net.sf.farrago.ojrex
Class FarragoOJRexCastImplementor

java.lang.Object
  net.sf.farrago.ojrex.FarragoOJRexImplementor
      net.sf.farrago.ojrex.FarragoOJRexCastImplementor

All Implemented Interfaces:

OJRexImplementor

public class FarragoOJRexCastImplementor
extends FarragoOJRexImplementor

FarragoOJRexCastImplementor implements Farrago specifics of OJRexImplementor for CAST expressions.

A cast is described in terms of an assignment: lhs = rhs, with "lhs" meaning the variable on the left hand side and "rhs" meaning the value right hand side. The general arguments are as follows:

• The left hand side always has a target type
• The left hand side optionally specifies a target variable. If one is not specified, a new variable will usually be created.
• The right hand side usually has a source type, but may not in the case of a UDX. If so, it can only be used for AssignableValues.
• The right hand side usually has a value, but may be omitted for dynamic parameters, such as those used for a UDX.

The two main kinds of assignment are to "primitive" types and to "AssignableValue" types. If the target type is "primitive", it is represented by a primitive Java value in generated code, or a thin wrapper around one. Non-primitive types are expected to fulfill the AssignableValue interface and are assigned using that interface.

Version:

$Id: //open/dev/farrago/src/net/sf/farrago/ojrex/FarragoOJRexCastImplementor.java#41 $

Author:

John V. Sichi

Nested Class Summary

private class

FarragoOJRexCastImplementor.CastHelper Helps to implement the CAST operator for a specific cast node.

Field Summary

private static StatementList

throwOverflowStmtList

Constructor Summary

FarragoOJRexCastImplementor()

Method Summary

Expression	convertCastOrAssignment(FarragoRexToOJTranslator translator, StatementList stmtList, String targetName, RelDataType lhsType, RelDataType rhsType, Expression lhsExp, Expression rhsExp) Generates code to cast an OJ expression as another type.
Expression	convertCastToAssignableValue(FarragoRexToOJTranslator translator, StatementList stmtList, RelDataType lhsType, RelDataType rhsType, Expression lhsExp, Expression rhsExp) Generates code to cast an OJ expression as another type.
private static StatementList	getThrowStmtList() Gets a list of statements that throw an overflow exception
Expression	implementFarrago(FarragoRexToOJTranslator translator, RexCall call, Expression[] operands) Refined version of OJRexImplementor.implement(org.eigenbase.oj.rex.RexToOJTranslator, org.eigenbase.rex.RexCall, openjava.ptree.Expression[]).

Methods inherited from class net.sf.farrago.ojrex.FarragoOJRexImplementor

canImplement, implement

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

throwOverflowStmtList

private static StatementList throwOverflowStmtList

Constructor Detail

FarragoOJRexCastImplementor

public FarragoOJRexCastImplementor()

Method Detail

getThrowStmtList

private static StatementList getThrowStmtList()

Gets a list of statements that throw an overflow exception

implementFarrago

public Expression implementFarrago(FarragoRexToOJTranslator translator,
                                   RexCall call,
                                   Expression[] operands)

Description copied from class: FarragoOJRexImplementor

Refined version of OJRexImplementor.implement(org.eigenbase.oj.rex.RexToOJTranslator, org.eigenbase.rex.RexCall, openjava.ptree.Expression[]).

Specified by:

implementFarrago in class FarragoOJRexImplementor

Parameters:

translator - provides Farrago-specific translation context

call - the call to be translated

operands - call's operands, which have already been translated independently

convertCastOrAssignment

public Expression convertCastOrAssignment(FarragoRexToOJTranslator translator,
                                          StatementList stmtList,
                                          String targetName,
                                          RelDataType lhsType,
                                          RelDataType rhsType,
                                          Expression lhsExp,
                                          Expression rhsExp)

Generates code to cast an OJ expression as another type. See class description for an explanation of arguments.

Returns:

resulting expression. If lhsExp was provided, assigns this expression to lhsExp.

convertCastToAssignableValue

public Expression convertCastToAssignableValue(FarragoRexToOJTranslator translator,
                                               StatementList stmtList,
                                               RelDataType lhsType,
                                               RelDataType rhsType,
                                               Expression lhsExp,
                                               Expression rhsExp)

Generates code to cast an OJ expression as another type. The target type is limited to being an AssignableValue. See class description for an explanation of the arguments.

Returns:

resulting expression. If lhsExp was provided, assigns this expression to lhsExp.