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@lloyd @octo
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/*
* Copyright (c) 2010-2011 Florian Forster <ff at octo.it>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/**
* \file yajl_tree.h
*
* Parses JSON data and returns the data in tree form.
*
* \author Florian Forster
* \date August 2010
*
* This interface makes quick parsing and extraction of
* smallish JSON docs trivial:
*
* \include example/parse_config.c
*/
#ifndef YAJL_TREE_H
#define YAJL_TREE_H 1
#include <yajl/yajl_common.h>
#ifdef __cplusplus
extern "C" {
#endif
/** possible data types that a yajl_val_s can hold */
typedef enum {
yajl_t_string = 1,
yajl_t_number = 2,
yajl_t_object = 3,
yajl_t_array = 4,
yajl_t_true = 5,
yajl_t_false = 6,
yajl_t_null = 7,
/** The any type isn't valid for yajl_val_s.type, but can be
* used as an argument to routines like yajl_tree_get().
*/
yajl_t_any = 8
} yajl_type;
#define YAJL_NUMBER_INT_VALID 0x01
#define YAJL_NUMBER_DOUBLE_VALID 0x02
/** A pointer to a node in the parse tree */
typedef struct yajl_val_s * yajl_val;
/**
* A JSON value representation capable of holding one of the seven
* types above. For "string", "number", "object", and "array"
* additional data is available in the union. The "YAJL_IS_*"
* and "YAJL_GET_*" macros below allow type checking and convenient
* value extraction.
*/
struct yajl_val_s
{
/** Type of the value contained. Use the "YAJL_IS_*" macros to check for a
* specific type. */
yajl_type type;
/** Type-specific data. You may use the "YAJL_GET_*" macros to access these
* members. */
union
{
char * string;
struct {
long long i; /*< integer value, if representable. */
double d; /*< double value, if representable. */
char *r; /*< unparsed number in string form. */
/** Signals whether the \em i and \em d members are
* valid. See \c YAJL_NUMBER_INT_VALID and
* \c YAJL_NUMBER_DOUBLE_VALID. */
unsigned int flags;
} number;
struct {
const char **keys; /*< Array of keys */
yajl_val *values; /*< Array of values. */
size_t len; /*< Number of key-value-pairs. */
} object;
struct {
yajl_val *values; /*< Array of elements. */
size_t len; /*< Number of elements. */
} array;
} u;
};
/**
* Parse a string.
*
* Parses an null-terminated string containing JSON data and returns a pointer
* to the top-level value (root of the parse tree).
*
* \param input Pointer to a null-terminated utf8 string containing
* JSON data.
* \param error_buffer Pointer to a buffer in which an error message will
* be stored if \em yajl_tree_parse fails, or
* \c NULL. The buffer will be initialized before
* parsing, so its content will be destroyed even if
* \em yajl_tree_parse succeeds.
* \param error_buffer_size Size of the memory area pointed to by
* \em error_buffer_size. If \em error_buffer_size is
* \c NULL, this argument is ignored.
*
* \returns Pointer to the top-level value or \c NULL on error. The memory
* pointed to must be freed using \em yajl_tree_free. In case of an error, a
* null terminated message describing the error in more detail is stored in
* \em error_buffer if it is not \c NULL.
*/
YAJL_API yajl_val yajl_tree_parse (const char *input,
char *error_buffer, size_t error_buffer_size);
/**
* Free a parse tree returned by "yajl_tree_parse".
*
* \param v Pointer to a JSON value returned by "yajl_tree_parse". Passing NULL
* is valid and results in a no-op.
*/
YAJL_API void yajl_tree_free (yajl_val v);
/**
* Access a nested value inside a tree.
*
* \param parent the node under which you'd like to extract values.
* \param path A null terminated array of strings, each the name of an object key
* \param type the yajl_type of the object you seek, or yajl_t_any if any will do.
*
* \returns a pointer to the found value, or NULL if we came up empty.
*
* Future Ideas: it'd be nice to move path to a string and implement support for
* a teeny tiny micro language here, so you can extract array elements, do things
* like .first and .last, even .length. Inspiration from JSONPath and css selectors?
* No it wouldn't be fast, but that's not what this API is about.
*/
YAJL_API yajl_val yajl_tree_get(yajl_val parent, const char ** path, yajl_type type);
/* Various convenience macros to check the type of a `yajl_val` */
#define YAJL_IS_STRING(v) (((v) != NULL) && ((v)->type == yajl_t_string))
#define YAJL_IS_NUMBER(v) (((v) != NULL) && ((v)->type == yajl_t_number))
#define YAJL_IS_INTEGER(v) (YAJL_IS_NUMBER(v) && ((v)->u.number.flags & YAJL_NUMBER_INT_VALID))
#define YAJL_IS_DOUBLE(v) (YAJL_IS_NUMBER(v) && ((v)->u.number.flags & YAJL_NUMBER_DOUBLE_VALID))
#define YAJL_IS_OBJECT(v) (((v) != NULL) && ((v)->type == yajl_t_object))
#define YAJL_IS_ARRAY(v) (((v) != NULL) && ((v)->type == yajl_t_array ))
#define YAJL_IS_TRUE(v) (((v) != NULL) && ((v)->type == yajl_t_true ))
#define YAJL_IS_FALSE(v) (((v) != NULL) && ((v)->type == yajl_t_false ))
#define YAJL_IS_NULL(v) (((v) != NULL) && ((v)->type == yajl_t_null ))
/** Given a yajl_val_string return a ptr to the bare string it contains,
* or NULL if the value is not a string. */
#define YAJL_GET_STRING(v) (YAJL_IS_STRING(v) ? (v)->u.string : NULL)
/** Get the string representation of a number. You should check type first,
* perhaps using YAJL_IS_NUMBER */
#define YAJL_GET_NUMBER(v) ((v)->u.number.r)
/** Get the double representation of a number. You should check type first,
* perhaps using YAJL_IS_DOUBLE */
#define YAJL_GET_DOUBLE(v) ((v)->u.number.d)
/** Get the 64bit (long long) integer representation of a number. You should
* check type first, perhaps using YAJL_IS_INTEGER */
#define YAJL_GET_INTEGER(v) ((v)->u.number.i)
/** Get a pointer to a yajl_val_object or NULL if the value is not an object. */
#define YAJL_GET_OBJECT(v) (YAJL_IS_OBJECT(v) ? &(v)->u.object : NULL)
/** Get a pointer to a yajl_val_array or NULL if the value is not an object. */
#define YAJL_GET_ARRAY(v) (YAJL_IS_ARRAY(v) ? &(v)->u.array : NULL)
#ifdef __cplusplus
}
#endif
#endif /* YAJL_TREE_H */