tools/aapt2/link/Linkers.h

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef AAPT_LINKER_LINKERS_H
#define AAPT_LINKER_LINKERS_H

#include <set>
#include <unordered_set>

#include "android-base/macros.h"

#include "Resource.h"
#include "process/IResourceTableConsumer.h"
#include "xml/XmlDom.h"

namespace aapt {

class ResourceTable;
class ResourceEntry;
struct ConfigDescription;

/**
 * Defines the location in which a value exists. This determines visibility of
 * other package's private symbols.
 */
struct CallSite {
  ResourceNameRef resource;
};

/**
 * Determines whether a versioned resource should be created. If a versioned
 * resource already exists, it takes precedence.
 */
bool ShouldGenerateVersionedResource(const ResourceEntry* entry,
                                     const ConfigDescription& config,
                                     const int sdk_version_to_generate);

class AutoVersioner : public IResourceTableConsumer {
 public:
  AutoVersioner() = default;

  bool Consume(IAaptContext* context, ResourceTable* table) override;

 private:
  DISALLOW_COPY_AND_ASSIGN(AutoVersioner);
};

class VersionCollapser : public IResourceTableConsumer {
 public:
  VersionCollapser() = default;

  bool Consume(IAaptContext* context, ResourceTable* table) override;

 private:
  DISALLOW_COPY_AND_ASSIGN(VersionCollapser);
};

/**
 * Removes duplicated key-value entries from dominated resources.
 */
class ResourceDeduper : public IResourceTableConsumer {
 public:
  ResourceDeduper() = default;

  bool Consume(IAaptContext* context, ResourceTable* table) override;

 private:
  DISALLOW_COPY_AND_ASSIGN(ResourceDeduper);
};

/**
 * If any attribute resource values are defined as public, this consumer will
 * move all private
 * attribute resource values to a private ^private-attr type, avoiding backwards
 * compatibility
 * issues with new apps running on old platforms.
 *
 * The Android platform ignores resource attributes it doesn't recognize, so an
 * app developer can
 * use new attributes in their layout XML files without worrying about
 * versioning. This assumption
 * actually breaks on older platforms. OEMs may add private attributes that are
 * used internally.
 * AAPT originally assigned all private attributes IDs immediately proceeding
 * the public attributes'
 * IDs.
 *
 * This means that on a newer Android platform, an ID previously assigned to a
 * private attribute
 * may end up assigned to a public attribute.
 *
 * App developers assume using the newer attribute is safe on older platforms
 * because it will
 * be ignored. Instead, the platform thinks the new attribute is an older,
 * private attribute and
 * will interpret it as such. This leads to unintended styling and exceptions
 * thrown due to
 * unexpected types.
 *
 * By moving the private attributes to a completely different type, this ID
 * conflict will never
 * occur.
 */
class PrivateAttributeMover : public IResourceTableConsumer {
 public:
  PrivateAttributeMover() = default;

  bool Consume(IAaptContext* context, ResourceTable* table) override;

 private:
  DISALLOW_COPY_AND_ASSIGN(PrivateAttributeMover);
};

class ResourceConfigValue;

class ProductFilter : public IResourceTableConsumer {
 public:
  using ResourceConfigValueIter =
      std::vector<std::unique_ptr<ResourceConfigValue>>::iterator;

  explicit ProductFilter(std::unordered_set<std::string> products)
      : products_(products) {}

  ResourceConfigValueIter SelectProductToKeep(
      const ResourceNameRef& name, const ResourceConfigValueIter begin,
      const ResourceConfigValueIter end, IDiagnostics* diag);

  bool Consume(IAaptContext* context, ResourceTable* table) override;

 private:
  std::unordered_set<std::string> products_;

  DISALLOW_COPY_AND_ASSIGN(ProductFilter);
};

class XmlAutoVersioner : public IXmlResourceConsumer {
 public:
  XmlAutoVersioner() = default;

  bool Consume(IAaptContext* context, xml::XmlResource* resource) override;

 private:
  DISALLOW_COPY_AND_ASSIGN(XmlAutoVersioner);
};

/**
 * Removes namespace nodes and URI information from the XmlResource.
 *
 * Once an XmlResource is processed by this consumer, it is no longer able to
 * have its attributes
 * parsed. As such, this XmlResource must have already been processed by
 * XmlReferenceLinker.
 */
class XmlNamespaceRemover : public IXmlResourceConsumer {
 public:
  explicit XmlNamespaceRemover(bool keep_uris = false)
      : keep_uris_(keep_uris){};

  bool Consume(IAaptContext* context, xml::XmlResource* resource) override;

 private:
  DISALLOW_COPY_AND_ASSIGN(XmlNamespaceRemover);

  bool keep_uris_;
};

/**
 * Resolves attributes in the XmlResource and compiles string values to resource
 * values.
 * Once an XmlResource is processed by this linker, it is ready to be flattened.
 */
class XmlReferenceLinker : public IXmlResourceConsumer {
 public:
  XmlReferenceLinker() = default;

  bool Consume(IAaptContext* context, xml::XmlResource* resource) override;

  /**
   * Once the XmlResource has been consumed, this returns the various SDK levels
   * in which
   * framework attributes used within the XML document were defined.
   */
  inline const std::set<int>& sdk_levels() const { return sdk_levels_found_; }

 private:
  DISALLOW_COPY_AND_ASSIGN(XmlReferenceLinker);

  std::set<int> sdk_levels_found_;
};

}  // namespace aapt

#endif /* AAPT_LINKER_LINKERS_H */