[C++] Update ninja file only when necessary

As this feature is incomplete, this is enabled only with
--regen flag.

I decided not to use ninja's "generator" feature because we
cannot create appropriate regeneration rules for globs in
Android. There are some directory names which are also used
as target names (e.g., "cts"). Ninja tries to build such
targets to check if regeneration is necessary.

1 files changed, 7 insertions, 1 deletions

diff --git a/ninja.h b/ninja.h
index 8846a2b..d7f9e32 100644
--- a/ninja.h
+++ b/ninja.h
@@ -15,6 +15,8 @@
 #ifndef NINJA_H_
 #define NINJA_H_
 
+#include <time.h>
+
 #include <string>
 #include <vector>
 
@@ -30,7 +32,11 @@ void GenerateNinja(const char* ninja_suffix,
                    const vector<DepNode*>& nodes,
                    Evaluator* ev,
                    bool build_all_targets,
-                   const string& orig_args);
+                   const string& orig_args,
+                   time_t start_time);
+
+bool NeedsRegen(const char* ninja_suffix,
+                const char* ninja_dir);
 
 // Exposed only for test.
 bool GetDepfileFromCommand(string* cmd, string* out);