daemon/json: helpers for using jsmn.

Also taken from pettycoin.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

daemon/json.h

@@ -0,0 +1,87 @@
+#ifndef LIGHTNING_DAEMON_JSON_H
+#define LIGHTNING_DAEMON_JSON_H
+#include "config.h"
+#include "stdbool.h"
+#include "stdlib.h"
+#include <ccan/tal/tal.h>
+
+#define JSMN_STRICT 1
+# include "jsmn/jsmn.h"
+
+struct json_result;
+
+/* Include " if it's a string. */
+const char *json_tok_contents(const char *buffer, const jsmntok_t *t);
+
+/* Include " if it's a string. */
+int json_tok_len(const jsmntok_t *t);
+
+/* Is this a string equal to str? */
+bool json_tok_streq(const char *buffer, const jsmntok_t *tok, const char *str);
+
+/* Extract number from this (may be a string, or a number literal) */
+bool json_tok_number(const char *buffer, const jsmntok_t *tok,
+		     unsigned int *num);
+
+/* Is this the null primitive? */
+bool json_tok_is_null(const char *buffer, const jsmntok_t *tok);
+
+/* Returns next token with same parent. */
+const jsmntok_t *json_next(const jsmntok_t *tok);
+
+/* Get the parameters (by position or name).  Followed by pairs
+ * of const char *name, const jsmntok_t **ret_ptr, then NULL.
+ * *ret_ptr will be set to NULL if it's a literal 'null' or not present.
+ */
+void json_get_params(const char *buffer, const jsmntok_t param[], ...);
+
+/* Get top-level member. */
+const jsmntok_t *json_get_member(const char *buffer, const jsmntok_t tok[],
+				 const char *label);
+
+/* Get index'th array member. */
+const jsmntok_t *json_get_arr(const char *buffer, const jsmntok_t tok[],
+			      size_t index);
+
+/* Guide is a string with . for members, [] around indexes. */
+const jsmntok_t *json_delve(const char *buffer,
+			    const jsmntok_t *tok,
+			    const char *guide);
+
+/* If input is complete and valid, return tokens. */
+jsmntok_t *json_parse_input(const char *input, int len, bool *valid);
+
+/* Creating JSON strings */
+
+/* '"fieldname" : [ ' or '[ ' if fieldname is NULL */
+void json_array_start(struct json_result *ptr, const char *fieldname);
+/* '"fieldname" : { ' or '{ ' if fieldname is NULL */
+void json_object_start(struct json_result *ptr, const char *fieldname);
+/* ' ], ' */
+void json_array_end(struct json_result *ptr);
+/* ' }, ' */
+void json_object_end(struct json_result *ptr);
+
+struct json_result *new_json_result(const tal_t *ctx);
+
+/* '"fieldname" : "value"' or '"value"' if fieldname is NULL*/
+void json_add_string(struct json_result *result, const char *fieldname, const char *value);
+/* '"fieldname" : literal' or 'literal' if fieldname is NULL*/
+void json_add_literal(struct json_result *result, const char *fieldname,
+		      const char *literal, int len);
+/* '"fieldname" : value' or 'value' if fieldname is NULL */
+void json_add_num(struct json_result *result, const char *fieldname,
+		  unsigned int value);
+/* '"fieldname" : true|false' or 'true|false' if fieldname is NULL */
+void json_add_bool(struct json_result *result, const char *fieldname,
+		   bool value);
+/* '"fieldname" : null' or 'null' if fieldname is NULL */
+void json_add_null(struct json_result *result, const char *fieldname);
+/* '"fieldname" : "0189abcdef..."' or "0189abcdef..." if fieldname is NULL */
+void json_add_hex(struct json_result *result, const char *fieldname,
+		  const void *data, size_t len);
+
+void json_add_object(struct json_result *result, ...);
+
+const char *json_result_string(const struct json_result *result);
+#endif /* LIGHTNING_DAEMON_JSON_H */