// Copyright 2016 The Bazel Authors. All rights reserved.
//
// 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.
package com.google.devtools.build.lib.rules.objc;
import com.google.common.base.Preconditions;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
import com.google.devtools.build.lib.collect.nestedset.NestedSet;
import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
import com.google.devtools.build.lib.vfs.PathFragment;
/**
* A provider that provides all protos and portable proto filters information in the transitive
* closure of its dependencies that are needed for generating and compiling only one version of
* proto files.
*
* <p>This provider also propagates the headers and search path for the protobuf runtime library.
* This solves the issue that the proto bundling behavior (gather all the protos in the top target
* and generate, compile and link only one version in the final binary) needs this data at the
* linking target but the dependency on the runtime library is defined on the objc_proto_library.
*
* <p>Ideally we should make objc_binary (and other linking targets such as ios_extension_binary)
* depend on the runtime library's ObjcProvider. Unfortunately this runs into a bug where Xcode
* project generation cannot handle the dependency if it points to a label in an external workspace
* (such as {@code @bazel_tools}). To avoid breaking Xcode project generation for all binary targets
* all the time (whether protos are used or not), the dependency is specified on objc_proto_library
* instead.
*/
public class ObjcProtoProvider implements TransitiveInfoProvider {
private final NestedSet<NestedSet<Artifact>> protoGroups;
private final NestedSet<Artifact> protobufHeaders;
private final NestedSet<PathFragment> protobufHeaderSearchPaths;
private final NestedSet<Artifact> portableProtoFilters;
private ObjcProtoProvider(
NestedSet<NestedSet<Artifact>> protoGroups,
NestedSet<Artifact> portableProtoFilters,
NestedSet<Artifact> protobufHeaders,
NestedSet<PathFragment> protobufHeaderSearchPaths) {
this.protoGroups = Preconditions.checkNotNull(protoGroups);
this.portableProtoFilters = Preconditions.checkNotNull(portableProtoFilters);
this.protobufHeaders = Preconditions.checkNotNull(protobufHeaders);
this.protobufHeaderSearchPaths = Preconditions.checkNotNull(protobufHeaderSearchPaths);
}
/** Returns the set of all proto groups that the dependencies of this provider has seen. */
public NestedSet<NestedSet<Artifact>> getProtoGroups() {
return protoGroups;
}
/** Returns the header artifacts provided by the Protobuf library. */
public NestedSet<Artifact> getProtobufHeaders() {
return protobufHeaders;
}
/** Returns the header search paths provided by the Protobuf library. */
public NestedSet<PathFragment> getProtobufHeaderSearchPaths() {
return protobufHeaderSearchPaths;
}
/**
* Returns the set of all the associated filters to the collected protos.
*/
public NestedSet<Artifact> getPortableProtoFilters() {
return portableProtoFilters;
}
/**
* A builder for this context with an API that is optimized for collecting information from
* several transitive dependencies.
*/
public static final class Builder {
private final NestedSetBuilder<NestedSet<Artifact>> protoGroups =
NestedSetBuilder.stableOrder();
private final NestedSetBuilder<Artifact> portableProtoFilters = NestedSetBuilder.stableOrder();
private final NestedSetBuilder<Artifact> protobufHeaders = NestedSetBuilder.stableOrder();
private final NestedSetBuilder<PathFragment> protobufHeaderSearchPaths =
NestedSetBuilder.linkOrder();
/**
* Adds a proto group to be propagated. Each group represents a proto_library target and
* contains protos to be built along with their transitive dependencies. We propagate protos as
* groups because the grouping provides relationship information between the protos, which can
* be used to limit the number of inputs to each proto generation action.
*/
public Builder addProtoGroup(NestedSet<Artifact> protoGroup) {
this.protoGroups.add(protoGroup);
return this;
}
/** Adds the header artifacts provided by the Protobuf library. */
public Builder addProtobufHeaders(NestedSet<Artifact> protobufHeaders) {
this.protobufHeaders.addTransitive(protobufHeaders);
return this;
}
/** Adds the header search paths provided by the Protobuf library. */
public Builder addProtobufHeaderSearchPaths(NestedSet<PathFragment> protobufHeaderSearchPaths) {
this.protobufHeaderSearchPaths.addTransitive(protobufHeaderSearchPaths);
return this;
}
/**
* Adds all the proto filters to the set of dependencies.
*/
public Builder addPortableProtoFilters(NestedSet<Artifact> protoFilters) {
this.portableProtoFilters.addTransitive(protoFilters);
return this;
}
/**
* Add all protos and filters from providers, and propagate them to any (transitive) dependers
* on this ObjcProtoProvider.
*/
public Builder addTransitive(Iterable<ObjcProtoProvider> providers) {
for (ObjcProtoProvider provider : providers) {
this.protoGroups.addTransitive(provider.getProtoGroups());
this.portableProtoFilters.addTransitive(provider.getPortableProtoFilters());
this.protobufHeaders.addTransitive(provider.getProtobufHeaders());
this.protobufHeaderSearchPaths.addTransitive(provider.getProtobufHeaderSearchPaths());
}
return this;
}
/**
* Whether this provider has any protos or filters.
*/
public boolean isEmpty() {
return protoGroups.isEmpty() && portableProtoFilters.isEmpty();
}
public ObjcProtoProvider build() {
return new ObjcProtoProvider(
protoGroups.build(),
portableProtoFilters.build(),
protobufHeaders.build(),
protobufHeaderSearchPaths.build());
}
}
}