text: /*-------------------------------------------------------------------------
   *
   * fmgr.h
   *	  Definitions for the Postgres function manager and function-call
   *	  interface.
   *
   * This file must be included by all Postgres modules that either define
   * or call fmgr-callable functions.
   *
   *
   * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   * $PostgreSQL: pgsql/src/include/fmgr.h,v 1.40 2005/10/15 02:49:41 momjian Exp $
   *
   *-------------------------------------------------------------------------
   */
  #ifndef FMGR_H
  #define FMGR_H
  
  /* We don't want to include primnodes.h here, so make a stub reference */
  typedef struct Node *fmNodePtr;
  
  
  /*
   * All functions that can be called directly by fmgr must have this signature.
   * (Other functions can be called by using a handler that does have this
   * signature.)
   */
  
  typedef struct FunctionCallInfoData *FunctionCallInfo;
  
  typedef Datum (*PGFunction) (FunctionCallInfo fcinfo);
  
  /*
   * This struct holds the system-catalog information that must be looked up
   * before a function can be called through fmgr.  If the same function is
   * to be called multiple times, the lookup need be done only once and the
   * info struct saved for re-use.
   */
  typedef struct FmgrInfo
  {
  	PGFunction	fn_addr;		/* pointer to function or handler to be called */
  	Oid			fn_oid;			/* OID of function (NOT of handler, if any) */
  	short		fn_nargs;		/* 0..FUNC_MAX_ARGS, or -1 if variable arg
  								 * count */
  	bool		fn_strict;		/* function is "strict" (NULL in => NULL out) */
  	bool		fn_retset;		/* function returns a set */
  	void	   *fn_extra;		/* extra space for use by handler */
  	MemoryContext fn_mcxt;		/* memory context to store fn_extra in */
  	fmNodePtr	fn_expr;		/* expression parse tree for call, or NULL */
  } FmgrInfo;
  
  /*
   * This struct is the data actually passed to an fmgr-called function.
   */
  typedef struct FunctionCallInfoData
  {
  	FmgrInfo   *flinfo;			/* ptr to lookup info used for this call */
  	fmNodePtr	context;		/* pass info about context of call */
  	fmNodePtr	resultinfo;		/* pass or return extra info about result */
  	bool		isnull;			/* function must set true if result is NULL */
  	short		nargs;			/* # arguments actually passed */
  	Datum		arg[FUNC_MAX_ARGS];		/* Arguments passed to function */
  	bool		argnull[FUNC_MAX_ARGS]; /* T if arg[i] is actually NULL */
  } FunctionCallInfoData;
  
  /*
   * This routine fills a FmgrInfo struct, given the OID
   * of the function to be called.
   */
  extern void fmgr_info(Oid functionId, FmgrInfo *finfo);
  
  /*
   * Same, when the FmgrInfo struct is in a memory context longer-lived than
   * CurrentMemoryContext.  The specified context will be set as fn_mcxt
   * and used to hold all subsidiary data of finfo.
   */
  extern void fmgr_info_cxt(Oid functionId, FmgrInfo *finfo,
  			  MemoryContext mcxt);
  
  /*
   * Copy an FmgrInfo struct
   */
  extern void fmgr_info_copy(FmgrInfo *dstinfo, FmgrInfo *srcinfo,
  			   MemoryContext destcxt);
  
  /*
   * This macro initializes all the fields of a FunctionCallInfoData except
   * for the arg[] and argnull[] arrays.	Performance testing has shown that
   * the fastest way to set up argnull[] for small numbers of arguments is to
   * explicitly set each required element to false, so we don't try to zero
   * out the argnull[] array in the macro.
   */
  #define InitFunctionCallInfoData(Fcinfo, Flinfo, Nargs, Context, Resultinfo) \
  	do { \
  		(Fcinfo).flinfo = (Flinfo); \
  		(Fcinfo).context = (Context); \
  		(Fcinfo).resultinfo = (Resultinfo); \
  		(Fcinfo).isnull = false; \
  		(Fcinfo).nargs = (Nargs); \
  	} while (0)
  
