Rewrite decodeURL as builtin function, remove now unused runtime functions.

src/uri.cc

Index: src/uri.cc
diff --git a/src/uri.cc b/src/uri.cc
index c459be5e53f4ad915d669a0122cec77b1d1889e2..152327ea6d1584f1d0c208fce9c04c52ee4dd77c 100644
--- a/src/uri.cc
+++ b/src/uri.cc
@@ -60,31 +60,23 @@ void AddHexEncodedToBuffer(uint8_t octet, List<uint8_t>* buffer) {
 }
 
 void EncodeSingle(uc16 c, List<uint8_t>* buffer) {
-  uint8_t x = (c >> 12) & 0xF;
-  uint8_t y = (c >> 6) & 63;
-  uint8_t z = c & 63;
-  if (c <= 0x007F) {
-    AddHexEncodedToBuffer(c, buffer);
-  } else if (c <= 0x07FF) {
-    AddHexEncodedToBuffer(y + 192, buffer);
-    AddHexEncodedToBuffer(z + 128, buffer);
-  } else {
-    AddHexEncodedToBuffer(x + 224, buffer);
-    AddHexEncodedToBuffer(y + 128, buffer);
-    AddHexEncodedToBuffer(z + 128, buffer);
+  char s[4];
+  int number_of_bytes;
+  number_of_bytes =
+      unibrow::Utf8::Encode(s, c, unibrow::Utf16::kNoPreviousCharacter, false);
+  for (int k = 0; k < number_of_bytes; k++) {
+    AddHexEncodedToBuffer(s[k], buffer);
   }
 }
 
 void EncodePair(uc16 cc1, uc16 cc2, List<uint8_t>* buffer) {
-  uint8_t u = ((cc1 >> 6) & 0xF) + 1;
-  uint8_t w = (cc1 >> 2) & 0xF;
-  uint8_t x = cc1 & 3;
-  uint8_t y = (cc2 >> 6) & 0xF;
-  uint8_t z = cc2 & 63;
-  AddHexEncodedToBuffer((u >> 2) + 240, buffer);
-  AddHexEncodedToBuffer((((u & 3) << 4) | w) + 128, buffer);
-  AddHexEncodedToBuffer(((x << 4) | y) + 128, buffer);
-  AddHexEncodedToBuffer(z + 128, buffer);
+  char s[4];
+  int number_of_bytes =
+      unibrow::Utf8::Encode(s, unibrow::Utf16::CombineSurrogatePair(cc1, cc2),
+                            unibrow::Utf16::kNoPreviousCharacter, false);
+  for (int k = 0; k < number_of_bytes; k++) {
+    AddHexEncodedToBuffer(s[k], buffer);
+  }
 }
 
 }  // anonymous namespace
@@ -131,5 +123,178 @@ Object* Uri::Encode(Isolate* isolate, Handle<String> uri, bool is_uri) {
   return *result;
 }
 
