text: /*-------------------------------------------------------------------------
   *
   * json.c
   *		JSON data type support.
   *
   * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   * IDENTIFICATION
   *	  src/backend/utils/adt/json.c
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include "access/htup_details.h"
  #include "access/transam.h"
  #include "catalog/pg_type.h"
  #include "executor/spi.h"
  #include "funcapi.h"
  #include "lib/stringinfo.h"
  #include "libpq/pqformat.h"
  #include "mb/pg_wchar.h"
  #include "miscadmin.h"
  #include "parser/parse_coerce.h"
  #include "utils/array.h"
  #include "utils/builtins.h"
  #include "utils/date.h"
  #include "utils/datetime.h"
  #include "utils/lsyscache.h"
  #include "utils/json.h"
  #include "utils/jsonapi.h"
  #include "utils/typcache.h"
  #include "utils/syscache.h"
  
  /*
   * The context of the parser is maintained by the recursive descent
   * mechanism, but is passed explicitly to the error reporting routine
   * for better diagnostics.
   */
  typedef enum					/* contexts of JSON parser */
  {
  	JSON_PARSE_VALUE,			/* expecting a value */
  	JSON_PARSE_STRING,			/* expecting a string (for a field name) */
  	JSON_PARSE_ARRAY_START,		/* saw '[', expecting value or ']' */
  	JSON_PARSE_ARRAY_NEXT,		/* saw array element, expecting ',' or ']' */
  	JSON_PARSE_OBJECT_START,	/* saw '{', expecting label or '}' */
  	JSON_PARSE_OBJECT_LABEL,	/* saw object label, expecting ':' */
  	JSON_PARSE_OBJECT_NEXT,		/* saw object value, expecting ',' or '}' */
  	JSON_PARSE_OBJECT_COMMA,	/* saw object ',', expecting next label */
  	JSON_PARSE_END				/* saw the end of a document, expect nothing */
  } JsonParseContext;
  
  typedef enum					/* type categories for datum_to_json */
  {
  	JSONTYPE_NULL,				/* null, so we didn't bother to identify */
  	JSONTYPE_BOOL,				/* boolean (built-in types only) */
  	JSONTYPE_NUMERIC,			/* numeric (ditto) */
  	JSONTYPE_DATE,				/* we use special formatting for datetimes */
  	JSONTYPE_TIMESTAMP,
  	JSONTYPE_TIMESTAMPTZ,
  	JSONTYPE_JSON,				/* JSON itself (and JSONB) */
  	JSONTYPE_ARRAY,				/* array */
  	JSONTYPE_COMPOSITE,			/* composite */
  	JSONTYPE_CAST,				/* something with an explicit cast to JSON */
  	JSONTYPE_OTHER				/* all else */
  } JsonTypeCategory;
  
  typedef struct JsonAggState
  {
  	StringInfo	str;
  	JsonTypeCategory key_category;
  	Oid			key_output_func;
  	JsonTypeCategory val_category;
  	Oid			val_output_func;
  } JsonAggState;
  
  static inline void json_lex(JsonLexContext *lex);
  static inline void json_lex_string(JsonLexContext *lex);
  static inline void json_lex_number(JsonLexContext *lex, char *s,
  								   bool *num_err, int *total_len);
  static inline void parse_scalar(JsonLexContext *lex, JsonSemAction *sem);
  static void parse_object_field(JsonLexContext *lex, JsonSemAction *sem);
  static void parse_object(JsonLexContext *lex, JsonSemAction *sem);
  static void parse_array_element(JsonLexContext *lex, JsonSemAction *sem);
  static void parse_array(JsonLexContext *lex, JsonSemAction *sem);
  static void report_parse_error(JsonParseContext ctx, JsonLexContext *lex) pg_attribute_noreturn();
  static void report_invalid_token(JsonLexContext *lex) pg_attribute_noreturn();
  static int	report_json_context(JsonLexContext *lex);
  static char *extract_mb_char(char *s);
  static void composite_to_json(Datum composite, StringInfo result,
  							  bool use_line_feeds);
  static void array_dim_to_json(StringInfo result, int dim, int ndims, int *dims,
  							  Datum *vals, bool *nulls, int *valcount,
  							  JsonTypeCategory tcategory, Oid outfuncoid,
  							  bool use_line_feeds);
  static void array_to_json_internal(Datum array, StringInfo result,
  								   bool use_line_feeds);
  static void json_categorize_type(Oid typoid,
  								 JsonTypeCategory *tcategory,
  								 Oid *outfuncoid);
  static void datum_to_json(Datum val, bool is_null, StringInfo result,
  						  JsonTypeCategory tcategory, Oid outfuncoid,
  						  bool key_scalar);
  static void add_json(Datum val, bool is_null, StringInfo result,
  					 Oid val_type, bool key_scalar);
  static text *catenate_stringinfo_string(StringInfo buffer, const char *addon);
  
  /* the null action object used for pure validation */
  static JsonSemAction nullSemAction =
  {
  	NULL, NULL, NULL, NULL, NULL,
  	NULL, NULL, NULL, NULL, NULL
  };
  
  /* Recursive Descent parser support routines */
  
  /*
   * lex_peek
   *
   * what is the current look_ahead token?
  */
  static inline JsonTokenType
  lex_peek(JsonLexContext *lex)
  {
  	return lex->token_type;
  }
  
  /*
   * lex_accept
   *
   * accept the look_ahead token and move the lexer to the next token if the
   * look_ahead token matches the token parameter. In that case, and if required,
   * also hand back the de-escaped lexeme.
   *
   * returns true if the token matched, false otherwise.
   */
  static inline bool
  lex_accept(JsonLexContext *lex, JsonTokenType token, char **lexeme)
  {
  	if (lex->token_type == token)
  	{
  		if (lexeme != NULL)
  		{
  			if (lex->token_type == JSON_TOKEN_STRING)
  			{
  				if (lex->strval != NULL)
  					*lexeme = pstrdup(lex->strval->data);
  			}
  			else
  			{
  				int			len = (lex->token_terminator - lex->token_start);
  				char	   *tokstr = palloc(len + 1);
  
  				memcpy(tokstr, lex->token_start, len);
  				tokstr[len] = '\0';
  				*lexeme = tokstr;
  			}
  		}
  		json_lex(lex);
  		return true;
  	}
  	return false;
  }
  
  /*
   * lex_accept
   *
   * move the lexer to the next token if the current look_ahead token matches
   * the parameter token. Otherwise, report an error.
   */
  static inline void
  lex_expect(JsonParseContext ctx, JsonLexContext *lex, JsonTokenType token)
  {
  	if (!lex_accept(lex, token, NULL))
  		report_parse_error(ctx, lex);
  }
  
  /* chars to consider as part of an alphanumeric token */
  #define JSON_ALPHANUMERIC_CHAR(c)  \
  	(((c) >= 'a' && (c) <= 'z') || \
  	 ((c) >= 'A' && (c) <= 'Z') || \
  	 ((c) >= '0' && (c) <= '9') || \
  	 (c) == '_' || \
  	 IS_HIGHBIT_SET(c))
  
  /*
   * Utility function to check if a string is a valid JSON number.
   *
   * str is of length len, and need not be null-terminated.
   */
  bool
  IsValidJsonNumber(const char *str, int len)
  {
  	bool		numeric_error;
  	int			total_len;
  	JsonLexContext dummy_lex;
  
  	if (len <= 0)
  		return false;
  
  	/*
  	 * json_lex_number expects a leading  '-' to have been eaten already.
  	 *
  	 * having to cast away the constness of str is ugly, but there's not much
  	 * easy alternative.
  	 */
  	if (*str == '-')
  	{
  		dummy_lex.input = unconstify(char *, str) +1;
  		dummy_lex.input_length = len - 1;
  	}
  	else
  	{
  		dummy_lex.input = unconstify(char *, str);
  		dummy_lex.input_length = len;
  	}
  
  	json_lex_number(&dummy_lex, dummy_lex.input, &numeric_error, &total_len);
  
  	return (!numeric_error) && (total_len == dummy_lex.input_length);
  }
  
  /*
   * Input.
   */
  Datum
  json_in(PG_FUNCTION_ARGS)
  {
  	char	   *json = PG_GETARG_CSTRING(0);
  	text	   *result = cstring_to_text(json);
  	JsonLexContext *lex;
  
  	/* validate it */
  	lex = makeJsonLexContext(result, false);
  	pg_parse_json(lex, &nullSemAction);
  
  	/* Internal representation is the same as text, for now */
  	PG_RETURN_TEXT_P(result);
  }
  
  /*
   * Output.
   */
  Datum
  json_out(PG_FUNCTION_ARGS)
  {
  	/* we needn't detoast because text_to_cstring will handle that */
  	Datum		txt = PG_GETARG_DATUM(0);
  
  	PG_RETURN_CSTRING(TextDatumGetCString(txt));
  }
  
  /*
   * Binary send.
   */
  Datum
  json_send(PG_FUNCTION_ARGS)
  {
  	text	   *t = PG_GETARG_TEXT_PP(0);
  	StringInfoData buf;
  
  	pq_begintypsend(&buf);
  	pq_sendtext(&buf, VARDATA_ANY(t), VARSIZE_ANY_EXHDR(t));
  	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
  }
  
  /*
   * Binary receive.
   */
  Datum
  json_recv(PG_FUNCTION_ARGS)
  {
  	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);
  	char	   *str;
  	int			nbytes;
  	JsonLexContext *lex;
  
  	str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
  
  	/* Validate it. */
  	lex = makeJsonLexContextCstringLen(str, nbytes, false);
  	pg_parse_json(lex, &nullSemAction);
  
