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Fix performance of readString #44

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Merged
merged 1 commit into from
Jan 18, 2019
Merged

Fix performance of readString #44

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107 changes: 62 additions & 45 deletions Sources/GraphQL/Language/Lexer.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -33,14 +33,14 @@ func advanceLexer(lexer: Lexer) throws -> Token {
lexer.lastToken = lexer.token
var token = lexer.lastToken

if token.kind != .eof {
if token.kind != .eof {
repeat {
token.next = try readToken(lexer: lexer, prev: token)
token = token.next!
} while token.kind == .comment

lexer.token = token
}
}

return token
}
Expand Down Expand Up @@ -105,6 +105,17 @@ func getTokenDesc(_ token: Token) -> String {
}

extension String {
func offset(of index: Index) -> Int {
return utf8.distance(from: startIndex, to: index)
}

func charCode(at index: Index) -> UInt8? {
guard index < utf8.endIndex else {
return nil
}
return utf8[index]
}

func charCode(at position: Int) -> UInt8? {
guard position < utf8.count else {
return nil
Expand All @@ -121,7 +132,7 @@ extension String {
}

func character(_ code: UInt8) -> Character {
return Character(UnicodeScalar(code))
return Character(UnicodeScalar(code))
}

/**
Expand Down Expand Up @@ -220,16 +231,16 @@ func readToken(lexer: Lexer, prev: Token) throws -> Token {
)
// .
case 46:
if body.charCode(at: position + 1) == 46 && body.charCode(at: position + 2) == 46 {
return Token(
kind: .spread,
start: position,
end: position + 3,
line: line,
column: col,
prev: prev
)
}
if body.charCode(at: position + 1) == 46 && body.charCode(at: position + 2) == 46 {
return Token(
kind: .spread,
start: position,
end: position + 3,
line: line,
column: col,
prev: prev
)
}
// :
case 58:
return Token(
Expand Down Expand Up @@ -535,14 +546,13 @@ func readDigits(source: Source, start: Int, firstCode: UInt8) throws -> Int {
*/
func readString(source: Source, start: Int, line: Int, col: Int, prev: Token) throws -> Token {
let body = source.body
let bodyLength = body.utf8.count
var position = start + 1
var chunkStart = position
var positionIndex = body.utf8.index(body.utf8.startIndex, offsetBy: start + 1)
var chunkStartIndex = positionIndex
var currentCode: UInt8? = 0
var value = ""

while position < bodyLength {
currentCode = body.charCode(at: position)
while positionIndex < body.utf8.endIndex {
currentCode = body.charCode(at: positionIndex)

// not LineTerminator not Quote (")
guard let code = currentCode, code != 0x000A && code != 0x000D && code != 34 else {
Expand All @@ -553,16 +563,17 @@ func readString(source: Source, start: Int, line: Int, col: Int, prev: Token) th
if code < 0x0020 && code != 0x0009 {
throw syntaxError(
source: source,
position: position,
position: body.offset(of: positionIndex),
description: "Invalid character within String: \(character(code))."
)
}

position += 1
let startIterationIndex = positionIndex
positionIndex = body.utf8.index(after: positionIndex)

if code == 92 { // \
value += body.slice(start: chunkStart, end: position - 1)
currentCode = body.charCode(at: position)
value += String(body.utf8[chunkStartIndex..<startIterationIndex])!
currentCode = body.charCode(at: positionIndex)

if let code = currentCode {
switch code {
Expand All @@ -575,53 +586,59 @@ func readString(source: Source, start: Int, line: Int, col: Int, prev: Token) th
case 114: value += "\r"
case 116: value += "\t"
case 117: // u
let aIndex = body.utf8.index(after: positionIndex)
let bIndex = body.utf8.index(after: aIndex)
let cIndex = body.utf8.index(after: bIndex)
let dIndex = body.utf8.index(after: cIndex)

