Housekeeping

src/modal.c

@@ -14,12 +14,6 @@ static char *regs[0x100], stack[0x10], *stack_ = stack;
 
 #define spacer(c) (c <= ' ' || c == '(' || c == ')')
 
-static void
-pushchr(char c)
-{
-	*dst_++ = c;
-}
-
 static char *
 walk(char *s)
 {
@@ -49,12 +43,12 @@ sint(char *s)
 static void
 device_write(char *s)
 {
-	char c = *s, *cap = walk(s), **reg = regs + '0';
+	char **reg = regs + '0';
 	/* phase: ALU */
 	if(*reg) {
 		int acc = sint(*reg++);
 		/* clang-format off */
-		switch(c) {
+		switch(*s) {
 		case '+': while(*reg) acc += sint(*reg++); break;
 		case '-': while(*reg) acc -= sint(*reg++); break;
 		case '*': while(*reg) acc *= sint(*reg++); break;
@@ -71,11 +65,12 @@ device_write(char *s)
 		/* clang-format on */
 		dst_ += snprintf(dst_, 0x10, "%d", acc);
 		return;
-	}
+	} else {
 		/* phase: string */
+		char *cap = walk(s);
 		if(*s == '(') s++, --cap;
 		while(s < cap) {
-		c = *s++;
+			char c = *s++;
 			if(c == '\\') {
 				switch(*s++) {
 				case 't': putc(0x09, stdout); break;
@@ -86,15 +81,16 @@ device_write(char *s)
 				putc(c, stdout);
 		}
 	}
+}
 
 static void
 device_read(void)
 {
 	char c, *origin = dst_;
 	while(fread(&c, 1, 1, stdin) && c >= ' ')
-		pushchr(c);
+		*dst_++ = c;
 	if(feof(stdin))
-		pushchr('E'), pushchr('O'), pushchr('F');
+		*dst_++ = 'E', *dst_++ = 'O', *dst_++ = 'F';
 	if(dst_ - origin == 0)
 		dst_--;
 }
@@ -102,46 +98,53 @@ device_read(void)
 static void
 write_reg(char r, char *reg)
 {
-	char c, *cap = walk(reg);
 	switch(r) {
 	case ':': device_write(reg); return;
 	case '~': device_read(); return;
-	case '^': /* op: join */
+	case '^': { /* op: join */
+		char c, *cap = walk(reg);
 		if(*reg == '(') reg++, --cap;
 		while(reg < cap && (c = *reg++))
-			if(!spacer(c)) pushchr(c);
+			if(!spacer(c)) *dst_++ = c;
 		return;
-	case '.': /* op: unwrap */
+	}
+	case '.': { /* op: unwrap */
+		char *cap = walk(reg);
 		if(*reg == '(') reg++, --cap;
-		while(reg < cap) pushchr(*reg++);
+		while(reg < cap) *dst_++ = *reg++;
 		return;
+	}
 	case '*': { /* op: explode */
 		int i, depth = 0;
+		char c, *cap = walk(reg);
 		if(*reg == '(' && reg[1] != ')') { /* tuple */
 			reg++;
 			while(reg < cap) {
 				while((c = *reg) && !spacer(c))
-					pushchr(c), reg++;
-				pushchr(' '), pushchr('('), reg++, depth++;
+					*dst_++ = c, reg++;
+				*dst_++ = ' ';
+				*dst_++ = '(', reg++, depth++;
 			}
 		} else /* token */
 			while((c = *reg++) && !spacer(c))
-				pushchr(c), pushchr(' '), pushchr('('), depth++;
-		for(i = 0; i < depth; i++) pushchr(')');
+				*dst_++ = c, *dst_++ = ' ', *dst_++ = '(', depth++;
+		for(i = 0; i < depth; i++) *dst_++ = ')';
 		return;
 	}
-	default:
-		while(reg < cap) pushchr(*reg++);
+	default: {
+		char *cap = walk(reg);
+		while(reg < cap) *dst_++ = *reg++;
 		return;
 	}
 	}
+}
 
 static int
 write_tail(char *s)
 {
 	while((*dst_++ = *s++))
 		;
-	pushchr(0);
+	*dst_ = 0;
 	if((flip = !flip))
 		src_ = bank_b, dst_ = bank_a;
 	else
@@ -175,14 +178,10 @@ apply_rule(Rule *r, char *s)
 	if(!spacer(c)) return 0;
 	/* phase: write rule */
 	while((c = *b++)) {
-		if(c == '?') {
-			rid = *b;
-			if((reg = regs[rid]))
-				b++, write_reg(rid, reg);
+		if(c == '?' && (rid = *b) && (reg = regs[rid]))
+			write_reg(rid, reg), b++;
 		else
-				pushchr(c);
-		} else
-			pushchr(c);
+			*dst_++ = c;
 	}
 	if(dst_ == origin) {
 		while(*s == ' ') s++;
@@ -274,10 +273,9 @@ rewrite(void)
 			for(r = rules; r < rules_; r++)
 				if(r->a && apply_rule(r, s)) return 1;
 		}
-		pushchr(c), last = c;
-		s++;
+		*dst_++ = last = c, s++;
 	}
-	pushchr(0);
+	*dst_++ = 0;
 	return 0;
 }
 
@@ -285,7 +283,7 @@ int
 main(int argc, char **argv)
 {
 	FILE *f;
-	int i, pl = 0, pr = 0, rw = 0;
+	int i, pr = 0, rw = 0;
 	char c, last = 0, *w = bank_a;
 	if(argc < 2)
 		return !printf("usage: modal [-vqn] source.modal\n");
@@ -304,15 +302,14 @@ main(int argc, char **argv)
 		if(c == ' ' && last == '(') continue;
 		if(c == ')' && last == ' ') w--;
 		if(c == ' ' && last == ' ') w--;
-		if(c == '(') pl++;
-		if(c == ')') pr++;
+		if(c == '(') pr++;
+		if(c == ')') pr--;
 		if(c == '(' && last != '?' && !spacer(last)) *w++ = ' ';
 		if(last == ')' && !spacer(c)) *w++ = ' ';
 		*w++ = last = c;
 	}
-	while(*(--w) <= ' ') *w = 0;
 	fclose(f);
-	if(pr != pl)
+	if(pr)
 		return !fprintf(stderr, "Modal program imbalanced.\n");
 	while(rewrite() && ++rw)
 		if(!cycles--) return !fprintf(stderr, "Modal rewrites exceeded.\n");