  	PG_RETURN_TEXT_P(cstring_to_text_with_len(str, nbytes));
  }
  
  /*
   * makeJsonLexContext
   *
   * lex constructor, with or without StringInfo object
   * for de-escaped lexemes.
   *
   * Without is better as it makes the processing faster, so only make one
   * if really required.
   *
   * If you already have the json as a text* value, use the first of these
   * functions, otherwise use  makeJsonLexContextCstringLen().
   */
  JsonLexContext *
  makeJsonLexContext(text *json, bool need_escapes)
  {
  	return makeJsonLexContextCstringLen(VARDATA_ANY(json),
  										VARSIZE_ANY_EXHDR(json),
  										need_escapes);
  }
  
  JsonLexContext *
  makeJsonLexContextCstringLen(char *json, int len, bool need_escapes)
  {
  	JsonLexContext *lex = palloc0(sizeof(JsonLexContext));
  
  	lex->input = lex->token_terminator = lex->line_start = json;
  	lex->line_number = 1;
  	lex->input_length = len;
  	if (need_escapes)
  		lex->strval = makeStringInfo();
  	return lex;
  }
  
  /*
   * pg_parse_json
   *
   * Publicly visible entry point for the JSON parser.
   *
   * lex is a lexing context, set up for the json to be processed by calling
   * makeJsonLexContext(). sem is a structure of function pointers to semantic
   * action routines to be called at appropriate spots during parsing, and a
   * pointer to a state object to be passed to those routines.
   */
  void
  pg_parse_json(JsonLexContext *lex, JsonSemAction *sem)
  {
  	JsonTokenType tok;
  
  	/* get the initial token */
  	json_lex(lex);
  
  	tok = lex_peek(lex);
  
  	/* parse by recursive descent */
  	switch (tok)
  	{
  		case JSON_TOKEN_OBJECT_START:
  			parse_object(lex, sem);
  			break;
  		case JSON_TOKEN_ARRAY_START:
  			parse_array(lex, sem);
  			break;
  		default:
  			parse_scalar(lex, sem); /* json can be a bare scalar */
  	}
  
  	lex_expect(JSON_PARSE_END, lex, JSON_TOKEN_END);
  
  }
  
  /*
   * json_count_array_elements
   *
   * Returns number of array elements in lex context at start of array token
   * until end of array token at same nesting level.
   *
   * Designed to be called from array_start routines.
   */
  int
  json_count_array_elements(JsonLexContext *lex)
  {
  	JsonLexContext copylex;
  	int			count;
  
  	/*
  	 * It's safe to do this with a shallow copy because the lexical routines
  	 * don't scribble on the input. They do scribble on the other pointers
  	 * etc, so doing this with a copy makes that safe.
  	 */
  	memcpy(&copylex, lex, sizeof(JsonLexContext));
  	copylex.strval = NULL;		/* not interested in values here */
  	copylex.lex_level++;
  
  	count = 0;
  	lex_expect(JSON_PARSE_ARRAY_START, &copylex, JSON_TOKEN_ARRAY_START);
  	if (lex_peek(&copylex) != JSON_TOKEN_ARRAY_END)
  	{
  		do
  		{
  			count++;
  			parse_array_element(&copylex, &nullSemAction);
  		}
  		while (lex_accept(&copylex, JSON_TOKEN_COMMA, NULL));
  	}
  	lex_expect(JSON_PARSE_ARRAY_NEXT, &copylex, JSON_TOKEN_ARRAY_END);
  
  	return count;
  }
  
  /*
   *	Recursive Descent parse routines. There is one for each structural
   *	element in a json document:
   *	  - scalar (string, number, true, false, null)
   *	  - array  ( [ ] )
   *	  - array element
   *	  - object ( { } )
   *	  - object field
   */
  static inline void
  parse_scalar(JsonLexContext *lex, JsonSemAction *sem)
  {
  	char	   *val = NULL;
  	json_scalar_action sfunc = sem->scalar;
  	char	  **valaddr;
  	JsonTokenType tok = lex_peek(lex);
  
  	valaddr = sfunc == NULL ? NULL : &val;
  
  	/* a scalar must be a string, a number, true, false, or null */
  	switch (tok)
  	{
  		case JSON_TOKEN_TRUE:
  			lex_accept(lex, JSON_TOKEN_TRUE, valaddr);
  			break;
  		case JSON_TOKEN_FALSE:
  			lex_accept(lex, JSON_TOKEN_FALSE, valaddr);
  			break;
  		case JSON_TOKEN_NULL:
  			lex_accept(lex, JSON_TOKEN_NULL, valaddr);
  			break;
  		case JSON_TOKEN_NUMBER:
  			lex_accept(lex, JSON_TOKEN_NUMBER, valaddr);
  			break;
  		case JSON_TOKEN_STRING:
  			lex_accept(lex, JSON_TOKEN_STRING, valaddr);
  			break;
  		default:
  			report_parse_error(JSON_PARSE_VALUE, lex);
  	}
  
  	if (sfunc != NULL)
  		(*sfunc) (sem->semstate, val, tok);
  }
  
  static void
  parse_object_field(JsonLexContext *lex, JsonSemAction *sem)
  {
  	/*
  	 * An object field is "fieldname" : value where value can be a scalar,
  	 * object or array.  Note: in user-facing docs and error messages, we
  	 * generally call a field name a "key".
  	 */
  
  	char	   *fname = NULL;	/* keep compiler quiet */
  	json_ofield_action ostart = sem->object_field_start;
  	json_ofield_action oend = sem->object_field_end;
  	bool		isnull;
  	char	  **fnameaddr = NULL;
  	JsonTokenType tok;
  
  	if (ostart != NULL || oend != NULL)
  		fnameaddr = &fname;
  
  	if (!lex_accept(lex, JSON_TOKEN_STRING, fnameaddr))
  		report_parse_error(JSON_PARSE_STRING, lex);
  
  	lex_expect(JSON_PARSE_OBJECT_LABEL, lex, JSON_TOKEN_COLON);
  
  	tok = lex_peek(lex);
  	isnull = tok == JSON_TOKEN_NULL;
  
  	if (ostart != NULL)
  		(*ostart) (sem->semstate, fname, isnull);
  
  	switch (tok)
  	{
  		case JSON_TOKEN_OBJECT_START:
  			parse_object(lex, sem);
  			break;
  		case JSON_TOKEN_ARRAY_START:
  			parse_array(lex, sem);
  			break;
  		default:
  			parse_scalar(lex, sem);
  	}
  
  	if (oend != NULL)
  		(*oend) (sem->semstate, fname, isnull);
  }
  
  static void
  parse_object(JsonLexContext *lex, JsonSemAction *sem)
  {
  	/*
  	 * an object is a possibly empty sequence of object fields, separated by
  	 * commas and surrounded by curly braces.
  	 */
  	json_struct_action ostart = sem->object_start;
  	json_struct_action oend = sem->object_end;
  	JsonTokenType tok;
  
  	check_stack_depth();
  
  	if (ostart != NULL)
  		(*ostart) (sem->semstate);
  
  	/*
  	 * Data inside an object is at a higher nesting level than the object
  	 * itself. Note that we increment this after we call the semantic routine
  	 * for the object start and restore it before we call the routine for the
  	 * object end.
  	 */
  	lex->lex_level++;
  
  	/* we know this will succeed, just clearing the token */
  	lex_expect(JSON_PARSE_OBJECT_START, lex, JSON_TOKEN_OBJECT_START);
  
  	tok = lex_peek(lex);
  	switch (tok)
  	{
  		case JSON_TOKEN_STRING:
  			parse_object_field(lex, sem);
  			while (lex_accept(lex, JSON_TOKEN_COMMA, NULL))
  				parse_object_field(lex, sem);
  			break;
  		case JSON_TOKEN_OBJECT_END:
  			break;
  		default:
  			/* case of an invalid initial token inside the object */
  			report_parse_error(JSON_PARSE_OBJECT_START, lex);
  	}
  
  	lex_expect(JSON_PARSE_OBJECT_NEXT, lex, JSON_TOKEN_OBJECT_END);
  
  	lex->lex_level--;
  
  	if (oend != NULL)
  		(*oend) (sem->semstate);
  }
  
  static void
  parse_array_element(JsonLexContext *lex, JsonSemAction *sem)
  {
  	json_aelem_action astart = sem->array_element_start;
  	json_aelem_action aend = sem->array_element_end;
  	JsonTokenType tok = lex_peek(lex);
  
  	bool		isnull;
  
  	isnull = tok == JSON_TOKEN_NULL;
  
  	if (astart != NULL)
  		(*astart) (sem->semstate, isnull);
  
  	/* an array element is any object, array or scalar */
  	switch (tok)
  	{
  		case JSON_TOKEN_OBJECT_START:
  			parse_object(lex, sem);
  			break;
  		case JSON_TOKEN_ARRAY_START:
  			parse_array(lex, sem);
  			break;
  		default:
  			parse_scalar(lex, sem);
  	}
  
  	if (aend != NULL)
  		(*aend) (sem->semstate, isnull);
  }
  
  static void
  parse_array(JsonLexContext *lex, JsonSemAction *sem)
  {
  	/*
  	 * an array is a possibly empty sequence of array elements, separated by
  	 * commas and surrounded by square brackets.
  	 */
  	json_struct_action astart = sem->array_start;
  	json_struct_action aend = sem->array_end;
  
  	check_stack_depth();
  
  	if (astart != NULL)
  		(*astart) (sem->semstate);
  
