1 files changed, 52 insertions, 0 deletions
diff --git a/lib/Basic/VersionTuple.cpp b/lib/Basic/VersionTuple.cpp
index 77aad39..4f479d0 100644
--- a/lib/Basic/VersionTuple.cpp
+++ b/lib/Basic/VersionTuple.cpp
@@ -34,3 +34,55 @@ raw_ostream& clang::operator<<(raw_ostream &Out,
     Out << '.' << *Subminor;
   return Out;
 }
+
+static bool parseInt(StringRef &input, unsigned &value) {
+  assert(value == 0);
+  if (input.empty()) return true;
+
+  char next = input[0];
+  input = input.substr(1);
+  if (next < '0' || next > '9') return true;
+  value = (unsigned) (next - '0');
+
+  while (!input.empty()) {
+    next = input[0];
+    if (next < '0' || next > '9') return false;
+    input = input.substr(1);
+    value = value * 10 + (unsigned) (next - '0');
+  }
+
+  return false;
+}
+
+bool VersionTuple::tryParse(StringRef input) {
+  unsigned major = 0, minor = 0, micro = 0;
+
+  // Parse the major version, [0-9]+
+  if (parseInt(input, major)) return true;
+
+  if (input.empty()) {
+    *this = VersionTuple(major);
+    return false;
+  }
+
+  // If we're not done, parse the minor version, \.[0-9]+
+  if (input[0] != '.') return true;
+  input = input.substr(1);
+  if (parseInt(input, minor)) return true;
+
+  if (input.empty()) {
+    *this = VersionTuple(major, minor);
+    return false;
+  }
+
+  // If we're not done, parse the micro version, \.[0-9]+
+  if (input[0] != '.') return true;
+  input = input.substr(1);
+  if (parseInt(input, micro)) return true;
+
+  // If we have characters left over, it's an error.
+  if (!input.empty()) return true;
+
+  *this = VersionTuple(major, minor, micro);
+  return false;
+}