[C++] Re-run commands only when certain directories are updated

1 files changed, 11 insertions, 0 deletions

diff --git a/strutil.cc b/strutil.cc
index 8665358..7afe743 100644
--- a/strutil.cc
+++ b/strutil.cc
@@ -406,3 +406,14 @@ string SortWordsInString(StringPiece s) {
   sort(toks.begin(), toks.end());
   return JoinStrings(toks, " ");
 }
+
+string ConcatDir(StringPiece b, StringPiece n) {
+  string r;
+  if (!b.empty()) {
+    b.AppendToString(&r);
+    r += '/';
+  }
+  n.AppendToString(&r);
+  NormalizePath(&r);
+  return r;
+}