  	/*
  	 * Data inside an array is at a higher nesting level than the array
  	 * itself. Note that we increment this after we call the semantic routine
  	 * for the array start and restore it before we call the routine for the
  	 * array end.
  	 */
  	lex->lex_level++;
  
  	lex_expect(JSON_PARSE_ARRAY_START, lex, JSON_TOKEN_ARRAY_START);
  	if (lex_peek(lex) != JSON_TOKEN_ARRAY_END)
  	{
  
  		parse_array_element(lex, sem);
  
  		while (lex_accept(lex, JSON_TOKEN_COMMA, NULL))
  			parse_array_element(lex, sem);
  	}
  
  	lex_expect(JSON_PARSE_ARRAY_NEXT, lex, JSON_TOKEN_ARRAY_END);
  
  	lex->lex_level--;
  
  	if (aend != NULL)
  		(*aend) (sem->semstate);
  }
  
  /*
   * Lex one token from the input stream.
   */
  static inline void
  json_lex(JsonLexContext *lex)
  {
  	char	   *s;
  	int			len;
  
  	/* Skip leading whitespace. */
  	s = lex->token_terminator;
  	len = s - lex->input;
  	while (len < lex->input_length &&
  		   (*s == ' ' || *s == '\t' || *s == '\n' || *s == '\r'))
  	{
  		if (*s == '\n')
  			++lex->line_number;
  		++s;
  		++len;
  	}
  	lex->token_start = s;
  
  	/* Determine token type. */
  	if (len >= lex->input_length)
  	{
  		lex->token_start = NULL;
  		lex->prev_token_terminator = lex->token_terminator;
  		lex->token_terminator = s;
  		lex->token_type = JSON_TOKEN_END;
  	}
  	else
  		switch (*s)
  		{
  				/* Single-character token, some kind of punctuation mark. */
  			case '{':
  				lex->prev_token_terminator = lex->token_terminator;
  				lex->token_terminator = s + 1;
  				lex->token_type = JSON_TOKEN_OBJECT_START;
  				break;
  			case '}':
  				lex->prev_token_terminator = lex->token_terminator;
  				lex->token_terminator = s + 1;
  				lex->token_type = JSON_TOKEN_OBJECT_END;
  				break;
  			case '[':
  				lex->prev_token_terminator = lex->token_terminator;
  				lex->token_terminator = s + 1;
  				lex->token_type = JSON_TOKEN_ARRAY_START;
  				break;
  			case ']':
  				lex->prev_token_terminator = lex->token_terminator;
  				lex->token_terminator = s + 1;
  				lex->token_type = JSON_TOKEN_ARRAY_END;
  				break;
  			case ',':
  				lex->prev_token_terminator = lex->token_terminator;
  				lex->token_terminator = s + 1;
  				lex->token_type = JSON_TOKEN_COMMA;
  				break;
  			case ':':
  				lex->prev_token_terminator = lex->token_terminator;
  				lex->token_terminator = s + 1;
  				lex->token_type = JSON_TOKEN_COLON;
  				break;
  			case '"':
  				/* string */
  				json_lex_string(lex);
  				lex->token_type = JSON_TOKEN_STRING;
  				break;
  			case '-':
  				/* Negative number. */
  				json_lex_number(lex, s + 1, NULL, NULL);
  				lex->token_type = JSON_TOKEN_NUMBER;
  				break;
  			case '0':
  			case '1':
  			case '2':
  			case '3':
  			case '4':
  			case '5':
  			case '6':
  			case '7':
  			case '8':
  			case '9':
  				/* Positive number. */
  				json_lex_number(lex, s, NULL, NULL);
  				lex->token_type = JSON_TOKEN_NUMBER;
  				break;
  			default:
  				{
  					char	   *p;
  
  					/*
  					 * We're not dealing with a string, number, legal
  					 * punctuation mark, or end of string.  The only legal
  					 * tokens we might find here are true, false, and null,
  					 * but for error reporting purposes we scan until we see a
  					 * non-alphanumeric character.  That way, we can report
  					 * the whole word as an unexpected token, rather than just
  					 * some unintuitive prefix thereof.
  					 */
  					for (p = s; p - s < lex->input_length - len && JSON_ALPHANUMERIC_CHAR(*p); p++)
  						 /* skip */ ;
  
  					/*
  					 * We got some sort of unexpected punctuation or an
  					 * otherwise unexpected character, so just complain about
  					 * that one character.
  					 */
  					if (p == s)
  					{
  						lex->prev_token_terminator = lex->token_terminator;
  						lex->token_terminator = s + 1;
  						report_invalid_token(lex);
  					}
  
  					/*
  					 * We've got a real alphanumeric token here.  If it
  					 * happens to be true, false, or null, all is well.  If
  					 * not, error out.
  					 */
  					lex->prev_token_terminator = lex->token_terminator;
  					lex->token_terminator = p;
  					if (p - s == 4)
  					{
  						if (memcmp(s, "true", 4) == 0)
  							lex->token_type = JSON_TOKEN_TRUE;
  						else if (memcmp(s, "null", 4) == 0)
  							lex->token_type = JSON_TOKEN_NULL;
  						else
  							report_invalid_token(lex);
  					}
  					else if (p - s == 5 && memcmp(s, "false", 5) == 0)
  						lex->token_type = JSON_TOKEN_FALSE;
  					else
  						report_invalid_token(lex);
  
  				}
  		}						/* end of switch */
  }
  
  /*
   * The next token in the input stream is known to be a string; lex it.
   */
  static inline void
  json_lex_string(JsonLexContext *lex)
  {
  	char	   *s;
  	int			len;
  	int			hi_surrogate = -1;
  
  	if (lex->strval != NULL)
  		resetStringInfo(lex->strval);
  
  	Assert(lex->input_length > 0);
  	s = lex->token_start;
  	len = lex->token_start - lex->input;
  	for (;;)
  	{
  		s++;
  		len++;
  		/* Premature end of the string. */
  		if (len >= lex->input_length)
  		{
  			lex->token_terminator = s;
  			report_invalid_token(lex);
  		}
  		else if (*s == '"')
  			break;
  		else if ((unsigned char) *s < 32)
  		{
  			/* Per RFC4627, these characters MUST be escaped. */
  			/* Since *s isn't printable, exclude it from the context string */
  			lex->token_terminator = s;
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  					 errmsg("invalid input syntax for type %s", "json"),
  					 errdetail("Character with value 0x%02x must be escaped.",
  							   (unsigned char) *s),
  					 report_json_context(lex)));
  		}
  		else if (*s == '\\')
  		{
  			/* OK, we have an escape character. */
  			s++;
  			len++;
  			if (len >= lex->input_length)
  			{
  				lex->token_terminator = s;
  				report_invalid_token(lex);
  			}
  			else if (*s == 'u')
  			{
  				int			i;
  				int			ch = 0;
  
  				for (i = 1; i <= 4; i++)
  				{
  					s++;
  					len++;
  					if (len >= lex->input_length)
  					{
  						lex->token_terminator = s;
  						report_invalid_token(lex);
  					}
  					else if (*s >= '0' && *s <= '9')
  						ch = (ch * 16) + (*s - '0');
  					else if (*s >= 'a' && *s <= 'f')
  						ch = (ch * 16) + (*s - 'a') + 10;
  					else if (*s >= 'A' && *s <= 'F')
  						ch = (ch * 16) + (*s - 'A') + 10;
  					else
  					{
  						lex->token_terminator = s + pg_mblen(s);
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  								 errmsg("invalid input syntax for type %s",
  										"json"),
  								 errdetail("\"\\u\" must be followed by four hexadecimal digits."),
  								 report_json_context(lex)));
  					}
  				}
  				if (lex->strval != NULL)
  				{
  					char		utf8str[5];
  					int			utf8len;
  
  					if (ch >= 0xd800 && ch <= 0xdbff)
  					{
  						if (hi_surrogate != -1)
  							ereport(ERROR,
  									(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  									 errmsg("invalid input syntax for type %s",
  											"json"),
  									 errdetail("Unicode high surrogate must not follow a high surrogate."),
  									 report_json_context(lex)));
  						hi_surrogate = (ch & 0x3ff) << 10;
  						continue;
  					}
  					else if (ch >= 0xdc00 && ch <= 0xdfff)
  					{
  						if (hi_surrogate == -1)
  							ereport(ERROR,
  									(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  									 errmsg("invalid input syntax for type %s", "json"),
  									 errdetail("Unicode low surrogate must follow a high surrogate."),
  									 report_json_context(lex)));
  						ch = 0x10000 + hi_surrogate + (ch & 0x3ff);
  						hi_surrogate = -1;
  					}
  
  					if (hi_surrogate != -1)
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  								 errmsg("invalid input syntax for type %s", "json"),
  								 errdetail("Unicode low surrogate must follow a high surrogate."),
  								 report_json_context(lex)));
  
  					/*
  					 * For UTF8, replace the escape sequence by the actual
  					 * utf8 character in lex->strval. Do this also for other
  					 * encodings if the escape designates an ASCII character,
  					 * otherwise raise an error.
  					 */
  
  					if (ch == 0)
  					{
  						/* We can't allow this, since our TEXT type doesn't */
  						ereport(ERROR,
  								(errcode(ERRCODE_UNTRANSLATABLE_CHARACTER),
  								 errmsg("unsupported Unicode escape sequence"),
  								 errdetail("\\u0000 cannot be converted to text."),
  								 report_json_context(lex)));
  					}
  					else if (GetDatabaseEncoding() == PG_UTF8)
  					{
  						unicode_to_utf8(ch, (unsigned char *) utf8str);
  						utf8len = pg_utf_mblen((unsigned char *) utf8str);
  						appendBinaryStringInfo(lex->strval, utf8str, utf8len);
  					}
  					else if (ch <= 0x007f)
  					{
  						/*
  						 * This is the only way to designate things like a
  						 * form feed character in JSON, so it's useful in all
  						 * encodings.
  						 */
  						appendStringInfoChar(lex->strval, (char) ch);
  					}
  					else
  					{
  						ereport(ERROR,
  								(errcode(ERRCODE_UNTRANSLATABLE_CHARACTER),
  								 errmsg("unsupported Unicode escape sequence"),
  								 errdetail("Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8."),
  								 report_json_context(lex)));
  					}
  
