a_single_character_is_invalid_inside_a_negated_character_class, propertyNameOrValueStart, pos - propertyNameOrValueStart);
}
else {
mayContainStrings = true;
}
}
else if (!valuesOfNonBinaryUnicodeProperties.General_Category.has(propertyNameOrValue) && !binaryUnicodeProperties.has(propertyNameOrValue)) {
error(Diagnostics.Unknown_Unicode_property_name_or_value, propertyNameOrValueStart, pos - propertyNameOrValueStart);
const suggestion = getSpellingSuggestion(propertyNameOrValue, [...valuesOfNonBinaryUnicodeProperties.General_Category, ...binaryUnicodeProperties, ...binaryUnicodePropertiesOfStrings], identity);
if (suggestion) {
error(Diagnostics.Did_you_mean_0, propertyNameOrValueStart, pos - propertyNameOrValueStart, suggestion);
}
}
}
scanExpectedChar(CharacterCodes.closeBrace);
if (!unicodeMode) {
error(Diagnostics.Unicode_property_value_expressions_are_only_available_when_the_Unicode_u_flag_or_the_Unicode_Sets_v_flag_is_set, start, pos - start);
}
}
else if (unicodeMode) {
else if (annexB) {
pos--;
return false;
}
else {
error(Diagnostics._0_must_be_followed_by_a_Unicode_property_value_expression_enclosed_in_braces, pos - 2, 2, String.fromCharCode(ch));
}
return true;
Expand Down
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