/*
 * op_error - utility routine to complain about an unresolvable operator
 */
static void
op_error(ParseState *pstate, List *op, char oprkind,
		 Oid arg1, Oid arg2,
		 FuncDetailCode fdresult, int location)
{
	if (fdresult == FUNCDETAIL_MULTIPLE)
		ereport(ERROR,
				(errcode(ERRCODE_AMBIGUOUS_FUNCTION),
				 errmsg("operator is not unique: %s",
						op_signature_string(op, oprkind, arg1, arg2)),
				 errhint("Could not choose a best candidate operator. "
						 "You might need to add explicit type casts."),
				 parser_errposition(pstate, location)));
	else
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("operator does not exist: %s",
						op_signature_string(op, oprkind, arg1, arg2)),
				 (!arg1 || !arg2) ?
				 errhint("No operator matches the given name and argument type. "
						 "You might need to add an explicit type cast.") :
				 errhint("No operator matches the given name and argument types. "
						 "You might need to add explicit type casts."),
				 parser_errposition(pstate, location)));
}

	/*
	 * Transform the subscript expressions.
	 */
	foreach(idx, indirection)
	{
		A_Indices  *ai = (A_Indices *) lfirst(idx);
		Node	   *subexpr;

		Assert(IsA(ai, A_Indices));
		if (isSlice)
		{
			if (ai->lidx)
			{
				subexpr = transformExpr(pstate, ai->lidx);
				/* If it's not int4 already, try to coerce */
				subexpr = coerce_to_target_type(pstate,
												subexpr, exprType(subexpr),
												INT4OID, -1,
												COERCION_ASSIGNMENT,
												COERCE_IMPLICIT_CAST,
												-1);
				if (subexpr == NULL)
					ereport(ERROR,
							(errcode(ERRCODE_DATATYPE_MISMATCH),
							 errmsg("array subscript must have type integer"),
						parser_errposition(pstate, exprLocation(ai->lidx))));
			}
			else
			{
				/* Make a constant 1 */
				subexpr = (Node *) makeConst(INT4OID,
											 -1,
											 InvalidOid,
											 sizeof(int32),
											 Int32GetDatum(1),
											 false,
											 true);		/* pass by value */
			}
			lowerIndexpr = lappend(lowerIndexpr, subexpr);
		}
		subexpr = transformExpr(pstate, ai->uidx);
		/* If it's not int4 already, try to coerce */
		subexpr = coerce_to_target_type(pstate,
										subexpr, exprType(subexpr),
										INT4OID, -1,
										COERCION_ASSIGNMENT,
										COERCE_IMPLICIT_CAST,
										-1);
		if (subexpr == NULL)
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("array subscript must have type integer"),
					 parser_errposition(pstate, exprLocation(ai->uidx))));
		upperIndexpr = lappend(upperIndexpr, subexpr);
	}

/*
 * LookupOperName
 *		Given a possibly-qualified operator name and exact input datatypes,
 *		look up the operator.
 *
 * Pass oprleft = InvalidOid for a prefix op, oprright = InvalidOid for
 * a postfix op.
 *
 * If the operator name is not schema-qualified, it is sought in the current
 * namespace search path.
 *
 * If the operator is not found, we return InvalidOid if noError is true,
 * else raise an error.  pstate and location are used only to report the
 * error position; pass NULL/-1 if not available.
 */
Oid
LookupOperName(ParseState *pstate, List *opername, Oid oprleft, Oid oprright,
			   bool noError, int location)
{
	Oid			result;

	result = OpernameGetOprid(opername, oprleft, oprright);
	if (OidIsValid(result))
		return result;

	/* we don't use op_error here because only an exact match is wanted */
	if (!noError)
	{
		char		oprkind;

		if (!OidIsValid(oprleft))
			oprkind = 'l';
		else if (!OidIsValid(oprright))
			oprkind = 'r';
		else
			oprkind = 'b';

		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("operator does not exist: %s",
						op_signature_string(opername, oprkind,
											oprleft, oprright)),
				 parser_errposition(pstate, location)));
	}

	return InvalidOid;
}

/*
 * Transform a ParamRef using fixed parameter types.
 */
static Node *
fixed_paramref_hook(ParseState *pstate, ParamRef *pref)
{
	FixedParamState *parstate = (FixedParamState *) pstate->p_ref_hook_state;
	int			paramno = pref->number;
	Param	   *param;