  				}
  			}
  			else if (lex->strval != NULL)
  			{
  				if (hi_surrogate != -1)
  					ereport(ERROR,
  							(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  							 errmsg("invalid input syntax for type %s",
  									"json"),
  							 errdetail("Unicode low surrogate must follow a high surrogate."),
  							 report_json_context(lex)));
  
  				switch (*s)
  				{
  					case '"':
  					case '\\':
  					case '/':
  						appendStringInfoChar(lex->strval, *s);
  						break;
  					case 'b':
  						appendStringInfoChar(lex->strval, '\b');
  						break;
  					case 'f':
  						appendStringInfoChar(lex->strval, '\f');
  						break;
  					case 'n':
  						appendStringInfoChar(lex->strval, '\n');
  						break;
  					case 'r':
  						appendStringInfoChar(lex->strval, '\r');
  						break;
  					case 't':
  						appendStringInfoChar(lex->strval, '\t');
  						break;
  					default:
  						/* Not a valid string escape, so error out. */
  						lex->token_terminator = s + pg_mblen(s);
  						ereport(ERROR,
  								(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  								 errmsg("invalid input syntax for type %s",
  										"json"),
  								 errdetail("Escape sequence \"\\%s\" is invalid.",
  										   extract_mb_char(s)),
  								 report_json_context(lex)));
  				}
  			}
  			else if (strchr("\"\\/bfnrt", *s) == NULL)
  			{
  				/*
  				 * Simpler processing if we're not bothered about de-escaping
  				 *
  				 * It's very tempting to remove the strchr() call here and
  				 * replace it with a switch statement, but testing so far has
  				 * shown it's not a performance win.
  				 */
  				lex->token_terminator = s + pg_mblen(s);
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  						 errmsg("invalid input syntax for type %s", "json"),
  						 errdetail("Escape sequence \"\\%s\" is invalid.",
  								   extract_mb_char(s)),
  						 report_json_context(lex)));
  			}
  
  		}
  		else if (lex->strval != NULL)
  		{
  			if (hi_surrogate != -1)
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  						 errmsg("invalid input syntax for type %s", "json"),
  						 errdetail("Unicode low surrogate must follow a high surrogate."),
  						 report_json_context(lex)));
  
  			appendStringInfoChar(lex->strval, *s);
  		}
  
  	}
  
  	if (hi_surrogate != -1)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  				 errmsg("invalid input syntax for type %s", "json"),
  				 errdetail("Unicode low surrogate must follow a high surrogate."),
  				 report_json_context(lex)));
  
  	/* Hooray, we found the end of the string! */
  	lex->prev_token_terminator = lex->token_terminator;
  	lex->token_terminator = s + 1;
  }
  
  /*
   * The next token in the input stream is known to be a number; lex it.
   *
   * In JSON, a number consists of four parts:
   *
   * (1) An optional minus sign ('-').
   *
   * (2) Either a single '0', or a string of one or more digits that does not
   *	   begin with a '0'.
   *
   * (3) An optional decimal part, consisting of a period ('.') followed by
   *	   one or more digits.  (Note: While this part can be omitted
   *	   completely, it's not OK to have only the decimal point without
   *	   any digits afterwards.)
   *
   * (4) An optional exponent part, consisting of 'e' or 'E', optionally
   *	   followed by '+' or '-', followed by one or more digits.  (Note:
   *	   As with the decimal part, if 'e' or 'E' is present, it must be
   *	   followed by at least one digit.)
   *
   * The 's' argument to this function points to the ostensible beginning
   * of part 2 - i.e. the character after any optional minus sign, or the
   * first character of the string if there is none.
   *
   * If num_err is not NULL, we return an error flag to *num_err rather than
   * raising an error for a badly-formed number.  Also, if total_len is not NULL
   * the distance from lex->input to the token end+1 is returned to *total_len.
   */
  static inline void
  json_lex_number(JsonLexContext *lex, char *s,
  				bool *num_err, int *total_len)
  {
  	bool		error = false;
  	int			len = s - lex->input;
  
  	/* Part (1): leading sign indicator. */
  	/* Caller already did this for us; so do nothing. */
  
  	/* Part (2): parse main digit string. */
  	if (len < lex->input_length && *s == '0')
  	{
  		s++;
  		len++;
  	}
  	else if (len < lex->input_length && *s >= '1' && *s <= '9')
  	{
  		do
  		{
  			s++;
  			len++;
  		} while (len < lex->input_length && *s >= '0' && *s <= '9');
  	}
  	else
  		error = true;
  
  	/* Part (3): parse optional decimal portion. */
  	if (len < lex->input_length && *s == '.')
  	{
  		s++;
  		len++;
  		if (len == lex->input_length || *s < '0' || *s > '9')
  			error = true;
  		else
  		{
  			do
  			{
  				s++;
  				len++;
  			} while (len < lex->input_length && *s >= '0' && *s <= '9');
  		}
  	}
  
  	/* Part (4): parse optional exponent. */
  	if (len < lex->input_length && (*s == 'e' || *s == 'E'))
  	{
  		s++;
  		len++;
  		if (len < lex->input_length && (*s == '+' || *s == '-'))
  		{
  			s++;
  			len++;
  		}
  		if (len == lex->input_length || *s < '0' || *s > '9')
  			error = true;
  		else
  		{
  			do
  			{
  				s++;
  				len++;
  			} while (len < lex->input_length && *s >= '0' && *s <= '9');
  		}
  	}
  
  	/*
  	 * Check for trailing garbage.  As in json_lex(), any alphanumeric stuff
  	 * here should be considered part of the token for error-reporting
  	 * purposes.
  	 */
  	for (; len < lex->input_length && JSON_ALPHANUMERIC_CHAR(*s); s++, len++)
  		error = true;
  
  	if (total_len != NULL)
  		*total_len = len;
  
  	if (num_err != NULL)
  	{
  		/* let the caller handle any error */
  		*num_err = error;
  	}
  	else
  	{
  		/* return token endpoint */
  		lex->prev_token_terminator = lex->token_terminator;
  		lex->token_terminator = s;
  		/* handle error if any */
  		if (error)
  			report_invalid_token(lex);
  	}
  }
  
  /*
   * Report a parse error.
   *
   * lex->token_start and lex->token_terminator must identify the current token.
   */
  static void
  report_parse_error(JsonParseContext ctx, JsonLexContext *lex)
  {
  	char	   *token;
  	int			toklen;
  
  	/* Handle case where the input ended prematurely. */
  	if (lex->token_start == NULL || lex->token_type == JSON_TOKEN_END)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  				 errmsg("invalid input syntax for type %s", "json"),
  				 errdetail("The input string ended unexpectedly."),
  				 report_json_context(lex)));
  
  	/* Separate out the current token. */
  	toklen = lex->token_terminator - lex->token_start;
  	token = palloc(toklen + 1);
  	memcpy(token, lex->token_start, toklen);
  	token[toklen] = '\0';
  
  	/* Complain, with the appropriate detail message. */
  	if (ctx == JSON_PARSE_END)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  				 errmsg("invalid input syntax for type %s", "json"),
  				 errdetail("Expected end of input, but found \"%s\".",
  						   token),
  				 report_json_context(lex)));
  	else
  	{
  		switch (ctx)
  		{
  			case JSON_PARSE_VALUE:
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  						 errmsg("invalid input syntax for type %s", "json"),
  						 errdetail("Expected JSON value, but found \"%s\".",
  								   token),
  						 report_json_context(lex)));
  				break;
  			case JSON_PARSE_STRING:
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  						 errmsg("invalid input syntax for type %s", "json"),
  						 errdetail("Expected string, but found \"%s\".",
  								   token),
  						 report_json_context(lex)));
  				break;
  			case JSON_PARSE_ARRAY_START:
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  						 errmsg("invalid input syntax for type %s", "json"),
  						 errdetail("Expected array element or \"]\", but found \"%s\".",
  								   token),
  						 report_json_context(lex)));
  				break;
  			case JSON_PARSE_ARRAY_NEXT:
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  						 errmsg("invalid input syntax for type %s", "json"),
  						 errdetail("Expected \",\" or \"]\", but found \"%s\".",
  								   token),
  						 report_json_context(lex)));
  				break;
  			case JSON_PARSE_OBJECT_START:
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  						 errmsg("invalid input syntax for type %s", "json"),
  						 errdetail("Expected string or \"}\", but found \"%s\".",
  								   token),
  						 report_json_context(lex)));
  				break;
  			case JSON_PARSE_OBJECT_LABEL:
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  						 errmsg("invalid input syntax for type %s", "json"),
  						 errdetail("Expected \":\", but found \"%s\".",
  								   token),
  						 report_json_context(lex)));
  				break;
  			case JSON_PARSE_OBJECT_NEXT:
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  						 errmsg("invalid input syntax for type %s", "json"),
  						 errdetail("Expected \",\" or \"}\", but found \"%s\".",
  								   token),
  						 report_json_context(lex)));
  				break;
  			case JSON_PARSE_OBJECT_COMMA:
  				ereport(ERROR,
  						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  						 errmsg("invalid input syntax for type %s", "json"),
  						 errdetail("Expected string, but found \"%s\".",
  								   token),
  						 report_json_context(lex)));
  				break;
  			default:
  				elog(ERROR, "unexpected json parse state: %d", ctx);
  		}
  	}
  }
  
  /*
   * Report an invalid input token.
   *
   * lex->token_start and lex->token_terminator must identify the token.
   */
  static void
  report_invalid_token(JsonLexContext *lex)
  {
  	char	   *token;
  	int			toklen;
  
