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common/json: new helper to scan JSON: json_scan.
This takes a JSON-style format string, and does intelligent parsing, removing a lot of boilerplate from code which needs to deal with JSON. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
Christian Decker
parent
24b6132ee8
commit
553daf17e0
3 changed files with 393 additions and 1 deletions
185
common/json.c
185
common/json.c
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@ -13,7 +13,6 @@
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#include <ctype.h>
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#include <errno.h>
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#include <inttypes.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <string.h>
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@ -756,6 +755,190 @@ const jsmntok_t *json_delve(const char *buffer,
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return tok;
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}
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/* talfmt take a ctx pointer and return NULL or a valid pointer.
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* fmt takes the argument, and returns a bool. */
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static bool handle_percent(const char *buffer,
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const jsmntok_t *tok,
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va_list *ap)
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{
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void *ctx;
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/* This is set to (dummy) json_scan if it's a non-tal fmt */
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ctx = va_arg(*ap, void *);
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if (ctx != json_scan) {
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void *(*talfmt)(void *, const char *, const jsmntok_t *);
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void **p;
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p = va_arg(*ap, void **);
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talfmt = va_arg(*ap, void *(*)(void *, const char *, const jsmntok_t *));
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*p = talfmt(ctx, buffer, tok);
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return *p != NULL;
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} else {
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bool (*fmt)(const char *, const jsmntok_t *, void *);
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void *p;
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p = va_arg(*ap, void *);
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fmt = va_arg(*ap, bool (*)(const char *, const jsmntok_t *, void *));
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return fmt(buffer, tok, p);
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}
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}
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/* GUIDE := OBJ | '%'
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* OBJ := '{' FIELDLIST '}'
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* FIELDLIST := FIELD [',' FIELD]*
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* FIELD := LITERAL ':' FIELDVAL
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* FIELDVAL := OBJ | LITERAL | '%'
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*/
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/* Returns NULL on failure, or offset into guide */
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static const char *parse_literal(const char *guide,
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const char **literal,
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size_t *len)
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{
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*literal = guide;
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*len = strspn(guide,
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"abcdefghijklmnopqrstuvwxyz"
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"0123456789"
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"_-");
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return guide + *len;
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}
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/* Recursion */
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static const char *parse_obj(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list *ap);
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static const char *parse_guide(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list *ap)
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{
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if (*guide == '{') {
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guide = parse_obj(buffer, tok, guide, ap);
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if (!guide)
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return NULL;
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assert(*guide == '}');
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return guide + 1;
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} else {
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assert(*guide == '%');
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if (!handle_percent(buffer, tok, ap))
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return NULL;
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return guide + 1;
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}
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}
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static const char *parse_fieldval(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list *ap)
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{
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if (*guide == '{') {
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guide = parse_obj(buffer, tok, guide, ap);
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if (!guide)
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return NULL;
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assert(*guide == '}');
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return guide + 1;
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} else if (*guide == '%') {
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if (!handle_percent(buffer, tok, ap))
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return NULL;
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return guide + 1;
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} else {
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const char *literal;
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size_t len;
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/* Literal must match exactly */
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guide = parse_literal(guide, &literal, &len);
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if (!memeq(buffer + tok->start, tok->end - tok->start,
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literal, len))
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return NULL;
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return guide;
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}
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}
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static const char *parse_field(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list *ap)
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{
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const jsmntok_t *member;
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size_t len;
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const char *memname;
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guide = parse_literal(guide, &memname, &len);
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assert(*guide == ':');
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member = json_get_membern(buffer, tok, memname, guide - memname);
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if (!member)
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return NULL;
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return parse_fieldval(buffer, member, guide + 1, ap);
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}
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static const char *parse_fieldlist(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list *ap)
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{
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for (;;) {
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guide = parse_field(buffer, tok, guide, ap);
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if (!guide)
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return NULL;
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if (*guide != ',')
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break;
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guide++;
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}
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return guide;
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}
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static const char *parse_obj(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list *ap)
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{
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assert(*guide == '{');
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if (tok->type != JSMN_OBJECT)
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return NULL;
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guide = parse_fieldlist(buffer, tok, guide + 1, ap);
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if (!guide)
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return NULL;
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return guide;
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}
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bool json_scanv(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list ap)
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{
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va_list cpy;
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/* We need this, since &ap doesn't work on some platforms... */
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va_copy(cpy, ap);
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guide = parse_guide(buffer, tok, guide, &cpy);
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va_end(cpy);
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if (!guide)
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return false;
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assert(guide[0] == '\0');
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return true;
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}
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bool json_scan(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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...)