	/* Check parameter number is valid */
	if (paramno <= 0 || paramno > parstate->numParams ||
		!OidIsValid(parstate->paramTypes[paramno - 1]))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_PARAMETER),
				 errmsg("there is no parameter $%d", paramno),
				 parser_errposition(pstate, pref->location)));

	param = makeNode(Param);
	param->paramkind = PARAM_EXTERN;
	param->paramid = paramno;
	param->paramtype = parstate->paramTypes[paramno - 1];
	param->paramtypmod = -1;
	param->paramcollid = get_typcollation(param->paramtype);
	param->location = pref->location;

	return (Node *) param;
}

/* compatible_oper()
 *	given an opname and input datatypes, find a compatible binary operator
 *
 *	This is tighter than oper() because it will not return an operator that
 *	requires coercion of the input datatypes (but binary-compatible operators
 *	are accepted).	Otherwise, the semantics are the same.
 */
Operator
compatible_oper(ParseState *pstate, List *op, Oid arg1, Oid arg2,
				bool noError, int location)
{
	Operator	optup;
	Form_pg_operator opform;

	/* oper() will find the best available match */
	optup = oper(pstate, op, arg1, arg2, noError, location);
	if (optup == (Operator) NULL)
		return (Operator) NULL; /* must be noError case */

	/* but is it good enough? */
	opform = (Form_pg_operator) GETSTRUCT(optup);
	if (IsBinaryCoercible(arg1, opform->oprleft) &&
		IsBinaryCoercible(arg2, opform->oprright))
		return optup;

	/* nope... */
	ReleaseSysCache(optup);

	if (!noError)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("operator requires run-time type coercion: %s",
						op_signature_string(op, 'b', arg1, arg2)),
				 parser_errposition(pstate, location)));

	return (Operator) NULL;
}

/*
 * Error context callback for inserting parser error location.
 *
 * Note that this will be called for *any* error occurring while the
 * callback is installed.  We avoid inserting an irrelevant error location
 * if the error is a query cancel --- are there any other important cases?
 */
static void
pcb_error_callback(void *arg)
{
	ParseCallbackState *pcbstate = (ParseCallbackState *) arg;

	if (geterrcode() != ERRCODE_QUERY_CANCELED)
		(void) parser_errposition(pcbstate->pstate, pcbstate->location);
}

/*
 * Traverse a fully-analyzed tree to verify that parameter symbols
 * match their types.  We need this because some Params might still
 * be UNKNOWN, if there wasn't anything to force their coercion,
 * and yet other instances seen later might have gotten coerced.
 */
static bool
check_parameter_resolution_walker(Node *node, ParseState *pstate)
{
	if (node == NULL)
		return false;
	if (IsA(node, Param))
	{
		Param	   *param = (Param *) node;

		if (param->paramkind == PARAM_EXTERN)
		{
			VarParamState *parstate = (VarParamState *) pstate->p_ref_hook_state;
			int			paramno = param->paramid;

			if (paramno <= 0 || /* shouldn't happen, but... */
				paramno > *parstate->numParams)
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_PARAMETER),
						 errmsg("there is no parameter $%d", paramno),
						 parser_errposition(pstate, param->location)));

			if (param->paramtype != (*parstate->paramTypes)[paramno - 1])
				ereport(ERROR,
						(errcode(ERRCODE_AMBIGUOUS_PARAMETER),
					 errmsg("could not determine data type of parameter $%d",
							paramno),
						 parser_errposition(pstate, param->location)));
		}
		return false;
	}
	if (IsA(node, Query))
	{
		/* Recurse into RTE subquery or not-yet-planned sublink subquery */
		return query_tree_walker((Query *) node,
								 check_parameter_resolution_walker,
								 (void *) pstate, 0);
	}
	return expression_tree_walker(node, check_parameter_resolution_walker,
								  (void *) pstate);
}

