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/*-------------------------------------------------------------------------
*
* jsonapi.h
* Declarations for JSON API support.
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/common/jsonapi.h
*
*-------------------------------------------------------------------------
*/
#ifndef JSONAPI_H
#define JSONAPI_H
#include "lib/stringinfo.h"
typedef enum JsonTokenType
{
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;
typedef enum JsonParseErrorType
{
JSON_SUCCESS,
JSON_ESCAPING_INVALID,
JSON_ESCAPING_REQUIRED,
JSON_EXPECTED_ARRAY_FIRST,
JSON_EXPECTED_ARRAY_NEXT,
JSON_EXPECTED_COLON,
JSON_EXPECTED_END,
JSON_EXPECTED_JSON,
JSON_EXPECTED_MORE,
JSON_EXPECTED_OBJECT_FIRST,
JSON_EXPECTED_OBJECT_NEXT,
JSON_EXPECTED_STRING,
JSON_INVALID_TOKEN,
JSON_UNICODE_CODE_POINT_ZERO,
JSON_UNICODE_ESCAPE_FORMAT,
JSON_UNICODE_HIGH_ESCAPE,
JSON_UNICODE_UNTRANSLATABLE,
JSON_UNICODE_HIGH_SURROGATE,
JSON_UNICODE_LOW_SURROGATE,
JSON_SEM_ACTION_FAILED /* error should already be reported */
} JsonParseErrorType;
/*
* 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;
int input_encoding;
char *token_start;
char *token_terminator;
char *prev_token_terminator;
JsonTokenType token_type;
int lex_level;
int line_number; /* line number, starting from 1 */
char *line_start; /* where that line starts within input */
StringInfo strval;
} JsonLexContext;
typedef JsonParseErrorType (*json_struct_action) (void *state);
typedef JsonParseErrorType (*json_ofield_action) (void *state, char *fname, bool isnull);
typedef JsonParseErrorType (*json_aelem_action) (void *state, bool isnull);
typedef JsonParseErrorType (*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.
*
* All action functions return JsonParseErrorType. If the result isn't
* JSON_SUCCESS, the parse is abandoned and that error code is returned.
* If it is JSON_SEM_ACTION_FAILED, the action function is responsible
* for having reported the error in some appropriate way.
*/
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;
/*
* pg_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 JsonParseErrorType pg_parse_json(JsonLexContext *lex,
JsonSemAction *sem);
/* the null action object used for pure validation */
extern PGDLLIMPORT JsonSemAction nullSemAction;
/*
* 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.
*
* The return value indicates whether any error occurred, while the number
* of elements is stored into *elements (but only if the return value is
* JSON_SUCCESS).
*/
extern JsonParseErrorType json_count_array_elements(JsonLexContext *lex,
int *elements);
/*
* constructor 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.
*/
extern JsonLexContext *makeJsonLexContextCstringLen(char *json,
int len,
int encoding,
bool need_escapes);
/* lex one token */
extern JsonParseErrorType json_lex(JsonLexContext *lex);
/* construct an error detail string for a json error */
extern char *json_errdetail(JsonParseErrorType error, JsonLexContext *lex);
/*
* Utility function to check if a string is a valid JSON number.
*
* str argument does not need to be nul-terminated.
*/
extern bool IsValidJsonNumber(const char *str, int len);
#endif /* JSONAPI_H */