src/main/starlark/builtins_bzl/common/java/proto/java_lite_proto_library.bzl

# Copyright 2021 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.

"""A Starlark implementation of the java_lite_proto_library rule."""

load(":common/java/java_semantics.bzl", "semantics")
load(":common/java/proto/java_proto_library.bzl", "JavaProtoAspectInfo", "java_compile_for_protos")
load(":common/proto/proto_common.bzl", "toolchains", "ProtoLangToolchainInfo", proto_common = "proto_common_do_not_use")

PROTO_TOOLCHAIN_ATTR = "_aspect_proto_toolchain_for_javalite"

java_common = _builtins.toplevel.java_common
ProtoInfo = _builtins.toplevel.ProtoInfo
JavaInfo = _builtins.toplevel.JavaInfo
ProguardSpecProvider = _builtins.toplevel.ProguardSpecProvider

def _aspect_impl(target, ctx):
    """Generates and compiles Java code for a proto_library dependency graph.

    Args:
      target: (Target) The `proto_library` target.
      ctx: (RuleContext) The rule context.

    Returns:
      ([JavaInfo, JavaProtoAspectInfo]) A JavaInfo describing compiled Java
      version of`proto_library` and `JavaProtoAspectInfo` with all source and
      runtime jars.
    """

    deps = [dep[JavaInfo] for dep in ctx.rule.attr.deps]
    exports = [exp[JavaInfo] for exp in ctx.rule.attr.exports]
    proto_toolchain_info = toolchains.find_toolchain(
        ctx,
        "_aspect_proto_toolchain_for_javalite",
        semantics.JAVA_LITE_PROTO_TOOLCHAIN,
    )
    source_jar = None

    if proto_common.experimental_should_generate_code(target[ProtoInfo], proto_toolchain_info, "java_lite_proto_library", target.label):
        source_jar = ctx.actions.declare_file(ctx.label.name + "-lite-src.jar")
        proto_common.compile(
            ctx.actions,
            target[ProtoInfo],
            proto_toolchain_info,
            [source_jar],
            experimental_output_files = "single",
        )
        runtime = proto_toolchain_info.runtime
        if runtime:
            deps.append(runtime[JavaInfo])

    java_info, jars = java_compile_for_protos(
        ctx,
        "-lite.jar",
        source_jar,
        deps,
        exports,
        injecting_rule_kind = "java_lite_proto_library",
    )
    transitive_jars = [dep[JavaProtoAspectInfo].jars for dep in ctx.rule.attr.deps]

    return [
        java_info,
        JavaProtoAspectInfo(jars = depset(jars, transitive = transitive_jars)),
    ]

java_lite_proto_aspect = aspect(
    implementation = _aspect_impl,
    attr_aspects = ["deps", "exports"],
    attrs = toolchains.if_legacy_toolchain({
        PROTO_TOOLCHAIN_ATTR: attr.label(
            default = configuration_field(fragment = "proto", name = "proto_toolchain_for_java_lite"),
        ),
    }),
    fragments = ["java"],
    required_providers = [ProtoInfo],
    provides = [JavaInfo, JavaProtoAspectInfo],
    toolchains = [semantics.JAVA_TOOLCHAIN] +
                 toolchains.use_toolchain(semantics.JAVA_LITE_PROTO_TOOLCHAIN),
)

def _rule_impl(ctx):
    """Merges results of `java_proto_aspect` in `deps`.

    `java_lite_proto_library` is identical to `java_proto_library` in every respect, except it
    builds JavaLite protos.
    Implementation of this rule is built on the implementation of `java_proto_library`.

    Args:
      ctx: (RuleContext) The rule context.
    Returns:
      ([JavaInfo, DefaultInfo, OutputGroupInfo, ProguardSpecProvider])
    """

    proto_toolchain_info = toolchains.find_toolchain(
        ctx,
        "_aspect_proto_toolchain_for_javalite",
        semantics.JAVA_LITE_PROTO_TOOLCHAIN,
    )
    runtime = proto_toolchain_info.runtime

    if runtime:
        proguard_provider_specs = runtime[ProguardSpecProvider]
    else:
        proguard_provider_specs = ProguardSpecProvider(depset())

    java_info = java_common.merge([dep[JavaInfo] for dep in ctx.attr.deps], merge_java_outputs = False)

    transitive_src_and_runtime_jars = depset(transitive = [dep[JavaProtoAspectInfo].jars for dep in ctx.attr.deps])
    transitive_runtime_jars = depset(transitive = [java_info.transitive_runtime_jars])

    java_info = semantics.add_constraints(java_info, ["android"])

    return [
        java_info,
        DefaultInfo(
            files = transitive_src_and_runtime_jars,
            runfiles = ctx.runfiles(transitive_files = transitive_runtime_jars),
        ),
        OutputGroupInfo(default = depset()),
        proguard_provider_specs,
    ]

java_lite_proto_library = rule(
    implementation = _rule_impl,
    attrs = {
        "deps": attr.label_list(providers = [ProtoInfo], aspects = [java_lite_proto_aspect]),
    } | toolchains.if_legacy_toolchain({
        PROTO_TOOLCHAIN_ATTR: attr.label(
            default = configuration_field(fragment = "proto", name = "proto_toolchain_for_java_lite"),
        ),
    }),
    provides = [JavaInfo],
    toolchains = toolchains.use_toolchain(semantics.JAVA_LITE_PROTO_TOOLCHAIN),
)