blang/src/ops.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "blang.h"

/* no-op */
void Ops_bang(struct State *s){
	return;
}

void Ops_percent(struct State *s){
	*(s->chart) = s->hand;
}

void Ops_carat(struct State *s){
	s->hand = 0;
}

void Ops_ampersand(struct State *s){
	s->hand = (char)s->chart;
}

void Ops_splat(struct State *s){
	s->chart = (char *)s->hand;
}

void Ops_plus(struct State *s){
	++(s->hand);
}

void Ops_dash(struct State *s){
	--(s->hand);
}

void Ops_right(struct State *s){
	putc((char)s->hand, stdout);
}

void Ops_left(struct State *s){
	s->hand = getc(stdin);
}

void Ops_semi(struct State *s){
	int c;

	while(
		(c = getc(stdin)) != EOF
		&& strchr("!\n", c) == NULL
	);
}

void Ops_cross(struct State *s){
	char *i;
	i = s->chart;
	s->chart = (char *)s->hand;
	s->hand = (unsigned char)i;
}

const struct {
	unsigned char name;
	void (*f)(struct State *);
} OPS[] = {
	{ '%', Ops_percent },
	{ '^', Ops_carat },
	{ '&', Ops_ampersand },
	{ '*', Ops_splat },
	{ '+', Ops_plus },
	{ '-', Ops_dash },
	{ '>', Ops_right },
	{ '<', Ops_left },
	{ 'x', Ops_cross },

	/* no-ops */
	{ '!', Ops_bang },
	{ ' ', Ops_bang },
	{ '\n', Ops_bang },
	{ '\r', Ops_bang },
	{ '\t', Ops_bang },
	{ '\v', Ops_bang }
};

/* Slower than a switch but you don't have to update it when you add new
 * ops! */
void (*Ops_lookup(char op))(struct State *){
	size_t i;

	for(i = 0; i < (sizeof OPS)/(sizeof *OPS); ++i)
		if(op == OPS[i].name)
			return OPS[i].f;
	return NULL;
}