C Source code pre-processing

[Burn Alting]

Hi Peoples,

Does anyone know of a utility which will take a C source file and strip 
#if/#else/#endif directives, just leaving the source code dependant upon a 
set of defines.

For example, say I had

	#if	SOURCE_ALTERNATIVE_01
		/*
		 * Source alternative 01
		 */
	#else	/* SOURCE_ALTERNATIVE_01 */
		/*
		 * Source
		 */
	#endif	/* SOURCE_ALTERNATIVE_01 */

then the execution of the utility I'm looking for would generate

	/*
	 * Source Alternative 01
	 */
if I had defined SOURCE_ALTERNATIVE_01 to be 1, or

	/*
	 * Source
	 */
if I had defined SOURCE_ALTERNATIVE_01 to be 0.

The -E option to gcc is no use, nor it appears are the various options to cpp 
(eg -P -C).

I suppose I could wip up something in lex/yacc but I'd rather check if 
someone has already done this.

Thanks in advance

Burn Alting
burn at goldweb.com.au