  	/* Separate out the offending token. */
  	toklen = lex->token_terminator - lex->token_start;
  	token = palloc(toklen + 1);
  	memcpy(token, lex->token_start, toklen);
  	token[toklen] = '\0';
  
  	ereport(ERROR,
  			(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
  			 errmsg("invalid input syntax for type %s", "json"),
  			 errdetail("Token \"%s\" is invalid.", token),
  			 report_json_context(lex)));
  }
  
  /*
   * Report a CONTEXT line for bogus JSON input.
   *
   * lex->token_terminator must be set to identify the spot where we detected
   * the error.  Note that lex->token_start might be NULL, in case we recognized
   * error at EOF.
   *
   * The return value isn't meaningful, but we make it non-void so that this
   * can be invoked inside ereport().
   */
  static int
  report_json_context(JsonLexContext *lex)
  {
  	const char *context_start;
  	const char *context_end;
  	const char *line_start;
  	int			line_number;
  	char	   *ctxt;
  	int			ctxtlen;
  	const char *prefix;
  	const char *suffix;
  
  	/* Choose boundaries for the part of the input we will display */
  	context_start = lex->input;
  	context_end = lex->token_terminator;
  	line_start = context_start;
  	line_number = 1;
  	for (;;)
  	{
  		/* Always advance over newlines */
  		if (context_start < context_end && *context_start == '\n')
  		{
  			context_start++;
  			line_start = context_start;
  			line_number++;
  			continue;
  		}
  		/* Otherwise, done as soon as we are close enough to context_end */
  		if (context_end - context_start < 50)
  			break;
  		/* Advance to next multibyte character */
  		if (IS_HIGHBIT_SET(*context_start))
  			context_start += pg_mblen(context_start);
  		else
  			context_start++;
  	}
  
  	/*
  	 * We add "..." to indicate that the excerpt doesn't start at the
  	 * beginning of the line ... but if we're within 3 characters of the
  	 * beginning of the line, we might as well just show the whole line.
  	 */
  	if (context_start - line_start <= 3)
  		context_start = line_start;
  
  	/* Get a null-terminated copy of the data to present */
  	ctxtlen = context_end - context_start;
  	ctxt = palloc(ctxtlen + 1);
  	memcpy(ctxt, context_start, ctxtlen);
  	ctxt[ctxtlen] = '\0';
  
  	/*
  	 * Show the context, prefixing "..." if not starting at start of line, and
  	 * suffixing "..." if not ending at end of line.
  	 */
  	prefix = (context_start > line_start) ? "..." : "";
  	suffix = (lex->token_type != JSON_TOKEN_END && context_end - lex->input < lex->input_length && *context_end != '\n' && *context_end != '\r') ? "..." : "";
  
  	errcontext("JSON data, line %d: %s%s%s",
  			   line_number, prefix, ctxt, suffix);
  
  	return 0;
  }
  
  /*
   * Extract a single, possibly multi-byte char from the input string.
   */
  static char *
  extract_mb_char(char *s)
  {
  	char	   *res;
  	int			len;
  
  	len = pg_mblen(s);
  	res = palloc(len + 1);
  	memcpy(res, s, len);
  	res[len] = '\0';
  
  	return res;
  }
  
  /*
   * Determine how we want to print values of a given type in datum_to_json.
   *
   * Given the datatype OID, return its JsonTypeCategory, as well as the type's
   * output function OID.  If the returned category is JSONTYPE_CAST, we
   * return the OID of the type->JSON cast function instead.
   */
  static void
  json_categorize_type(Oid typoid,
  					 JsonTypeCategory *tcategory,
  					 Oid *outfuncoid)
  {
  	bool		typisvarlena;
  
  	/* Look through any domain */
  	typoid = getBaseType(typoid);
  
  	*outfuncoid = InvalidOid;
  
  	/*
  	 * We need to get the output function for everything except date and
  	 * timestamp types, array and composite types, booleans, and non-builtin
  	 * types where there's a cast to json.
  	 */
  
  	switch (typoid)
  	{
  		case BOOLOID:
  			*tcategory = JSONTYPE_BOOL;
  			break;
  
  		case INT2OID:
  		case INT4OID:
  		case INT8OID:
  		case FLOAT4OID:
  		case FLOAT8OID:
  		case NUMERICOID:
  			getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
  			*tcategory = JSONTYPE_NUMERIC;
  			break;
  
  		case DATEOID:
  			*tcategory = JSONTYPE_DATE;
  			break;
  
  		case TIMESTAMPOID:
  			*tcategory = JSONTYPE_TIMESTAMP;
  			break;
  
  		case TIMESTAMPTZOID:
  			*tcategory = JSONTYPE_TIMESTAMPTZ;
  			break;
  
  		case JSONOID:
  		case JSONBOID:
  			getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
  			*tcategory = JSONTYPE_JSON;
  			break;
  
  		default:
  			/* Check for arrays and composites */
  			if (OidIsValid(get_element_type(typoid)) || typoid == ANYARRAYOID
  				|| typoid == RECORDARRAYOID)
  				*tcategory = JSONTYPE_ARRAY;
  			else if (type_is_rowtype(typoid))	/* includes RECORDOID */
  				*tcategory = JSONTYPE_COMPOSITE;
  			else
  			{
  				/* It's probably the general case ... */
  				*tcategory = JSONTYPE_OTHER;
  				/* but let's look for a cast to json, if it's not built-in */
  				if (typoid >= FirstNormalObjectId)
  				{
  					Oid			castfunc;
  					CoercionPathType ctype;
  
  					ctype = find_coercion_pathway(JSONOID, typoid,
  												  COERCION_EXPLICIT,
  												  &castfunc);
  					if (ctype == COERCION_PATH_FUNC && OidIsValid(castfunc))
  					{
  						*tcategory = JSONTYPE_CAST;
  						*outfuncoid = castfunc;
  					}
  					else
  					{
  						/* non builtin type with no cast */
  						getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
  					}
  				}
  				else
  				{
  					/* any other builtin type */
  					getTypeOutputInfo(typoid, outfuncoid, &typisvarlena);
  				}
  			}
  			break;
  	}
  }
  
  /*
   * Turn a Datum into JSON text, appending the string to "result".
   *
   * tcategory and outfuncoid are from a previous call to json_categorize_type,
   * except that if is_null is true then they can be invalid.
   *
   * If key_scalar is true, the value is being printed as a key, so insist
   * it's of an acceptable type, and force it to be quoted.
   */
  static void
  datum_to_json(Datum val, bool is_null, StringInfo result,
  			  JsonTypeCategory tcategory, Oid outfuncoid,
  			  bool key_scalar)
  {
  	char	   *outputstr;
  	text	   *jsontext;
  
  	check_stack_depth();
  
  	/* callers are expected to ensure that null keys are not passed in */
  	Assert(!(key_scalar && is_null));
  
  	if (is_null)
  	{
  		appendStringInfoString(result, "null");
  		return;
  	}
  
  	if (key_scalar &&
  		(tcategory == JSONTYPE_ARRAY ||
  		 tcategory == JSONTYPE_COMPOSITE ||
  		 tcategory == JSONTYPE_JSON ||
  		 tcategory == JSONTYPE_CAST))
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("key value must be scalar, not array, composite, or json")));
  
  	switch (tcategory)
  	{
  		case JSONTYPE_ARRAY:
  			array_to_json_internal(val, result, false);
  			break;
  		case JSONTYPE_COMPOSITE:
  			composite_to_json(val, result, false);
  			break;
  		case JSONTYPE_BOOL:
  			outputstr = DatumGetBool(val) ? "true" : "false";
  			if (key_scalar)
  				escape_json(result, outputstr);
  			else
  				appendStringInfoString(result, outputstr);
  			break;
  		case JSONTYPE_NUMERIC:
  			outputstr = OidOutputFunctionCall(outfuncoid, val);
  
  			/*
  			 * Don't call escape_json for a non-key if it's a valid JSON
  			 * number.
  			 */
  			if (!key_scalar && IsValidJsonNumber(outputstr, strlen(outputstr)))
  				appendStringInfoString(result, outputstr);
  			else
  				escape_json(result, outputstr);
  			pfree(outputstr);
  			break;
  		case JSONTYPE_DATE:
  			{
  				char		buf[MAXDATELEN + 1];
  
  				JsonEncodeDateTime(buf, val, DATEOID);
  				appendStringInfo(result, "\"%s\"", buf);
  			}
  			break;
  		case JSONTYPE_TIMESTAMP:
  			{
  				char		buf[MAXDATELEN + 1];
  
  				JsonEncodeDateTime(buf, val, TIMESTAMPOID);
  				appendStringInfo(result, "\"%s\"", buf);
  			}
  			break;
  		case JSONTYPE_TIMESTAMPTZ:
  			{
  				char		buf[MAXDATELEN + 1];
  
  				JsonEncodeDateTime(buf, val, TIMESTAMPTZOID);
  				appendStringInfo(result, "\"%s\"", buf);
  			}
  			break;
  		case JSONTYPE_JSON:
  			/* JSON and JSONB output will already be escaped */
  			outputstr = OidOutputFunctionCall(outfuncoid, val);
  			appendStringInfoString(result, outputstr);
  			pfree(outputstr);
  			break;
  		case JSONTYPE_CAST:
  			/* outfuncoid refers to a cast function, not an output function */
  			jsontext = DatumGetTextPP(OidFunctionCall1(outfuncoid, val));
  			outputstr = text_to_cstring(jsontext);
  			appendStringInfoString(result, outputstr);
  			pfree(outputstr);
  			pfree(jsontext);
  			break;
  		default:
  			outputstr = OidOutputFunctionCall(outfuncoid, val);
  			escape_json(result, outputstr);
  			pfree(outputstr);
  			break;
  	}
  }
  
