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[xcodegen] Avoid an intermediate String #78291

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Merged
merged 1 commit into from
Dec 19, 2024
Merged

[xcodegen] Avoid an intermediate String #78291

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42 changes: 18 additions & 24 deletions utils/swift-xcodegen/Sources/Xcodeproj/PropertyList.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -51,33 +51,12 @@ extension PropertyList {
writePlistRepresentation(to: &writer)
return Data(writer.bytes)
}

/// Escapes the string for plist.
/// Finds the instances of quote (") and backward slash (\) and prepends
/// the escape character backward slash (\).
static func escape(string: String) -> String {
func needsEscape(_ char: UInt8) -> Bool {
return char == UInt8(ascii: "\\") || char == UInt8(ascii: "\"")
}

guard let pos = string.utf8.firstIndex(where: needsEscape) else {
return string
}
var newString = String(string[..<pos])
for char in string.utf8[pos...] {
if needsEscape(char) {
newString += "\\"
}
newString += String(UnicodeScalar(char))
}
return newString
}
}

fileprivate extension PropertyList {
struct UTF8Writer {
var level: Int = 0
var bytes: [UInt8] = []
private(set) var level: Int = 0
private(set) var bytes: [UInt8] = []
init() {
self += "// !$*UTF8*$!\n"
}
Expand All @@ -88,6 +67,10 @@ fileprivate extension PropertyList {
level -= 1
}

mutating func append(_ byte: UInt8) {
bytes.append(byte)
}

static func += (writer: inout UTF8Writer, str: StaticString) {
str.withUTF8Buffer { utf8 in
writer.bytes += utf8
Expand All @@ -104,6 +87,17 @@ fileprivate extension PropertyList {
self += " "
}
}

/// Appends the given string, with instances of quote (") and backward slash
/// (\) characters escaped with a backslash.
mutating func appendEscaped(_ string: String) {
for char in string.utf8 {
if char == UInt8(ascii: "\\") || char == UInt8(ascii: "\"") {
append(UInt8(ascii: "\\"))
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Suggested change
append(UInt8(ascii: "\\"))
append(UInt8(ascii: #"\"#))

🙂

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When there's only a single character to escape I tend to prefer just writing the backslash, especially as things like #"""# look weird. I think I'd rather keep things locally consistent here, I don't feel too strongly about it though

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I see. I do not actually have a preference, but I was curious about yours, on the off chance that a raw string had occurred to you.

}
append(char)
}
}
}

/// Private function to generate OPENSTEP-style plist representation.
Expand All @@ -116,7 +110,7 @@ fileprivate extension PropertyList {

case .string(let string):
writer += "\""
writer += PropertyList.escape(string: string)
writer.appendEscaped(string)
writer += "\""

case .array(let array):
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