tools/gn/args.h

   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
  14 extern 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.
  23 class 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   // Returns the value corresponding to the given argument name, or NULL if no
  35   // argument is set.
  36   const Value* GetArgOverride(const char* name) const;
  37
  38   // Gets all overrides set on the build.
  39   Scope::KeyValueMap GetAllOverrides() const;
  40
  41   // Sets up the root scope for a toolchain. This applies the default system
  42   // flags, then any overrides stored in this object, then applies any
  43   // toolchain overrides specified in the argument.
  44   void SetupRootScope(Scope* dest,
  45                       const Scope::KeyValueMap& toolchain_overrides) const;
  46
  47   // Sets up the given scope with arguments passed in.
  48   //
  49   // If the values specified in the args are not already set, the values in
  50   // the args list will be used (which are assumed to be the defaults), but
  51   // they will not override the system defaults or the current overrides.
  52   //
  53   // All args specified in the input will be marked as "used".
  54   //
  55   // On failure, the err will be set and it will return false.
  56   bool DeclareArgs(const Scope::KeyValueMap& args,
  57                    Scope* scope_to_set,
  58                    Err* err) const;
  59
  60   // Checks to see if any of the overrides ever used were never declared as
  61   // arguments. If there are, this returns false and sets the error.
  62   bool VerifyAllOverridesUsed(Err* err) const;
  63
  64   // Adds all declared arguments to the given output list. If the values exist
  65   // in the list already, their values will be overwriten, but other values
  66   // already in the list will remain.
  67   void MergeDeclaredArguments(Scope::KeyValueMap* dest) const;
  68
  69  private:
  70   using DeclaredArgumentsPerToolchain =
  71       base::hash_map<const Settings*, Scope::KeyValueMap>;
  72
  73   // Sets the default config based on the current system.
  74   void SetSystemVarsLocked(Scope* scope) const;
  75
  76   // Sets the given vars on the given scope.
  77   void ApplyOverridesLocked(const Scope::KeyValueMap& values,
  78                             Scope* scope) const;
  79
  80   void SaveOverrideRecordLocked(const Scope::KeyValueMap& values) const;
  81
  82   // Returns the KeyValueMap used for arguments declared for the specified
  83   // toolchain.
  84   Scope::KeyValueMap& DeclaredArgumentsForToolchainLocked(Scope* scope) const;
  85
  86   // Since this is called during setup which we assume is single-threaded,
  87   // this is not protected by the lock. It should be set only during init.
  88   Scope::KeyValueMap overrides_;
  89
  90   mutable base::Lock lock_;
  91
  92   // Maintains a list of all overrides we've ever seen. This is the main
  93   // |overrides_| as well as toolchain overrides. Tracking this allows us to
  94   // check for overrides that were specified but never used.
  95   mutable Scope::KeyValueMap all_overrides_;
  96
  97   // Maps from Settings (which corresponds to a toolchain) to the map of
  98   // declared variables. This is used to tracks all variables declared in any
  99   // buildfile. This is so we can see if the user set variables on the command
 100   // line that are not used anywhere. Each map is toolchain specific as each
 101   // toolchain may define variables in different locations.
 102   mutable DeclaredArgumentsPerToolchain declared_arguments_per_toolchain_;
 103
 104   Args& operator=(const Args& other);  // Disallow assignment.
 105 };
 106
 107 #endif  // TOOLS_GN_ARGS_H_