Add code to de-register patterns.

include/eval.h

@@ -114,6 +114,15 @@ liblex_result eval_config_free(eval_config* config);
  * @return LIBLEX_SUCCESS if all goes well, or LIBLEX_MALLOC if there was an allocation failure.
  */
 liblex_result eval_config_add(eval_config* config, const char* pattern, int pattern_id);
+/**
+ * Removes a pattern from this configuration that has been previously
+ * registered.
+ * @param config the configuration to add the pattern to.
+ * @param pattern the pattern to remove.
+ * @param pattern_id the id associated with the pattern.
+ * @return LIBLEX_SUCCESS if all goes well, or LIBLEX_MALLOC if there was an allocation failure.
+ */
+liblex_result eval_config_remove(eval_config* config, const char* pattern, int pattern_id);
 /**
  * Evaluates / finds a single word.
  * @param string the string to evaluate.

src/eval.c

@@ -41,14 +41,34 @@ liblex_result eval_config_add(eval_config* config, const char* ptrn, int pattern
   return result;
 }
 
-int _eval_config_foreach_free(void *data, va_list args){
-  eval_state* state = data;
-  int result = pattern_free(state->pattern) == LIBLEX_SUCCESS ? 0 : EVAL_FOREACH_MALLOC;
+liblex_result _eval_config_free_state(eval_state* state) {
+  liblex_result result = pattern_free(state->pattern);
   free(state->pattern);
   free(state);
   return result;
 }
 
+liblex_result eval_config_remove(eval_config* config, const char* pattern, int pattern_id) {
+  liblex_result result = LIBLEX_SUCCESS;
+  ll_node** head = &(config->states.head);
+  while(*head && result == LIBLEX_SUCCESS) {
+    eval_state* current_state = (*head)->data;
+    if(strcmp(current_state->source, pattern) == 0 && current_state->pattern->head->pattern_id == pattern_id) {
+      ll_node* to_delete = *head;
+      (*head) = (*head)->next;
+      free(to_delete);
+      result = _eval_config_free_state(current_state);
+    } else {
+      head = &((*head)->next);
+    }
+  }
+  return result;
+}
+
+int _eval_config_foreach_free(void* data, va_list args){
+  return _eval_config_free_state(data) == LIBLEX_SUCCESS ? 0 : EVAL_FOREACH_MALLOC;
+}
+
 liblex_result eval_config_free(eval_config* config){
   liblex_result result = foreach_errors[ll_foreach(&config->states, NULL, compare_always, _eval_config_foreach_free)];
   ll_free(&config->states);