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# Copyright 2015 MongoDB Inc.
#
# 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.
import json
import SCons
import itertools
# Implements the ability for SCons to emit a compilation database for the MongoDB project. See
# http://clang.llvm.org/docs/JSONCompilationDatabase.html for details on what a compilation
# database is, and why you might want one. The only user visible entry point here is
# 'env.CompilationDatabase'. This method takes an optional 'target' to name the file that
# should hold the compilation database, otherwise, the file defaults to compile_commands.json,
# which is the name that most clang tools search for by default.
# TODO: Is there a better way to do this than this global? Right now this exists so that the
# emitter we add can record all of the things it emits, so that the scanner for the top level
# compilation database can access the complete list, and also so that the writer has easy
# access to write all of the files. But it seems clunky. How can the emitter and the scanner
# communicate more gracefully?
__COMPILATION_DB_ENTRIES = []
# We make no effort to avoid rebuilding the entries. Someday, perhaps we could and even
# integrate with the cache, but there doesn't seem to be much call for it.
class __CompilationDbNode(SCons.Node.Python.Value):
def __init__(self, value):
SCons.Node.Python.Value.__init__(self, value)
self.Decider(changed_since_last_build_node)
def changed_since_last_build_node(child, target, prev_ni, node):
""" Dummy decider to force always building"""
return True
def makeEmitCompilationDbEntry(comstr):
"""
Effectively this creates a lambda function to capture:
* command line
* source
* target
:param comstr: unevaluated command line
:return: an emitter which has captured the above
"""
user_action = SCons.Action.Action(comstr)
def EmitCompilationDbEntry(target, source, env):
"""
This emitter will be added to each c/c++ object build to capture the info needed
for clang tools
:param target: target node(s)
:param source: source node(s)
:param env: Environment for use building this node
:return: target(s), source(s)
"""
dbtarget = __CompilationDbNode(source)
entry = env.__COMPILATIONDB_Entry(
target=dbtarget,
source=[],
__COMPILATIONDB_UTARGET=target,
__COMPILATIONDB_USOURCE=source,
__COMPILATIONDB_UACTION=user_action,
__COMPILATIONDB_ENV=env,
)
# TODO: Technically, these next two lines should not be required: it should be fine to
# cache the entries. However, they don't seem to update properly. Since they are quick
# to re-generate disable caching and sidestep this problem.
env.AlwaysBuild(entry)
env.NoCache(entry)
__COMPILATION_DB_ENTRIES.append(dbtarget)
return target, source
return EmitCompilationDbEntry
def CompilationDbEntryAction(target, source, env, **kw):
"""
Create a dictionary with evaluated command line, target, source
and store that info as an attribute on the target
(Which has been stored in __COMPILATION_DB_ENTRIES array
:param target: target node(s)
:param source: source node(s)
:param env: Environment for use building this node
:param kw:
:return: None
"""
command = env["__COMPILATIONDB_UACTION"].strfunction(
target=env["__COMPILATIONDB_UTARGET"], source=env["__COMPILATIONDB_USOURCE"], env=env["__COMPILATIONDB_ENV"],
)
entry = {
"directory": env.Dir("#").abspath,
"command": command,
"file": str(env["__COMPILATIONDB_USOURCE"][0]),
}
target[0].write(entry)
def WriteCompilationDb(target, source, env):
entries = []
for s in __COMPILATION_DB_ENTRIES:
entries.append(s.read())
with open(str(target[0]), "w") as target_file:
json.dump(entries, target_file, sort_keys=True, indent=4, separators=(",", ": "))
def ScanCompilationDb(node, env, path):
return __COMPILATION_DB_ENTRIES
def generate(env, **kwargs):
static_obj, shared_obj = SCons.Tool.createObjBuilders(env)
env["COMPILATIONDB_COMSTR"] = kwargs.get("COMPILATIONDB_COMSTR", "Building compilation database $TARGET")
components_by_suffix = itertools.chain(
itertools.product(
env["CPPSUFFIXES"],
[
(static_obj, SCons.Defaults.StaticObjectEmitter, "$CXXCOM"),
(shared_obj, SCons.Defaults.SharedObjectEmitter, "$SHCXXCOM"),
],
),
)
for entry in components_by_suffix:
suffix = entry[0]
builder, base_emitter, command = entry[1]
# Ensure we have a valid entry
# used to auto ignore header files
if suffix in builder.emitter:
emitter = builder.emitter[suffix]
builder.emitter[suffix] = SCons.Builder.ListEmitter([emitter, makeEmitCompilationDbEntry(command),])
env["BUILDERS"]["__COMPILATIONDB_Entry"] = SCons.Builder.Builder(
action=SCons.Action.Action(CompilationDbEntryAction, None),
)
env["BUILDERS"]["__COMPILATIONDB_Database"] = SCons.Builder.Builder(
action=SCons.Action.Action(WriteCompilationDb, "$COMPILATIONDB_COMSTR"),
target_scanner=SCons.Scanner.Scanner(function=ScanCompilationDb, node_class=None),
)
def CompilationDatabase(env, target):
result = env.__COMPILATIONDB_Database(target=target, source=[])
env.AlwaysBuild(result)
env.NoCache(result)
return result
env.AddMethod(CompilationDatabase, "CompilationDatabase")
def exists(env):
return True
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