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46dbb25 Dec 30, 2016
@cpq @dimonomid @rojer @mmikulicic
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/*
* Copyright (c) 2004-2013 Sergey Lyubka <valenok@gmail.com>
* Copyright (c) 2013 Cesanta Software Limited
* All rights reserved
*
* This library is dual-licensed: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation. For the terms of this
* license, see <http: *www.gnu.org/licenses/>.
*
* You are free to use this library under the terms of the GNU General
* Public License, but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* Alternatively, you can license this library under a commercial
* license, as set out in <http://cesanta.com/products.html>.
*/
#ifndef CS_FROZEN_FROZEN_H_
#define CS_FROZEN_FROZEN_H_
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
/* JSON token type */
enum json_token_type {
JSON_TYPE_INVALID = 0, /* memsetting to 0 should create INVALID value */
JSON_TYPE_STRING,
JSON_TYPE_NUMBER,
JSON_TYPE_TRUE,
JSON_TYPE_FALSE,
JSON_TYPE_NULL,
JSON_TYPE_OBJECT_START,
JSON_TYPE_OBJECT_END,
JSON_TYPE_ARRAY_START,
JSON_TYPE_ARRAY_END,
JSON_TYPES_CNT
};
/*
* Structure containing token type and value. Used in `json_walk()` and
* `json_scanf()` with the format specifier `%T`.
*/
struct json_token {
const char *ptr; /* Points to the beginning of the value */
int len; /* Value length */
enum json_token_type type; /* Type of the token, possible values are above */
};
#define JSON_INVALID_TOKEN \
{ 0, 0, JSON_TYPE_INVALID }
/* Error codes */
#define JSON_STRING_INVALID -1
#define JSON_STRING_INCOMPLETE -2
/*
* Callback-based SAX-like API.
*
* Property name and length is given only if it's available: i.e. if current
* event is an object's property. In other cases, `name` is `NULL`. For
* example, name is never given:
* - For the first value in the JSON string;
* - For events JSON_TYPE_OBJECT_END and JSON_TYPE_ARRAY_END
*
* E.g. for the input `{ "foo": 123, "bar": [ 1, 2, { "baz": true } ] }`,
* the sequence of callback invocations will be as follows:
*
* - type: JSON_TYPE_OBJECT_START, name: NULL, path: "", value: NULL
* - type: JSON_TYPE_NUMBER, name: "foo", path: ".foo", value: "123"
* - type: JSON_TYPE_ARRAY_START, name: "bar", path: ".bar", value: NULL
* - type: JSON_TYPE_NUMBER, name: "0", path: ".bar[0]", value: "1"
* - type: JSON_TYPE_NUMBER, name: "1", path: ".bar[1]", value: "2"
* - type: JSON_TYPE_OBJECT_START, name: "2", path: ".bar[2]", value: NULL
* - type: JSON_TYPE_TRUE, name: "baz", path: ".bar[2].baz", value: "true"
* - type: JSON_TYPE_OBJECT_END, name: NULL, path: ".bar[2]", value: "{ \"baz\":
*true }"
* - type: JSON_TYPE_ARRAY_END, name: NULL, path: ".bar", value: "[ 1, 2, {
*\"baz\": true } ]"
* - type: JSON_TYPE_OBJECT_END, name: NULL, path: "", value: "{ \"foo\": 123,
*\"bar\": [ 1, 2, { \"baz\": true } ] }"
*/
typedef void (*json_walk_callback_t)(void *callback_data, const char *name,
size_t name_len, const char *path,
const struct json_token *token);
/*
* Parse `json_string`, invoking `callback` in a way similar to SAX parsers;
* see `json_walk_callback_t`.
*/
int json_walk(const char *json_string, int json_string_length,
json_walk_callback_t callback, void *callback_data);
/*
* JSON generation API.
* struct json_out abstracts output, allowing alternative printing plugins.
