Improve parser errors slightly

src/main.c

@@ -79,7 +79,12 @@ int main(int argc, const char **argv) {
             }
 
             struct ucl_object *sexp = ucl_parse(line);
-            struct ucl_object *result = ucl_evaluate(scope, ucl_car(sexp));
+            struct ucl_object *result = NULL;
+            if (sexp->type == UCL_TYPE_ERROR) {
+                result = sexp;
+            } else {
+                result = ucl_evaluate(scope, ucl_car(sexp));
+            }
             ucl_print_obj(result);
             printf("\n");
 

src/parse.c

@@ -1,5 +1,6 @@
 #include "uclisp.h"
 #include "internal.h"
+#include "utility.h"
 
 // TODO: remove these
 #include <stdbool.h>
@@ -20,6 +21,8 @@ static const char *reserved_symbols[] = {
 };
 
 // TODO: remove malloc and strndup calls
+// TODO: refresh this with newer 'object' code
+// TODO: Syntatic sugar for quote
 
 static bool ucl_is_whitespace(char c) {
     return c == ' ' || c == '\n' || c == '\t';
@@ -68,6 +71,7 @@ struct ucl_object *ucl_token_next(const char **curr_src) {
                 str = strndup(start + 1, *curr_src - start - 2);
                 return ucl_cell_create(ucl_string_create(str), NULL);
             case '0'...'9': {
+                // TODO: Add support for negative integers
                 char *end = NULL;
                 long value = strtol(*curr_src, &end, 0);
                 *curr_src = end;
@@ -141,6 +145,9 @@ static struct ucl_object *ucl_parse_tokens_recursive(struct ucl_object **token_i
     assert((*token_iter)->type == UCL_TYPE_CELL);
 
     struct ucl_object *token = (*token_iter)->cell.car;
+    if (token == NULL) {
+        return NULL;
+    }
     struct ucl_object *next_sexp = ucl_parse_token_atom(token);
     if (next_sexp != NULL) {
         *token_iter = (*token_iter)->cell.cdr;
@@ -154,7 +161,13 @@ static struct ucl_object *ucl_parse_tokens_recursive(struct ucl_object **token_i
         // Consume the START_LIST_CHAR
         *token_iter = (*token_iter)->cell.cdr;
         while (1) {
+            if (*token_iter == NULL) {
+                // Unexpected end of parsing
+                return ucl_error_create("Unmatched open parenthesis");
+            }
+
             token = (*token_iter)->cell.car;
+
             if (token->type == UCL_TYPE_SYMBOL && token->symbol[0] == END_LIST_CHAR) {
                 *token_iter = (*token_iter)->cell.cdr;
                 if (list == NULL) {
@@ -164,6 +177,7 @@ static struct ucl_object *ucl_parse_tokens_recursive(struct ucl_object **token_i
             }
 
             next_sexp = ucl_parse_tokens_recursive(token_iter);
+            UCL_RET_IF_ERROR(next_sexp);
             if (next_sexp == NULL) {
                 // Error somewhere in the recursive parsing
                 ucl_object_delete(list);
@@ -174,12 +188,11 @@ static struct ucl_object *ucl_parse_tokens_recursive(struct ucl_object **token_i
             next_node = &(*next_node)->cell.cdr;
         }
     } else if (token->symbol[0] == END_LIST_CHAR) {
-        // Mismatched parens
+        return ucl_error_create("Unmatched closed parenthesis");
-        return NULL;
     }
     // Any other symbol type should have been an atom, this shouldn't happen
     assert(false);
-    return NULL;
+    return ucl_error_create("Unreachable parse error");
 }
 
 // parse_tokens -> doesn't care about quotes, terminates on EOF
@@ -192,8 +205,8 @@ struct ucl_object *ucl_parse_tokens(struct ucl_object *tokens) {
 
     while (*token_iter != NULL) {
         struct ucl_object *new_sexp = ucl_parse_tokens_recursive(token_iter);
-        if (new_sexp == NULL) {
+        if (new_sexp == NULL || new_sexp->type == UCL_TYPE_ERROR) {
-            goto error;
+            return new_sexp;
         }
 
         *next_cell = ucl_cell_create(new_sexp, NULL);
@@ -206,7 +219,6 @@ struct ucl_object *ucl_parse_tokens(struct ucl_object *tokens) {
 
     return resultl;
   error:
-    ucl_object_delete(resultl);
     return NULL;
 }
 
@@ -214,13 +226,13 @@ struct ucl_object *ucl_parse_tokens(struct ucl_object *tokens) {
 // all sexps in the source (return a list of sexps)?
 struct ucl_object *ucl_parse(const char *source) {
     struct ucl_object *tokens = ucl_tokenize(source);
+    if (tokens == NULL) {
+        tokens = ucl_nil_create();
+    }
+    UCL_RET_IF_ERROR(tokens);
     struct ucl_object *sexp  = ucl_parse_tokens(tokens);
-    ucl_object_delete(tokens);
+    if (sexp == NULL) {
+        return ucl_nil_create();
+    }
     return sexp;
 }
-
-/* struct ParseResult *ucl_parse(const char *source) { */
-/*     struct Cell *tokens = ucl_tokenize(source); */
-/*     struct Cell *sexp = n */
-
-/* } */

src/special.c

@@ -5,6 +5,8 @@
 
 #include <assert.h>
 
+// TODO: Macro support?
+
 struct ucl_object *ucl_special_let(struct ucl_scope *scope, struct ucl_object *args) {
     // TODO: Check arguments
     struct ucl_object *assignments = ucl_car(args);

test/test_parse.c

@@ -4,6 +4,7 @@
 
 #include "uclisp.h"
 #include "internal.h"
+#include "testing_helpers.h"
 
 /* static struct ucl_parse_result *result; */
 static struct ucl_object *response;
@@ -331,6 +332,20 @@ static void test_parse_nested(void) {
     TEST_ASSERT_EQUAL_STRING("foo", response->cell.car->cell.car->cell.car->symbol);
 }
 
+static void test_parse_mismatched_open(void) {
+    response = ucl_parse("(");
+
+    TEST_ASSERT_NOT_NULL(response);
+    TEST_ASSERT_OBJ_ERROR(response);
+}
+
+static void test_parse_mismatched_closed(void) {
+    response = ucl_parse(")");
+
+    TEST_ASSERT_NOT_NULL(response);
+    TEST_ASSERT_OBJ_ERROR(response);
+}
+
 
 int main(void) {
     UNITY_BEGIN();
@@ -357,5 +372,7 @@ int main(void) {
     RUN_TEST(test_parse_2elem);
     RUN_TEST(test_parse_2elem_str);
     RUN_TEST(test_parse_nested);
+    RUN_TEST(test_parse_mismatched_open);
+    RUN_TEST(test_parse_mismatched_closed);
     return UNITY_END();
 }