add a new static method to portably determine whether a patch is
absolute or not, based on a patch by Gregory Curfman!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73368 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/System/Path.h b/include/llvm/System/Path.h
index de2f173..05be221 100644
--- a/include/llvm/System/Path.h
+++ b/include/llvm/System/Path.h
@@ -309,6 +309,11 @@
       /// @brief Determine if the path is absolute.
       bool isAbsolute() const;
 
+      /// This function determines if the path name is absolute, as opposed to
+      /// relative.
+      /// @brief Determine if the path is absolute.
+      static bool isAbsolute(const char *NameStart, unsigned NameLen);
+
       /// This function opens the file associated with the path name provided by
       /// the Path object and reads its magic number. If the magic number at the
       /// start of the file matches \p magic, true is returned. In all other
diff --git a/lib/System/Unix/Path.inc b/lib/System/Unix/Path.inc
index d5edee1..1f73571 100644
--- a/lib/System/Unix/Path.inc
+++ b/lib/System/Unix/Path.inc
@@ -104,6 +104,14 @@
 }
 
 bool
+Path::isAbsolute(const char *NameStart, unsigned NameLen) {
+  assert(NameStart);
+  if (NameLen == 0)
+    return false;
+  return NameStart[0] == '/';
+}
+
+bool
 Path::isAbsolute() const {
   if (path.empty())
     return false;
diff --git a/lib/System/Win32/Path.inc b/lib/System/Win32/Path.inc
index fbf8f66..62da3a3 100644
--- a/lib/System/Win32/Path.inc
+++ b/lib/System/Win32/Path.inc
@@ -125,6 +125,20 @@
   return true;
 }
 
+bool
+Path::isAbsolute(const char *NameStart, unsigned NameLen) {
+  assert(NameStart);
+  switch (NameLen) {
+  case 0:
+    return false;
+  case 1:
+  case 2:
+    return NameStart[0] == '/';
+  default:
+    return NameStart[0] == '/' || (NameStart[1] == ':' && NameStart[2] == '/');
+  }
+}
+
 bool 
 Path::isAbsolute() const {
   switch (path.length()) {