74 lines
2.3 KiB
Plaintext
74 lines
2.3 KiB
Plaintext
#
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# Copyright 2021 Google, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at:
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# Flex (fast lexical analyzer generator) is used for parsing languages. It is
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# commonly used with a parser generator (like Bison).
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# Generate source files using Flex.
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#
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# Note: We generate .cc files for Flex. However, you must set %option c++ if you
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# want to generate a C++ scanner class. We don't use --c++ in case you have
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# %option reentrant set, which is mutually exclusive with %option c++.
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#
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# Parameters:
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# sources: Files used to generate the lexers.
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template("flex_source") {
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action_name = "${target_name}_gen"
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action_foreach(action_name) {
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forward_variables_from(invoker, [ "sources" ])
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assert(defined(sources), "sources must be set")
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foreach(s, sources) {
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assert(get_path_info(s, "extension") == "ll",
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"Expecting Flex extension ll: ${s}")
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}
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script = "//common-mk/file_generator_wrapper.py"
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outformat = "${target_gen_dir}/{{source_name_part}}.cc"
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args = [
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"flex",
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"-o",
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outformat,
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"{{source}}",
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]
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outputs = [ outformat ]
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}
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all_dependent_config_name = "_${target_name}_all_dependent_config"
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config(all_dependent_config_name) {
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include_dirs = [ "${target_gen_dir}" ]
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}
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source_set(target_name) {
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sources = get_target_outputs(":${action_name}")
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all_dependent_configs = [ ":${all_dependent_config_name}" ]
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deps = [ ":${action_name}" ]
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if (defined(invoker.deps)) {
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deps += invoker.deps
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}
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if (defined(invoker.configs)) {
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configs += invoker.configs
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}
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# Silence some warnings. The autogenerated code includes parts that have
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# fallthroughs and unreachable code. This may silence legitimate issues in
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# user written code in the lexer as well. User beware!
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cflags_cc = [
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"-Wno-implicit-fallthrough",
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"-Wno-unreachable-code",
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]
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}
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}
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