  /*
   * This macro invokes a function given a filled-in FunctionCallInfoData
   * struct.	The macro result is the returned Datum --- but note that
   * caller must still check fcinfo->isnull!	Also, if function is strict,
   * it is caller's responsibility to verify that no null arguments are present
   * before calling.
   */
  #define FunctionCallInvoke(fcinfo)	((* (fcinfo)->flinfo->fn_addr) (fcinfo))
  
  
  /*-------------------------------------------------------------------------
   *		Support macros to ease writing fmgr-compatible functions
   *
   * A C-coded fmgr-compatible function should be declared as
   *
   *		Datum
   *		function_name(PG_FUNCTION_ARGS)
   *		{
   *			...
   *		}
   *
   * It should access its arguments using appropriate PG_GETARG_xxx macros
   * and should return its result using PG_RETURN_xxx.
   *
   *-------------------------------------------------------------------------
   */
  
  /* Standard parameter list for fmgr-compatible functions */
  #define PG_FUNCTION_ARGS	FunctionCallInfo fcinfo
  
  /*
   * Get number of arguments passed to function.
   */
  #define PG_NARGS() (fcinfo->nargs)
  
  /*
   * If function is not marked "proisstrict" in pg_proc, it must check for
   * null arguments using this macro.  Do not try to GETARG a null argument!
   */
  #define PG_ARGISNULL(n)  (fcinfo->argnull[n])
  
  /*
   * Support for fetching detoasted copies of toastable datatypes (all of
   * which are varlena types).  pg_detoast_datum() gives you either the input
   * datum (if not toasted) or a detoasted copy allocated with palloc().
   * pg_detoast_datum_copy() always gives you a palloc'd copy --- use it
   * if you need a modifiable copy of the input.	Caller is expected to have
   * checked for null inputs first, if necessary.
   *
   * Note: it'd be nice if these could be macros, but I see no way to do that
   * without evaluating the arguments multiple times, which is NOT acceptable.
   */
  extern struct varlena *pg_detoast_datum(struct varlena * datum);
  extern struct varlena *pg_detoast_datum_copy(struct varlena * datum);
  extern struct varlena *pg_detoast_datum_slice(struct varlena * datum,
  					   int32 first, int32 count);
  
  #define PG_DETOAST_DATUM(datum) \
  	pg_detoast_datum((struct varlena *) DatumGetPointer(datum))
  #define PG_DETOAST_DATUM_COPY(datum) \
  	pg_detoast_datum_copy((struct varlena *) DatumGetPointer(datum))
  #define PG_DETOAST_DATUM_SLICE(datum,f,c) \
  		pg_detoast_datum_slice((struct varlena *) DatumGetPointer(datum), \
  		(int32) f, (int32) c)
  
  /*
   * Support for cleaning up detoasted copies of inputs.	This must only
   * be used for pass-by-ref datatypes, and normally would only be used
   * for toastable types.  If the given pointer is different from the
   * original argument, assume it's a palloc'd detoasted copy, and pfree it.
   * NOTE: most functions on toastable types do not have to worry about this,
   * but we currently require that support functions for indexes not leak
   * memory.
   */
  #define PG_FREE_IF_COPY(ptr,n) \
  	do { \
  		if ((Pointer) (ptr) != PG_GETARG_POINTER(n)) \
  			pfree(ptr); \
  	} while (0)
  