  /*
   * Encode 'value' of datetime type 'typid' into JSON string in ISO format using
   * optionally preallocated buffer 'buf'.
   */
  char *
  JsonEncodeDateTime(char *buf, Datum value, Oid typid)
  {
  	if (!buf)
  		buf = palloc(MAXDATELEN + 1);
  
  	switch (typid)
  	{
  		case DATEOID:
  			{
  				DateADT		date;
  				struct pg_tm tm;
  
  				date = DatumGetDateADT(value);
  
  				/* Same as date_out(), but forcing DateStyle */
  				if (DATE_NOT_FINITE(date))
  					EncodeSpecialDate(date, buf);
  				else
  				{
  					j2date(date + POSTGRES_EPOCH_JDATE,
  						   &(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
  					EncodeDateOnly(&tm, USE_XSD_DATES, buf);
  				}
  			}
  			break;
  		case TIMEOID:
  			{
  				TimeADT		time = DatumGetTimeADT(value);
  				struct pg_tm tt,
  						   *tm = &tt;
  				fsec_t		fsec;
  
  				/* Same as time_out(), but forcing DateStyle */
  				time2tm(time, tm, &fsec);
  				EncodeTimeOnly(tm, fsec, false, 0, USE_XSD_DATES, buf);
  			}
  			break;
  		case TIMETZOID:
  			{
  				TimeTzADT  *time = DatumGetTimeTzADTP(value);
  				struct pg_tm tt,
  						   *tm = &tt;
  				fsec_t		fsec;
  				int			tz;
  
  				/* Same as timetz_out(), but forcing DateStyle */
  				timetz2tm(time, tm, &fsec, &tz);
  				EncodeTimeOnly(tm, fsec, true, tz, USE_XSD_DATES, buf);
  			}
  			break;
  		case TIMESTAMPOID:
  			{
  				Timestamp	timestamp;
  				struct pg_tm tm;
  				fsec_t		fsec;
  
  				timestamp = DatumGetTimestamp(value);
  				/* Same as timestamp_out(), but forcing DateStyle */
  				if (TIMESTAMP_NOT_FINITE(timestamp))
  					EncodeSpecialTimestamp(timestamp, buf);
  				else if (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, NULL) == 0)
  					EncodeDateTime(&tm, fsec, false, 0, NULL, USE_XSD_DATES, buf);
  				else
  					ereport(ERROR,
  							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
  							 errmsg("timestamp out of range")));
  			}
  			break;
  		case TIMESTAMPTZOID:
  			{
  				TimestampTz timestamp;
  				struct pg_tm tm;
  				int			tz;
  				fsec_t		fsec;
  				const char *tzn = NULL;
  
  				timestamp = DatumGetTimestampTz(value);
  				/* Same as timestamptz_out(), but forcing DateStyle */
  				if (TIMESTAMP_NOT_FINITE(timestamp))
  					EncodeSpecialTimestamp(timestamp, buf);
  				else if (timestamp2tm(timestamp, &tz, &tm, &fsec, &tzn, NULL) == 0)
  					EncodeDateTime(&tm, fsec, true, tz, tzn, USE_XSD_DATES, buf);
  				else
  					ereport(ERROR,
  							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
  							 errmsg("timestamp out of range")));
  			}
  			break;
  		default:
  			elog(ERROR, "unknown jsonb value datetime type oid %d", typid);
  			return NULL;
  	}
  
  	return buf;
  }
  
  /*
   * Process a single dimension of an array.
   * If it's the innermost dimension, output the values, otherwise call
   * ourselves recursively to process the next dimension.
   */
  static void
  array_dim_to_json(StringInfo result, int dim, int ndims, int *dims, Datum *vals,
  				  bool *nulls, int *valcount, JsonTypeCategory tcategory,
  				  Oid outfuncoid, bool use_line_feeds)
  {
  	int			i;
  	const char *sep;
  
  	Assert(dim < ndims);
  
  	sep = use_line_feeds ? ",\n " : ",";
  
  	appendStringInfoChar(result, '[');
  
  	for (i = 1; i <= dims[dim]; i++)
  	{
  		if (i > 1)
  			appendStringInfoString(result, sep);
  
  		if (dim + 1 == ndims)
  		{
  			datum_to_json(vals[*valcount], nulls[*valcount], result, tcategory,
  						  outfuncoid, false);
  			(*valcount)++;
  		}
  		else
  		{
  			/*
  			 * Do we want line feeds on inner dimensions of arrays? For now
  			 * we'll say no.
  			 */
  			array_dim_to_json(result, dim + 1, ndims, dims, vals, nulls,
  							  valcount, tcategory, outfuncoid, false);
  		}
  	}
  
  	appendStringInfoChar(result, ']');
  }
  
  /*
   * Turn an array into JSON.
   */
  static void
  array_to_json_internal(Datum array, StringInfo result, bool use_line_feeds)
  {
  	ArrayType  *v = DatumGetArrayTypeP(array);
  	Oid			element_type = ARR_ELEMTYPE(v);
  	int		   *dim;
  	int			ndim;
  	int			nitems;
  	int			count = 0;
  	Datum	   *elements;
  	bool	   *nulls;
  	int16		typlen;
  	bool		typbyval;
  	char		typalign;
  	JsonTypeCategory tcategory;
  	Oid			outfuncoid;
  
  	ndim = ARR_NDIM(v);
  	dim = ARR_DIMS(v);
  	nitems = ArrayGetNItems(ndim, dim);
  
  	if (nitems <= 0)
  	{
  		appendStringInfoString(result, "[]");
  		return;
  	}
  
  	get_typlenbyvalalign(element_type,
  						 &typlen, &typbyval, &typalign);
  
  	json_categorize_type(element_type,
  						 &tcategory, &outfuncoid);
  
  	deconstruct_array(v, element_type, typlen, typbyval,
  					  typalign, &elements, &nulls,
  					  &nitems);
  
  	array_dim_to_json(result, 0, ndim, dim, elements, nulls, &count, tcategory,
  					  outfuncoid, use_line_feeds);
  
  	pfree(elements);
  	pfree(nulls);
  }
  
  /*
   * Turn a composite / record into JSON.
   */
  static void
  composite_to_json(Datum composite, StringInfo result, bool use_line_feeds)
  {
  	HeapTupleHeader td;
  	Oid			tupType;
  	int32		tupTypmod;
  	TupleDesc	tupdesc;
  	HeapTupleData tmptup,
  			   *tuple;
  	int			i;
  	bool		needsep = false;
  	const char *sep;
  
  	sep = use_line_feeds ? ",\n " : ",";
  
  	td = DatumGetHeapTupleHeader(composite);
  
  	/* Extract rowtype info and find a tupdesc */
  	tupType = HeapTupleHeaderGetTypeId(td);
  	tupTypmod = HeapTupleHeaderGetTypMod(td);
  	tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
  
  	/* Build a temporary HeapTuple control structure */
  	tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
  	tmptup.t_data = td;
  	tuple = &tmptup;
  
  	appendStringInfoChar(result, '{');
  
  	for (i = 0; i < tupdesc->natts; i++)
  	{
  		Datum		val;
  		bool		isnull;
  		char	   *attname;
  		JsonTypeCategory tcategory;
  		Oid			outfuncoid;
  		Form_pg_attribute att = TupleDescAttr(tupdesc, i);
  
  		if (att->attisdropped)
  			continue;
  
  		if (needsep)
  			appendStringInfoString(result, sep);
  		needsep = true;
  
  		attname = NameStr(att->attname);
  		escape_json(result, attname);
  		appendStringInfoChar(result, ':');
  
  		val = heap_getattr(tuple, i + 1, tupdesc, &isnull);
  
  		if (isnull)
  		{
  			tcategory = JSONTYPE_NULL;
  			outfuncoid = InvalidOid;
  		}
  		else
  			json_categorize_type(att->atttypid, &tcategory, &outfuncoid);
  
  		datum_to_json(val, isnull, result, tcategory, outfuncoid, false);
  	}
  
  	appendStringInfoChar(result, '}');
  	ReleaseTupleDesc(tupdesc);
  }
  
  /*
   * Append JSON text for "val" to "result".
   *
   * This is just a thin wrapper around datum_to_json.  If the same type will be
   * printed many times, avoid using this; better to do the json_categorize_type
   * lookups only once.
   */
  static void
  add_json(Datum val, bool is_null, StringInfo result,
  		 Oid val_type, bool key_scalar)
  {
  	JsonTypeCategory tcategory;
  	Oid			outfuncoid;
  
  	if (val_type == InvalidOid)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("could not determine input data type")));
  
  	if (is_null)
  	{
  		tcategory = JSONTYPE_NULL;
  		outfuncoid = InvalidOid;
  	}
  	else
  		json_categorize_type(val_type,
  							 &tcategory, &outfuncoid);
  
  	datum_to_json(val, is_null, result, tcategory, outfuncoid, key_scalar);
  }
  
  /*
   * SQL function array_to_json(row)
   */
  Datum
  array_to_json(PG_FUNCTION_ARGS)
  {
  	Datum		array = PG_GETARG_DATUM(0);
  	StringInfo	result;
  
  	result = makeStringInfo();
  
  	array_to_json_internal(array, result, false);
  
  	PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
  }
  
  /*
   * SQL function array_to_json(row, prettybool)
   */
  Datum
  array_to_json_pretty(PG_FUNCTION_ARGS)
  {
  	Datum		array = PG_GETARG_DATUM(0);
  	bool		use_line_feeds = PG_GETARG_BOOL(1);
  	StringInfo	result;
  
  	result = makeStringInfo();
  
  	array_to_json_internal(array, result, use_line_feeds);
  
  	PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
  }
  
  /*
   * SQL function row_to_json(row)
   */
  Datum
  row_to_json(PG_FUNCTION_ARGS)
  {
  	Datum		array = PG_GETARG_DATUM(0);
  	StringInfo	result;
  
  	result = makeStringInfo();
  
  	composite_to_json(array, result, false);
  
