saffron.rel
Class InternalTranslator

java.lang.Object
  |
  +--openjava.ptree.util.ParseTreeVisitor
        |
        +--openjava.ptree.util.EvaluationShuttle
              |
              +--saffron.rel.InternalTranslator

Direct Known Subclasses:

AggInternalTranslator

class InternalTranslator

extends EvaluationShuttle

Converts an expression into one which references only internal variables.

For example, the filter expression emp.sal > 50 from select * from emp where emp.sal > 50 becomes $input0.sal > 50. And emp.deptno == dept.deptno becomes $input.$0.deptno == $input.$1.deptno.

Field Summary

(package private) Rel[]	inputs
(package private) QueryInfo	queryInfo

Fields inherited from class openjava.ptree.util.EvaluationShuttle

Constructor Summary

(package private)

InternalTranslator(QueryInfo queryInfo, Rel[] inputs)

Method Summary

Expression	evaluateDown(Variable p)
Expression	evaluateUp(AliasedExpression p)
(package private) Expression	lookupExp(String name) Returns an expression with which to reference a from-list item.
void	visit(QueryExpression p) Do not walk into a sub-query.

Methods inherited from class openjava.ptree.util.EvaluationShuttle

evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateDown, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, evaluateUp, getEnvironment, setEnvironment, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit

Methods inherited from class openjava.ptree.util.ParseTreeVisitor

visit, visit, visit, visit, visit, visit, visit, visit, visit

Methods inherited from class java.lang.Object

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

Field Detail

queryInfo

QueryInfo queryInfo

inputs

Rel[] inputs

Constructor Detail

InternalTranslator

InternalTranslator(QueryInfo queryInfo,
                   Rel[] inputs)

Method Detail

evaluateUp

public Expression evaluateUp(AliasedExpression p)

Overrides:

evaluateUp in class EvaluationShuttle

evaluateDown

public Expression evaluateDown(Variable p)

Overrides:

evaluateDown in class EvaluationShuttle

visit

public void visit(QueryExpression p)

Do not walk into a sub-query.

Overrides:

visit in class EvaluationShuttle

lookupExp

Expression lookupExp(String name)

Returns an expression with which to reference a from-list item.

Parameters:

name - the alias of the from item

Returns:

a Variable or FieldAccess