  /* Macros for fetching arguments of standard types */
  
  #define PG_GETARG_DATUM(n)	 (fcinfo->arg[n])
  #define PG_GETARG_INT32(n)	 DatumGetInt32(PG_GETARG_DATUM(n))
  #define PG_GETARG_UINT32(n)  DatumGetUInt32(PG_GETARG_DATUM(n))
  #define PG_GETARG_INT16(n)	 DatumGetInt16(PG_GETARG_DATUM(n))
  #define PG_GETARG_UINT16(n)  DatumGetUInt16(PG_GETARG_DATUM(n))
  #define PG_GETARG_CHAR(n)	 DatumGetChar(PG_GETARG_DATUM(n))
  #define PG_GETARG_BOOL(n)	 DatumGetBool(PG_GETARG_DATUM(n))
  #define PG_GETARG_OID(n)	 DatumGetObjectId(PG_GETARG_DATUM(n))
  #define PG_GETARG_POINTER(n) DatumGetPointer(PG_GETARG_DATUM(n))
  #define PG_GETARG_CSTRING(n) DatumGetCString(PG_GETARG_DATUM(n))
  #define PG_GETARG_NAME(n)	 DatumGetName(PG_GETARG_DATUM(n))
  /* these macros hide the pass-by-reference-ness of the datatype: */
  #define PG_GETARG_FLOAT4(n)  DatumGetFloat4(PG_GETARG_DATUM(n))
  #define PG_GETARG_FLOAT8(n)  DatumGetFloat8(PG_GETARG_DATUM(n))
  #define PG_GETARG_INT64(n)	 DatumGetInt64(PG_GETARG_DATUM(n))
  /* use this if you want the raw, possibly-toasted input datum: */
  #define PG_GETARG_RAW_VARLENA_P(n)	((struct varlena *) PG_GETARG_POINTER(n))
  /* use this if you want the input datum de-toasted: */
  #define PG_GETARG_VARLENA_P(n) PG_DETOAST_DATUM(PG_GETARG_DATUM(n))
  /* DatumGetFoo macros for varlena types will typically look like this: */
  #define DatumGetByteaP(X)			((bytea *) PG_DETOAST_DATUM(X))
  #define DatumGetTextP(X)			((text *) PG_DETOAST_DATUM(X))
  #define DatumGetBpCharP(X)			((BpChar *) PG_DETOAST_DATUM(X))
  #define DatumGetVarCharP(X)			((VarChar *) PG_DETOAST_DATUM(X))
  #define DatumGetHeapTupleHeader(X)	((HeapTupleHeader) PG_DETOAST_DATUM(X))
  /* And we also offer variants that return an OK-to-write copy */
  #define DatumGetByteaPCopy(X)		((bytea *) PG_DETOAST_DATUM_COPY(X))
  #define DatumGetTextPCopy(X)		((text *) PG_DETOAST_DATUM_COPY(X))
  #define DatumGetBpCharPCopy(X)		((BpChar *) PG_DETOAST_DATUM_COPY(X))
  #define DatumGetVarCharPCopy(X)		((VarChar *) PG_DETOAST_DATUM_COPY(X))
  #define DatumGetHeapTupleHeaderCopy(X)	((HeapTupleHeader) PG_DETOAST_DATUM_COPY(X))
  /* Variants which return n bytes starting at pos. m */
  #define DatumGetByteaPSlice(X,m,n)	((bytea *) PG_DETOAST_DATUM_SLICE(X,m,n))
  #define DatumGetTextPSlice(X,m,n)	((text *) PG_DETOAST_DATUM_SLICE(X,m,n))
  #define DatumGetBpCharPSlice(X,m,n) ((BpChar *) PG_DETOAST_DATUM_SLICE(X,m,n))
  #define DatumGetVarCharPSlice(X,m,n) ((VarChar *) PG_DETOAST_DATUM_SLICE(X,m,n))
  /* GETARG macros for varlena types will typically look like this: */
  #define PG_GETARG_BYTEA_P(n)		DatumGetByteaP(PG_GETARG_DATUM(n))
  #define PG_GETARG_TEXT_P(n)			DatumGetTextP(PG_GETARG_DATUM(n))
  #define PG_GETARG_BPCHAR_P(n)		DatumGetBpCharP(PG_GETARG_DATUM(n))
  #define PG_GETARG_VARCHAR_P(n)		DatumGetVarCharP(PG_GETARG_DATUM(n))
  #define PG_GETARG_HEAPTUPLEHEADER(n)	DatumGetHeapTupleHeader(PG_GETARG_DATUM(n))
  /* And we also offer variants that return an OK-to-write copy */
  #define PG_GETARG_BYTEA_P_COPY(n)	DatumGetByteaPCopy(PG_GETARG_DATUM(n))
  #define PG_GETARG_TEXT_P_COPY(n)	DatumGetTextPCopy(PG_GETARG_DATUM(n))
  #define PG_GETARG_BPCHAR_P_COPY(n)	DatumGetBpCharPCopy(PG_GETARG_DATUM(n))
  #define PG_GETARG_VARCHAR_P_COPY(n) DatumGetVarCharPCopy(PG_GETARG_DATUM(n))
  #define PG_GETARG_HEAPTUPLEHEADER_COPY(n)	DatumGetHeapTupleHeaderCopy(PG_GETARG_DATUM(n))
  /* And a b-byte slice from position a -also OK to write */
  #define PG_GETARG_BYTEA_P_SLICE(n,a,b) DatumGetByteaPSlice(PG_GETARG_DATUM(n),a,b)
  #define PG_GETARG_TEXT_P_SLICE(n,a,b)  DatumGetTextPSlice(PG_GETARG_DATUM(n),a,b)
  #define PG_GETARG_BPCHAR_P_SLICE(n,a,b) DatumGetBpCharPSlice(PG_GETARG_DATUM(n),a,b)
  #define PG_GETARG_VARCHAR_P_SLICE(n,a,b) DatumGetVarCharPSlice(PG_GETARG_DATUM(n),a,b)
  