/*
 * Transform a ParamRef using variable parameter types.
 *
 * The only difference here is we must enlarge the parameter type array
 * as needed.
 */
static Node *
variable_paramref_hook(ParseState *pstate, ParamRef *pref)
{
	VarParamState *parstate = (VarParamState *) pstate->p_ref_hook_state;
	int			paramno = pref->number;
	Oid		   *pptype;
	Param	   *param;

	/* Check parameter number is in range */
	if (paramno <= 0 || paramno > INT_MAX / sizeof(Oid))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_PARAMETER),
				 errmsg("there is no parameter $%d", paramno),
				 parser_errposition(pstate, pref->location)));
	if (paramno > *parstate->numParams)
	{
		/* Need to enlarge param array */
		if (*parstate->paramTypes)
			*parstate->paramTypes = (Oid *) repalloc(*parstate->paramTypes,
													 paramno * sizeof(Oid));
		else
			*parstate->paramTypes = (Oid *) palloc(paramno * sizeof(Oid));
		/* Zero out the previously-unreferenced slots */
		MemSet(*parstate->paramTypes + *parstate->numParams,
			   0,
			   (paramno - *parstate->numParams) * sizeof(Oid));
		*parstate->numParams = paramno;
	}

	/* Locate param's slot in array */
	pptype = &(*parstate->paramTypes)[paramno - 1];

	/* If not seen before, initialize to UNKNOWN type */
	if (*pptype == InvalidOid)
		*pptype = UNKNOWNOID;

	param = makeNode(Param);
	param->paramkind = PARAM_EXTERN;
	param->paramid = paramno;
	param->paramtype = *pptype;
	param->paramtypmod = -1;
	param->paramcollid = get_typcollation(param->paramtype);
	param->location = pref->location;

	return (Node *) param;
}

/*
 *	Parse a function call
 *
 *	For historical reasons, Postgres tries to treat the notations tab.col
 *	and col(tab) as equivalent: if a single-argument function call has an
 *	argument of complex type and the (unqualified) function name matches
 *	any attribute of the type, we take it as a column projection.  Conversely
 *	a function of a single complex-type argument can be written like a
 *	column reference, allowing functions to act like computed columns.
 *
 *	Hence, both cases come through here.  The is_column parameter tells us
 *	which syntactic construct is actually being dealt with, but this is
 *	intended to be used only to deliver an appropriate error message,
 *	not to affect the semantics.  When is_column is true, we should have
 *	a single argument (the putative table), unqualified function name
 *	equal to the column name, and no aggregate decoration.
 *
 *	The argument expressions (in fargs) must have been transformed already.
 */
Node *
ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
                  List *agg_order, bool agg_star, bool agg_distinct, 
                  bool is_column, WindowSpec *over, int location, 
                  Node *agg_filter)
{
	Oid			rettype = InvalidOid;
	Oid			funcid = InvalidOid;
	ListCell   *l;
	ListCell   *nextl;
	Node	   *first_arg = NULL;
	int			nargs;
	Oid			actual_arg_types[FUNC_MAX_ARGS];
	Oid		   *declared_arg_types = NULL;
	Node	   *retval = NULL;
	bool		retset = false;
	bool        retstrict = false;
	bool        retordered = false;
	FuncDetailCode fdresult;

	/*
	 * Most of the rest of the parser just assumes that functions do not have
	 * more than FUNC_MAX_ARGS parameters.	We have to test here to protect
	 * against array overruns, etc.  Of course, this may not be a function,
	 * but the test doesn't hurt.
	 */
	if (list_length(fargs) > FUNC_MAX_ARGS)
		ereport(ERROR,
				(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
				 errmsg("cannot pass more than %d arguments to a function",
						FUNC_MAX_ARGS),
				 parser_errposition(pstate, location)));

