org.eigenbase.sql.fun
Class SqlSubstringFunction

java.lang.Object
  org.eigenbase.sql.SqlOperator
      org.eigenbase.sql.SqlFunction
          org.eigenbase.sql.fun.SqlSubstringFunction

public class SqlSubstringFunction
extends SqlFunction

Definition of the "SUBSTRING" builtin SQL function.

Since:

Sep 5, 2004

Version:

$Id: //open/dev/farrago/src/org/eigenbase/sql/fun/SqlSubstringFunction.java#22 $

Author:

Wael Chatila

Field Summary

Fields inherited from class org.eigenbase.sql.SqlOperator

MaxPrec, NL

Constructor Summary

SqlSubstringFunction()
Creates the SqlSubstringFunction.

Method Summary

boolean	checkOperandTypes(SqlCallBinding callBinding, boolean throwOnFailure) Checks that the operand values in a SqlCall to this operator are valid.
String	getAllowedSignatures(String opName) Returns a string describing the expected operand types of a call, e.g.
SqlMonotonicity	getMonotonicity(SqlCall call, SqlValidatorScope scope) Returns whether this operator is monotonic.
SqlOperandCountRange	getOperandCountRange() Returns a constraint on the number of operands expected by this operator.
String	getSignatureTemplate(int operandsCount) Returns a template describing how the operator signature is to be built.
void	unparse(SqlWriter writer, SqlNode[] operands, int leftPrec, int rightPrec) Writes a SQL representation of a call to this operator to a writer, including parentheses if the operators on either side are of greater precedence.

Methods inherited from class org.eigenbase.sql.SqlFunction

deriveType, getFunctionType, getNameAsId, getParamTypes, getSqlIdentifier, getSyntax, isQuantifierAllowed, validateCall, validateQuantifier

Methods inherited from class org.eigenbase.sql.SqlOperator

acceptCall, acceptCall, adjustType, argumentMustBeScalar, checkOperandCount, createCall, createCall, createCall, createCall, equals, getAllowedSignatures, getKind, getLeftPrec, getName, getOperandTypeChecker, getOperandTypeInference, getReturnTypeInference, getRightPrec, hashCode, inferReturnType, inferReturnType, isAggregator, isDeterministic, isDynamicFunction, isName, leftPrec, preValidateCall, requiresDecimalExpansion, rewriteCall, rightPrec, toString, unparseListClause, unparseListClause, validateOperands

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

SqlSubstringFunction

SqlSubstringFunction()

Creates the SqlSubstringFunction.

Method Detail

getSignatureTemplate

public String getSignatureTemplate(int operandsCount)

Description copied from class: SqlOperator

Returns a template describing how the operator signature is to be built. E.g for the binary + operator the template looks like "{1} {0} {2}" {0} is the operator, subsequent numbers are operands.

Overrides:

getSignatureTemplate in class SqlOperator

Parameters:

operandsCount - is used with functions that can take a variable number of operands

Returns:

signature template, or null to indicate that a default template will suffice

getAllowedSignatures

public String getAllowedSignatures(String opName)

Description copied from class: SqlOperator

Returns a string describing the expected operand types of a call, e.g. "SUBSTRING(VARCHAR, INTEGER, INTEGER)" where the name (SUBSTRING in this example) can be replaced by a specifed name.

Overrides:

getAllowedSignatures in class SqlOperator

checkOperandTypes

public boolean checkOperandTypes(SqlCallBinding callBinding,
                                 boolean throwOnFailure)

Description copied from class: SqlOperator

Checks that the operand values in a SqlCall to this operator are valid. Subclasses must either override this method or supply an instance of SqlOperandTypeChecker to the constructor.

Overrides:

checkOperandTypes in class SqlOperator

Parameters:

callBinding - description of call

throwOnFailure - whether to throw an exception if check fails (otherwise returns false in that case)

Returns:

whether check succeeded

getOperandCountRange

public SqlOperandCountRange getOperandCountRange()

Description copied from class: SqlOperator

Returns a constraint on the number of operands expected by this operator. Subclasses may override this method; when they don't, the range is derived from the SqlOperandTypeChecker associated with this operator.

Overrides:

getOperandCountRange in class SqlOperator

Returns:

acceptable range

unparse

public void unparse(SqlWriter writer,
                    SqlNode[] operands,
                    int leftPrec,
                    int rightPrec)

Description copied from class: SqlOperator

Writes a SQL representation of a call to this operator to a writer, including parentheses if the operators on either side are of greater precedence.

The default implementation of this method delegates to SqlSyntax.unparse(org.eigenbase.sql.SqlWriter, org.eigenbase.sql.SqlOperator, org.eigenbase.sql.SqlNode[], int, int).

Overrides:

unparse in class SqlFunction

getMonotonicity

public SqlMonotonicity getMonotonicity(SqlCall call,
                                       SqlValidatorScope scope)

Description copied from class: SqlOperator

Returns whether this operator is monotonic.

Default implementation returns SqlMonotonicity.NotMonotonic.

Overrides:

getMonotonicity in class SqlOperator

Parameters:

call - Call to this operator

scope - Scope in which the call occurs