/* // $Id: //guest/julian_hyde/saffron/src/main/saffron/opt/Query.java#2 $ // Saffron preprocessor and data engine // Copyright (C) 2002 Julian Hyde <julian.hyde@mail.com> // // This library is free software; you can redistribute it and/or // modify it under the terms of the GNU Library General Public // License as published by the Free Software Foundation; either // version 2 of the License, or (at your option) any later version. // // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU // Library General Public License for more details. // // You should have received a copy of the GNU Library General Public // License along with this library; if not, write to the // Free Software Foundation, Inc., 59 Temple Place - Suite 330, // Boston, MA 02111-1307, USA. // // See the COPYING file located in the top-level-directory of // the archive of this library for complete text of license. */ package saffron.opt; import saffron.rel.Rel; import java.util.HashMap; /** * A <code>Query</code> represents a set of {@link saffron.rel.Rel}s which come from the * same <code>select</code> statement. **/ public class Query { private int nextCorel = 0; /** * Maps name of correlating variable (e.g. "$Corel3") to the {@link Rel} * which implements it. */ HashMap mapCorelToRel; /** * Maps a from-list expression to the name of the correlating variable * which references it. This is for forward-references, caused when from * items have correlating variables. We will later resolve to a * {@link Rel}. */ public HashMap mapDeferredToCorel; public Query() { mapCorelToRel = new HashMap(); mapDeferredToCorel = new HashMap(); } /** * Constructs a new name for a correlating variable. It is unique within * the whole query. **/ public String createCorel() { int n = nextCorel++; return "$corel" + n; } /** * Maps a correlating variable to a {@link Rel}. */ public void mapCorel(String name, Rel rel) { mapCorelToRel.put(name, rel); } /** * Creates a name for a correlating variable for which no {@link Rel} has * been created yet. * * @param deferredLookup contains the information required to resolve the * variable later */ public String createCorelUnresolved(Object deferredLookup) { int n = nextCorel++; String name = "$corel" + n; mapDeferredToCorel.put(deferredLookup, name); return name; } /** * Returns the relational expression which populates a correlating * variable. **/ public Rel lookupCorel(String name) { return (Rel) mapCorelToRel.get(name); } } // End Query.java
# | Change | User | Description | Committed | |
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#2 | 1801 | Julian Hyde |
saffron: add ObjectSchema; rules can now be matched more than once; started to implement correlations in queries in from list. |
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#1 | 1467 | Julian Hyde |
saffron: First saffron check-in; incorporate my changes to openjava. |