	/* 
	 * Perform the FILTER -> CASE transform.
	 *    FUNC(expr) FILTER (WHERE cond)  =>  FUNC(CASE WHEN cond THEN expr END)
	 * This must be done for every parameter of the function and special handling
	 * is needed for FUNC(*).  
	 *
	 * For this to be a valid transform we must assume that NULLs passed into
	 * the function will not change the result.  This assumption is not valid
	 * for count(*), which is why we need special processing for this case.  If
	 * it is not a valid assumption for other cases we may need to rethink how
	 * we implement FILTER.
	 */
	if (agg_filter) 
	{
		List *newfargs = NULL;

		if (agg_star || !fargs)
		{
			/*
			 * FUNC(*) => assume that datatype doesn't matter 
			 * By converting agg_star into a conditional constant boolean 
			 * expression we get the correct results for count(*) since it
			 * will then supress the NULLs returned by the CASE statement.
			 */
			CaseExpr  *c = makeNode(CaseExpr);
			CaseWhen  *w = makeNode(CaseWhen);
			A_Const   *a = makeNode(A_Const);
			a->val.type  = T_Integer;
			a->val.val.ival = 1;    /* Actual value shouldn't matter */
			w->expr      = (Expr *) agg_filter;
			w->result    = (Expr *) a;
			c->casetype  = InvalidOid;  /* will analyze in a moment */
			c->arg       = (Expr *) NULL;
			c->defresult = (Expr *) NULL;
			c->args      = list_make1(w);
			newfargs     = list_make1(c);
		
			/* 
			 * Since we haven't checked the compatability of our function with
			 * agg_star we can not clear the local bit yet, otherwise we would
			 * loose track of the fact that this was an agg_star operation prior
			 * to transformation.
			 */
		}
		else
		{
			Assert(fargs && list_length(fargs) > 0);

//.........这里部分代码省略.........

/*
 * make_scalar_array_op()
 *		Build expression tree for "scalar op ANY/ALL (array)" construct.
 */
Expr *
make_scalar_array_op(ParseState *pstate, List *opname,
					 bool useOr,
					 Node *ltree, Node *rtree,
					 int location)
{
	Oid			ltypeId,
				rtypeId,
				atypeId,
				res_atypeId;
	Operator	tup;
	Form_pg_operator opform;
	Oid			actual_arg_types[2];
	Oid			declared_arg_types[2];
	List	   *args;
	Oid			rettype;
	ScalarArrayOpExpr *result;

	ltypeId = exprType(ltree);
	atypeId = exprType(rtree);

	/*
	 * The right-hand input of the operator will be the element type of the
	 * array.  However, if we currently have just an untyped literal on the
	 * right, stay with that and hope we can resolve the operator.
	 */
	if (atypeId == UNKNOWNOID)
		rtypeId = UNKNOWNOID;
	else
	{
		rtypeId = get_base_element_type(atypeId);
		if (!OidIsValid(rtypeId))
			ereport(ERROR,
					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				   errmsg("op ANY/ALL (array) requires array on right side"),
					 parser_errposition(pstate, location)));
	}

	/* Now resolve the operator */
	tup = oper(pstate, opname, ltypeId, rtypeId, false, location);
	opform = (Form_pg_operator) GETSTRUCT(tup);

	/* Check it's not a shell */
	if (!RegProcedureIsValid(opform->oprcode))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("operator is only a shell: %s",
						op_signature_string(opname,
											opform->oprkind,
											opform->oprleft,
											opform->oprright)),
				 parser_errposition(pstate, location)));

	args = list_make2(ltree, rtree);
	actual_arg_types[0] = ltypeId;
	actual_arg_types[1] = rtypeId;
	declared_arg_types[0] = opform->oprleft;
	declared_arg_types[1] = opform->oprright;

	/*
	 * enforce consistency with polymorphic argument and return types,
	 * possibly adjusting return type or declared_arg_types (which will be
	 * used as the cast destination by make_fn_arguments)
	 */
	rettype = enforce_generic_type_consistency(actual_arg_types,
											   declared_arg_types,
											   2,
											   opform->oprresult,
											   false);

	/*
	 * Check that operator result is boolean
	 */
	if (rettype != BOOLOID)
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
			 errmsg("op ANY/ALL (array) requires operator to yield boolean"),
				 parser_errposition(pstate, location)));
	if (get_func_retset(opform->oprcode))
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
		  errmsg("op ANY/ALL (array) requires operator not to return a set"),
				 parser_errposition(pstate, location)));

	/*
	 * Now switch back to the array type on the right, arranging for any
	 * needed cast to be applied.  Beware of polymorphic operators here;
	 * enforce_generic_type_consistency may or may not have replaced a
	 * polymorphic type with a real one.
	 */
	if (IsPolymorphicType(declared_arg_types[1]))
	{
		/* assume the actual array type is OK */
		res_atypeId = atypeId;
	}
	else
//.........这里部分代码省略.........