  /* To return a NULL do this: */
  #define PG_RETURN_NULL()  \
  	do { fcinfo->isnull = true; return (Datum) 0; } while (0)
  
  /* A few internal functions return void (which is not the same as NULL!) */
  #define PG_RETURN_VOID()	 return (Datum) 0
  
  /* Macros for returning results of standard types */
  
  #define PG_RETURN_DATUM(x)	 return (x)
  #define PG_RETURN_INT32(x)	 return Int32GetDatum(x)
  #define PG_RETURN_UINT32(x)  return UInt32GetDatum(x)
  #define PG_RETURN_INT16(x)	 return Int16GetDatum(x)
  #define PG_RETURN_CHAR(x)	 return CharGetDatum(x)
  #define PG_RETURN_BOOL(x)	 return BoolGetDatum(x)
  #define PG_RETURN_OID(x)	 return ObjectIdGetDatum(x)
  #define PG_RETURN_POINTER(x) return PointerGetDatum(x)
  #define PG_RETURN_CSTRING(x) return CStringGetDatum(x)
  #define PG_RETURN_NAME(x)	 return NameGetDatum(x)
  /* these macros hide the pass-by-reference-ness of the datatype: */
  #define PG_RETURN_FLOAT4(x)  return Float4GetDatum(x)
  #define PG_RETURN_FLOAT8(x)  return Float8GetDatum(x)
  #define PG_RETURN_INT64(x)	 return Int64GetDatum(x)
  /* RETURN macros for other pass-by-ref types will typically look like this: */
  #define PG_RETURN_BYTEA_P(x)   PG_RETURN_POINTER(x)
  #define PG_RETURN_TEXT_P(x)    PG_RETURN_POINTER(x)
  #define PG_RETURN_BPCHAR_P(x)  PG_RETURN_POINTER(x)
  #define PG_RETURN_VARCHAR_P(x) PG_RETURN_POINTER(x)
  #define PG_RETURN_HEAPTUPLEHEADER(x)  PG_RETURN_POINTER(x)
  
