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Optimize skipNewlines scanning #280

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

Optimize skipNewlines scanning #280

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68 changes: 36 additions & 32 deletions Sources/TOMLDecoder/ParserImplementation.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -70,7 +70,7 @@ extension Parser {
case CodeUnits.space, CodeUnits.tab:
// ignore white spaces
position += 1
while position < bytes.count {
while position < count {
let ws = bytes[position]
if ws != CodeUnits.space, ws != CodeUnits.tab {
break
Expand Down Expand Up @@ -395,9 +395,6 @@ extension Parser {
var isValidKey = true
while index < range.upperBound {
let ch = bytes[index]
if ch == CodeUnits.lf || ch == CodeUnits.dot {
break
}
if isBareKeyChar[Int(ch)] {
index += 1
continue
Expand All @@ -414,9 +411,6 @@ extension Parser {
var index = start
while index < range.upperBound {
let ch = bytes[index]
if ch == CodeUnits.lf {
break
}
if isValueChar[Int(ch)] {
index += 1
continue
Expand Down Expand Up @@ -522,20 +516,22 @@ extension Parser {
}

let count = bytes.count
var position = cursor
var lineNumber = currentLineNumber

while cursor < count {
let ch = bytes[cursor]
while position < count {
let ch = bytes[position]
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]
while position + 8 <= count {
let c0 = bytes[position]
let c1 = bytes[position + 1]
let c2 = bytes[position + 2]
let c3 = bytes[position + 3]
let c4 = bytes[position + 4]
let c5 = bytes[position + 5]
let c6 = bytes[position + 6]
let c7 = bytes[position + 7]

if c0 == CodeUnits.space || c0 == CodeUnits.tab,
c1 == CodeUnits.space || c1 == CodeUnits.tab,
Expand All @@ -546,39 +542,41 @@ extension Parser {
c6 == CodeUnits.space || c6 == CodeUnits.tab,
c7 == CodeUnits.space || c7 == CodeUnits.tab
{
cursor += 8
position += 8
} else {
break
}
}

while cursor < count {
let ws = bytes[cursor]
while position < count {
let ws = bytes[position]
if ws != CodeUnits.space, ws != CodeUnits.tab {
break
}
cursor += 1
position += 1
}
continue
}
switch ch {
case CodeUnits.lf:
currentLineNumber += 1
cursor += 1
lineNumber += 1
position += 1
case CodeUnits.cr:
if cursor + 1 < count, bytes[cursor + 1] == CodeUnits.lf {
currentLineNumber += 1
cursor += 2
if position + 1 < count, bytes[position + 1] == CodeUnits.lf {
lineNumber += 1
position += 2
} else {
// Bare CR, let nextToken handle error
cursor = position
currentLineNumber = lineNumber
try nextToken(bytes: bytes, isDotSpecial: isDotSpecial)
return
}
case CodeUnits.pound:
// Comment
cursor += 1
while cursor < count {
let c = bytes[cursor]
position += 1
while position < count {
let c = bytes[position]
if c == CodeUnits.lf {
break // Leave LF for next iteration to handle line number
}
Expand All @@ -587,25 +585,31 @@ extension Parser {
c == CodeUnits.delete
{
if c == CodeUnits.cr {
if cursor + 1 < count, bytes[cursor + 1] == CodeUnits.lf {
if position + 1 < count, bytes[position + 1] == CodeUnits.lf {
// CRLF ends comment
break
}
}
// Let nextToken throw the error
cursor = position
currentLineNumber = lineNumber
try nextToken(bytes: bytes, isDotSpecial: isDotSpecial)
return
}
cursor += 1
position += 1
}
default:
// Found something else, stop skipping
cursor = position
currentLineNumber = lineNumber
try nextToken(bytes: bytes, isDotSpecial: isDotSpecial)
return
}
}

// If we hit EOF or loop finishes
cursor = position
currentLineNumber = lineNumber
try nextToken(bytes: bytes, isDotSpecial: isDotSpecial)
}

Expand Down
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