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/*-------------------------------------------------------------------------
*
* jsonapi.h
* Declarations for JSON API support.
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/utils/jsonapi.h
*
*-------------------------------------------------------------------------
*/
#ifndef JSONAPI_H
#define JSONAPI_H
#include "lib/stringinfo.h"
typedef enum
{
JSON_TOKEN_INVALID,
JSON_TOKEN_STRING,
JSON_TOKEN_NUMBER,
JSON_TOKEN_OBJECT_START,
JSON_TOKEN_OBJECT_END,
JSON_TOKEN_ARRAY_START,
JSON_TOKEN_ARRAY_END,
JSON_TOKEN_COMMA,
JSON_TOKEN_COLON,
JSON_TOKEN_TRUE,
JSON_TOKEN_FALSE,
JSON_TOKEN_NULL,
JSON_TOKEN_END
} JsonTokenType;
/*
* All the fields in this structure should be treated as read-only.
*
* If strval is not null, then it should contain the de-escaped value
* of the lexeme if it's a string. Otherwise most of these field names
* should be self-explanatory.
*
* line_number and line_start are principally for use by the parser's
* error reporting routines.
* token_terminator and prev_token_terminator point to the character
* AFTER the end of the token, i.e. where there would be a nul byte
* if we were using nul-terminated strings.
*/
typedef struct JsonLexContext
{
char *input;
int input_length;
char *token_start;
char *token_terminator;
char *prev_token_terminator;
JsonTokenType token_type;
int lex_level;
int line_number;
char *line_start;
StringInfo strval;
} JsonLexContext;
typedef void (*json_struct_action) (void *state);
typedef void (*json_ofield_action) (void *state, char *fname, bool isnull);
typedef void (*json_aelem_action) (void *state, bool isnull);
typedef void (*json_scalar_action) (void *state, char *token, JsonTokenType tokentype);
/*
* Semantic Action structure for use in parsing json.
* Any of these actions can be NULL, in which case nothing is done at that
* point, Likewise, semstate can be NULL. Using an all-NULL structure amounts
* to doing a pure parse with no side-effects, and is therefore exactly
* what the json input routines do.
*
* The 'fname' and 'token' strings passed to these actions are palloc'd.
* They are not free'd or used further by the parser, so the action function
* is free to do what it wishes with them.
*/
typedef struct JsonSemAction
{
void *semstate;
json_struct_action object_start;
json_struct_action object_end;
json_struct_action array_start;
json_struct_action array_end;
json_ofield_action object_field_start;
json_ofield_action object_field_end;
json_aelem_action array_element_start;
json_aelem_action array_element_end;
json_scalar_action scalar;
} JsonSemAction;
/*
* parse_json will parse the string in the lex calling the
* action functions in sem at the appropriate points. It is
* up to them to keep what state they need in semstate. If they
* need access to the state of the lexer, then its pointer
* should be passed to them as a member of whatever semstate
* points to. If the action pointers are NULL the parser
* does nothing and just continues.
*/
extern void pg_parse_json(JsonLexContext *lex, JsonSemAction *sem);
/*
* json_count_array_elements performs a fast secondary parse to determine the
* number of elements in passed array lex context. It should be called from an
* array_start action.
*/
extern int json_count_array_elements(JsonLexContext *lex);
/*
* constructors for JsonLexContext, with or without strval element.
* If supplied, the strval element will contain a de-escaped version of
* the lexeme. However, doing this imposes a performance penalty, so
* it should be avoided if the de-escaped lexeme is not required.
*
* If you already have the json as a text* value, use the first of these
* functions, otherwise use makeJsonLexContextCstringLen().
*/
extern JsonLexContext *makeJsonLexContext(text *json, bool need_escapes);
extern JsonLexContext *makeJsonLexContextCstringLen(char *json,
int len,
bool need_escapes);
/*
* Utility function to check if a string is a valid JSON number.
*
* str agrument does not need to be nul-terminated.
*/
extern bool IsValidJsonNumber(const char *str, int len);
#endif /* JSONAPI_H */
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