  
  /*-------------------------------------------------------------------------
   *		Support for detecting call convention of dynamically-loaded functions
   *
   * Dynamically loaded functions may use either the version-1 ("new style")
   * or version-0 ("old style") calling convention.  Version 1 is the call
   * convention defined in this header file; version 0 is the old "plain C"
   * convention.	A version-1 function must be accompanied by the macro call
   *
   *		PG_FUNCTION_INFO_V1(function_name);
   *
   * Note that internal functions do not need this decoration since they are
   * assumed to be version-1.
   *
   *-------------------------------------------------------------------------
   */
  
  typedef struct
  {
  	int			api_version;	/* specifies call convention version number */
  	/* More fields may be added later, for version numbers > 1. */
  } Pg_finfo_record;
  
  /* Expected signature of an info function */
  typedef Pg_finfo_record *(*PGFInfoFunction) (void);
  
  /* Macro to build an info function associated with the given function name */
  
  #define PG_FUNCTION_INFO_V1(funcname) \
  extern Pg_finfo_record * CppConcat(pg_finfo_,funcname) (void); \
  Pg_finfo_record * \
  CppConcat(pg_finfo_,funcname) (void) \
  { \
  	static Pg_finfo_record my_finfo = { 1 }; \
  	return &my_finfo; \
  } \
  extern int no_such_variable
  
  
  /*-------------------------------------------------------------------------
   *		Support routines and macros for callers of fmgr-compatible functions
   *-------------------------------------------------------------------------
   */
  
  /* These are for invocation of a specifically named function with a
   * directly-computed parameter list.  Note that neither arguments nor result
   * are allowed to be NULL.
   */
  extern Datum DirectFunctionCall1(PGFunction func, Datum arg1);
  extern Datum DirectFunctionCall2(PGFunction func, Datum arg1, Datum arg2);
  extern Datum DirectFunctionCall3(PGFunction func, Datum arg1, Datum arg2,
  					Datum arg3);
  extern Datum DirectFunctionCall4(PGFunction func, Datum arg1, Datum arg2,
  					Datum arg3, Datum arg4);
  extern Datum DirectFunctionCall5(PGFunction func, Datum arg1, Datum arg2,
  					Datum arg3, Datum arg4, Datum arg5);
  extern Datum DirectFunctionCall6(PGFunction func, Datum arg1, Datum arg2,
  					Datum arg3, Datum arg4, Datum arg5,
  					Datum arg6);
  extern Datum DirectFunctionCall7(PGFunction func, Datum arg1, Datum arg2,
  					Datum arg3, Datum arg4, Datum arg5,
  					Datum arg6, Datum arg7);
  extern Datum DirectFunctionCall8(PGFunction func, Datum arg1, Datum arg2,
  					Datum arg3, Datum arg4, Datum arg5,
  					Datum arg6, Datum arg7, Datum arg8);
  extern Datum DirectFunctionCall9(PGFunction func, Datum arg1, Datum arg2,
  					Datum arg3, Datum arg4, Datum arg5,
  					Datum arg6, Datum arg7, Datum arg8,
  					Datum arg9);
  
  /* These are for invocation of a previously-looked-up function with a
   * directly-computed parameter list.  Note that neither arguments nor result
   * are allowed to be NULL.
   */
  extern Datum FunctionCall1(FmgrInfo *flinfo, Datum arg1);
  extern Datum FunctionCall2(FmgrInfo *flinfo, Datum arg1, Datum arg2);
  extern Datum FunctionCall3(FmgrInfo *flinfo, Datum arg1, Datum arg2,
  			  Datum arg3);
  extern Datum FunctionCall4(FmgrInfo *flinfo, Datum arg1, Datum arg2,
  			  Datum arg3, Datum arg4);
  extern Datum FunctionCall5(FmgrInfo *flinfo, Datum arg1, Datum arg2,
  			  Datum arg3, Datum arg4, Datum arg5);
  extern Datum FunctionCall6(FmgrInfo *flinfo, Datum arg1, Datum arg2,
  			  Datum arg3, Datum arg4, Datum arg5,
  			  Datum arg6);
  extern Datum FunctionCall7(FmgrInfo *flinfo, Datum arg1, Datum arg2,
  			  Datum arg3, Datum arg4, Datum arg5,
  			  Datum arg6, Datum arg7);
  extern Datum FunctionCall8(FmgrInfo *flinfo, Datum arg1, Datum arg2,
  			  Datum arg3, Datum arg4, Datum arg5,
  			  Datum arg6, Datum arg7, Datum arg8);
  extern Datum FunctionCall9(FmgrInfo *flinfo, Datum arg1, Datum arg2,
  			  Datum arg3, Datum arg4, Datum arg5,
  			  Datum arg6, Datum arg7, Datum arg8,
  			  Datum arg9);
  
