swig_python.bzl

# Copyright 2010-2024 Google LLC
# 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.

""" Bazel rules for building swig files."""

def _py_wrap_cc_impl(ctx):
    srcs = ctx.files.srcs
    if len(srcs) != 1:
        fail("Exactly one SWIG source file label must be specified.", "srcs")
    module_name = ctx.attr.module_name
    src = ctx.files.srcs[0]
    inputs = set([src])
    inputs += ctx.files.i_includes
    for dep in ctx.attr.deps:
        inputs += dep.cc.transitive_headers
    inputs += ctx.files._swiglib
    inputs += ctx.files.toolchain_deps
    swig_include_dirs = set(_get_repository_roots(ctx, inputs))
    swig_include_dirs += sorted([f.dirname for f in ctx.files._swiglib])
    args = [
        "-c++",
        "-python",
        "-module",
        module_name,
        "-o",
        ctx.outputs.cc_out.path,
        "-outdir",
        ctx.outputs.py_out.dirname,
    ]
    args += ["-l" + f.path for f in ctx.files.i_includes]
    args += ["-I" + i for i in swig_include_dirs]
    args.append(src.path)
    outputs = [ctx.outputs.cc_out, ctx.outputs.py_out]
    ctx.actions.run(
        executable = ctx.executable._swig,
        arguments = args,
        inputs = list(inputs),
        outputs = outputs,
        mnemonic = "PythonSwig",
        progress_message = "SWIGing " + src.path,
    )
    return [
        DefaultInfo(files = depset(outputs)),
    ]

_py_wrap_cc = rule(
    attrs = {
        "srcs": attr.label_list(
            mandatory = True,
            allow_files = True,
        ),
        "swig_includes": attr.label_list(
            allow_files = True,
        ),
        "deps": attr.label_list(
            allow_files = True,
            providers = ["cc"],
        ),
        "toolchain_deps": attr.label_list(
            allow_files = True,
        ),
        "module_name": attr.string(mandatory = True),
        "py_module_name": attr.string(mandatory = True),
        "_swig": attr.label(
            default = Label("@swig//:swig"),
            executable = True,
            cfg = "exec",
        ),
        "_swiglib": attr.label(
            default = Label("@swig//:templates"),
            allow_files = True,
        ),
    },
    outputs = {
        "cc_out": "%{module_name}.cc",
        "py_out": "%{py_module_name}.py",
    },
    implementation = _py_wrap_cc_impl,
)