stdlib/NSString APIs on String: add more tests and fix a crash in

_countFormatSpecifiers() that was triggered by non-BMP characters in the format
string


Swift SVN r21014

stdlib/core/StringCore.swift

@@ -259,6 +259,7 @@ public struct _StringCore {
     let p = UnsafeMutablePointer<UInt8>(_pointerToNth(position).value)
     // Always dereference two bytes, but when elements are 8 bits we
     // multiply the high byte by 0.
+    // FIXME(performance): use masking instead of multiplication.
     return UTF16.CodeUnit(p.memory)
       + UTF16.CodeUnit((p + 1).memory) * _highByteMultiplier
   }

stdlib/core/StringLegacy.swift

@@ -159,7 +159,7 @@ extension String {
       }
       res = res * 10
 
-      var d = Int(c.value - _asUnicodeScalar("0").value)
+      var d = Int(c.value - UnicodeScalar("0").value)
       // Underflow occurs if res - d < Int.min.
       if res < Int.min + d {
         return .None

stdlib/core/UnicodeScalar.swift

@@ -233,16 +233,6 @@ public func <(lhs: UnicodeScalar, rhs: UnicodeScalar) -> Bool {
   return lhs.value < rhs.value
 }
 
-/// Helper to provide type context to guide type inference in code like::
-///
-///   var value = digit - _asUnicodeScalar("0")
-public func _asUnicodeScalar(us: UnicodeScalar) -> UnicodeScalar {
-  return us
-}
-public func _asUTF16CodeUnit(us: UnicodeScalar) -> UTF16.CodeUnit {
-  return UTF16.CodeUnit(us.value)
-}
-
 extension UnicodeScalar {
   struct UTF16View {
     var value: UnicodeScalar

stdlib/objc/Foundation/NSStringAPI.swift

@@ -35,21 +35,27 @@ func _toNSRange(r: Range<String.Index>) -> NSRange {
 }
 
 func _countFormatSpecifiers(a: String) -> Int {
-  var lastChar = _asUTF16CodeUnit(".") // anything other than % would work here
+  // The implementation takes advantage of the fact that internal
+  // representation of String is UTF-16.  Because we only care about the ASCII
+  // percent character, we don't need to decode UTF-16.
+
+  let percentUTF16  = UTF16.CodeUnit(("%" as UnicodeScalar).value)
+  let notPercentUTF16: UTF16.CodeUnit = 0
+  var lastChar = notPercentUTF16 // anything other than % would work here
   var count = 0
 
-  for c in a.unicodeScalars {
-    if lastChar == _asUTF16CodeUnit("%") {
-      if c == "%" {
+  for c in a.utf16 {
+    if lastChar == percentUTF16 {
+      if c == percentUTF16 {
         // a "%" following this one should not be taken as literal
-        lastChar = _asUTF16CodeUnit(".") 
+        lastChar = notPercentUTF16
       }
       else {
         ++count
-        lastChar = _asUTF16CodeUnit(c)
+        lastChar = c
       }
     } else {
-      lastChar = _asUTF16CodeUnit(c)
+      lastChar = c
     }
   }
   return count

test/stdlib/NSStringAPI.swift

@@ -717,12 +717,21 @@ NSStringAPIs.test("init(utf16CodeUnitsNoCopy:count:freeWhenDone:)") {
 }
 
 NSStringAPIs.test("init(format:_:...)") {
+  expectEqual("", String(format: ""))
+  expectEqual(
+    "abc абв \u{0001F60A}", String(format: "abc абв \u{0001F60A}"))
+
   let world: NSString = "world"
   expectEqual("Hello, world!%42",
       String(format: "Hello, %@!%%%ld", world, 42))
 }
 
 NSStringAPIs.test("init(format:arguments:)") {
+  expectEqual("", String(format: "", arguments: []))
+  expectEqual(
+    "abc абв \u{0001F60A}",
+    String(format: "abc абв \u{0001F60A}", arguments: []))
+
   let world: NSString = "world"
   let args: [CVarArgType] = [ world, 42 ]
   expectEqual("Hello, world!%42",
@@ -1079,6 +1088,17 @@ NSStringAPIs.test("stringByAddingPercentEscapesUsingEncoding(_:)") {
 }
 
 NSStringAPIs.test("stringByAppendingFormat(_:_:...)") {
+  expectEqual("", "".stringByAppendingFormat(""))
+  expectEqual("a", "a".stringByAppendingFormat(""))
+  expectEqual(
+    "abc абв \u{0001F60A}",
+    "abc абв \u{0001F60A}".stringByAppendingFormat(""))
+
+  let formatArg: NSString = "привет мир \u{0001F60A}"
+  expectEqual(
+    "abc абв \u{0001F60A}def привет мир \u{0001F60A} 42",
+    "abc абв \u{0001F60A}"
+      .stringByAppendingFormat("def %@ %ld", formatArg, 42))
   // FIXME
 }
 
@@ -1091,7 +1111,10 @@ NSStringAPIs.test("stringByAppendingPathExtension(_:)") {
 }
 
 NSStringAPIs.test("stringByAppendingString(_:)") {
-  // FIXME
+  expectEqual("", "".stringByAppendingString(""))
+  expectEqual("a", "a".stringByAppendingString(""))
+  expectEqual("a", "".stringByAppendingString("a"))
+  expectEqual("さ\u{3099}", "さ".stringByAppendingString("\u{3099}"))
 }
 
 NSStringAPIs.test("stringByDeletingLastPathComponent") {