Package org.apache.calcite.sql.fun

Class SqlConvertFunction

java.lang.Object

org.apache.calcite.sql.SqlOperator

org.apache.calcite.sql.SqlFunction

org.apache.calcite.sql.fun.SqlConvertFunction

Direct Known Subclasses:

SqlTranslateFunction

public class SqlConvertFunction
extends SqlFunction

The CONVERT function, which converts a string from one character set to another.

Also the base class for the CONVERT(string USING transcoding) and TRANSLATE(string USING transcoding) functions (see SqlTranslateFunction).

The SQL syntax is

   CONVERT(characterString, sourceCharset, destCharset)
 

Field Summary

Fields inherited from class org.apache.calcite.sql.SqlOperator

kind, MDX_PRECEDENCE, NL

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	SqlConvertFunction(String name)
protected	SqlConvertFunction(String name, SqlKind kind, @Nullable SqlReturnTypeInference returnTypeInference, @Nullable SqlOperandTypeInference operandTypeInference, @Nullable SqlOperandTypeChecker operandTypeChecker, SqlFunctionCategory category)

Method Summary

Modifier and Type	Method	Description
<R> void	acceptCall(SqlVisitor<R> visitor, SqlCall call, boolean onlyExpressions, SqlBasicVisitor.ArgHandler<R> argHandler)	Accepts a SqlVisitor, directing an SqlBasicVisitor.ArgHandler to visit an operand of a call.
boolean	checkOperandTypes(SqlCallBinding callBinding, boolean throwOnFailure)	Checks that the operand values in a SqlCall to this operator are valid.
RelDataType	deriveType(SqlValidator validator, SqlValidatorScope scope, SqlCall call)	Derives the type of a call to this operator.
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, SqlCall call, 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.
void	validateCall(SqlCall call, SqlValidator validator, SqlValidatorScope scope, SqlValidatorScope operandScope)	Validates a call to this operator.

Methods inherited from class org.apache.calcite.sql.SqlFunction

getFunctionType, getNameAsId, getParamNames, getParamTypes, getSqlIdentifier, getSyntax, isQuantifierAllowed, validateQuantifier

Methods inherited from class org.apache.calcite.sql.SqlOperator

acceptCall, adjustType, allowsFraming, argumentMustBeScalar, checkOperandCount, constructArgNameList, constructArgTypeList, constructOperandList, createCall, createCall, createCall, createCall, createCall, createCall, createCall, deriveOperandType, equals, getAllowedSignatures, getAllowedSignatures, getKind, getLeftPrec, getMonotonicity, getMonotonicity, getName, getOperandTypeChecker, getOperandTypeInference, getReturnTypeInference, getRightPrec, getStrongPolicyInference, hashCode, inferReturnType, inferReturnType, isAggregator, isDeterministic, isDynamicFunction, isGroup, isGroupAuxiliary, isName, isSymmetrical, leftPrec, not, preValidateCall, requiresDecimalExpansion, requiresOrder, requiresOver, reverse, rewriteCall, rightPrec, toString, unparseListClause, unparseListClause, validateOperands, validRexOperands

Methods inherited from class java.lang.Object

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

Constructor Details

SqlConvertFunction

protected SqlConvertFunction(String name)

SqlConvertFunction

protected SqlConvertFunction(String name,
 SqlKind kind,
 @Nullable SqlReturnTypeInference returnTypeInference,
 @Nullable SqlOperandTypeInference operandTypeInference,
 @Nullable SqlOperandTypeChecker operandTypeChecker,
 SqlFunctionCategory category)

Method Details

validateCall

public void validateCall(SqlCall call,
 SqlValidator validator,
 SqlValidatorScope scope,
 SqlValidatorScope operandScope)

Description copied from class: SqlOperator

Validates a call to this operator.

This method should not perform type-derivation or perform validation related related to types. That is done later, by SqlOperator.deriveType(SqlValidator, SqlValidatorScope, SqlCall). This method should focus on structural validation.

A typical implementation of this method first validates the operands, then performs some operator-specific logic. The default implementation just validates the operands.

This method is the default implementation of SqlCall.validate(org.apache.calcite.sql.validate.SqlValidator, org.apache.calcite.sql.validate.SqlValidatorScope); but note that some sub-classes of SqlCall never call this method.

Overrides:

validateCall in class SqlFunction

Parameters:

call - the call to this operator

validator - the active validator

scope - validator scope

operandScope - validator scope in which to validate operands to this call; usually equal to scope, but not always because some operators introduce new scopes

See Also:

• SqlNode.validateExpr(SqlValidator, SqlValidatorScope)
• SqlOperator.deriveType(SqlValidator, SqlValidatorScope, SqlCall)

acceptCall

public <R> void acceptCall(SqlVisitor<R> visitor,
 SqlCall call,
 boolean onlyExpressions,
 SqlBasicVisitor.ArgHandler<R> argHandler)

Description copied from class: SqlOperator

Accepts a SqlVisitor, directing an SqlBasicVisitor.ArgHandler to visit an operand of a call.

The argument handler allows fine control about how the operands are visited, and how the results are combined.

Overrides:

acceptCall in class SqlOperator

Parameters:

visitor - Visitor

call - Call to visit

onlyExpressions - If true, ignores operands which are not expressions. For example, in the call to the AS operator

argHandler - Called for each operand

deriveType

public RelDataType deriveType(SqlValidator validator,
 SqlValidatorScope scope,
 SqlCall call)

Description copied from class: SqlOperator

Derives the type of a call to this operator.

This method is an intrinsic part of the validation process so, unlike SqlOperator.inferReturnType(org.apache.calcite.sql.SqlOperatorBinding), specific operators would not typically override this method.

Overrides:

deriveType in class SqlFunction

Parameters:

validator - Validator

scope - Scope of validation

call - Call to this operator

Returns:

Type of call

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

unparse

public void unparse(SqlWriter writer,
 SqlCall call,
 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.apache.calcite.sql.SqlWriter, org.apache.calcite.sql.SqlOperator, org.apache.calcite.sql.SqlCall, int, int).

Overrides:

unparse in class SqlFunction

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

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