json: add print, copy, and remove functions

Needed for check command.  I left the print function in since it was so
convenient for debugging purposes.

Signed-off-by: Mark Beckwith <wythe@intrig.com>

common/json.c

@@ -216,3 +216,69 @@ again:
 
 	return toks;
 }
+
+const char *jsmntype_to_string(jsmntype_t t)
+{
+	switch (t) {
+		case JSMN_UNDEFINED :
+			return "UNDEFINED";
+		case JSMN_OBJECT :
+			return "OBJECT";
+		case JSMN_ARRAY :
+			return "ARRAY";
+		case JSMN_STRING :
+			return "STRING";
+		case JSMN_PRIMITIVE :
+			return "PRIMITIVE";
+	}
+	return "INVALID";
+}
+
+void json_tok_print(const char *buffer, const jsmntok_t *tok)
+{
+	const jsmntok_t *first = tok;
+	const jsmntok_t *last = json_next(tok);
+	printf("size: %d, count: %td\n", tok->size, last - first);
+	while (first != last) {
+		printf("%td. %.*s, %s\n", first - tok,
+		        first->end - first->start, buffer + first->start,
+			jsmntype_to_string(first->type));
+		first++;
+	}
+	printf("\n");
+}
+
+jsmntok_t *json_tok_copy(const tal_t *ctx, const jsmntok_t *tok)
+{
+	const jsmntok_t *first = tok;
+	const jsmntok_t *last = json_next(tok);
+
+	if (!tok)
+		return NULL;
+	jsmntok_t *arr = tal_arr(ctx, jsmntok_t, last - first);
+	jsmntok_t *dest = arr;
+	while (first != last)
+		*dest++ = *first++;
+
+	return arr;
+}
+
+void json_tok_remove(jsmntok_t **tokens, jsmntok_t *tok, size_t num)
+{
+	assert(*tokens);
+	assert((*tokens)->type == JSMN_ARRAY || (*tokens)->type == JSMN_OBJECT);
+	const jsmntok_t *src = tok;
+	const jsmntok_t *end = json_next(*tokens);
+	jsmntok_t *dest = tok;
+	int remove_count;
+
+	for (int i = 0; i < num; i++)
+		src = json_next(src);
+
+	remove_count = src - tok;
+
+	memmove(dest, src, sizeof(jsmntok_t) * (end - src));
+
+	tal_resize(tokens, tal_count(*tokens) - remove_count);
+	(*tokens)->size -= num;
+}

common/json.h

@@ -57,4 +57,19 @@ const jsmntok_t *json_get_arr(const jsmntok_t tok[], size_t index);
 /* If input is complete and valid, return tokens. */
 jsmntok_t *json_parse_input(const char *input, int len, bool *valid);
 
+/* Convert a jsmntype_t enum to a human readable string. */
+const char *jsmntype_to_string(jsmntype_t t);
+
+/* Print a json value for debugging purposes. */
+void json_tok_print(const char *buffer, const jsmntok_t *params);
+
+/* Return a copy of a json value as an array. */
+jsmntok_t *json_tok_copy(const tal_t *ctx, const jsmntok_t *tok);
+
+/*
+ * Remove @num json values from a json array or object. @tok points
+ * to the first value to remove.  The array will be resized.
+ */
+void json_tok_remove(jsmntok_t **tokens, jsmntok_t *tok, size_t num);
+
 #endif /* LIGHTNING_COMMON_JSON_H */