add result style error handling

1 files changed, 23 insertions, 20 deletions

diff --git a/src/as_tokenizer.c b/src/as_tokenizer.c
index 6c40b9f..f2c3ccb 100644
--- a/src/as_tokenizer.c
+++ b/src/as_tokenizer.c
@@ -71,8 +71,9 @@ int is_part_of_identifier(int c) {
     return 0;
 }
 
-struct token * next_token_impl(struct allocator * alct, struct input_stream * s) {
-    struct token  * t = allocate(alct, sizeof(struct token));
+struct result next_token_impl(struct allocator * alct, struct input_stream * s) {
+    const char *errmsg;
+    struct token * t = allocate(alct, sizeof(struct token));
     int c;
     while (1) {
         c = input_stream_peek_char(s);
@@ -82,12 +83,12 @@ struct token * next_token_impl(struct allocator * alct, struct input_stream * s)
         if (c == '\n') {
             input_stream_next_char(s);
             *t = (struct token){.type = TK_NEWLINE, .line = s->line, .col = s->col};
-            return t;
+            return (struct result){.value = t, .errmsg = NULL};
         }
         if (c == ':') {
             input_stream_next_char(s);
             *t = (struct token){.type = TK_COLON, .line = s->line, .col = s->col};
-            return t;
+            return (struct result){.value = t, .errmsg = NULL};
         }
         if (c == ' ' || c == '\t') {
             input_stream_next_char(s);
@@ -104,17 +105,17 @@ struct token * next_token_impl(struct allocator * alct, struct input_stream * s)
                 }
             } 
             *t = (struct token){.type = TK_ARG, .ival = ival, .line = s->line, .col = s->col};
-            return t;
+            return (struct result){.value = t, .errmsg = NULL};
         }
         if (is_start_of_identifier(c)) {
             size_t line = s->line;
             size_t col = s->col;
             char *sval = allocate(alct, 256);
             size_t i = 0;
-            while(1) {
+            while (1) {
                 if (i >= 255) {
-                    fprintf(stderr, "error: identifier too long\n");
-                    exit(1);
+                    errmsg = safe_sprintf(alct, "error: identifier too long\n");
+                    return (struct result){.value = NULL, .errmsg = errmsg};
                 }
                 input_stream_next_char(s);
                 sval[i++] = c;
@@ -126,34 +127,36 @@ struct token * next_token_impl(struct allocator * alct, struct input_stream * s)
             sval[i] = '\0';
             if (isOp(sval)) {
                 *t = (struct token){.type = TK_OP, .sval = sval, .line = line, .col = col};
-                return t;
+                return (struct result){.value = t, .errmsg = NULL};
             }
             *t = (struct token){.type = TK_TAG, .sval = sval, .line = line, .col = col};
-            return t;
+            return (struct result){.value = t, .errmsg = NULL};
         }
-        fprintf(stderr, "error: invalid character %c at line %d, col %d\n", c, s->line, s->col);
+        errmsg = safe_sprintf(alct, "error: invalid character %c at line %d, col %d\n", c, s->line, s->col);
+        return (struct result){.value = NULL, .errmsg = errmsg};
     }
     // end of file
     *t = (struct token){.type = TK_ENDOFFILE};
-    return t;
+    return (struct result){.value = t, .errmsg = NULL};
 }
 
-struct token * next_token(struct allocator * alct, struct token_stream * ts) {
+struct result next_token(struct allocator * alct, struct token_stream * ts) {
     if (ts->buf != NULL) {
         struct token * t = ts->buf;
         ts->buf = NULL;
-        return t;
+        return (struct result){.value = t, .errmsg = NULL};
     }
-    struct token  * t = next_token_impl(alct, ts->s);
-    return t;
+    return next_token_impl(alct, ts->s);
 }
 
-struct token * peek_token(struct allocator * alct, struct token_stream * ts) {
+struct result peek_token(struct allocator * alct, struct token_stream * ts) {
     if (ts->buf != NULL) {
-        return ts->buf;
+        return (struct result){.value = ts->buf, .errmsg = NULL};
     }
-    ts->buf = next_token_impl(alct, ts->s);
-    return ts->buf;
+    struct result result = next_token_impl(alct, ts->s);
+    if (result.errmsg != NULL) return result;
+    ts->buf = result.value;
+    return result;
 }
 
 void print_token(struct token  * t) {