Merge pull request apple#636 from tbkka/perf-text-bool

Perf:  direct parsing of bool in text format

Author: tbkka

Performance/generators/swift.sh

@@ -27,7 +27,9 @@ function print_swift_set_field() {
       echo "    }"
       ;;
     repeated\ bool)
-      echo "    message.field$num = [true, false, true, false, true, false, true, false]"
+      echo "    for _ in 0..<repeatedCount {"
+      echo "      message.field$num.append(true)"
+      echo "    }"
       ;;
     repeated\ string)
       echo "    for _ in 0..<repeatedCount {"

Sources/SwiftProtobuf/TextFormatScanner.swift

@@ -54,8 +54,10 @@ private let asciiUpperE = UInt8(ascii: "E")
 private let asciiLowerF = UInt8(ascii: "f")
 private let asciiUpperF = UInt8(ascii: "F")
 private let asciiLowerI = UInt8(ascii: "i")
+private let asciiLowerL = UInt8(ascii: "l")
 private let asciiLowerN = UInt8(ascii: "n")
 private let asciiLowerR = UInt8(ascii: "r")
+private let asciiLowerS = UInt8(ascii: "s")
 private let asciiLowerT = UInt8(ascii: "t")
 private let asciiUpperT = UInt8(ascii: "T")
 private let asciiLowerU = UInt8(ascii: "u")
@@ -720,6 +722,20 @@ internal struct TextFormatScanner {
         return d
     }
 
+    // Skip specified characters if they all match
+    private mutating func skipOptionalCharacters(bytes: [UInt8]) {
+        let start = p
+        for b in bytes {
+            if p == end || p[0] != b {
+                p = start
+                return
+            }
+            p += 1
+        }
+    }
+
+    // Skip following keyword if it matches (case-insensitively)
+    // the given keyword (specified as a series of bytes).
     private mutating func skipOptionalKeyword(bytes: [UInt8]) -> Bool {
         let start = p
         for b in bytes {
@@ -817,20 +833,47 @@ internal struct TextFormatScanner {
             throw TextFormatDecodingError.malformedText
         }
         let c = p[0]
+        p += 1
+        let result: Bool
         switch c {
-        case asciiZero, asciiOne, asciiLowerF, asciiUpperF, asciiLowerT, asciiUpperT:
-            switch parseIdentifier() {
-            case "0", "f", "false", "False":
-                return false
-            case "1", "t", "true", "True":
-                return true
-            default:
-                break
+        case asciiZero:
+            result = false
+        case asciiOne:
+            result = true
+        case asciiLowerF, asciiUpperF:
+            if p != end {
+                let alse = [asciiLowerA, asciiLowerL, asciiLowerS, asciiLowerE]
+                skipOptionalCharacters(bytes: alse)
+            }
+            result = false
+        case asciiLowerT, asciiUpperT:
+            if p != end {
+                let rue = [asciiLowerR, asciiLowerU, asciiLowerE]
+                skipOptionalCharacters(bytes: rue)
             }
+            result = true
         default:
-            break
+            throw TextFormatDecodingError.malformedText
+        }
+        if p == end {
+            return result
+        }
+        switch p[0] {
+        case asciiSpace,
+             asciiTab,
+             asciiNewLine,
+             asciiCarriageReturn,
+             asciiHash,
+             asciiComma,
+             asciiSemicolon,
+             asciiCloseSquareBracket,
+             asciiCloseCurlyBracket,
+             asciiCloseAngleBracket:
+            skipWhitespace()
+            return result
+        default:
+            throw TextFormatDecodingError.malformedText
         }
-        throw TextFormatDecodingError.malformedText
     }
 
     internal mutating func nextOptionalEnumName() throws -> UnsafeBufferPointer<UInt8>? {

Tests/SwiftProtobufTests/Test_TextFormat_proto3.swift

@@ -394,6 +394,12 @@ class Test_TextFormat_proto3: XCTestCase, PBTestHelpers {
         let b = Proto3Unittest_TestAllTypes.with {$0.optionalDouble = Double.nan}
         XCTAssertEqual("optional_double: nan\n", b.textFormatString())
 
+        assertTextFormatDecodeSucceeds("optional_double: 1.0\n") {(o: MessageTestType) in
+            return o.optionalDouble == 1.0
+        }
+        assertTextFormatDecodeSucceeds("12: 1.0\n") {(o: MessageTestType) in
+            return o.optionalDouble == 1.0
+        }
         assertTextFormatDecodeSucceeds("optional_double: INFINITY\n") {(o: MessageTestType) in
             return o.optionalDouble == Double.infinity
         }
@@ -475,8 +481,17 @@ class Test_TextFormat_proto3: XCTestCase, PBTestHelpers {
         assertTextFormatDecodeSucceeds("optional_bool:0\n ") {(o: MessageTestType) in
             return o.optionalBool == false
         }
+        assertTextFormatDecodeSucceeds("13:0\n ") {(o: MessageTestType) in
+            return o.optionalBool == false
+        }
+        assertTextFormatDecodeSucceeds("13:1\n ") {(o: MessageTestType) in
+            return o.optionalBool == true
+        }
 
         assertTextFormatDecodeFails("optional_bool: 10\n")
+        assertTextFormatDecodeFails("optional_bool: 1optional_double: 1.0\n")
+        assertTextFormatDecodeFails("optional_bool: t12: 1.0\n")
+        assertTextFormatDecodeFails("optional_bool: true12: 1.0\n")
         assertTextFormatDecodeFails("optional_bool: tRue\n")
         assertTextFormatDecodeFails("optional_bool: tr\n")
         assertTextFormatDecodeFails("optional_bool: tru\n")