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{
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va_list ap;
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bool ret;
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va_start(ap, guide);
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ret = json_scanv(buffer, tok, guide, ap);
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va_end(ap);
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return ret;
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}
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void json_add_num(struct json_stream *result, const char *fieldname, unsigned int value)
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{
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json_add_member(result, fieldname, false, "%u", value);
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@ -5,6 +5,7 @@
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#include <ccan/short_types/short_types.h>
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#include <ccan/tal/tal.h>
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#include <common/errcode.h>
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#include <stdarg.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdlib.h>
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@ -156,6 +157,33 @@ const jsmntok_t *json_delve(const char *buffer,
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const jsmntok_t *tok,
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const char *guide);
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/* Guide is % for a token: each must be followed by JSON_SCAN(). */
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bool json_scan(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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...);
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/* eg. JSON_SCAN(json_to_bool, &boolvar) */
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#define JSON_SCAN(fmt, var) \
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json_scan, \
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((var) + 0*sizeof(fmt((const char *)NULL, \
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(const jsmntok_t *)NULL, var) == true)), \
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(fmt)
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/* eg. JSON_SCAN_TAL(tmpctx, json_strdup, &charvar) */
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#define JSON_SCAN_TAL(ctx, fmt, var) \
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(ctx), \
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((var) + 0*sizeof((*var) = fmt((ctx), \
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(const char *)NULL, \
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(const jsmntok_t *)NULL))), \
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(fmt)
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/* Already-have-varargs version */
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bool json_scanv(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list ap);
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/* Iterator macro for array: i is counter, t is token ptr, arr is JSMN_ARRAY */
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#define json_for_each_arr(i, t, arr) \
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for (i = 0, t = (arr) + 1; i < (arr)->size; t = json_next(t), i++)
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181
common/test/run-json_scan.c
Normal file
181
common/test/run-json_scan.c
Normal file
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@ -0,0 +1,181 @@
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#include "../json.c"
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#include <assert.h>
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#include <ccan/mem/mem.h>
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#include <ccan/tal/str/str.h>
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#include <common/amount.h>
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#include <common/json.h>
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#include <common/setup.h>
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#include <common/utils.h>
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#include <inttypes.h>
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#include <stdio.h>
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#include <wire/wire.h>
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/* AUTOGENERATED MOCKS START */
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/* Generated stub for amount_asset_is_main */
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bool amount_asset_is_main(struct amount_asset *asset UNNEEDED)
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{ fprintf(stderr, "amount_asset_is_main called!\n"); abort(); }
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/* Generated stub for amount_asset_to_sat */
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struct amount_sat amount_asset_to_sat(struct amount_asset *asset UNNEEDED)
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{ fprintf(stderr, "amount_asset_to_sat called!\n"); abort(); }
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/* Generated stub for amount_sat */
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struct amount_sat amount_sat(u64 satoshis UNNEEDED)
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{ fprintf(stderr, "amount_sat called!\n"); abort(); }
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/* Generated stub for amount_sat_add */
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bool amount_sat_add(struct amount_sat *val UNNEEDED,
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struct amount_sat a UNNEEDED,
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struct amount_sat b UNNEEDED)
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{ fprintf(stderr, "amount_sat_add called!\n"); abort(); }
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/* Generated stub for amount_sat_eq */
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bool amount_sat_eq(struct amount_sat a UNNEEDED, struct amount_sat b UNNEEDED)
