/** @file parser.h
 *
 * macros suitable for writing parsers.
 *
 */
/******************************************************************************/
#ifndef PARSER_H
#define PARSER_H

/**
 * return from a parser function. setting state for reentry.
 */
#define PARSER_RETURN(state, n) \
	do { (state)=__LINE__; return (n); case __LINE__: ; } while(0)

/**
 * wrap parser code with these macros to create a re-entry state machine.
 * @see PARSER_END
 */
#define PARSER_BEGIN(state) switch((state)) { parser_entry: case 0:

/**
 * wrap parser code with these macros to create a re-entry state machine.
 * @see PARSER_BEGIN
 */
#define PARSER_END }

/**
 * wait until the condition is true, forces parser function to return n until
 * cond is true.
 */
#define PARSER_UNTIL(state, n, cond) while(!(cond)) { PARSER_RETURN(state, n); }

/**
 * restart the parser.
 */
#define PARSER_RESTART(state) do { (state)=0; goto parser_entry; } while(0)

/**
 * macro used for appending a character to a buffer.
 */
#define PARSER_BUFFER_APPEND(buf, ofs, max, ch) \
	do { if((ofs)<(max)) (buf)[(ofs)++]=ch; } while(0)


#endif