tisp

commit 49f7ff371efb1645cb75aad8d1927c4ae04bfd13
parent f1978aa4417a14995690809a0029308587e74fb9
Author: Ed van Bruggen <edvb@uw.edu>
Date:   Thu, 22 Mar 2018 22:14:49 -0700

Fix bugs in parsing and evaluating of symbols

After symbol was evaluated it would get free'ed, preventing it from
being read again. Also corrects problems in the reading of symbols in
lists, (a b (c) d) would be read as (a b (c d)) for example.

Diffstat:
tisp.c
 | 
36
+++++++++++++++++++++---------------

1 file changed, 21 insertions(+), 15 deletions(-)
diff --git a/tisp.c b/tisp.c
@@ -106,7 +106,7 @@ struct Val nil;
 #include "config.h"
 
 static int
-issymbol(char c)
+issym(char c)
 {
 	return BETWEEN(c, 'a', 'z') || strchr("+-*/", c);
 }
@@ -287,7 +287,7 @@ read_int(Str str)
 }
 
 Val
-read_string(Str str)
+read_str(Str str)
 {
 	int len = 0;
 	char *s = ++str->d;
@@ -297,13 +297,20 @@ read_string(Str str)
 }
 
 Val
-read_symbol(Str str)
+read_sym(Str str)
 {
-	int len = 0;
-	char *sym = str->d;
-	for (; *str->d && issymbol(*str->d++); len++);
-	sym[len] = '\0';
-	return mk_sym(estrdup(sym));
+	int n = 1;
+	int i = 0;
+	char *sym = emalloc(n);
+	for (; issym(*str->d); str->d++) {
+		sym[i++] = *str->d;
+		if (i == n) {
+			n *= 2;
+			sym = erealloc(sym, n);
+		}
+	}
+	sym[i] = '\0';
+	return mk_sym(sym);
 }
 
 Val
@@ -320,6 +327,7 @@ read_list(Str str)
 	}
 	b = mk_list(n, a);
 	free(a);
+	str->d++;
 	skip_spaces(str);
 	return b;
 }
@@ -328,12 +336,12 @@ Val
 read_val(Str str)
 {
 	skip_spaces(str);
-	if (isdigit(*str->d)) /* TODO negitive numbers */
+	if (isdigit(*str->d)) /* TODO negative numbers */
 		return read_int(str);
 	if (*str->d == '"') /* TODO fix */
-		return read_string(str);
-	if (issymbol(*str->d))
-		return read_symbol(str);
+		return read_str(str);
+	if (issym(*str->d))
+		return read_sym(str);
 	if (*str->d == '(')
 		return read_list(str);
 	return NULL;
@@ -386,13 +394,12 @@ eval_pair(Hash env, Val v)
 {
 	int cap = 1, size = 0;
 	Val *new = emalloc(sizeof(Val));
-	while (!nilp(v)) {
+	for (; !nilp(v); v = cdr(v)) {
 		new[size++] = tisp_eval(env, car(v));
 		if (size == cap) {
 			cap *= 2;
 			new = erealloc(new, cap*sizeof(Val));
 		}
-		v = cdr(v);
 	}
 	Val ret = mk_list(size, new);
 	free(new);
@@ -547,7 +554,6 @@ main(int argc, char *argv[])
 
 		tisp_print(v);
 		putchar('\n');
-		val_free(v);
 		if (str) break;
 	}