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Unified Diff: src/objects.cc

Issue 2339123002: [builtins] Move StringLastIndexOf to a builtin. (Closed)
Patch Set: Variable renaming to make things a bit clearer Created 4 years, 3 months ago
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Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 20701a73edf89ec5cc5d13e3352ba397bab55fc5..eb0cb4a52ebdefbf3d1b83c8f0027933efb6b3f0 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -11636,6 +11636,118 @@ int String::IndexOf(Isolate* isolate, Handle<String> sub, Handle<String> pat,
return SearchString(isolate, seq_sub.ToUC16Vector(), pat_vector, start_index);
}
+namespace { // for String.Prototype.lastIndexOf
+
+template <typename schar, typename pchar>
+int StringMatchBackwards(Vector<const schar> subject,
+ Vector<const pchar> pattern, int idx) {
+ int pattern_length = pattern.length();
+ DCHECK(pattern_length >= 1);
+ DCHECK(idx + pattern_length <= subject.length());
+
+ if (sizeof(schar) == 1 && sizeof(pchar) > 1) {
+ for (int i = 0; i < pattern_length; i++) {
+ uc16 c = pattern[i];
+ if (c > String::kMaxOneByteCharCode) {
+ return -1;
+ }
+ }
+ }
+
+ pchar pattern_first_char = pattern[0];
+ for (int i = idx; i >= 0; i--) {
+ if (subject[i] != pattern_first_char) continue;
+ int j = 1;
+ while (j < pattern_length) {
+ if (pattern[j] != subject[i + j]) {
+ break;
+ }
+ j++;
+ }
+ if (j == pattern_length) {
+ return i;
+ }
+ }
+ return -1;
+}
+
+} // namespace
+
+Object* String::LastIndexOf(Isolate* isolate, Handle<Object> receiver,
+ Handle<Object> search, Handle<Object> position) {
+ if (receiver->IsNull(isolate) || receiver->IsUndefined(isolate)) {
+ THROW_NEW_ERROR_RETURN_FAILURE(
+ isolate, NewTypeError(MessageTemplate::kCalledOnNullOrUndefined,
+ isolate->factory()->NewStringFromAsciiChecked(
+ "String.prototype.lastIndexOf")));
+ }
+ Handle<String> receiver_string;
+ ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, receiver_string,
+ Object::ToString(isolate, receiver));
+
+ Handle<String> search_string;
+ ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, search_string,
+ Object::ToString(isolate, search));
+
+ ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, position,
+ Object::ToNumber(position));
+
+ uint32_t start_index;
+
+ if (position->IsNaN()) {
+ start_index = receiver_string->length();
+ } else {
+ ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, position,
+ Object::ToInteger(isolate, position));
+
+ double position_number = std::max(position->Number(), 0.0);
+ position_number = std::min(position_number,
+ static_cast<double>(receiver_string->length()));
+ start_index = static_cast<uint32_t>(position_number);
+ }
+
+ uint32_t pattern_length = search_string->length();
+ uint32_t receiver_length = receiver_string->length();
+
+ if (start_index + pattern_length > receiver_length) {
+ start_index = receiver_length - pattern_length;
+ }
+
+ if (pattern_length == 0) {
+ return Smi::FromInt(start_index);
+ }
+
+ receiver_string = String::Flatten(receiver_string);
+ search_string = String::Flatten(search_string);
+
+ int last_index = -1;
+ DisallowHeapAllocation no_gc; // ensure vectors stay valid
+
+ String::FlatContent receiver_content = receiver_string->GetFlatContent();
+ String::FlatContent search_content = search_string->GetFlatContent();
+
+ if (search_content.IsOneByte()) {
+ Vector<const uint8_t> pat_vector = search_content.ToOneByteVector();
+ if (receiver_content.IsOneByte()) {
+ last_index = StringMatchBackwards(receiver_content.ToOneByteVector(),
+ pat_vector, start_index);
+ } else {
+ last_index = StringMatchBackwards(receiver_content.ToUC16Vector(),
+ pat_vector, start_index);
+ }
+ } else {
+ Vector<const uc16> pat_vector = search_content.ToUC16Vector();
+ if (receiver_content.IsOneByte()) {
+ last_index = StringMatchBackwards(receiver_content.ToOneByteVector(),
+ pat_vector, start_index);
+ } else {
+ last_index = StringMatchBackwards(receiver_content.ToUC16Vector(),
+ pat_vector, start_index);
+ }
+ }
+ return Smi::FromInt(last_index);
+}
+
bool String::IsUtf8EqualTo(Vector<const char> str, bool allow_prefix_match) {
int slen = length();
// Can't check exact length equality, but we can check bounds.
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