4 files changed, 31 insertions, 8 deletions

diff --git a/colm/global.h b/colm/global.h
index 5801436d..58b98077 100644
--- a/colm/global.h
+++ b/colm/global.h
@@ -67,6 +67,7 @@ extern bool gblLibrary;
 extern long gblActiveRealm;
 extern char machineMain[];
 extern const char *exportHeaderFn;
+extern bool rangeCrossesZero;
 
 struct colm_location;
 
diff --git a/colm/keyops.h b/colm/keyops.h
index 924fa7ab..094b09e2 100644
--- a/colm/keyops.h
+++ b/colm/keyops.h
@@ -35,6 +35,7 @@ enum MarkType
 
 typedef unsigned long long Size;
 
+/* This key struct does not implement unsigned. */
 struct Key
 {
 private:
@@ -57,12 +58,8 @@ public:
 	Key( const Key &key ) : key(key.key) {}
 	Key( long key ) : key(key) {}
 
-	/* Returns the value used to represent the key. This value must be
-	 * interpreted based on signedness. */
 	long getVal() const { return key; };
 
-	/* Returns the key casted to a long long. This form of the key does not
-	 * require and signedness interpretation. */
 	long long getLongLong() const;
 
 	bool isUpper() const { return ( 'A' <= key && key <= 'Z' ); }
diff --git a/colm/main.cc b/colm/main.cc
index def8b150..519a42aa 100644
--- a/colm/main.cc
+++ b/colm/main.cc
@@ -90,6 +90,7 @@ bool run = false;
 bool addUniqueEmptyProductions = false;
 bool gblLibrary = false;
 long gblActiveRealm = 0;
+bool rangeCrossesZero = false;
 
 ArgsVector includePaths;
 ArgsVector libraryPaths;
@@ -545,12 +546,15 @@ bool inSourceTree( const char *argv0, char *&location )
 
 void processArgs( int argc, const char **argv )
 {
-	ParamCheck pc( "cD:e:x:I:L:vdliro:S:M:vHh?-:sVa:m:b:E:", argc, argv );
+	ParamCheck pc( "RcD:e:x:I:L:vdliro:S:M:vHh?-:sVa:m:b:E:", argc, argv );
 
 	while ( pc.check() ) {
 		switch ( pc.state ) {
 		case ParamCheck::match:
 			switch ( pc.parameter ) {
+			case 'R':
+				rangeCrossesZero = true;
+				break;
 			case 'I':
 				includePaths.append( pc.parameterArg );
 				break;
diff --git a/colm/parsetree.cc b/colm/parsetree.cc
index 572f0610..cf97fa23 100644
--- a/colm/parsetree.cc
+++ b/colm/parsetree.cc
@@ -1228,16 +1228,37 @@ FsmGraph *Range::walk( Compiler *pd )
 	delete lowerFsm;
 	delete upperFsm;
 
+	bool span0 = false;
+	if ( rangeCrossesZero && lowKey >= 0 && highKey < 0 )
+		span0 = true;
+
 	/* Validate the range. */
-	if ( lowKey > highKey ) {
+	if ( !span0 && lowKey > highKey ) {
 		/* Recover by setting upper to lower; */
 		error(lowerLit->loc) << "lower end of range is greater then upper end" << endl;
 		highKey = lowKey;
 	}
 
 	/* Return the range now that it is validated. */
-	FsmGraph *retFsm = new FsmGraph();
-	retFsm->rangeFsm( lowKey, highKey );
+	FsmGraph *retFsm = 0;
+	if ( span0 ) {
+		FsmGraph *first = new FsmGraph();
+		FsmGraph *second = new FsmGraph();
+		Key k128 = 127;
+		Key kn127 = -128;
+		first->rangeFsm( lowKey, k128 );
+		second->rangeFsm( kn127, highKey );
+
+		first->unionOp( second );
+		first->minimizePartition2();
+		retFsm = first;
+	}
+	else {
+		/* Usual case. */
+		retFsm = new FsmGraph();
+		retFsm->rangeFsm( lowKey, highKey );
+	}
+
 	return retFsm;
 }