utils/Burg/sample.gr

%{
#include <stdio.h>

typedef struct node *NODEPTR_TYPE;

struct node {
	int op, state_label;
	NODEPTR_TYPE left, right;
};

#define OP_LABEL(p)	((p)->op)
#define STATE_LABEL(p)	((p)->state_label)
#define LEFT_CHILD(p)	((p)->left)
#define RIGHT_CHILD(p)	((p)->right)
#define PANIC		printf
%}

%start reg
%term Assign=1 Constant=2 Fetch=3 Four=4 Mul=5 Plus=6
%%
con:  Constant                = 1 (0);
con:  Four                    = 2 (0);
addr: con                     = 3 (0);
addr: Plus(con,reg)           = 4 (0);
addr: Plus(con,Mul(Four,reg)) = 5 (0);
reg:  Fetch(addr)             = 6 (1);
reg:  Assign(addr,reg)        = 7 (1);

%%

#define Assign 1
#define Constant 2
#define Fetch 3
#define Four 4
#define Mul 5
#define Plus 6

#ifdef __STDC__
#define ARGS(x) x
#else
#define ARGS(x) ()
#endif

NODEPTR_TYPE buildtree ARGS((int, NODEPTR_TYPE, NODEPTR_TYPE));
void printcover ARGS((NODEPTR_TYPE, int, int));
void printtree ARGS((NODEPTR_TYPE));
int treecost ARGS((NODEPTR_TYPE, int, int));
void printMatches ARGS((NODEPTR_TYPE));
int main ARGS((void));

NODEPTR_TYPE buildtree(op, left, right) int op; NODEPTR_TYPE left; NODEPTR_TYPE right; {
	NODEPTR_TYPE p;
	extern void *malloc ARGS((unsigned));

	p = (NODEPTR_TYPE) malloc(sizeof *p);
	p->op = op;
	p->left = left;
	p->right = right;
	return p;
}

void printcover(p, goalnt, indent) NODEPTR_TYPE p; int goalnt; int indent; {
	int eruleno = burm_rule(STATE_LABEL(p), goalnt);
	short *nts = burm_nts[eruleno];
	NODEPTR_TYPE kids[10];
	int i;
	
	if (eruleno == 0) {
		printf("no cover\n");
		return;
	}
	for (i = 0; i < indent; i++)
		printf(".");
	printf("%s\n", burm_string[eruleno]);
	burm_kids(p, eruleno, kids);
	for (i = 0; nts[i]; i++)
		printcover(kids[i], nts[i], indent+1);
}

void printtree(p) NODEPTR_TYPE p; {
	int op = burm_op_label(p);

	printf("%s", burm_opname[op]);
	switch (burm_arity[op]) {
	case 0:
		break;
	case 1:
		printf("(");
		printtree(burm_child(p, 0));
		printf(")");
		break;
	case 2:
		printf("(");
		printtree(burm_child(p, 0));
		printf(", ");
		printtree(burm_child(p, 1));
		printf(")");
		break;
	}
}

int treecost(p, goalnt, costindex) NODEPTR_TYPE p; int goalnt; int costindex; {
	int eruleno = burm_rule(STATE_LABEL(p), goalnt);
	int cost = burm_cost[eruleno][costindex], i;
	short *nts = burm_nts[eruleno];
	NODEPTR_TYPE kids[10];

	burm_kids(p, eruleno, kids);
	for (i = 0; nts[i]; i++)
		cost += treecost(kids[i], nts[i], costindex);
	return cost;
}

void printMatches(p) NODEPTR_TYPE p; {
	int nt;
	int eruleno;

	printf("Node 0x%lx= ", (unsigned long)p);
	printtree(p);
	printf(" matched rules:\n");
	for (nt = 1; burm_ntname[nt] != (char*)NULL; nt++)
		if ((eruleno = burm_rule(STATE_LABEL(p), nt)) != 0)
			printf("\t%s\n", burm_string[eruleno]);
}

main() {
	NODEPTR_TYPE p;

	p = buildtree(Assign,
		buildtree(Constant, 0, 0),
		buildtree(Fetch,
			buildtree(Plus,
				buildtree(Constant, 0, 0),
				buildtree(Mul,
					buildtree(Four, 0, 0),
					buildtree(Fetch, buildtree(Constant, 0, 0), 0)
				)
			),
			0
		)
	);
	printtree(p);
	printf("\n\n");
	burm_label(p);
	printcover(p, 1, 0);
	printf("\nCover cost == %d\n\n", treecost(p, 1, 0));
	printMatches(p);
	return 0;
}