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// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef TOOLS_GN_ARGS_H_
#define TOOLS_GN_ARGS_H_
#include <map>
#include <mutex>
#include <set>
#include <unordered_map>
#include "base/macros.h"
#include "gn/scope.h"
class Err;
class SourceFile;
extern const char kBuildArgs_Help[];
// Manages build arguments. It stores the global arguments specified on the
// command line, and sets up the root scope with the proper values.
// This class tracks accesses so we can report errors about unused variables.
// The use case is if the user specifies an override on the command line, but
// no buildfile actually uses that variable. We want to be able to report that
// the argument was unused.
class Args {
struct ValueWithOverride {
ValueWithOverride(const Value& def_val);
Value default_value; // Default value given in declare_args.
bool has_override; // True indicates override_value is valid.
Value override_value; // From .gn or the current build's "gn args".
using ValueWithOverrideMap = std::map<std::string_view, ValueWithOverride>;
Args(const Args& other);
// Specifies overrides of the build arguments. These are normally specified
// on the command line.
void AddArgOverride(const char* name, const Value& value);
void AddArgOverrides(const Scope::KeyValueMap& overrides);
// Specifies default overrides of the build arguments. These are normally
// specified in the .gn file.
void AddDefaultArgOverrides(const Scope::KeyValueMap& overrides);
// Returns the value corresponding to the given argument name, or NULL if no
// argument is set.
const Value* GetArgOverride(const char* name) const;
// Sets up the root scope for a toolchain. This applies the default system
// flags and saves the toolchain overrides so they can be applied to
// declare_args blocks that appear when loading files in that toolchain.
void SetupRootScope(Scope* dest,
const Scope::KeyValueMap& toolchain_overrides) const;
// Sets up the given scope with arguments passed in.
// If the values specified in the args are not already set, the values in
// the args list will be used (which are assumed to be the defaults), but
// they will not override the system defaults or the current overrides.
// All args specified in the input will be marked as "used".
// On failure, the err will be set and it will return false.
bool DeclareArgs(const Scope::KeyValueMap& args,
Scope* scope_to_set,
Err* err) const;
// Checks to see if any of the overrides ever used were never declared as
// arguments. If there are, this returns false and sets the error.
bool VerifyAllOverridesUsed(Err* err) const;
// Returns information about all arguments, both defaults and overrides.
// This is used for the help system which is not performance critical. Use a
// map instead of a hash map so the arguments are sorted alphabetically.
ValueWithOverrideMap GetAllArguments() const;
// Returns the set of build files that may affect the build arguments, please
// refer to Scope for how this is determined.
const SourceFileSet& build_args_dependency_files() const {
return build_args_dependency_files_;
void set_build_args_dependency_files(
const SourceFileSet& build_args_dependency_files) {
build_args_dependency_files_ = build_args_dependency_files;
using ArgumentsPerToolchain =
std::unordered_map<const Settings*, Scope::KeyValueMap>;
// Sets the default config based on the current system.
void SetSystemVarsLocked(Scope* scope) const;
// Sets the given already declared vars on the given scope.
void ApplyOverridesLocked(const Scope::KeyValueMap& values,
Scope* scope) const;
void SaveOverrideRecordLocked(const Scope::KeyValueMap& values) const;
// Returns the KeyValueMap used for arguments declared for the specified
// toolchain.
Scope::KeyValueMap& DeclaredArgumentsForToolchainLocked(Scope* scope) const;
// Returns the KeyValueMap used for overrides for the specified
// toolchain.
Scope::KeyValueMap& OverridesForToolchainLocked(Scope* scope) const;
// Since this is called during setup which we assume is single-threaded,
// this is not protected by the lock. It should be set only during init.
Scope::KeyValueMap overrides_;
mutable std::mutex lock_;
// Maintains a list of all overrides we've ever seen. This is the main
// |overrides_| as well as toolchain overrides. Tracking this allows us to
// check for overrides that were specified but never used.
mutable Scope::KeyValueMap all_overrides_;
// Maps from Settings (which corresponds to a toolchain) to the map of
// declared variables. This is used to tracks all variables declared in any
// buildfile. This is so we can see if the user set variables on the command
// line that are not used anywhere. Each map is toolchain specific as each
// toolchain may define variables in different locations.
mutable ArgumentsPerToolchain declared_arguments_per_toolchain_;
// Overrides for individual toolchains. This is necessary so we
// can apply the correct override for the current toolchain, once
// we see an argument declaration.
mutable ArgumentsPerToolchain toolchain_overrides_;
SourceFileSet build_args_dependency_files_;
#endif // TOOLS_GN_ARGS_H_