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Check for delimiter before lookahead in advanceIfMultilineStringDelimiter #3199

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Merged
hamishknight merged 1 commit into from
Dec 9, 2025
Merged

Check for delimiter before lookahead in advanceIfMultilineStringDelimiter #3199

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21 changes: 12 additions & 9 deletions Sources/SwiftParser/Lexer/Cursor.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -814,11 +814,19 @@ extension Lexer.Cursor {
openingRawStringDelimiters: Int?
) -> Bool {
precondition(self.previous == #"""#)

var delimEnd = self
guard delimEnd.advance(matching: #"""#),
case let delimLast = delimEnd,
delimEnd.advance(matching: #"""#)
else {
return false
}

// Test for single-line string literals that resemble multiline delimiter.
var sameLineCloseCheck = self
_ = sameLineCloseCheck.advance()
if let openingRawStringDelimiters, openingRawStringDelimiters != 0 {
// Scan if the current line contains `"` followed by `openingRawStringDelimiters` `#` characters
var sameLineCloseCheck = delimLast
while sameLineCloseCheck.is(notAt: "\r", "\n") {
if sameLineCloseCheck.advance(matching: #"""#) {
if sameLineCloseCheck.advanceIfStringDelimiter(delimiterLength: openingRawStringDelimiters) {
Expand All @@ -831,13 +839,8 @@ extension Lexer.Cursor {
}
}

var tmp = self
if tmp.advance(matching: #"""#) && tmp.advance(matching: #"""#) {
self = tmp
return true
}

return false
self = delimEnd
return true
}

/// Read a single UTF-8 scalar, which may span multiple bytes.
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