135 lines
4.2 KiB
C
135 lines
4.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* jsonapi.h
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* Declarations for JSON API support.
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*
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* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/utils/jsonapi.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef JSONAPI_H
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#define JSONAPI_H
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#include "lib/stringinfo.h"
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typedef enum
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{
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JSON_TOKEN_INVALID,
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JSON_TOKEN_STRING,
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JSON_TOKEN_NUMBER,
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JSON_TOKEN_OBJECT_START,
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JSON_TOKEN_OBJECT_END,
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JSON_TOKEN_ARRAY_START,
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JSON_TOKEN_ARRAY_END,
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JSON_TOKEN_COMMA,
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JSON_TOKEN_COLON,
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JSON_TOKEN_TRUE,
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JSON_TOKEN_FALSE,
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JSON_TOKEN_NULL,
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JSON_TOKEN_END
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} JsonTokenType;
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/*
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* All the fields in this structure should be treated as read-only.
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*
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* If strval is not null, then it should contain the de-escaped value
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* of the lexeme if it's a string. Otherwise most of these field names
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* should be self-explanatory.
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*
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* line_number and line_start are principally for use by the parser's
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* error reporting routines.
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* token_terminator and prev_token_terminator point to the character
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* AFTER the end of the token, i.e. where there would be a nul byte
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* if we were using nul-terminated strings.
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*/
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typedef struct JsonLexContext
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{
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char *input;
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int input_length;
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char *token_start;
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char *token_terminator;
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char *prev_token_terminator;
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JsonTokenType token_type;
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int lex_level;
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int line_number;
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char *line_start;
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StringInfo strval;
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} JsonLexContext;
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typedef void (*json_struct_action) (void *state);
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typedef void (*json_ofield_action) (void *state, char *fname, bool isnull);
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typedef void (*json_aelem_action) (void *state, bool isnull);
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typedef void (*json_scalar_action) (void *state, char *token, JsonTokenType tokentype);
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/*
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* Semantic Action structure for use in parsing json.
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* Any of these actions can be NULL, in which case nothing is done at that
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* point, Likewise, semstate can be NULL. Using an all-NULL structure amounts
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* to doing a pure parse with no side-effects, and is therefore exactly
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* what the json input routines do.
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*
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* The 'fname' and 'token' strings passed to these actions are palloc'd.
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* They are not free'd or used further by the parser, so the action function
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* is free to do what it wishes with them.
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*/
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typedef struct JsonSemAction
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{
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void *semstate;
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json_struct_action object_start;
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json_struct_action object_end;
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json_struct_action array_start;
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json_struct_action array_end;
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json_ofield_action object_field_start;
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json_ofield_action object_field_end;
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json_aelem_action array_element_start;
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json_aelem_action array_element_end;
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json_scalar_action scalar;
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} JsonSemAction;
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/*
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* parse_json will parse the string in the lex calling the
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* action functions in sem at the appropriate points. It is
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* up to them to keep what state they need in semstate. If they
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* need access to the state of the lexer, then its pointer
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* should be passed to them as a member of whatever semstate
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* points to. If the action pointers are NULL the parser
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* does nothing and just continues.
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*/
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extern void pg_parse_json(JsonLexContext *lex, JsonSemAction *sem);
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/*
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* json_count_array_elements performs a fast secondary parse to determine the
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* number of elements in passed array lex context. It should be called from an
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* array_start action.
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*/
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extern int json_count_array_elements(JsonLexContext *lex);
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/*
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* constructors for JsonLexContext, with or without strval element.
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* If supplied, the strval element will contain a de-escaped version of
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* the lexeme. However, doing this imposes a performance penalty, so
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* it should be avoided if the de-escaped lexeme is not required.
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*
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* If you already have the json as a text* value, use the first of these
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* functions, otherwise use makeJsonLexContextCstringLen().
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*/
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extern JsonLexContext *makeJsonLexContext(text *json, bool need_escapes);
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extern JsonLexContext *makeJsonLexContextCstringLen(char *json,
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int len,
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bool need_escapes);
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/*
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* Utility function to check if a string is a valid JSON number.
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*
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* str argument does not need to be nul-terminated.
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*/
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extern bool IsValidJsonNumber(const char *str, int len);
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#endif /* JSONAPI_H */
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