net.sf.saffron.opt
Class OptUtil

java.lang.Object
  |
  +--net.sf.saffron.opt.OptUtil

public abstract class OptUtil

extends Object

OptUtil defines static utility methods for use in optimizing SaffronRels.

Since:

26 September, 2003

Version:

$Id: //open/saffron/src/net/sf/saffron/opt/OptUtil.java#4 $

Author:

jhyde

Nested Class Summary

private static class	OptUtil.RelHolder
private static class	OptUtil.VariableSetVisitor
private static class	OptUtil.VariableUsedVisitor

Field Summary

private static Variable	var0
private static Variable	var1

Constructor Summary

OptUtil()

Method Summary

static SaffronRel	clone(SaffronRel rel)
static SaffronRel[]	clone(SaffronRel[] rels)
static int	getInputOrdinal(String name) Returns the ordinal of the input represented by the variable name, or -1 if it does not represent an input.
static Set	getVariablesSet(SaffronRel rel) Returns a list of variables set by a relational expression or its descendants.
static String[]	getVariablesSetAndUsed(SaffronRel rel0, SaffronRel rel1) Returns a set of distinct variables set by rel0 and used by rel1.
static Set	getVariablesUsed(SaffronRel rel) Returns a list of variables used by a relational expression or its descendants.
static SaffronRel	go(RelVisitor visitor, SaffronRel p) Sets a RelVisitor going on a given relational expression, and returns the result.
static FieldAccess	makeFieldAccess(Expression expr, int field) Constructs a reference to the fieldth field of an expression.
static Expression	makeFieldAccess(Expression expr, String fieldName) Constructs a reference to a named field of an expression.
static FieldAccess	makeFieldAccess(int ordinal, int field) Constructs a reference to the fieldth field of the ordinalth input.
static String	makeName(int ordinal) Constructs the name for the ordinalth input.
static Variable	makeReference(int ordinal)
static String	toString(SaffronRel[] a)

Methods inherited from class java.lang.Object

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

Field Detail

var0

private static final Variable var0

var1

private static final Variable var1

Constructor Detail

OptUtil

public OptUtil()

Method Detail

getInputOrdinal

public static int getInputOrdinal(String name)

Returns the ordinal of the input represented by the variable name, or -1 if it does not represent an input.

getVariablesSet

public static Set getVariablesSet(SaffronRel rel)

Returns a list of variables set by a relational expression or its descendants.

getVariablesSetAndUsed

public static String[] getVariablesSetAndUsed(SaffronRel rel0,
                                              SaffronRel rel1)

Returns a set of distinct variables set by rel0 and used by rel1.

getVariablesUsed

public static Set getVariablesUsed(SaffronRel rel)

Returns a list of variables used by a relational expression or its descendants. The list may contain duplicates.

clone

public static SaffronRel clone(SaffronRel rel)

clone

public static SaffronRel[] clone(SaffronRel[] rels)

go

public static SaffronRel go(RelVisitor visitor,
                            SaffronRel p)

Sets a RelVisitor going on a given relational expression, and returns the result.

makeFieldAccess

public static FieldAccess makeFieldAccess(int ordinal,
                                          int field)

Constructs a reference to the field^th field of the ordinal^th input.

makeFieldAccess

public static FieldAccess makeFieldAccess(Expression expr,
                                          int field)

Constructs a reference to the field^th field of an expression.

makeFieldAccess

public static Expression makeFieldAccess(Expression expr,
                                         String fieldName)

Constructs a reference to a named field of an expression.

makeName

public static String makeName(int ordinal)

Constructs the name for the ordinalth input. For example, makeName(0) returns "$input0".

makeReference

public static Variable makeReference(int ordinal)

toString

public static String toString(SaffronRel[] a)