let charCode = uniCharCode(
a: body.charCode(at: position + 1)!,
b: body.charCode(at: position + 2)!,
c: body.charCode(at: position + 3)!,
d: body.charCode(at: position + 4)!
a: body.utf8[aIndex],
b: body.utf8[bIndex],
c: body.utf8[cIndex],
d: body.utf8[dIndex]
)

if charCode < 0 {
throw syntaxError(
source: source,
position: position,
position: body.offset(of: positionIndex),
description:
"Invalid character escape sequence: " +
"\\u\(body.slice(start: position + 1, end: position + 5))."
"\\u\(body.utf8[aIndex...dIndex])."
)
}

value += String(Character(UnicodeScalar(UInt32(charCode))!))
position += 4

positionIndex = dIndex
default:
throw syntaxError(
source: source,
position: position,
position: body.offset(of: positionIndex),
description: "Invalid character escape sequence: \\\(character(code))."
)
}
}

position += 1
chunkStart = position
positionIndex = body.utf8.index(after: positionIndex)
chunkStartIndex = positionIndex
}
}

if currentCode != 34 { // quote (")
throw syntaxError(
source: source,
position: position,
position: body.offset(of: positionIndex),
description: "Unterminated string."
)
}

value += body.slice(start: chunkStart, end: position)
value += String(body.utf8[chunkStartIndex..<positionIndex])!

return Token(
kind: .string,
start: start,
end: position + 1,
end: body.offset(of: positionIndex) + 1,
line: line,
column: col,
value: value,
Expand All @@ -640,7 +657,7 @@ func readString(source: Source, start: Int, line: Int, col: Int, prev: Token) th
* which means the result of ORing the char2hex() will also be negative.
*/
func uniCharCode(a: UInt8, b: UInt8, c: UInt8, d: UInt8) -> Int {
return char2hex(a) << 12 | char2hex(b) << 8 | char2hex(c) << 4 | char2hex(d)
return char2hex(a) << 12 | char2hex(b) << 8 | char2hex(c) << 4 | char2hex(d)
}

/**
Expand All @@ -654,9 +671,9 @@ func uniCharCode(a: UInt8, b: UInt8, c: UInt8, d: UInt8) -> Int {
func char2hex(_ a: UInt8) -> Int {
let a = Int(a)
return a >= 48 && a <= 57 ? a - 48 : // 0-9
a >= 65 && a <= 70 ? a - 55 : // A-F
a >= 97 && a <= 102 ? a - 87 : // a-f
-1
a >= 65 && a <= 70 ? a - 55 : // A-F
a >= 97 && a <= 102 ? a - 87 : // a-f
-1
}

/**
Expand All @@ -670,12 +687,12 @@ func readName(source: Source, position: Int, line: Int, col: Int, prev: Token) -
var end = position + 1

while end != bodyLength,
let code = body.charCode(at: end),
(code == 95 || // _
code >= 48 && code <= 57 || // 0-9
code >= 65 && code <= 90 || // A-Z
code >= 97 && code <= 122) { // a-z
end += 1
let code = body.charCode(at: end),
(code == 95 || // _
code >= 48 && code <= 57 || // 0-9
code >= 65 && code <= 90 || // A-Z
code >= 97 && code <= 122) { // a-z
end += 1
}

return Token(
Expand Down
9 changes: 9 additions & 0 deletions Tests/GraphQLTests/LanguageTests/LexerTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -199,6 +199,15 @@ class LexerTests : XCTestCase {
XCTAssertEqual(token, expected)
}

func testLongStrings() throws {
measure {
let token = try! lexOne("\"\(String(repeating: "123456", count: 10_000))\"")

XCTAssertEqual(token.start, 0)
XCTAssertEqual(token.end, 60_002)
}
}

func testStringErrors() throws {
XCTAssertThrowsError(try lexOne("\""))
// "Syntax Error GraphQL (1:2) Unterminated string"
Expand Down