de.fuberlin.wiwiss.d2rq.algebra
Class ColumnRenamer
java.lang.Object
de.fuberlin.wiwiss.d2rq.algebra.ColumnRenamer
- Direct Known Subclasses:
- AliasMap, ColumnRenamerMap
public abstract class ColumnRenamer
- extends Object
Something that can rename columns in various objects.
- Version:
- $Id: ColumnRenamer.java,v 1.4 2007/10/22 10:21:16 cyganiak Exp $
- Author:
- Richard Cyganiak (richard@cyganiak.de)
Field Summary |
static ColumnRenamer |
NULL
An optimized ColumnRenamer that leaves every column unchanged |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
NULL
public static final ColumnRenamer NULL
- An optimized ColumnRenamer that leaves every column unchanged
ColumnRenamer
public ColumnRenamer()
invertMap
protected static final Map invertMap(Map m)
- Returns a new map with keys and values exchanged. Lossy if multiple
keys in the original have equal values.
- Parameters:
m
- The original map
- Returns:
- An inverse map
applyTo
public abstract Attribute applyTo(Attribute original)
- Parameters:
original
- A column
- Returns:
- The renamed version of that column, or the same column if the renamer
does not apply to this argument
applyTo
public Join applyTo(Join original)
- Parameters:
original
- A join
- Returns:
- A join with all columns renamed according to this Renamer
applyTo
public Expression applyTo(Expression original)
- Parameters:
original
- An expression
- Returns:
- An expression with all columns renamed according to this Renamer
applyToJoinSet
public Set applyToJoinSet(Set joins)
applyTo
public abstract AliasMap applyTo(AliasMap aliases)