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// Copyright 2017 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "core/fpdfapi/parser/cpdf_object_walker.h"
#include <utility>
#include "core/fpdfapi/parser/cpdf_array.h"
#include "core/fpdfapi/parser/cpdf_dictionary.h"
#include "core/fpdfapi/parser/cpdf_stream.h"
#include "third_party/base/ptr_util.h"
namespace {
class StreamIterator final : public CPDF_ObjectWalker::SubobjectIterator {
public:
explicit StreamIterator(const CPDF_Stream* stream)
: SubobjectIterator(stream) {}
~StreamIterator() override {}
bool IsFinished() const override { return IsStarted() && is_finished_; }
const CPDF_Object* IncrementImpl() override {
ASSERT(IsStarted());
ASSERT(!IsFinished());
is_finished_ = true;
return object()->GetDict();
}
void Start() override {}
private:
bool is_finished_ = false;
};
class DictionaryIterator final : public CPDF_ObjectWalker::SubobjectIterator {
public:
explicit DictionaryIterator(const CPDF_Dictionary* dictionary)
: SubobjectIterator(dictionary) {}
~DictionaryIterator() override {}
bool IsFinished() const override {
return IsStarted() && dict_iterator_ == object()->GetDict()->end();
}
const CPDF_Object* IncrementImpl() override {
ASSERT(IsStarted());
ASSERT(!IsFinished());
const CPDF_Object* result = dict_iterator_->second.get();
dict_key_ = dict_iterator_->first;
++dict_iterator_;
return result;
}
void Start() override {
ASSERT(!IsStarted());
dict_iterator_ = object()->GetDict()->begin();
}
ByteString dict_key() const { return dict_key_; }
private:
CPDF_Dictionary::const_iterator dict_iterator_;
ByteString dict_key_;
};
class ArrayIterator final : public CPDF_ObjectWalker::SubobjectIterator {
public:
explicit ArrayIterator(const CPDF_Array* array) : SubobjectIterator(array) {}
~ArrayIterator() override {}
bool IsFinished() const override {
return IsStarted() && arr_iterator_ == object()->AsArray()->end();
}
const CPDF_Object* IncrementImpl() override {
ASSERT(IsStarted());
ASSERT(!IsFinished());
const CPDF_Object* result = arr_iterator_->get();
++arr_iterator_;
return result;
}
void Start() override { arr_iterator_ = object()->AsArray()->begin(); }
public:
CPDF_Array::const_iterator arr_iterator_;
};
} // namespace
CPDF_ObjectWalker::SubobjectIterator::~SubobjectIterator() {}
const CPDF_Object* CPDF_ObjectWalker::SubobjectIterator::Increment() {
if (!IsStarted()) {
Start();
is_started_ = true;
}
while (!IsFinished()) {
const CPDF_Object* result = IncrementImpl();
if (result)
return result;
}
return nullptr;
}
CPDF_ObjectWalker::SubobjectIterator::SubobjectIterator(
const CPDF_Object* object)
: object_(object) {
ASSERT(object_);
}
// static
std::unique_ptr<CPDF_ObjectWalker::SubobjectIterator>
CPDF_ObjectWalker::MakeIterator(const CPDF_Object* object) {
if (object->IsStream())
return pdfium::MakeUnique<StreamIterator>(object->AsStream());
if (object->IsDictionary())
return pdfium::MakeUnique<DictionaryIterator>(object->AsDictionary());
if (object->IsArray())
return pdfium::MakeUnique<ArrayIterator>(object->AsArray());
return nullptr;
}
CPDF_ObjectWalker::CPDF_ObjectWalker(const CPDF_Object* root)
: next_object_(root) {}
CPDF_ObjectWalker::~CPDF_ObjectWalker() = default;
const CPDF_Object* CPDF_ObjectWalker::GetNext() {
while (!stack_.empty() || next_object_) {
if (next_object_) {
auto new_iterator = MakeIterator(next_object_.Get());
if (new_iterator) {
// Schedule walk within composite objects.
stack_.push(std::move(new_iterator));
}
auto* result = next_object_.Get();
next_object_ = nullptr;
return result;
}
SubobjectIterator* it = stack_.top().get();
if (it->IsFinished()) {
stack_.pop();
} else {
next_object_ = it->Increment();
parent_object_ = it->object();
dict_key_ = parent_object_->IsDictionary()
? static_cast<DictionaryIterator*>(it)->dict_key()
: ByteString();
current_depth_ = stack_.size();
}
}
dict_key_ = ByteString();
current_depth_ = 0;
return nullptr;
}
void CPDF_ObjectWalker::SkipWalkIntoCurrentObject() {
if (stack_.empty() || stack_.top()->IsStarted())
return;
stack_.pop();
}
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