  /* These are for invocation of a function identified by OID with a
   * directly-computed parameter list.  Note that neither arguments nor result
   * are allowed to be NULL.	These are essentially FunctionLookup() followed
   * by FunctionCallN().	If the same function is to be invoked repeatedly,
   * do the FunctionLookup() once and then use FunctionCallN().
   */
  extern Datum OidFunctionCall1(Oid functionId, Datum arg1);
  extern Datum OidFunctionCall2(Oid functionId, Datum arg1, Datum arg2);
  extern Datum OidFunctionCall3(Oid functionId, Datum arg1, Datum arg2,
  				 Datum arg3);
  extern Datum OidFunctionCall4(Oid functionId, Datum arg1, Datum arg2,
  				 Datum arg3, Datum arg4);
  extern Datum OidFunctionCall5(Oid functionId, Datum arg1, Datum arg2,
  				 Datum arg3, Datum arg4, Datum arg5);
  extern Datum OidFunctionCall6(Oid functionId, Datum arg1, Datum arg2,
  				 Datum arg3, Datum arg4, Datum arg5,
  				 Datum arg6);
  extern Datum OidFunctionCall7(Oid functionId, Datum arg1, Datum arg2,
  				 Datum arg3, Datum arg4, Datum arg5,
  				 Datum arg6, Datum arg7);
  extern Datum OidFunctionCall8(Oid functionId, Datum arg1, Datum arg2,
  				 Datum arg3, Datum arg4, Datum arg5,
  				 Datum arg6, Datum arg7, Datum arg8);
  extern Datum OidFunctionCall9(Oid functionId, Datum arg1, Datum arg2,
  				 Datum arg3, Datum arg4, Datum arg5,
  				 Datum arg6, Datum arg7, Datum arg8,
  				 Datum arg9);
  
  
  /*
   * Routines in fmgr.c
   */
  extern Pg_finfo_record *fetch_finfo_record(void *filehandle, char *funcname);
  extern void clear_external_function_hash(void *filehandle);
  extern Oid	fmgr_internal_function(const char *proname);
  extern Oid	get_fn_expr_rettype(FmgrInfo *flinfo);
  extern Oid	get_fn_expr_argtype(FmgrInfo *flinfo, int argnum);
  extern Oid	get_call_expr_argtype(fmNodePtr expr, int argnum);
  
  /*
   * Routines in dfmgr.c
   */
  extern char *Dynamic_library_path;
  
  extern PGFunction load_external_function(char *filename, char *funcname,
  					   bool signalNotFound, void **filehandle);
  extern PGFunction lookup_external_function(void *filehandle, char *funcname);
  extern void load_file(char *filename);
  
  
  /*
   * !!! OLD INTERFACE !!!
   *
   * fmgr() is the only remaining vestige of the old-style caller support
   * functions.  It's no longer used anywhere in the Postgres distribution,
   * but we should leave it around for a release or two to ease the transition
   * for user-supplied C functions.  OidFunctionCallN() replaces it for new
   * code.
   */
  
  /*
   * DEPRECATED, DO NOT USE IN NEW CODE
   */
  extern char *fmgr(Oid procedureId,...);
  
  #endif   /* FMGR_H */
  