/*
* Kodkod -- Copyright (c) 2005-present, Emina Torlak
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package kodkod.ast;
import java.util.Iterator;
import kodkod.ast.operator.ExprOperator;
import kodkod.ast.visitor.ReturnVisitor;
import kodkod.ast.visitor.VoidVisitor;
import kodkod.util.collections.Containers;
/**
* A relational {@linkplain kodkod.ast.Expression expression} with more than two children,
* composed with an nary {@linkplain ExprOperator operator}.
*
* @specfield op: ExprOperator
* @invariant op.nary()
* @invariant #children > 2
* @author Emina Torlak
*/
public final class NaryExpression extends Expression implements Iterable<Expression>{
private final ExprOperator op;
private final int arity;
private final Expression[] children;
/**
* Constructs a new associative expression: op(children)
* @requires children array is not modified while in use by this associative expression
* @requires some op.op[children]
* @ensures this.children' = children && this.op' = op
*/
NaryExpression(ExprOperator op, Expression[] children) {
assert children.length>2;
if (!op.nary())
throw new IllegalArgumentException("Cannot construct an nary expression using the non-nary operator " + op);
this.op = op;
this.children = children;
switch(op) {
case UNION : case INTERSECTION : case OVERRIDE :
this.arity = children[0].arity();
for(int i = 1; i < children.length; i++) {
if (children[i].arity()!=arity)
throw new IllegalArgumentException("Incompatible arities: " + children[0] + " and " + children[i]);
}
break;
case PRODUCT :
int sum = 0;
for(Expression child : children) { sum += child.arity(); }
this.arity = sum;
break;
default :
throw new IllegalArgumentException("Unknown associative operator: " + op);
}
}
/**
* Returns the arity of this associative expression.
* @return this.arity
* @see kodkod.ast.Expression#arity()
*/
public final int arity() { return arity; }
/**
* Returns this.op.
* @return this.op
*/
public ExprOperator op() { return op ; }
/**
* Returns the number of children of this expression.
* @return #this.children
*/
public int size() { return children.length; }
/**
* Returns the ith child of this associative expression.
* @requires 0 <= i < #this.children
* @return this.children[i]
*/
public Expression child(int i) { return children[i]; }
/**
* Returns an iterator over this expression's children,
* in the increasing order of indices.
* @return an iterator over this expression's children,
* in the increasing order of indices.
*/
public Iterator<Expression> iterator() { return Containers.iterate(children); }
/**
* {@inheritDoc}
* @see kodkod.ast.Expression#accept(kodkod.ast.visitor.ReturnVisitor)
*/
@Override
public <E, F, D, I> E accept(ReturnVisitor<E, F, D, I> visitor) {
return visitor.visit(this);
}
/**
* {@inheritDoc}
* @see kodkod.ast.Node#accept(kodkod.ast.visitor.VoidVisitor)
*/
@Override
public void accept(VoidVisitor visitor) {
visitor.visit(this);
}
/**
* {@inheritDoc}
* @see kodkod.ast.Node#toString()
*/
@Override
public String toString() {
final StringBuilder s = new StringBuilder("(");
s.append(child(0));
for(int i = 1, size = size(); i < size; i++) {
s.append(" ");
s.append(op);
s.append(" ");
s.append(child(i));
}
s.append(")");
return s.toString();
}
}