/*
 * make_op()
 *		Operator expression construction.
 *
 * Transform operator expression ensuring type compatibility.
 * This is where some type conversion happens.
 *
 * As with coerce_type, pstate may be NULL if no special unknown-Param
 * processing is wanted.
 */
Expr *
make_op(ParseState *pstate, List *opname, Node *ltree, Node *rtree,
		int location)
{
	Oid			ltypeId,
				rtypeId;
	Operator	tup;
	Form_pg_operator opform;
	Oid			actual_arg_types[2];
	Oid			declared_arg_types[2];
	int			nargs;
	List	   *args;
	Oid			rettype;
	OpExpr	   *result;

	/* Select the operator */
	if (rtree == NULL)
	{
		/* right operator */
		ltypeId = exprType(ltree);
		rtypeId = InvalidOid;
		tup = right_oper(pstate, opname, ltypeId, false, location);
	}
	else if (ltree == NULL)
	{
		/* left operator */
		rtypeId = exprType(rtree);
		ltypeId = InvalidOid;
		tup = left_oper(pstate, opname, rtypeId, false, location);
	}
	else
	{
		/* otherwise, binary operator */
		ltypeId = exprType(ltree);
		rtypeId = exprType(rtree);
		tup = oper(pstate, opname, ltypeId, rtypeId, false, location);
	}

	opform = (Form_pg_operator) GETSTRUCT(tup);

	/* Check it's not a shell */
	if (!RegProcedureIsValid(opform->oprcode))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("operator is only a shell: %s",
						op_signature_string(opname,
											opform->oprkind,
											opform->oprleft,
											opform->oprright)),
				 parser_errposition(pstate, location)));

	/* Do typecasting and build the expression tree */
	if (rtree == NULL)
	{
		/* right operator */
		args = list_make1(ltree);
		actual_arg_types[0] = ltypeId;
		declared_arg_types[0] = opform->oprleft;
		nargs = 1;
	}
	else if (ltree == NULL)
	{
		/* left operator */
		args = list_make1(rtree);
		actual_arg_types[0] = rtypeId;
		declared_arg_types[0] = opform->oprright;
		nargs = 1;
	}
	else
	{
		/* otherwise, binary operator */
		args = list_make2(ltree, rtree);
		actual_arg_types[0] = ltypeId;
		actual_arg_types[1] = rtypeId;
		declared_arg_types[0] = opform->oprleft;
		declared_arg_types[1] = opform->oprright;
		nargs = 2;
	}

	/*
	 * enforce consistency with polymorphic argument and return types,
	 * possibly adjusting return type or declared_arg_types (which will be
	 * used as the cast destination by make_fn_arguments)
	 */
	rettype = enforce_generic_type_consistency(actual_arg_types,
											   declared_arg_types,
											   nargs,
											   opform->oprresult,
											   false);

//.........这里部分代码省略.........

/*
 * Coerce a Param to a query-requested datatype, in the varparams case.
 */
static Node *
variable_coerce_param_hook(ParseState *pstate, Param *param,
						   Oid targetTypeId, int32 targetTypeMod,
						   int location)
{
	if (param->paramkind == PARAM_EXTERN && param->paramtype == UNKNOWNOID)
	{
		/*
		 * Input is a Param of previously undetermined type, and we want to
		 * update our knowledge of the Param's type.
		 */
		VarParamState *parstate = (VarParamState *) pstate->p_ref_hook_state;
		Oid		   *paramTypes = *parstate->paramTypes;
		int			paramno = param->paramid;

		if (paramno <= 0 ||		/* shouldn't happen, but... */
			paramno > *parstate->numParams)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_PARAMETER),
					 errmsg("there is no parameter $%d", paramno),
					 parser_errposition(pstate, param->location)));

		if (paramTypes[paramno - 1] == UNKNOWNOID)
		{
			/* We've successfully resolved the type */
			paramTypes[paramno - 1] = targetTypeId;
		}
		else if (paramTypes[paramno - 1] == targetTypeId)
		{
			/* We previously resolved the type, and it matches */
		}
		else
		{
			/* Ooops */
			ereport(ERROR,
					(errcode(ERRCODE_AMBIGUOUS_PARAMETER),
					 errmsg("inconsistent types deduced for parameter $%d",
							paramno),
					 errdetail("%s versus %s",
							   format_type_be(paramTypes[paramno - 1]),
							   format_type_be(targetTypeId)),
					 parser_errposition(pstate, param->location)));
		}

		param->paramtype = targetTypeId;

