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Speed up parser token scanning #279

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Merged
dduan merged 1 commit into from
Dec 29, 2025
Merged

Speed up parser token scanning #279

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72 changes: 41 additions & 31 deletions Sources/TOMLDecoder/ParserImplementation.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -121,6 +121,8 @@ extension Parser {
}

func scanString(range: Range<Int>, lineNumber: Int) throws(TOMLError) {
let isBareKeyChar = CodeUnits.isBareKeyChar
let isValueChar = CodeUnits.isValueChar
let start = range.lowerBound
let head = bytes[start]
if (head >= CodeUnits.lowerA && head <= CodeUnits.lowerZ) ||
Expand All @@ -130,7 +132,7 @@ extension Parser {
var index = start + 1
while index < range.upperBound {
let ch = bytes[index]
if CodeUnits.isBareKeyChar[Int(ch)] {
if isBareKeyChar[Int(ch)] {
index += 1
continue
}
Expand Down Expand Up @@ -396,7 +398,7 @@ extension Parser {
if ch == CodeUnits.lf || ch == CodeUnits.dot {
break
}
if CodeUnits.isBareKeyChar[Int(ch)] {
if isBareKeyChar[Int(ch)] {
index += 1
continue
}
Expand All @@ -415,7 +417,7 @@ extension Parser {
if ch == CodeUnits.lf {
break
}
if CodeUnits.isValueChar[Int(ch)] {
if isValueChar[Int(ch)] {
index += 1
continue
}
Expand Down Expand Up @@ -522,33 +524,43 @@ extension Parser {
let count = bytes.count

while cursor < count {
// 8x unrolling for space/tab skipping
while cursor + 8 <= count {
let c0 = bytes[cursor]
let c1 = bytes[cursor + 1]
let c2 = bytes[cursor + 2]
let c3 = bytes[cursor + 3]
let c4 = bytes[cursor + 4]
let c5 = bytes[cursor + 5]
let c6 = bytes[cursor + 6]
let c7 = bytes[cursor + 7]

if c0 == CodeUnits.space || c0 == CodeUnits.tab,
c1 == CodeUnits.space || c1 == CodeUnits.tab,
c2 == CodeUnits.space || c2 == CodeUnits.tab,
c3 == CodeUnits.space || c3 == CodeUnits.tab,
c4 == CodeUnits.space || c4 == CodeUnits.tab,
c5 == CodeUnits.space || c5 == CodeUnits.tab,
c6 == CodeUnits.space || c6 == CodeUnits.tab,
c7 == CodeUnits.space || c7 == CodeUnits.tab
{
cursor += 8
} else {
break
let ch = bytes[cursor]
if ch == CodeUnits.space || ch == CodeUnits.tab {
// 8x unrolling for space/tab skipping
while cursor + 8 <= count {
let c0 = bytes[cursor]
let c1 = bytes[cursor + 1]
let c2 = bytes[cursor + 2]
let c3 = bytes[cursor + 3]
let c4 = bytes[cursor + 4]
let c5 = bytes[cursor + 5]
let c6 = bytes[cursor + 6]
let c7 = bytes[cursor + 7]

if c0 == CodeUnits.space || c0 == CodeUnits.tab,
c1 == CodeUnits.space || c1 == CodeUnits.tab,
c2 == CodeUnits.space || c2 == CodeUnits.tab,
c3 == CodeUnits.space || c3 == CodeUnits.tab,
c4 == CodeUnits.space || c4 == CodeUnits.tab,
c5 == CodeUnits.space || c5 == CodeUnits.tab,
c6 == CodeUnits.space || c6 == CodeUnits.tab,
c7 == CodeUnits.space || c7 == CodeUnits.tab
{
cursor += 8
} else {
break
}
}
}

let ch = bytes[cursor]
while cursor < count {
let ws = bytes[cursor]
if ws != CodeUnits.space, ws != CodeUnits.tab {
break
}
cursor += 1
}
continue
}
switch ch {
case CodeUnits.lf:
currentLineNumber += 1
Expand All @@ -562,8 +574,6 @@ extension Parser {
try nextToken(bytes: bytes, isDotSpecial: isDotSpecial)
return
}
case CodeUnits.space, CodeUnits.tab:
cursor += 1
case CodeUnits.pound:
// Comment
cursor += 1
Expand Down Expand Up @@ -765,7 +775,7 @@ extension Parser {

arrays[arrayIndex].elements.append(.leaf(token))

try eatToken(bytes: bytes, kind: .string, isDotSpecial: true)
try nextToken(bytes: bytes, isDotSpecial: true)

case .lbracket: // Nested array
if arrays[arrayIndex].kind == nil {
Expand Down
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