2 files changed, 37 insertions, 0 deletions
diff --git a/include/clang/Driver/Options.h b/include/clang/Driver/Options.h
index d98a530bbf..f83e5ceace 100644
--- a/include/clang/Driver/Options.h
+++ b/include/clang/Driver/Options.h
@@ -24,6 +24,8 @@ namespace options {
   };
 }
   
+  class Arg;
+  class ArgList;
   class Option;
 
   /// OptTable - Provide access to the Option info table.
@@ -50,6 +52,18 @@ namespace options {
     /// getOption - Get the given \arg id's Option instance, lazily
     /// creating it if necessary.
     const Option *getOption(options::ID id) const;
+
+    /// parseOneArg - Parse a single argument; returning the new
+    /// argument and updating Index.
+    ///
+    /// \param [in] [out] Index - The current parsing position in the
+    /// argument string list; on return this will be the index of the
+    /// next option to parse.
+    ///
+    /// \param IndexEnd - The last argument string index to consider
+    /// when parsing.
+    Arg *ParseOneArg(const ArgList &Args, unsigned &Index, 
+                     unsigned IndexEnd) const;
   };
 }
 }
diff --git a/lib/Driver/OptTable.cpp b/lib/Driver/OptTable.cpp
index 070c12e154..284e3ba1e2 100644
--- a/lib/Driver/OptTable.cpp
+++ b/lib/Driver/OptTable.cpp
@@ -9,6 +9,8 @@
 
 #include "clang/Driver/Options.h"
 
+#include "clang/Driver/Arg.h"
+#include "clang/Driver/ArgList.h"
 #include "clang/Driver/Option.h"
 #include <cassert>
 
@@ -115,3 +117,24 @@ Option *OptTable::constructOption(options::ID id) const {
 
   return Opt;
 }
+
+Arg *OptTable::ParseOneArg(const ArgList &Args, unsigned &Index, 
+                           unsigned IndexEnd) const {
+  const char *Str = Args.getArgString(Index);
+
+  // Anything that doesn't start with '-' is an input.
+  if (Str[0] != '-')
+    return new PositionalArg(getOption(InputOpt), Index++);
+
+  for (unsigned j = UnknownOpt + 1; j < getNumOptions(); ++j) {
+    const char *OptName = getOptionName((options::ID) (j + 1));
+    
+    // Arguments are only accepted by options which prefix them.
+    if (memcmp(Str, OptName, strlen(OptName)) == 0)
+      if (Arg *A = getOption((options::ID) (j + 1))->accept(Args, Index))
+        return A;
+  }
+
+  return new PositionalArg(getOption(UnknownOpt), Index++);
+}
+