		/*
		 * Note: it is tempting here to set the Param's paramtypmod to
		 * targetTypeMod, but that is probably unwise because we have no
		 * infrastructure that enforces that the value delivered for a Param
		 * will match any particular typmod.  Leaving it -1 ensures that a
		 * run-time length check/coercion will occur if needed.
		 */
		param->paramtypmod = -1;

		/*
		 * This module always sets a Param's collation to be the default for
		 * its datatype.  If that's not what you want, you should be using
		 * the more general parser substitution hooks.
		 */
		param->paramcollid = get_typcollation(param->paramtype);

		/* Use the leftmost of the param's and coercion's locations */
		if (location >= 0 &&
			(param->location < 0 || location < param->location))
			param->location = location;

		return (Node *) param;
	}

	/* Else signal to proceed with normal coercion */
	return NULL;
}

/*
 *	Parse a function call
 *
 *	For historical reasons, Postgres tries to treat the notations tab.col
 *	and col(tab) as equivalent: if a single-argument function call has an
 *	argument of complex type and the (unqualified) function name matches
 *	any attribute of the type, we take it as a column projection.  Conversely
 *	a function of a single complex-type argument can be written like a
 *	column reference, allowing functions to act like computed columns.
 *
 *	Hence, both cases come through here.  The is_column parameter tells us
 *	which syntactic construct is actually being dealt with, but this is
 *	intended to be used only to deliver an appropriate error message,
 *	not to affect the semantics.  When is_column is true, we should have
 *	a single argument (the putative table), unqualified function name
 *	equal to the column name, and no aggregate or variadic decoration.
 *	Also, when is_column is true, we return NULL on failure rather than
 *	reporting a no-such-function error.
 *
 *	The argument expressions (in fargs) must have been transformed already.
 *	But the agg_order expressions, if any, have not been.
 */
Node *
ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
				  List *agg_order, bool agg_star, bool agg_distinct,
				  bool func_variadic,
				  WindowDef *over, bool is_column, int location)
{
	Oid			rettype;
	Oid			funcid;
	ListCell   *l;
	ListCell   *nextl;
	Node	   *first_arg = NULL;
	int			nargs;
	int			nargsplusdefs;
	Oid			actual_arg_types[FUNC_MAX_ARGS];
	Oid		   *declared_arg_types;
	List	   *argnames;
	List	   *argdefaults;
	Node	   *retval;
	bool		retset;
	int			nvargs;
	FuncDetailCode fdresult;

	/*
	 * Most of the rest of the parser just assumes that functions do not have
	 * more than FUNC_MAX_ARGS parameters.	We have to test here to protect
	 * against array overruns, etc.  Of course, this may not be a function,
	 * but the test doesn't hurt.
	 */
	if (list_length(fargs) > FUNC_MAX_ARGS)
		ereport(ERROR,
				(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
			 errmsg_plural("cannot pass more than %d argument to a function",
						   "cannot pass more than %d arguments to a function",
						   FUNC_MAX_ARGS,
						   FUNC_MAX_ARGS),
				 parser_errposition(pstate, location)));

