ml-yacc/lib/parser2.sml

74 	* The distance-parser:
76 	This parser includes an additional argument distance.  It pushes
77 	elements on the queue until it has parsed distance tokens, or an
237 	(lex result * lexer), a state stack, a queue, and a distance
239 	with the nth token shifted on top, a queue, a distance, and action
252 			  queue,distance) =
261 			       Fifo.put((newStack,newLexPair),queue),distance-1)
267 				 queue,distance)
269 		 | ERROR => (lexPair,stack,queue,distance,SOME nextAction)
270 		 | ACCEPT => (lexPair,stack,queue,distance,SOME nextAction)
304 	(* now number elements of stateList, giving distance from
316 	   distance = the number of tokens beyond the error token which the
323 	   {pos : int, distance : int, leftPos: 'b, rightPos: 'b,
330 	  let val CHANGE {distance,new,orig,pos,...} = c
331 	  in (print ("{distance= " ^ (Int.toString distance));
340 (* parse: given a lexPair, a stack, and the distance from the error
341    token, return the distance past the error token that we are able to parse.*)
345              of (_,_,_,distance,SOME ACCEPT) =>
346 		        if maxAdvance-distance-1 >= 0
348 			    else maxAdvance-distance-1
349 	      | (_,_,_,distance,_) => maxAdvance - distance - 1
360 		 val distance = parse(lex',stack,pos+length new-length orig)
361 	      in if distance >= minAdvance + keywordsDelta new
363 				distance=distance,orig=orig,new=new}]
444 	  foldr (fn (CHANGE {distance,...},high) => Int.max(distance,high)) 0 l
446 (* maxDist: max distance past error taken that we could parse *)
453 	      (fn(c as CHANGE{distance,...}) =>
454 		  if distance=maxDist then [c] else [])
519 	let val distance = 15   (* defer distance tokens *)
521 	    val maxAdvance = Int.max(lookahead,0)(* max distance for parse check *)
532 	      | loop (lexPair,stack,queue,distance,SOME ERROR) =
534 		 in loop (distanceParse(lexPair,stack,queue,distance))
539 	in loop (distanceParse(lexPair,startStack,startQueue,distance))