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

include/llvm/System/Path.h

@@ -309,6 +309,11 @@ namespace sys {
       /// @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

lib/System/Unix/Path.inc

@@ -103,6 +103,14 @@ Path::isValid() const {
   return i >= len;
 }
 
+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())

lib/System/Win32/Path.inc

@@ -125,6 +125,20 @@ Path::isValid() const {
   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()) {