  	PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
  }
  
  /*
   * SQL function row_to_json(row, prettybool)
   */
  Datum
  row_to_json_pretty(PG_FUNCTION_ARGS)
  {
  	Datum		array = PG_GETARG_DATUM(0);
  	bool		use_line_feeds = PG_GETARG_BOOL(1);
  	StringInfo	result;
  
  	result = makeStringInfo();
  
  	composite_to_json(array, result, use_line_feeds);
  
  	PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
  }
  
  /*
   * SQL function to_json(anyvalue)
   */
  Datum
  to_json(PG_FUNCTION_ARGS)
  {
  	Datum		val = PG_GETARG_DATUM(0);
  	Oid			val_type = get_fn_expr_argtype(fcinfo->flinfo, 0);
  	StringInfo	result;
  	JsonTypeCategory tcategory;
  	Oid			outfuncoid;
  
  	if (val_type == InvalidOid)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("could not determine input data type")));
  
  	json_categorize_type(val_type,
  						 &tcategory, &outfuncoid);
  
  	result = makeStringInfo();
  
  	datum_to_json(val, false, result, tcategory, outfuncoid, false);
  
  	PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
  }
  
  /*
   * json_agg transition function
   *
   * aggregate input column as a json array value.
   */
  Datum
  json_agg_transfn(PG_FUNCTION_ARGS)
  {
  	MemoryContext aggcontext,
  				oldcontext;
  	JsonAggState *state;
  	Datum		val;
  
  	if (!AggCheckCallContext(fcinfo, &aggcontext))
  	{
  		/* cannot be called directly because of internal-type argument */
  		elog(ERROR, "json_agg_transfn called in non-aggregate context");
  	}
  
  	if (PG_ARGISNULL(0))
  	{
  		Oid			arg_type = get_fn_expr_argtype(fcinfo->flinfo, 1);
  
  		if (arg_type == InvalidOid)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  					 errmsg("could not determine input data type")));
  
  		/*
  		 * Make this state object in a context where it will persist for the
  		 * duration of the aggregate call.  MemoryContextSwitchTo is only
  		 * needed the first time, as the StringInfo routines make sure they
  		 * use the right context to enlarge the object if necessary.
  		 */
  		oldcontext = MemoryContextSwitchTo(aggcontext);
  		state = (JsonAggState *) palloc(sizeof(JsonAggState));
  		state->str = makeStringInfo();
  		MemoryContextSwitchTo(oldcontext);
  
  		appendStringInfoChar(state->str, '[');
  		json_categorize_type(arg_type, &state->val_category,
  							 &state->val_output_func);
  	}
  	else
  	{
  		state = (JsonAggState *) PG_GETARG_POINTER(0);
  		appendStringInfoString(state->str, ", ");
  	}
  
  	/* fast path for NULLs */
  	if (PG_ARGISNULL(1))
  	{
  		datum_to_json((Datum) 0, true, state->str, JSONTYPE_NULL,
  					  InvalidOid, false);
  		PG_RETURN_POINTER(state);
  	}
  
  	val = PG_GETARG_DATUM(1);
  
  	/* add some whitespace if structured type and not first item */
  	if (!PG_ARGISNULL(0) &&
  		(state->val_category == JSONTYPE_ARRAY ||
  		 state->val_category == JSONTYPE_COMPOSITE))
  	{
  		appendStringInfoString(state->str, "\n ");
  	}
  
  	datum_to_json(val, false, state->str, state->val_category,
  				  state->val_output_func, false);
  
  	/*
  	 * The transition type for json_agg() is declared to be "internal", which
  	 * is a pass-by-value type the same size as a pointer.  So we can safely
  	 * pass the JsonAggState pointer through nodeAgg.c's machinations.
  	 */
  	PG_RETURN_POINTER(state);
  }
  
  /*
   * json_agg final function
   */
  Datum
  json_agg_finalfn(PG_FUNCTION_ARGS)
  {
  	JsonAggState *state;
  
  	/* cannot be called directly because of internal-type argument */
  	Assert(AggCheckCallContext(fcinfo, NULL));
  
  	state = PG_ARGISNULL(0) ?
  		NULL :
  		(JsonAggState *) PG_GETARG_POINTER(0);
  
  	/* NULL result for no rows in, as is standard with aggregates */
  	if (state == NULL)
  		PG_RETURN_NULL();
  
  	/* Else return state with appropriate array terminator added */
  	PG_RETURN_TEXT_P(catenate_stringinfo_string(state->str, "]"));
  }
  
  /*
   * json_object_agg transition function.
   *
   * aggregate two input columns as a single json object value.
   */
  Datum
  json_object_agg_transfn(PG_FUNCTION_ARGS)
  {
  	MemoryContext aggcontext,
  				oldcontext;
  	JsonAggState *state;
  	Datum		arg;
  
  	if (!AggCheckCallContext(fcinfo, &aggcontext))
  	{
  		/* cannot be called directly because of internal-type argument */
  		elog(ERROR, "json_object_agg_transfn called in non-aggregate context");
  	}
  
  	if (PG_ARGISNULL(0))
  	{
  		Oid			arg_type;
  
  		/*
  		 * Make the StringInfo in a context where it will persist for the
  		 * duration of the aggregate call. Switching context is only needed
  		 * for this initial step, as the StringInfo routines make sure they
  		 * use the right context to enlarge the object if necessary.
  		 */
  		oldcontext = MemoryContextSwitchTo(aggcontext);
  		state = (JsonAggState *) palloc(sizeof(JsonAggState));
  		state->str = makeStringInfo();
  		MemoryContextSwitchTo(oldcontext);
  
  		arg_type = get_fn_expr_argtype(fcinfo->flinfo, 1);
  
  		if (arg_type == InvalidOid)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  					 errmsg("could not determine data type for argument %d", 1)));
  
  		json_categorize_type(arg_type, &state->key_category,
  							 &state->key_output_func);
  
  		arg_type = get_fn_expr_argtype(fcinfo->flinfo, 2);
  
  		if (arg_type == InvalidOid)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  					 errmsg("could not determine data type for argument %d", 2)));
  
  		json_categorize_type(arg_type, &state->val_category,
  							 &state->val_output_func);
  
  		appendStringInfoString(state->str, "{ ");
  	}
  	else
  	{
  		state = (JsonAggState *) PG_GETARG_POINTER(0);
  		appendStringInfoString(state->str, ", ");
  	}
  
  	/*
  	 * Note: since json_object_agg() is declared as taking type "any", the
  	 * parser will not do any type conversion on unknown-type literals (that
  	 * is, undecorated strings or NULLs).  Such values will arrive here as
  	 * type UNKNOWN, which fortunately does not matter to us, since
  	 * unknownout() works fine.
  	 */
  
  	if (PG_ARGISNULL(1))
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("field name must not be null")));
  
  	arg = PG_GETARG_DATUM(1);
  
  	datum_to_json(arg, false, state->str, state->key_category,
  				  state->key_output_func, true);
  
  	appendStringInfoString(state->str, " : ");
  
  	if (PG_ARGISNULL(2))
  		arg = (Datum) 0;
  	else
  		arg = PG_GETARG_DATUM(2);
  
  	datum_to_json(arg, PG_ARGISNULL(2), state->str, state->val_category,
  				  state->val_output_func, false);
  
  	PG_RETURN_POINTER(state);
  }
  
  /*
   * json_object_agg final function.
   */
  Datum
  json_object_agg_finalfn(PG_FUNCTION_ARGS)
  {
  	JsonAggState *state;
  
  	/* cannot be called directly because of internal-type argument */
  	Assert(AggCheckCallContext(fcinfo, NULL));
  
  	state = PG_ARGISNULL(0) ? NULL : (JsonAggState *) PG_GETARG_POINTER(0);
  
  	/* NULL result for no rows in, as is standard with aggregates */
  	if (state == NULL)
  		PG_RETURN_NULL();
  
  	/* Else return state with appropriate object terminator added */
  	PG_RETURN_TEXT_P(catenate_stringinfo_string(state->str, " }"));
  }
  
  /*
   * Helper function for aggregates: return given StringInfo's contents plus
   * specified trailing string, as a text datum.  We need this because aggregate
   * final functions are not allowed to modify the aggregate state.
   */
  static text *
  catenate_stringinfo_string(StringInfo buffer, const char *addon)
  {
  	/* custom version of cstring_to_text_with_len */
  	int			buflen = buffer->len;
  	int			addlen = strlen(addon);
  	text	   *result = (text *) palloc(buflen + addlen + VARHDRSZ);
  
  	SET_VARSIZE(result, buflen + addlen + VARHDRSZ);
  	memcpy(VARDATA(result), buffer->data, buflen);
  	memcpy(VARDATA(result) + buflen, addon, addlen);
  
  	return result;
  }
  
  /*
   * SQL function json_build_object(variadic "any")
   */
  Datum
  json_build_object(PG_FUNCTION_ARGS)
  {
  	int			nargs = PG_NARGS();
  	int			i;
  	const char *sep = "";
  	StringInfo	result;
  	Datum	   *args;
  	bool	   *nulls;
  	Oid		   *types;
  
  	/* fetch argument values to build the object */
  	nargs = extract_variadic_args(fcinfo, 0, false, &args, &types, &nulls);
  
  	if (nargs < 0)
  		PG_RETURN_NULL();
  
  	if (nargs % 2 != 0)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("argument list must have even number of elements"),
  		/* translator: %s is a SQL function name */
  				 errhint("The arguments of %s must consist of alternating keys and values.",
  						 "json_build_object()")));
  
  	result = makeStringInfo();
  
  	appendStringInfoChar(result, '{');
  
  	for (i = 0; i < nargs; i += 2)
  	{
  		appendStringInfoString(result, sep);
  		sep = ", ";
  
