YAJL  2.1.0
Data Structures | Typedefs | Enumerations | Functions
yajl_parse.h File Reference
#include <yajl/yajl_common.h>
#include <stddef.h>

Go to the source code of this file.

Data Structures

struct  yajl_callbacks
 

Typedefs

typedef struct yajl_handle_t * yajl_handle
 

Enumerations

enum  yajl_status { yajl_status_ok, yajl_status_client_canceled, yajl_status_error }
 
enum  yajl_option {
  yajl_allow_comments = 0x01, yajl_dont_validate_strings = 0x02, yajl_allow_trailing_garbage = 0x04, yajl_allow_multiple_values = 0x08,
  yajl_allow_partial_values = 0x10
}
 

Functions

YAJL_API const char * yajl_status_to_string (yajl_status code)
 
YAJL_API yajl_handle yajl_alloc (const yajl_callbacks *callbacks, yajl_alloc_funcs *afs, void *ctx)
 
YAJL_API int yajl_config (yajl_handle h, yajl_option opt,...)
 
YAJL_API void yajl_free (yajl_handle handle)
 
YAJL_API yajl_status yajl_parse (yajl_handle hand, const unsigned char *jsonText, size_t jsonTextLength)
 
YAJL_API yajl_status yajl_complete_parse (yajl_handle hand)
 
YAJL_API unsigned char * yajl_get_error (yajl_handle hand, int verbose, const unsigned char *jsonText, size_t jsonTextLength)
 
YAJL_API size_t yajl_get_bytes_consumed (yajl_handle hand)
 
YAJL_API void yajl_free_error (yajl_handle hand, unsigned char *str)
 

Detailed Description

Interface to YAJL's JSON stream parsing facilities.

Typedef Documentation

typedef struct yajl_handle_t* yajl_handle

an opaque handle to a parser

Enumeration Type Documentation

configuration parameters for the parser, these may be passed to yajl_config() along with option specific argument(s). In general, all configuration parameters default to off.

Enumerator
yajl_allow_comments 

Ignore javascript style comments present in JSON input. Non-standard, but rather fun arguments: toggled off with integer zero, on otherwise.

example: yajl_config(h, yajl_allow_comments, 1); // turn comment support on

yajl_dont_validate_strings 

When set the parser will verify that all strings in JSON input are valid UTF8 and will emit a parse error if this is not so. When set, this option makes parsing slightly more expensive (~7% depending on processor and compiler in use)

example: yajl_config(h, yajl_dont_validate_strings, 1); // disable utf8 checking

yajl_allow_trailing_garbage 

By default, upon calls to yajl_complete_parse(), yajl will ensure the entire input text was consumed and will raise an error otherwise. Enabling this flag will cause yajl to disable this check. This can be useful when parsing json out of a that contains more than a single JSON document.

yajl_allow_multiple_values 

Allow multiple values to be parsed by a single handle. The entire text must be valid JSON, and values can be seperated by any kind of whitespace. This flag will change the behavior of the parser, and cause it continue parsing after a value is parsed, rather than transitioning into a complete state. This option can be useful when parsing multiple values from an input stream.

yajl_allow_partial_values 

When yajl_complete_parse() is called the parser will check that the top level value was completely consumed. I.E., if called whilst in the middle of parsing a value yajl will enter an error state (premature EOF). Setting this flag suppresses that check and the corresponding error.

error codes returned from this interface

Enumerator
yajl_status_ok 

no error was encountered

yajl_status_client_canceled 

a client callback returned zero, stopping the parse

yajl_status_error 

An error occured during the parse. Call yajl_get_error for more information about the encountered error

Function Documentation

YAJL_API yajl_handle yajl_alloc ( const yajl_callbacks callbacks,
yajl_alloc_funcs afs,
void *  ctx 
)

allocate a parser handle

Parameters
callbacksa yajl callbacks structure specifying the functions to call when different JSON entities are encountered in the input text. May be NULL, which is only useful for validation.
afsmemory allocation functions, may be NULL for to use C runtime library routines (malloc and friends)
ctxa context pointer that will be passed to callbacks.
Examples:
reformatter/json_reformat.c.
YAJL_API yajl_status yajl_complete_parse ( yajl_handle  hand)

Parse any remaining buffered json. Since yajl is a stream-based parser, without an explicit end of input, yajl sometimes can't decide if content at the end of the stream is valid or not. For example, if "1" has been fed in, yajl can't know whether another digit is next or some character that would terminate the integer token.

Parameters
hand- a handle to the json parser allocated with yajl_alloc
Examples:
reformatter/json_reformat.c.
YAJL_API int yajl_config ( yajl_handle  h,
yajl_option  opt,
  ... 
)

allow the modification of parser options subsequent to handle allocation (via yajl_alloc)

Returns
zero in case of errors, non-zero otherwise
Examples:
reformatter/json_reformat.c.
YAJL_API void yajl_free ( yajl_handle  handle)

free a parser handle

Examples:
reformatter/json_reformat.c.
YAJL_API void yajl_free_error ( yajl_handle  hand,
unsigned char *  str 
)

free an error returned from yajl_get_error

Examples:
reformatter/json_reformat.c.
YAJL_API size_t yajl_get_bytes_consumed ( yajl_handle  hand)

get the amount of data consumed from the last chunk passed to YAJL.

In the case of a successful parse this can help you understand if the entire buffer was consumed (which will allow you to handle "junk at end of input").

In the event an error is encountered during parsing, this function affords the client a way to get the offset into the most recent chunk where the error occured. 0 will be returned if no error was encountered.

YAJL_API unsigned char* yajl_get_error ( yajl_handle  hand,
int  verbose,
const unsigned char *  jsonText,
size_t  jsonTextLength 
)

get an error string describing the state of the parse.

If verbose is non-zero, the message will include the JSON text where the error occured, along with an arrow pointing to the specific char.

Returns
A dynamically allocated string will be returned which should be freed with yajl_free_error
Examples:
reformatter/json_reformat.c.
YAJL_API yajl_status yajl_parse ( yajl_handle  hand,
const unsigned char *  jsonText,
size_t  jsonTextLength 
)

Parse some json!

Parameters
hand- a handle to the json parser allocated with yajl_alloc
jsonText- a pointer to the UTF8 json text to be parsed
jsonTextLength- the length, in bytes, of input text
Examples:
reformatter/json_reformat.c.
YAJL_API const char* yajl_status_to_string ( yajl_status  code)

attain a human readable, english, string for an error