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{ fprintf(stderr, "amount_sat_eq called!\n"); abort(); }
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/* Generated stub for amount_sat_greater_eq */
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bool amount_sat_greater_eq(struct amount_sat a UNNEEDED, struct amount_sat b UNNEEDED)
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{ fprintf(stderr, "amount_sat_greater_eq called!\n"); abort(); }
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/* Generated stub for amount_sat_sub */
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bool amount_sat_sub(struct amount_sat *val UNNEEDED,
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struct amount_sat a UNNEEDED,
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struct amount_sat b UNNEEDED)
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{ fprintf(stderr, "amount_sat_sub called!\n"); abort(); }
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/* Generated stub for amount_sat_to_asset */
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struct amount_asset amount_sat_to_asset(struct amount_sat *sat UNNEEDED, const u8 *asset UNNEEDED)
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{ fprintf(stderr, "amount_sat_to_asset called!\n"); abort(); }
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/* Generated stub for amount_tx_fee */
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struct amount_sat amount_tx_fee(u32 fee_per_kw UNNEEDED, size_t weight UNNEEDED)
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{ fprintf(stderr, "amount_tx_fee called!\n"); abort(); }
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/* Generated stub for fromwire */
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const u8 *fromwire(const u8 **cursor UNNEEDED, size_t *max UNNEEDED, void *copy UNNEEDED, size_t n UNNEEDED)
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{ fprintf(stderr, "fromwire called!\n"); abort(); }
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/* Generated stub for fromwire_amount_sat */
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struct amount_sat fromwire_amount_sat(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
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{ fprintf(stderr, "fromwire_amount_sat called!\n"); abort(); }
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/* Generated stub for fromwire_bool */
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bool fromwire_bool(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
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{ fprintf(stderr, "fromwire_bool called!\n"); abort(); }
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/* Generated stub for fromwire_fail */
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void *fromwire_fail(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
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{ fprintf(stderr, "fromwire_fail called!\n"); abort(); }
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/* Generated stub for fromwire_secp256k1_ecdsa_signature */
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void fromwire_secp256k1_ecdsa_signature(const u8 **cursor UNNEEDED, size_t *max UNNEEDED,
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secp256k1_ecdsa_signature *signature UNNEEDED)
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{ fprintf(stderr, "fromwire_secp256k1_ecdsa_signature called!\n"); abort(); }
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/* Generated stub for fromwire_sha256 */
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void fromwire_sha256(const u8 **cursor UNNEEDED, size_t *max UNNEEDED, struct sha256 *sha256 UNNEEDED)
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{ fprintf(stderr, "fromwire_sha256 called!\n"); abort(); }
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/* Generated stub for fromwire_tal_arrn */
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u8 *fromwire_tal_arrn(const tal_t *ctx UNNEEDED,
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const u8 **cursor UNNEEDED, size_t *max UNNEEDED, size_t num UNNEEDED)
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{ fprintf(stderr, "fromwire_tal_arrn called!\n"); abort(); }
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/* Generated stub for fromwire_u16 */
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u16 fromwire_u16(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
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{ fprintf(stderr, "fromwire_u16 called!\n"); abort(); }
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/* Generated stub for fromwire_u32 */
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u32 fromwire_u32(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
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{ fprintf(stderr, "fromwire_u32 called!\n"); abort(); }
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/* Generated stub for fromwire_u64 */
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u64 fromwire_u64(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
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{ fprintf(stderr, "fromwire_u64 called!\n"); abort(); }
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/* Generated stub for fromwire_u8 */
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u8 fromwire_u8(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
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{ fprintf(stderr, "fromwire_u8 called!\n"); abort(); }
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/* Generated stub for fromwire_u8_array */
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void fromwire_u8_array(const u8 **cursor UNNEEDED, size_t *max UNNEEDED, u8 *arr UNNEEDED, size_t num UNNEEDED)
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{ fprintf(stderr, "fromwire_u8_array called!\n"); abort(); }
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/* Generated stub for json_add_member */
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void json_add_member(struct json_stream *js UNNEEDED,
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const char *fieldname UNNEEDED,
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bool quote UNNEEDED,
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const char *fmt UNNEEDED, ...)
