73 lines
2.8 KiB
Python
73 lines
2.8 KiB
Python
"""
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This file contains general helper macros that make our BUILD.bazel files easier to read.
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"""
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def select_multi(values_map, default, name = ""):
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"""select() but allowing multiple matches of the keys.
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select_multi works around a restriction in native select() that prevents multiple
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keys from being matched unless one is a strict subset of another. For some features,
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we allow multiple of that component to be active. For example, with codecs, we let
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the clients mix and match anywhere from 0 built in codecs to all of them.
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select_multi takes a given map and turns it into several distinct select statements
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that have the effect of using any values associated with any active keys.
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For example, if the following parameters are passed in:
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values_map = {
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":alpha": ["apple", "apricot"],
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":beta": ["banana"],
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":gamma": ["grapefruit"],
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},
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default = []
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it will be unrolled into the following select statements
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[] + select({
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":apple": ["apple", "apricot"],
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"//conditions:default": [],
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}) + select({
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":beta": ["banana"],
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"//conditions:default": [],
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}) + select({
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":gamma": ["grapefruit"],
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"//conditions:default": [],
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})
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Args:
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values_map: dictionary of labels to a list of labels, just like select()
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default: list of labels, the value that should be used if any of the options do not match.
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This is typically an empty list
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name: string unused, https://github.com/bazelbuild/buildtools/blob/master/WARNINGS.md#unnamed-macro
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Returns:
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A list of values that is filled in by the generated select statements.
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"""
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if len(values_map) == 0:
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return default
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rv = []
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for key, value in values_map.items():
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rv += select({
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key: value,
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"//conditions:default": default,
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})
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return rv
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def generated_cc_atom(name, **kwargs):
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"""A self-annotating label for a generated cc_library for exactly one file.
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Args:
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name: string, the name of the cc_library
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**kwargs: All other arguments are passed verbatim to cc_library
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"""
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if len(kwargs.get("srcs", [])) > 1 or len(kwargs.get("hdrs", [])) > 1:
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fail("Cannot have more than one src or hdr file in generated_cc_atom")
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if len(kwargs.get("srcs", [])) > 0 and len(kwargs.get("hdrs", [])) > 0:
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fail("Cannot set both srcs and hdrs in generated_cc_atom")
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if len(kwargs.get("srcs", [])) == 0 and len(kwargs.get("hdrs", [])) == 0:
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fail("Must set exactly one of srcs or hdrs in generated_cc_atom")
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deps = kwargs.get("deps", [])
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deps.append("//bazel:defines_from_flags")
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kwargs["deps"] = deps
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native.cc_library(
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name = name,
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**kwargs
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)
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