1// Copyright (c) 2013 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef TOOLS_GN_ARGS_H_
6#define TOOLS_GN_ARGS_H_
7
8#include "base/basictypes.h"
9#include "base/containers/hash_tables.h"
10#include "base/synchronization/lock.h"
11#include "tools/gn/err.h"
12#include "tools/gn/scope.h"
13
14extern const char kBuildArgs_Help[];
15
16// Manages build arguments. It stores the global arguments specified on the
17// command line, and sets up the root scope with the proper values.
18//
19// This class tracks accesses so we can report errors about unused variables.
20// The use case is if the user specifies an override on the command line, but
21// no buildfile actually uses that variable. We want to be able to report that
22// the argument was unused.
23class Args {
24 public:
25  Args();
26  Args(const Args& other);
27  ~Args();
28
29  // Specifies overrides of the build arguments. These are normally specified
30  // on the command line.
31  void AddArgOverride(const char* name, const Value& value);
32  void AddArgOverrides(const Scope::KeyValueMap& overrides);
33
34  // Sets up the root scope for a toolchain. This applies the default system
35  // flags, then any overrides stored in this object, then applies any
36  // toolchain overrides specified in the argument.
37  void SetupRootScope(Scope* dest,
38                      const Scope::KeyValueMap& toolchain_overrides) const;
39
40  // Sets up the given scope with arguments passed in.
41  //
42  // If the values specified in the args are not already set, the values in
43  // the args list will be used (which are assumed to be the defaults), but
44  // they will not override the system defaults or the current overrides.
45  //
46  // All args specified in the input will be marked as "used".
47  //
48  // On failure, the err will be set and it will return false.
49  bool DeclareArgs(const Scope::KeyValueMap& args,
50                   Scope* scope_to_set,
51                   Err* err) const;
52
53  // Checks to see if any of the overrides ever used were never declared as
54  // arguments. If there are, this returns false and sets the error.
55  bool VerifyAllOverridesUsed(Err* err) const;
56
57  // This function is not threadsafe, it must only be used when
58  // single-threaded. It's used to implement the "args" command.
59  const Scope::KeyValueMap& declared_arguments() const {
60    return declared_arguments_;
61  }
62
63 private:
64  // Sets the default config based on the current system.
65  void SetSystemVars(Scope* scope) const;
66
67  // Sets the given vars on the given scope.
68  void ApplyOverrides(const Scope::KeyValueMap& values, Scope* scope) const;
69
70  void SaveOverrideRecord(const Scope::KeyValueMap& values) const;
71
72  // Since this is called during setup which we assume is single-threaded,
73  // this is not protected by the lock. It should be set only during init.
74  Scope::KeyValueMap overrides_;
75
76  mutable base::Lock lock_;
77
78  // Maintains a list of all overrides we've ever seen. This is the main
79  // |overrides_| as well as toolchain overrides. Tracking this allows us to
80  // check for overrides that were specified but never used.
81  mutable Scope::KeyValueMap all_overrides_;
82
83  // Tracks all variables declared in any buildfile. This is so we can see if
84  // the user set variables on the command line that are not used anywhere.
85  mutable Scope::KeyValueMap declared_arguments_;
86
87  Args& operator=(const Args& other);  // Disallow assignment.
88};
89
90#endif  // TOOLS_GN_ARGS_H_
91