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{ fprintf(stderr, "json_add_member called!\n"); abort(); }
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/* Generated stub for json_member_direct */
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char *json_member_direct(struct json_stream *js UNNEEDED,
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const char *fieldname UNNEEDED, size_t extra UNNEEDED)
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{ fprintf(stderr, "json_member_direct called!\n"); abort(); }
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/* Generated stub for towire */
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void towire(u8 **pptr UNNEEDED, const void *data UNNEEDED, size_t len UNNEEDED)
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{ fprintf(stderr, "towire called!\n"); abort(); }
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/* Generated stub for towire_amount_sat */
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void towire_amount_sat(u8 **pptr UNNEEDED, const struct amount_sat sat UNNEEDED)
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{ fprintf(stderr, "towire_amount_sat called!\n"); abort(); }
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/* Generated stub for towire_bool */
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void towire_bool(u8 **pptr UNNEEDED, bool v UNNEEDED)
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{ fprintf(stderr, "towire_bool called!\n"); abort(); }
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/* Generated stub for towire_secp256k1_ecdsa_signature */
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void towire_secp256k1_ecdsa_signature(u8 **pptr UNNEEDED,
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const secp256k1_ecdsa_signature *signature UNNEEDED)
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{ fprintf(stderr, "towire_secp256k1_ecdsa_signature called!\n"); abort(); }
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/* Generated stub for towire_sha256 */
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void towire_sha256(u8 **pptr UNNEEDED, const struct sha256 *sha256 UNNEEDED)
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{ fprintf(stderr, "towire_sha256 called!\n"); abort(); }
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/* Generated stub for towire_u16 */
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void towire_u16(u8 **pptr UNNEEDED, u16 v UNNEEDED)
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{ fprintf(stderr, "towire_u16 called!\n"); abort(); }
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/* Generated stub for towire_u32 */
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void towire_u32(u8 **pptr UNNEEDED, u32 v UNNEEDED)
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{ fprintf(stderr, "towire_u32 called!\n"); abort(); }
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/* Generated stub for towire_u64 */
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void towire_u64(u8 **pptr UNNEEDED, u64 v UNNEEDED)
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{ fprintf(stderr, "towire_u64 called!\n"); abort(); }
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/* Generated stub for towire_u8 */
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void towire_u8(u8 **pptr UNNEEDED, u8 v UNNEEDED)
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{ fprintf(stderr, "towire_u8 called!\n"); abort(); }
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/* Generated stub for towire_u8_array */
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void towire_u8_array(u8 **pptr UNNEEDED, const u8 *arr UNNEEDED, size_t num UNNEEDED)
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{ fprintf(stderr, "towire_u8_array called!\n"); abort(); }
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/* AUTOGENERATED MOCKS END */
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static bool json_to_tok(const char *buffer, const jsmntok_t *tok,
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const jsmntok_t **t)
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{
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*t = tok;
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return true;
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}
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int main(int argc, char *argv[])
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{
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const jsmntok_t *toks, *t;
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char *buf;
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char *s;
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u32 u32val;
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u8 *hex;
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common_setup(argv[0]);
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buf = tal_strdup(tmpctx, "{\"1\":\"one\", \"2\":\"two\", \"3\":{\"three\": {\"deeper\": 17}}}");
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toks = json_parse_simple(tmpctx, buf, strlen(buf));
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assert(toks);
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assert(toks->size == 3);
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/* These are direct matches, and they work. */
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assert(json_scan(buf, toks, "{1:one}"));
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assert(json_scan(buf, toks, "{1:one,2:two}"));
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assert(json_scan(buf, toks, "{2:two,1:one}"));
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assert(json_scan(buf, toks, "{2:two,1:one,3:{three:{deeper:17}}}"));
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/* These do not match */
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assert(!json_scan(buf, toks, "{2:one}"));
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assert(!json_scan(buf, toks, "{1:one,2:tw}"));
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assert(!json_scan(buf, toks, "{1:one,2:twoo}"));
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assert(!json_scan(buf, toks, "{4:one}"));
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assert(!json_scan(buf, toks, "{2:two,1:one,3:three}"));
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assert(!json_scan(buf, toks, "{3:{three:deeper}}"));
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assert(!json_scan(buf, toks, "{3:{three:{deeper:{}}}}"));
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/* These capture simple values. */
|
||||
assert(json_scan(buf, toks, "{3:{three:{deeper:%}}}",
|
||||
JSON_SCAN(json_to_number, &u32val)));
|
||||
assert(u32val == 17);
|
||||
assert(!json_scan(buf, toks, "{1:%}",
|
||||
JSON_SCAN(json_to_number, &u32val)));
|
||||
assert(json_scan(buf, toks, "{1:%}",
|
||||
JSON_SCAN_TAL(tmpctx, json_strdup, &s)));
|
||||
assert(tal_parent(s) == tmpctx);
|
||||
assert(streq(s, "one"));
|
||||
|
||||
assert(!json_scan(buf, toks, "{1:%}",
|
||||
JSON_SCAN_TAL(tmpctx, json_tok_bin_from_hex, &hex)));
|
||||
|
||||
assert(json_scan(buf, toks, "{3:%}", JSON_SCAN(json_to_tok, &t)));
|
||||
assert(t == &toks[6]);
|
||||
|
||||
common_shutdown();
|
||||
}
|
||||
Loading…
Add table
Reference in a new issue