Support more configurability in GN toolchains

tools/gn/substitution_type.h

 // Copyright 2014 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_SUBSTITUTION_TYPE_H_
 #define TOOLS_GN_SUBSTITUTION_TYPE_H_
 
 #include <vector>
 
 class Err;
 class ParseNode;
 
 // Keep kSubstitutionNames, kSubstitutionNinjaNames and the
 // IsValid*Substutition functions in sync if you change anything here.
 enum SubstitutionType {
   SUBSTITUTION_LITERAL = 0,
 
   // The index of the first pattern. To loop overal all patterns, go from here
   // until NUM_TYPES.
   SUBSTITUTION_FIRST_PATTERN,
 
+  // These map to Ninja's {in} and {out} variables.
   SUBSTITUTION_SOURCE = SUBSTITUTION_FIRST_PATTERN,  // {{source}}
+  SUBSTITUTION_OUTPUT,  // {{output}}
+
+  // Valid for all compiler tools.
   SUBSTITUTION_SOURCE_NAME_PART,  // {{source_name_part}}
   SUBSTITUTION_SOURCE_FILE_PART,  // {{source_file_part}}
   SUBSTITUTION_SOURCE_DIR,  // {{source_dir}}
   SUBSTITUTION_SOURCE_ROOT_RELATIVE_DIR,  // {{root_relative_dir}}
   SUBSTITUTION_SOURCE_GEN_DIR,  // {{source_gen_dir}}
   SUBSTITUTION_SOURCE_OUT_DIR,  // {{source_out_dir}}
 
-  // Valid for all compiler and linker tools (depends on target).
-  SUBSTITUTION_OUTPUT,  // {{output}}
+  // Valid for all compiler and linker tools. These depend on the target and
+  // no not vary on a per-file basis.
+  SUBSTITUTION_LABEL,  // {{label}}
   SUBSTITUTION_ROOT_GEN_DIR,  // {{root_gen_dir}}
   SUBSTITUTION_ROOT_OUT_DIR,  // {{root_out_dir}}
   SUBSTITUTION_TARGET_GEN_DIR,  // {{target_gen_dir}}
   SUBSTITUTION_TARGET_OUT_DIR,  // {{target_out_dir}}
   SUBSTITUTION_TARGET_OUTPUT_NAME,  // {{target_output_name}}
 
   // Valid for compiler tools.
   SUBSTITUTION_CFLAGS,  // {{cflags}}
   SUBSTITUTION_CFLAGS_C,  // {{cflags_c}}
   SUBSTITUTION_CFLAGS_CC,  // {{cflags_cc}}
@@ skipping 14 matching lines @@
 
 // An array of size SUBSTITUTION_NUM_TYPES that lists the names of the
 // substitution patterns, including the curly braces. So, for example,
 // kSubstitutionNames[SUBSTITUTION_SOURCE] == "{{source}}".
 extern const char* kSubstitutionNames[SUBSTITUTION_NUM_TYPES];
 
 // Ninja variables corresponding to each substitution. These do not include
 // the dollar sign.
 extern const char* kSubstitutionNinjaNames[SUBSTITUTION_NUM_TYPES];
 
+// A wrapper around an array if flags indicating whether a give substitution
+// type is required in some context. By convention, the LITERAL type bit is
+// not set.
+struct SubstitutionBits {
+  SubstitutionBits();
+
+  // Merges any bits set in the given "other" to this one. This object will
+  // then be the union of all bits in the two lists.
+  void MergeFrom(const SubstitutionBits& other);
+
+  // Converts the substitution type bitfield (with a true set for each required
+  // item) to a vector of the types listed. Does not include LITERAL.
+  void FillVector(std::vector<SubstitutionType>* vect) const;
+
+  bool used[SUBSTITUTION_NUM_TYPES];
+};
+
 // Returns true if the given substitution pattern references the output
 // directory. This is used to check strings that begin with a substitution to
 // verify that the produce a file in the output directory.
 bool SubstitutionIsInOutputDir(SubstitutionType type);
 
 // Returns true if the given substitution is valid for the named purpose.
 bool IsValidSourceSubstitution(SubstitutionType type);
 // Both compiler and linker tools.
 bool IsValidToolSubstutition(SubstitutionType type);
 bool IsValidCompilerSubstitution(SubstitutionType type);
 bool IsValidCompilerOutputsSubstitution(SubstitutionType type);
 bool IsValidLinkerSubstitution(SubstitutionType type);
 bool IsValidLinkerOutputsSubstitution(SubstitutionType type);
+bool IsValidCopySubstitution(SubstitutionType type);
 
 // Like the "IsValid..." version above but checks a list of types and sets a
 // an error blaming the given source if the test fails.
 bool EnsureValidSourcesSubstitutions(
     const std::vector<SubstitutionType>& types,
     const ParseNode* origin,
     Err* err);
 
 #endif  // TOOLS_GN_SUBSTITUTION_TYPE_H_