  		/* process key */
  		if (nulls[i])
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  					 errmsg("argument %d cannot be null", i + 1),
  					 errhint("Object keys should be text.")));
  
  		add_json(args[i], false, result, types[i], true);
  
  		appendStringInfoString(result, " : ");
  
  		/* process value */
  		add_json(args[i + 1], nulls[i + 1], result, types[i + 1], false);
  	}
  
  	appendStringInfoChar(result, '}');
  
  	PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
  }
  
  /*
   * degenerate case of json_build_object where it gets 0 arguments.
   */
  Datum
  json_build_object_noargs(PG_FUNCTION_ARGS)
  {
  	PG_RETURN_TEXT_P(cstring_to_text_with_len("{}", 2));
  }
  
  /*
   * SQL function json_build_array(variadic "any")
   */
  Datum
  json_build_array(PG_FUNCTION_ARGS)
  {
  	int			nargs;
  	int			i;
  	const char *sep = "";
  	StringInfo	result;
  	Datum	   *args;
  	bool	   *nulls;
  	Oid		   *types;
  
  	/* fetch argument values to build the array */
  	nargs = extract_variadic_args(fcinfo, 0, false, &args, &types, &nulls);
  
  	if (nargs < 0)
  		PG_RETURN_NULL();
  
  	result = makeStringInfo();
  
  	appendStringInfoChar(result, '[');
  
  	for (i = 0; i < nargs; i++)
  	{
  		appendStringInfoString(result, sep);
  		sep = ", ";
  		add_json(args[i], nulls[i], result, types[i], false);
  	}
  
  	appendStringInfoChar(result, ']');
  
  	PG_RETURN_TEXT_P(cstring_to_text_with_len(result->data, result->len));
  }
  
  /*
   * degenerate case of json_build_array where it gets 0 arguments.
   */
  Datum
  json_build_array_noargs(PG_FUNCTION_ARGS)
  {
  	PG_RETURN_TEXT_P(cstring_to_text_with_len("[]", 2));
  }
  
  /*
   * SQL function json_object(text[])
   *
   * take a one or two dimensional array of text as key/value pairs
   * for a json object.
   */
  Datum
  json_object(PG_FUNCTION_ARGS)
  {
  	ArrayType  *in_array = PG_GETARG_ARRAYTYPE_P(0);
  	int			ndims = ARR_NDIM(in_array);
  	StringInfoData result;
  	Datum	   *in_datums;
  	bool	   *in_nulls;
  	int			in_count,
  				count,
  				i;
  	text	   *rval;
  	char	   *v;
  
  	switch (ndims)
  	{
  		case 0:
  			PG_RETURN_DATUM(CStringGetTextDatum("{}"));
  			break;
  
  		case 1:
  			if ((ARR_DIMS(in_array)[0]) % 2)
  				ereport(ERROR,
  						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
  						 errmsg("array must have even number of elements")));
  			break;
  
  		case 2:
  			if ((ARR_DIMS(in_array)[1]) != 2)
  				ereport(ERROR,
  						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
  						 errmsg("array must have two columns")));
  			break;
  
  		default:
  			ereport(ERROR,
  					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
  					 errmsg("wrong number of array subscripts")));
  	}
  
  	deconstruct_array(in_array,
  					  TEXTOID, -1, false, 'i',
  					  &in_datums, &in_nulls, &in_count);
  
  	count = in_count / 2;
  
  	initStringInfo(&result);
  
  	appendStringInfoChar(&result, '{');
  
  	for (i = 0; i < count; ++i)
  	{
  		if (in_nulls[i * 2])
  			ereport(ERROR,
  					(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  					 errmsg("null value not allowed for object key")));
  
  		v = TextDatumGetCString(in_datums[i * 2]);
  		if (i > 0)
  			appendStringInfoString(&result, ", ");
  		escape_json(&result, v);
  		appendStringInfoString(&result, " : ");
  		pfree(v);
  		if (in_nulls[i * 2 + 1])
  			appendStringInfoString(&result, "null");
  		else
  		{
  			v = TextDatumGetCString(in_datums[i * 2 + 1]);
  			escape_json(&result, v);
  			pfree(v);
  		}
  	}
  
  	appendStringInfoChar(&result, '}');
  
  	pfree(in_datums);
  	pfree(in_nulls);
  
  	rval = cstring_to_text_with_len(result.data, result.len);
  	pfree(result.data);
  
  	PG_RETURN_TEXT_P(rval);
  
  }
  
  /*
   * SQL function json_object(text[], text[])
   *
   * take separate key and value arrays of text to construct a json object
   * pairwise.
   */
  Datum
  json_object_two_arg(PG_FUNCTION_ARGS)
  {
  	ArrayType  *key_array = PG_GETARG_ARRAYTYPE_P(0);
  	ArrayType  *val_array = PG_GETARG_ARRAYTYPE_P(1);
  	int			nkdims = ARR_NDIM(key_array);
  	int			nvdims = ARR_NDIM(val_array);
  	StringInfoData result;
  	Datum	   *key_datums,
  			   *val_datums;
  	bool	   *key_nulls,
  			   *val_nulls;
  	int			key_count,
  				val_count,
  				i;
  	text	   *rval;
  	char	   *v;
  
  	if (nkdims > 1 || nkdims != nvdims)
  		ereport(ERROR,
  				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
  				 errmsg("wrong number of array subscripts")));
  
  	if (nkdims == 0)
  		PG_RETURN_DATUM(CStringGetTextDatum("{}"));
  
  	deconstruct_array(key_array,
  					  TEXTOID, -1, false, 'i',
  					  &key_datums, &key_nulls, &key_count);
  
  	deconstruct_array(val_array,
  					  TEXTOID, -1, false, 'i',
  					  &val_datums, &val_nulls, &val_count);
  
  	if (key_count != val_count)
  		ereport(ERROR,
  				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
  				 errmsg("mismatched array dimensions")));
  
  	initStringInfo(&result);
  
  	appendStringInfoChar(&result, '{');
  
  	for (i = 0; i < key_count; ++i)
  	{
  		if (key_nulls[i])
  			ereport(ERROR,
  					(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  					 errmsg("null value not allowed for object key")));
  
  		v = TextDatumGetCString(key_datums[i]);
  		if (i > 0)
  			appendStringInfoString(&result, ", ");
  		escape_json(&result, v);
  		appendStringInfoString(&result, " : ");
  		pfree(v);
  		if (val_nulls[i])
  			appendStringInfoString(&result, "null");
  		else
  		{
  			v = TextDatumGetCString(val_datums[i]);
  			escape_json(&result, v);
  			pfree(v);
  		}
  	}
  
  	appendStringInfoChar(&result, '}');
  
  	pfree(key_datums);
  	pfree(key_nulls);
  	pfree(val_datums);
  	pfree(val_nulls);
  
  	rval = cstring_to_text_with_len(result.data, result.len);
  	pfree(result.data);
  
  	PG_RETURN_TEXT_P(rval);
  }
  
  
  /*
   * Produce a JSON string literal, properly escaping characters in the text.
   */
  void
  escape_json(StringInfo buf, const char *str)
  {
  	const char *p;
  
  	appendStringInfoCharMacro(buf, '"');
  	for (p = str; *p; p++)
  	{
  		switch (*p)
  		{
  			case '\b':
  				appendStringInfoString(buf, "\\b");
  				break;
  			case '\f':
  				appendStringInfoString(buf, "\\f");
  				break;
  			case '\n':
  				appendStringInfoString(buf, "\\n");
  				break;
  			case '\r':
  				appendStringInfoString(buf, "\\r");
  				break;
  			case '\t':
  				appendStringInfoString(buf, "\\t");
  				break;
  			case '"':
  				appendStringInfoString(buf, "\\\"");
  				break;
  			case '\\':
  				appendStringInfoString(buf, "\\\\");
  				break;
  			default:
  				if ((unsigned char) *p < ' ')
  					appendStringInfo(buf, "\\u%04x", (int) *p);
  				else
  					appendStringInfoCharMacro(buf, *p);
  				break;
  		}
  	}
  	appendStringInfoCharMacro(buf, '"');
  }
  
  /*
   * SQL function json_typeof(json) -> text
   *
   * Returns the type of the outermost JSON value as TEXT.  Possible types are
   * "object", "array", "string", "number", "boolean", and "null".
   *
   * Performs a single call to json_lex() to get the first token of the supplied
   * value.  This initial token uniquely determines the value's type.  As our
   * input must already have been validated by json_in() or json_recv(), the
   * initial token should never be JSON_TOKEN_OBJECT_END, JSON_TOKEN_ARRAY_END,
   * JSON_TOKEN_COLON, JSON_TOKEN_COMMA, or JSON_TOKEN_END.
   */
  Datum
  json_typeof(PG_FUNCTION_ARGS)
  {
  	text	   *json;
  
  	JsonLexContext *lex;
  	JsonTokenType tok;
  	char	   *type;
  
  	json = PG_GETARG_TEXT_PP(0);
  	lex = makeJsonLexContext(json, false);
  
  	/* Lex exactly one token from the input and check its type. */
  	json_lex(lex);
  	tok = lex_peek(lex);
  	switch (tok)
  	{
  		case JSON_TOKEN_OBJECT_START:
  			type = "object";
  			break;
  		case JSON_TOKEN_ARRAY_START:
  			type = "array";
  			break;
  		case JSON_TOKEN_STRING:
  			type = "string";
  			break;
  		case JSON_TOKEN_NUMBER:
  			type = "number";
  			break;
  		case JSON_TOKEN_TRUE:
  		case JSON_TOKEN_FALSE:
  			type = "boolean";
  			break;
  		case JSON_TOKEN_NULL:
  			type = "null";
  			break;
  		default:
  			elog(ERROR, "unexpected json token: %d", tok);
  	}
  
  	PG_RETURN_TEXT_P(cstring_to_text(type));
  }
  