+namespace {  // anonymous namespace for DecodeURI helper functions
+
+bool IsReservedPredicate(uc16 c) {
+  switch (c) {
+    case '#':
+    case '$':
+    case '&':
+    case '+':
+    case ',':
+    case '/':
+    case ':':
+    case ';':
+    case '=':
+    case '?':
+    case '@':
+      return true;
+    default:
+      return false;
+  }
+}
+
+bool IsRepalcementCharacter(List<uint8_t>* octets) {
+  // 0xFFFD is %ef%bf%bd
+  if (octets->length() != 3 || octets->at(0) != 0xef || octets->at(1) != 0xbf ||
+      octets->at(2) != 0xbd) {
+    return false;
+  }
+  return true;
+}
+
+bool DecodeOctets(List<uint8_t>* octets, List<uc16>* two_byte_buffer) {
+  size_t cursor = 0;
+  uc32 value = unibrow::Utf8::ValueOf(octets->ToConstVector().start(),
+                                      octets->length(), &cursor);
+  // kBadChar is the Replacement Character, which is the decoding of
+  // valid input %ef%bf%bd
+  if (value == unibrow::Utf8::kBadChar && !IsRepalcementCharacter(octets)) {
+    return false;
+  }
+
+  if (value <= unibrow::Utf16::kMaxNonSurrogateCharCode) {
+    two_byte_buffer->Add(value);
+  } else {
+    two_byte_buffer->Add(unibrow::Utf16::LeadSurrogate(value));
+    two_byte_buffer->Add(unibrow::Utf16::TrailSurrogate(value));
+  }
+  return true;
+}
+
+bool TwoDigitHex(uc16& decoded, int k, String::FlatContent* uri_content) {
+  char high = HexValue(uri_content->Get(k + 1));
+  char low = HexValue(uri_content->Get(k + 2));
+  if (high < 0 || low < 0) {
+    return false;
+  }
+  decoded = (high << 4) | low;
+  return true;
+}
+
+template <typename T>
+void AddToBuffer(uc16 decoded, String::FlatContent* uri_content, int k,
+                 bool is_uri, List<T>* buffer) {
+  if (is_uri && IsReservedPredicate(decoded)) {
+    buffer->Add('%');
+    buffer->Add(uri_content->Get(k + 1));
+    buffer->Add(uri_content->Get(k + 2));
+  } else {
+    buffer->Add(decoded);
+  }
+}
+
+bool IntoTwoByte(int index, bool is_uri, int uri_length,
+                 String::FlatContent* uri_content,
+                 List<uc16>* two_byte_buffer) {
+  for (int k = index; k < uri_length; k++) {
+    uc16 code = uri_content->Get(k);
+    if (code == '%') {
+      uc16 decoded;
+      if (k + 2 >= uri_length || !TwoDigitHex(decoded, k, uri_content)) {
+        return false;
+      }
+      k += 2;
+      if (decoded > unibrow::Utf8::kMaxOneByteChar) {
+        int n = 0;
+        while (((decoded << ++n) & 0x80) != 0) {
+        }
+        if (n == 1 || n > 4 || k + 3 * (n - 1) >= uri_length) {
+          return false;
+        }
+        List<uint8_t> octets;
+        octets.Add(decoded);
+
+        for (int i = 1; i < n; i++) {
+          uc16 decodedTrail;
+
+          if (uri_content->Get(++k) != '%' || k + 2 >= uri_length ||
+              !TwoDigitHex(decodedTrail, k, uri_content)) {
+            return false;
+          }
+          k += 2;
+          octets.Add(decodedTrail);
+        }
+
+        if (!DecodeOctets(&octets, two_byte_buffer)) {
+          return false;
+        }
+      } else {
+        AddToBuffer(decoded, uri_content, k - 2, is_uri, two_byte_buffer);
+      }
+    } else {
+      two_byte_buffer->Add(code);
+    }
+  }
+  return true;
+}
+
+bool IntoOneAndTwoByte(Handle<String> uri, bool is_uri,
+                       List<uint8_t>* one_byte_buffer,
+                       List<uc16>* two_byte_buffer) {
+  DisallowHeapAllocation no_gc;
+  String::FlatContent uri_content = uri->GetFlatContent();
+
+  int uri_length = uri->length();
+  for (int k = 0; k < uri_length; k++) {
+    uc16 code = uri_content.Get(k);
+    if (code == '%') {
+      uc16 decoded;
+      if (k + 2 >= uri_length || !TwoDigitHex(decoded, k, &uri_content)) {
+        return false;
+      }
+
+      if (decoded > unibrow::Utf8::kMaxOneByteChar) {
+        return IntoTwoByte(k, is_uri, uri_length, &uri_content,
+                           two_byte_buffer);
+      }
+
+      AddToBuffer(decoded, &uri_content, k, is_uri, one_byte_buffer);
+      k += 2;
+    } else {
+      if (code > unibrow::Utf8::kMaxOneByteChar) {
+        return IntoTwoByte(k, is_uri, uri_length, &uri_content,
+                           two_byte_buffer);
+      }
+      one_byte_buffer->Add(code);
+    }
+  }
+  return true;
+}
+
+}  // anonymous namespace
+
+Object* Uri::Decode(Isolate* isolate, Handle<String> uri, bool is_uri) {
+  uri = String::Flatten(uri);
+  List<uint8_t> one_byte_buffer;
+  List<uc16> two_byte_buffer;
+
+  if (!IntoOneAndTwoByte(uri, is_uri, &one_byte_buffer, &two_byte_buffer)) {
+    THROW_NEW_ERROR_RETURN_FAILURE(isolate, NewURIError());
+  }
+
+  Handle<String> left = isolate->factory()->InternalizeOneByteString(
+      one_byte_buffer.ToConstVector());
+
+  Handle<String> right = isolate->factory()->InternalizeTwoByteString(
+      two_byte_buffer.ToConstVector());
+
+  Handle<String> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result, isolate->factory()->NewConsString(left, right));
+
+  return *result;
+}
+
 }  // namespace internal
 }  // namespace v8