Bug fix and hot path for quantified . (swiftlang#658)

Bug fix in newline hot path, and apply hot path to quantified dot

Author: milseman

Sources/_StringProcessing/Engine/MEBuiltins.swift

@@ -63,10 +63,10 @@ extension Processor {
       switch payload.semanticLevel {
       case .graphemeCluster:
         return input.index(after: currentPosition) == subjectBounds.upperBound
-         && input[currentPosition].isNewline
+        && input[currentPosition].isNewline
       case .unicodeScalar:
         return input.unicodeScalars.index(after: currentPosition) == subjectBounds.upperBound
-         && input.unicodeScalars[currentPosition].isNewline
+        && input.unicodeScalars[currentPosition].isNewline
       }
 
     case .endOfSubject: return currentPosition == subjectBounds.upperBound
@@ -121,6 +121,7 @@ extension Processor {
 
 // MARK: Matching `.`
 extension String {
+  // TODO: Should the below have a `limitedBy` parameter?
 
   func _matchAnyNonNewline(
     at currentPosition: String.Index,
@@ -155,11 +156,11 @@ extension String {
       return .unknown
     }
     switch asciiValue {
-      case ._lineFeed, ._carriageReturn:
-        return .definite(nil)
-      default:
-        assert(!isCRLF)
-        return .definite(next)
+    case (._lineFeed)...(._carriageReturn):
+      return .definite(nil)
+    default:
+      assert(!isCRLF)
+      return .definite(next)
     }
   }
 
@@ -183,6 +184,7 @@ extension String {
 
 // MARK: - Built-in character class matching
 extension String {
+  // TODO: Should the below have a `limitedBy` parameter?
 
   // Mentioned in ProgrammersManual.md, update docs if redesigned
   func _matchBuiltinCC(

Sources/_StringProcessing/Engine/MEQuantify.swift

@@ -1,31 +1,37 @@
 extension Processor {
   func _doQuantifyMatch(_ payload: QuantifyPayload) -> Input.Index? {
-    var next: Input.Index?
+    // FIXME: is the below updated for scalar semantics?
     switch payload.type {
     case .bitset:
-      next = input.matchBitset(
+      return input.matchBitset(
         registers[payload.bitset], at: currentPosition, limitedBy: end)
     case .asciiChar:
-      next = input.matchScalar(
+      return input.matchScalar(
         UnicodeScalar.init(_value: UInt32(payload.asciiChar)),
         at: currentPosition,
         limitedBy: end,
         boundaryCheck: true)
     case .builtin:
+      // FIXME: bounds check? endIndex or end?
+
       // We only emit .quantify if it consumes a single character
-      next = input._matchBuiltinCC(
+      return input._matchBuiltinCC(
         payload.builtin,
         at: currentPosition,
         isInverted: payload.builtinIsInverted,
         isStrictASCII: payload.builtinIsStrict,
         isScalarSemantics: false)
     case .any:
-      // TODO: call out to existing code with quick check
-      let matched = currentPosition != input.endIndex
-        && (!input[currentPosition].isNewline || payload.anyMatchesNewline)
-      next = matched ? input.index(after: currentPosition) : nil
+      // FIXME: endIndex or end?
+      guard currentPosition < input.endIndex else { return nil }
+
+      if payload.anyMatchesNewline {
+        return input.index(after: currentPosition)
+      }
+
+      return input._matchAnyNonNewline(
+        at: currentPosition, isScalarSemantics: false)
     }
-    return next
   }
 
   /// Generic quantify instruction interpreter

Tests/RegexTests/MatchTests.swift

@@ -1891,6 +1891,11 @@ extension RegexTests {
   func testSingleLineMode() {
     firstMatchTest(#".+"#, input: "a\nb", match: "a")
     firstMatchTest(#"(?s:.+)"#, input: "a\nb", match: "a\nb")
+
+    // We recognize LF, line tab, FF, and CR as newlines by default
+    firstMatchTest(#"."#, input: "\u{A}\u{B}\u{C}\u{D}\nb", match: "b")
+    firstMatchTest(#".+"#, input: "\u{A}\u{B}\u{C}\u{D}\nbb", match: "bb")
+
   }
 
   func testMatchNewlines() {