Adding break iterator support to the i18n api extension....

src/extensions/experimental/break-iterator.cc

+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "break-iterator.h"
+
+#include "unicode/brkiter.h"
+#include "unicode/locid.h"
+#include "unicode/rbbi.h"
+#include "unicode/uloc.h"
+
+namespace v8 {
+namespace internal {
+
+v8::Persistent<v8::ObjectTemplate> BreakIterator::break_iterator_template_;
+
+// Unpacks break iterator object from corresponding JavaScript object.
+static icu::BreakIterator* UnpackBreakIterator(v8::Handle<v8::Object> obj) {
+  return static_cast<icu::BreakIterator*>(obj->GetPointerFromInternalField(0));

[Mads Ager (chromium), 2011/02/28 13:03:32]

You need to be more careful here. The users of UnpackBreakIterator are
functions. These functions can be moved to other objects and therefore the
holder does not need to be a break iterator object at all.

Instead of using an ObjectTemplate for you break iterator wrappers I think you
should use a FunctionTemplate instead. Then here you can check that the argument
is an instance of that function template. If it is, it will have be internal
field and the value in it will be a BreakIterator pointer.

Have a look at FunctionTemplate. You add the methods on the instance_template as
you do now. Then you can use templ->HasInstance(obj).

[Nebojša Ćirić, 2011/02/28 20:42:41]

Done.

+}
+
+// Release memory we allocated for the BreakIterator once the JS object that
+// holds the pointer gets garbage collected.
+static void DeleteBreakIterator(v8::Persistent<v8::Value> object,
+                                void* param) {
+  delete UnpackBreakIterator(v8::Persistent<v8::Object>::Cast(object));

[Mads Ager (chromium), 2011/02/28 13:03:32]

You need to do object.Dispose() as well to delete the persistent handle as well.
This callback needs to be used on all break iterator instances instead of on the
template (see below).

[Nebojša Ćirić, 2011/02/28 20:42:41]

Done.

+}
+
+// Assigns new text to the iterator.
+static v8::Handle<v8::Value> BreakIteratorAdoptText(
+    const v8::Arguments& args) {
+  if (args.Length() != 1 || !args[0]->IsString()) {
+    return v8::ThrowException(v8::Exception::SyntaxError(
+        v8::String::New("Text input is required.")));
+  }
+
+  icu::BreakIterator* break_iterator = UnpackBreakIterator(args.Holder());
+
+  v8::Local<v8::String> text_value = args[0]->ToString();
+  UnicodeString text(*v8::String::Value(text_value),
+                     text_value->Length());
+
+  break_iterator->setText(text);
+
+  return v8::Undefined();
+}
+
+// Moves iterator to the beginning of the string and returns new position.
+static v8::Handle<v8::Value> BreakIteratorFirst(const v8::Arguments& args) {
+  icu::BreakIterator* break_iterator = UnpackBreakIterator(args.Holder());
+
+  return v8::Int32::New(break_iterator->first());
+}
+
+// Moves iterator to the next position and returns it.
+static v8::Handle<v8::Value> BreakIteratorNext(const v8::Arguments& args) {
+  icu::BreakIterator* break_iterator = UnpackBreakIterator(args.Holder());
+
+  return v8::Int32::New(break_iterator->next());
+}
+
+// Returns current iterator's current position.
+static v8::Handle<v8::Value> BreakIteratorCurrent(const v8::Arguments& args) {
+  icu::BreakIterator* break_iterator = UnpackBreakIterator(args.Holder());
+
+  return v8::Int32::New(break_iterator->current());
+}
+
+// Returns type of the item from current position.
+// This call is only valid for word break iterators. Others just return 0.
+static v8::Handle<v8::Value> BreakIteratorBreakType(
+    const v8::Arguments& args) {
+  icu::BreakIterator* break_iterator = UnpackBreakIterator(args.Holder());
+
+  // TODO(cira): Remove cast once ICU fixes base BreakIterator class.
+  int32_t status =
+      static_cast<RuleBasedBreakIterator*>(break_iterator)->getRuleStatus();
+  // Keep return values in sync with JavaScript BreakType enum.
+  if (status >= UBRK_WORD_NONE && status < UBRK_WORD_NONE_LIMIT) {
+    return v8::Int32::New(UBRK_WORD_NONE);
+  } else if (status >= UBRK_WORD_NUMBER && status < UBRK_WORD_NUMBER_LIMIT) {
+    return v8::Int32::New(UBRK_WORD_NUMBER);
+  } else if (status >= UBRK_WORD_LETTER && status < UBRK_WORD_LETTER_LIMIT) {
+    return v8::Int32::New(UBRK_WORD_LETTER);
+  } else if (status >= UBRK_WORD_KANA && status < UBRK_WORD_KANA_LIMIT) {
+    return v8::Int32::New(UBRK_WORD_KANA);
+  } else if (status >= UBRK_WORD_IDEO && status < UBRK_WORD_IDEO_LIMIT) {
+    return v8::Int32::New(UBRK_WORD_IDEO);
+  } else {
+    return v8::Int32::New(-1);
+  }
+}
+
+v8::Handle<v8::Value> BreakIterator::JSBreakIterator(
+    const v8::Arguments& args) {
+  // No need to check args here, we do it in JavaScript.
+
+  const char* locale = *v8::String::Utf8Value(args[0]->ToString());
+  icu::Locale icu_locale(locale);
+
+  UErrorCode status = U_ZERO_ERROR;
+  icu::BreakIterator* break_iterator = NULL;
+  const char* type = *v8::String::Utf8Value(args[1]->ToString());
+  if (!strcmp(type, "character")) {
+    break_iterator =
+        icu::BreakIterator::createCharacterInstance(icu_locale, status);
+  } else if (!strcmp(type, "word")) {
+    break_iterator =
+        icu::BreakIterator::createWordInstance(icu_locale, status);
+  } else if (!strcmp(type, "sentence")) {
+    break_iterator =
+        icu::BreakIterator::createSentenceInstance(icu_locale, status);
+  } else if (!strcmp(type, "line")) {
+    break_iterator =
+        icu::BreakIterator::createLineInstance(icu_locale, status);
+  } else {
+    return v8::ThrowException(v8::Exception::SyntaxError(
+        v8::String::New("Invalid iterator type.")));
+  }
+
+  if (U_FAILURE(status)) {
+    delete break_iterator;
+    return v8::ThrowException(v8::Exception::Error(
+        v8::String::New("Failed to create break iterator.")));
+  }
+
+  v8::HandleScope handle_scope;