	/*
	 * Extract arg type info in preparation for function lookup.
	 *
	 * If any arguments are Param markers of type VOID, we discard them from
	 * the parameter list.	This is a hack to allow the JDBC driver to not
	 * have to distinguish "input" and "output" parameter symbols while
	 * parsing function-call constructs.  We can't use foreach() because we
	 * may modify the list ...
	 */
	nargs = 0;
	for (l = list_head(fargs); l != NULL; l = nextl)
	{
		Node	   *arg = lfirst(l);
		Oid			argtype = exprType(arg);

		nextl = lnext(l);

		if (argtype == VOIDOID && IsA(arg, Param) &&!is_column)
		{
			fargs = list_delete_ptr(fargs, arg);
			continue;
		}

		actual_arg_types[nargs++] = argtype;
	}

	/*
	 * Check for named arguments; if there are any, build a list of names.
	 *
	 * We allow mixed notation (some named and some not), but only with all
	 * the named parameters after all the unnamed ones.  So the name list
	 * corresponds to the last N actual parameters and we don't need any extra
	 * bookkeeping to match things up.
	 */
	argnames = NIL;
	foreach(l, fargs)
	{
		Node	   *arg = lfirst(l);

		if (IsA(arg, NamedArgExpr))
		{
//.........这里部分代码省略.........

				if (strcmp(na->name, (char *) lfirst(lc)) == 0)
					ereport(ERROR,
							(errcode(ERRCODE_SYNTAX_ERROR),
						   errmsg("argument name \"%s\" used more than once",
								  na->name),
							 parser_errposition(pstate, na->location)));
			}
			argnames = lappend(argnames, na->name);
		}
		else
		{
			if (argnames != NIL)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
				  errmsg("positional argument cannot follow named argument"),
						 parser_errposition(pstate, exprLocation(arg))));
		}
	}

	if (fargs)
	{
		first_arg = linitial(fargs);
		Assert(first_arg != NULL);
	}

	/*
	 * Check for column projection: if function has one argument, and that
	 * argument is of complex type, and function name is not qualified, then
	 * the "function call" could be a projection.  We also check that there
	 * wasn't any aggregate or variadic decoration, nor an argument name.
	 */

/*
 *	Parse a function call
 *
 *	For historical reasons, Postgres tries to treat the notations tab.col
 *	and col(tab) as equivalent: if a single-argument function call has an
 *	argument of complex type and the (unqualified) function name matches
 *	any attribute of the type, we take it as a column projection.  Conversely
 *	a function of a single complex-type argument can be written like a
 *	column reference, allowing functions to act like computed columns.
 *
 *	Hence, both cases come through here.  The is_column parameter tells us
 *	which syntactic construct is actually being dealt with, but this is
 *	intended to be used only to deliver an appropriate error message,
 *	not to affect the semantics.  When is_column is true, we should have
 *	a single argument (the putative table), unqualified function name
 *	equal to the column name, and no aggregate or variadic decoration.
 *
 *	The argument expressions (in fargs) must have been transformed already.
 */
Node *
ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
				  bool agg_star, bool agg_distinct, bool func_variadic,
				  WindowDef *over, bool is_column, int location)
{
	Oid			rettype;
	Oid			funcid;
	ListCell   *l;
	ListCell   *nextl;
	Node	   *first_arg = NULL;
	int			nargs;
	int			nargsplusdefs;
	Oid			actual_arg_types[FUNC_MAX_ARGS];
	Oid		   *declared_arg_types;
	List	   *argdefaults;
	Node	   *retval;
	bool		retset;
	int			nvargs;
	FuncDetailCode fdresult;

	/*
	 * Most of the rest of the parser just assumes that functions do not have
	 * more than FUNC_MAX_ARGS parameters.	We have to test here to protect
	 * against array overruns, etc.  Of course, this may not be a function,
	 * but the test doesn't hurt.
	 */
	if (list_length(fargs) > FUNC_MAX_ARGS)
		ereport(ERROR,
				(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
			 errmsg_plural("cannot pass more than %d argument to a function",
						   "cannot pass more than %d arguments to a function",
						   FUNC_MAX_ARGS,
						   FUNC_MAX_ARGS),
				 parser_errposition(pstate, location)));