*/
struct json_out {
int (*printer)(struct json_out *, const char *str, size_t len);
union {
struct {
char *buf;
size_t size;
size_t len;
} buf;
void *data;
FILE *fp;
} u;
};
extern int json_printer_buf(struct json_out *, const char *, size_t);
extern int json_printer_file(struct json_out *, const char *, size_t);
#define JSON_OUT_BUF(buf, len) \
{ \
json_printer_buf, { \
{ buf, len, 0 } \
} \
}
#define JSON_OUT_FILE(fp) \
{ \
json_printer_file, { \
{ (void *) fp, 0, 0 } \
} \
}
typedef int (*json_printf_callback_t)(struct json_out *, va_list *ap);
/*
* Generate formatted output into a given sting buffer.
* This is a superset of printf() function, with extra format specifiers:
* - `%B` print json boolean, `true` or `false`. Accepts an `int`.
* - `%Q` print quoted escaped string or `null`. Accepts a `const char *`.
* - `%.*Q` same as `%Q`, but with length. Accepts `int`, `const char *`
* - `%V` print quoted base64-encoded string. Accepts a `const char *`, `int`.
* - `%H` print quoted hex-encoded string. Accepts a `int`, `const char *`.
* - `%M` invokes a json_printf_callback_t function. That callback function
* can consume more parameters.
*
* Return number of bytes printed. If the return value is bigger then the
* supplied buffer, that is an indicator of overflow. In the overflow case,
* overflown bytes are not printed.
*/
int json_printf(struct json_out *, const char *fmt, ...);
int json_vprintf(struct json_out *, const char *fmt, va_list ap);
/*
* Helper %M callback that prints contiguous C arrays.
* Consumes void *array_ptr, size_t array_size, size_t elem_size, char *fmt
* Return number of bytes printed.
*/
int json_printf_array(struct json_out *, va_list *ap);
/*
* Scan JSON string `str`, performing scanf-like conversions according to `fmt`.
* This is a `scanf()` - like function, with following differences:
*
* 1. Object keys in the format string may be not quoted, e.g. "{key: %d}"
* 2. Order of keys in an object is irrelevant.
* 3. Several extra format specifiers are supported:
* - %B: consumes `int *`, expects boolean `true` or `false`.
* - %Q: consumes `char **`, expects quoted, JSON-encoded string. Scanned
* string is malloc-ed, caller must free() the string.
* - %V: consumes `char **`, `int *`. Expects base64-encoded string.
* Result string is base64-decoded, malloced and NUL-terminated.
* The length of result string is stored in `int *` placeholder.
* Caller must free() the result.
* - %H: consumes `int *`, `char **`.
* Expects a hex-encoded string, e.g. "fa014f".
* Result string is hex-decoded, malloced and NUL-terminated.
* The length of the result string is stored in `int *` placeholder.
* Caller must free() the result.
* - %M: consumes custom scanning function pointer and
* `void *user_data` parameter - see json_scanner_t definition.
* - %T: consumes `struct json_token *`, fills it out with matched token.
*
* Return number of elements successfully scanned & converted.
* Negative number means scan error.
*/
int json_scanf(const char *str, int str_len, const char *fmt, ...);
int json_vscanf(const char *str, int str_len, const char *fmt, va_list ap);
/* json_scanf's %M handler */
typedef void (*json_scanner_t)(const char *str, int len, void *user_data);
/*
* Helper function to scan array item with given path and index.
* Fills `token` with the matched JSON token.
* Return 0 if no array element found, otherwise non-0.
*/
int json_scanf_array_elem(const char *s, int len, const char *path, int index,
struct json_token *token);
/*
* Unescape JSON-encoded string src,slen into dst, dlen.
* src and dst may overlap.
* If destination buffer is too small (or zero-length), result string is not
* written but the length is counted nevertheless (similar to snprintf).
* Return the length of unescaped string in bytes.
*/
int json_unescape(const char *src, int slen, char *dst, int dlen);
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* CS_FROZEN_FROZEN_H_ */