[Mads Ager (chromium), 2011/02/28 13:03:32]

Is there a reason not have have this handle scope earlier in this method? You
are also allocating strings above for instance. The handles for those might as
well be local as well.

[Nebojša Ćirić, 2011/02/28 20:42:41]

Done.

+
+  if (break_iterator_template_.IsEmpty()) {
+    v8::Handle<v8::ObjectTemplate> raw_template(v8::ObjectTemplate::New());
+    raw_template->SetInternalFieldCount(1);
+    raw_template->Set(v8::String::New("adoptText"),
+                      v8::FunctionTemplate::New(BreakIteratorAdoptText));
+    raw_template->Set(v8::String::New("first"),
+                      v8::FunctionTemplate::New(BreakIteratorFirst));
+    raw_template->Set(v8::String::New("next"),
+                      v8::FunctionTemplate::New(BreakIteratorNext));
+    raw_template->Set(v8::String::New("current"),
+                      v8::FunctionTemplate::New(BreakIteratorCurrent));
+    raw_template->Set(v8::String::New("breakType"),
+                      v8::FunctionTemplate::New(BreakIteratorBreakType));
+    break_iterator_template_ =
+        v8::Persistent<v8::ObjectTemplate>::New(raw_template);
+    // Make template weak so we can delete iterator once GC kicks in.

[Mads Ager (chromium), 2011/02/28 13:03:32]

This is not the thing that you want to make weak. The break_iterator_template
does not correspond to a concrete break iterator?

[Nebojša Ćirić, 2011/02/28 20:42:41]

Yip, it felt weird when I did it. Never occurred to me I should make actual
Object persistent.

Done.

On 2011/02/28 13:03:32, Mads Ager wrote:

+    break_iterator_template_.MakeWeak(NULL, DeleteBreakIterator);
+  }
+
+  // Create an empty object wrapper.
+  v8::Handle<v8::Object> wrapper = break_iterator_template_->NewInstance();
+  // Set break iterator as internal field of the resulting JS object.
+  wrapper->SetPointerInInternalField(0, break_iterator);

[Mads Ager (chromium), 2011/02/28 13:03:32]

This is where you set up the correspondence. Here you need to decide on the
memory management story that you want. I think your BreakIterator instance needs
to have a reference (persistent handle) to the wrapper so it can return it again
for the next access to it. Also, that will allow you to tie the life-time of the
wrapper to the lifetime of the breakiterator C++ instance. 

Is the breakiterator C++ instance used by anything else than JavaScript? If not,
then each break iterator C++ instance should have a persistent handle to the JS
wrapper. This persistent handle should be weak and in the callback you should
call dispose on the persistent handle *and* delete the break iterator object.

 

[Nebojša Ćirić, 2011/02/28 20:42:41]

Done.

+
+  return handle_scope.Close(wrapper);
+}
+
+} }  // namespace v8::internal