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An OSGi bundle for Saxon-HE
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2013 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.expr.flwor;
import net.sf.saxon.expr.Binding;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.VariableReference;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.expr.parser.ExpressionVisitor;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trans.XPathException;
import java.util.List;
/**
* A "Clause" refers specifically to one of the clauses of a FLWOR expression, for example the "for"
* clause, the "let" clause, the "where" or "order by" clause. (The "return" clause, however, is not
* modelled as a Clause).
*/
public abstract class Clause {
public static final int FOR = 0;
public static final int LET = 1;
public static final int WINDOW = 2;
public static final int GROUPBYCLAUSE = 3;
public static final int COUNT = 4;
public static final int ORDERBYCLAUSE = 5;
public static final int WHERE = 6;
public static final int TRACE = 7;
private int locationId;
/**
* Get the location ID, which can be used in conjunction with a LocationProvider to determine
* the system ID and line number of the clause
* @return the location ID
*/
public int getLocationId() {
return locationId;
}
/**
* Set the location ID, which can be used in conjunction with a LocationProvider to determine
* the system ID and line number of the clause
* @param locationId the location ID
*/
public void setLocationId(int locationId) {
this.locationId = locationId;
}
/**
* Create a copy of this clause
* @return the copied clause
*/
public abstract Clause copy();
/**
* Optimize any expressions contained within this clause
* @param visitor the ExpressionVisitor, providing access to static context information
* @param contextItemType the type of the context item
* @throws XPathException if any error is detected
*/
public void optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException {}
/**
* Type-check any expression contained within this clause
* @param visitor the ExpressionVisitor, providing access to static context information
* @throws XPathException if any error is detected
*/
public void typeCheck(ExpressionVisitor visitor) throws XPathException {
}
/**
* Get a pull-mode tuple stream that implements the functionality of this clause, taking its
* input from another tuple stream which this clause modifies
*
* @param base the input tuple stream
* @param context the dynamic evaluation context
* @return the output tuple stream
*/
public abstract TuplePull getPullStream(TuplePull base, XPathContext context);
/**
* Get a push-mode tuple stream that implements the functionality of this clause, supplying its
* output to another tuple stream
*
* @param destination the output tuple stream
* @param context the dynamic evaluation context
* @return the push tuple stream that implements the functionality of this clause of the FLWOR
* expression
*/
public abstract TuplePush getPushStream(TuplePush destination, XPathContext context);
/**
* Process the subexpressions of this clause
* @param processor the expression processor used to process the subexpressions
* @throws XPathException if any error is detected
*/
public abstract void processSubExpressions(ExpressionProcessor processor) throws XPathException;
/**
* Diagnostic print of expression structure. The abstract expression tree
* is written to the supplied output destination.
*
* @param out the expression presenter used to display the structure
*/
public abstract void explain(ExpressionPresenter out);
/**
* Get the variables bound by this clause
* @return the variable bindings
*/
public LocalVariableBinding[] getRangeVariables() {
return new LocalVariableBinding[0];
}
/**
* Build a list of all references to a variables declared in this clause
* @param visitor the expression visitor
* @param binding a variable declared in this clause
* @param refs the list of variable references, initially empty, to which the method will append
*/
public void gatherVariableReferences(final ExpressionVisitor visitor, Binding binding, List refs){}
/**
* Determine whether the clause contains a reference to a local variable binding that cannot be inlined
* @param binding the binding for the local variable in question
* @return true if this clause uses the variable in a way that does not permit inlining
*/
public boolean containsNonInlineableVariableReference(Binding binding) {
return false;
}
/**
* Supply improved type information to the expressions that contain references to the variables declared in this clause
* @param visitor the expression visitor
* @param references the list of variable references
* @param returnExpr the expression in the return clause
*/
public void refineVariableType(final ExpressionVisitor visitor, List references, Expression returnExpr){}
/**
* Get a keyword identifying what kind of clause this is
* @return the kind of clause
*/
public abstract int getClauseKey();
}