	/*
	 * Extract arg type info in preparation for function lookup.
	 *
	 * If any arguments are Param markers of type VOID, we discard them from
	 * the parameter list.	This is a hack to allow the JDBC driver to not
	 * have to distinguish "input" and "output" parameter symbols while
	 * parsing function-call constructs.  We can't use foreach() because we
	 * may modify the list ...
	 */
	nargs = 0;
	for (l = list_head(fargs); l != NULL; l = nextl)
	{
		Node	   *arg = lfirst(l);
		Oid			argtype = exprType(arg);

		nextl = lnext(l);

		if (argtype == VOIDOID && IsA(arg, Param) &&!is_column)
		{
			fargs = list_delete_ptr(fargs, arg);
			continue;
		}

		actual_arg_types[nargs++] = argtype;
	}

	if (fargs)
	{
		first_arg = linitial(fargs);
		Assert(first_arg != NULL);
	}

	/*
	 * Check for column projection: if function has one argument, and that
	 * argument is of complex type, and function name is not qualified, then
	 * the "function call" could be a projection.  We also check that there
	 * wasn't any aggregate or variadic decoration.
	 */
	if (nargs == 1 && !agg_star && !agg_distinct && over == NULL &&
		!func_variadic && list_length(funcname) == 1)
	{
		Oid			argtype = actual_arg_types[0];

		if (argtype == RECORDOID || ISCOMPLEX(argtype))
		{
			retval = ParseComplexProjection(pstate,
//.........这里部分代码省略.........

/*
 * make_scalar_array_op()
 *		Build expression tree for "scalar op ANY/ALL (array)" construct.
 */
Expr *
make_scalar_array_op(ParseState *pstate, List *opname,
					 bool useOr,
					 Node *ltree, Node *rtree,
					 int location)
{
	Oid			ltypeId,
				rtypeId,
				atypeId,
				res_atypeId;
	Operator	tup;
	Form_pg_operator opform;
	Oid			actual_arg_types[2];
	Oid			declared_arg_types[2];
	List	   *args;
	Oid			rettype;
	ScalarArrayOpExpr *result;

	ltypeId = exprType(ltree);
	atypeId = exprType(rtree);

	/*
	 * The right-hand input of the operator will be the element type of the
	 * array.  However, if we currently have just an untyped literal on the
	 * right, stay with that and hope we can resolve the operator.
	 */
	if (atypeId == UNKNOWNOID)
		rtypeId = UNKNOWNOID;
	else
	{
		rtypeId = get_element_type(atypeId);
		if (!OidIsValid(rtypeId))
			ereport(ERROR,
					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				   errmsg("op ANY/ALL (array) requires array on right side"),
						   errOmitLocation(true),
					 parser_errposition(pstate, location)));
	}

	/* Now resolve the operator */
	tup = oper(pstate, opname, ltypeId, rtypeId, false, location);
	opform = (Form_pg_operator) GETSTRUCT(tup);

	args = list_make2(ltree, rtree);
	actual_arg_types[0] = ltypeId;
	actual_arg_types[1] = rtypeId;
	declared_arg_types[0] = opform->oprleft;
	declared_arg_types[1] = opform->oprright;

	/*
	 * enforce consistency with ANYARRAY and ANYELEMENT argument and return
	 * types, possibly adjusting return type or declared_arg_types (which will
	 * be used as the cast destination by make_fn_arguments)
	 */
	rettype = enforce_generic_type_consistency(actual_arg_types,
											   declared_arg_types,
											   2,
											   opform->oprresult);

	/*
	 * Check that operator result is boolean
	 */
	if (rettype != BOOLOID)
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
			 errmsg("op ANY/ALL (array) requires operator to yield boolean"),
					 errOmitLocation(true),
				 parser_errposition(pstate, location)));
	if (get_func_retset(opform->oprcode))
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
		  errmsg("op ANY/ALL (array) requires operator not to return a set"),
				  errOmitLocation(true),
				 parser_errposition(pstate, location)));

	/*
	 * Now switch back to the array type on the right, arranging for any
	 * needed cast to be applied.
	 */
	res_atypeId = get_array_type(declared_arg_types[1]);
	if (!OidIsValid(res_atypeId))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("could not find array type for data type %s",
						format_type_be(declared_arg_types[1])),
				 errOmitLocation(true),
				 parser_errposition(pstate, location)));
	actual_arg_types[1] = atypeId;
	declared_arg_types[1] = res_atypeId;

	/* perform the necessary typecasting of arguments */
	make_fn_arguments(pstate, args, actual_arg_types, declared_arg_types);

	/* and build the expression node */
	result = makeNode(ScalarArrayOpExpr);
	result->opno = oprid(tup);
//.........这里部分代码省略.........