/*
* 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 kodkod.ast.operator.ExprOperator;
import kodkod.ast.visitor.ReturnVisitor;
import kodkod.ast.visitor.VoidVisitor;
/**
* A relational {@link kodkod.ast.Expression expression} with two children.
*
* @specfield left: Expression
* @specfield right: Expression
* @specfield op: ExprOperator
* @specfield op.binary()
* @invariant children = 0->left + 1->right
* @author Emina Torlak
*/
public final class BinaryExpression extends Expression {
private final ExprOperator op;
private final Expression left;
private final Expression right;
private final int arity;
/**
* Constructs a new binary expression: left op right
*
* @ensures this.left' = left && this.right' = right && this.op' = op
* @throws NullPointerException left = null || right = null || op = null
* @throws IllegalArgumentException left and right cannot be combined with the specified operator.
*/
BinaryExpression(final Expression left, final ExprOperator op, final Expression right) {
switch(op) {
case UNION : case INTERSECTION : case DIFFERENCE : case OVERRIDE :
this.arity = left.arity();
if (arity!=right.arity())
throw new IllegalArgumentException("Incompatible arities: " + left + " and " + right);
break;
case JOIN :
this.arity = left.arity() + right.arity() - 2;
if (arity < 1)
throw new IllegalArgumentException("Incompatible arities: " + left + " and " + right);
break;
case PRODUCT :
this.arity = left.arity() + right.arity();
break;
default :
throw new IllegalArgumentException("Not a binary operator: " + op);
}
this.op = op;
this.left = left;
this.right = right;
}
/**
* Returns the arity of this binary expression.
* @return this.arity
* @see kodkod.ast.Expression#arity()
*/
public int arity() {
return arity;
}
/**
* Returns this.op.
* @return this.op
*/
public ExprOperator op() { return op ; }
/**
* Returns the left child of this.
* @return this.left
*/
public Expression left() {return left;}
/**
* Returns the right child of this.
* @return this.right
*/
public Expression right() {return right;}
/**
* {@inheritDoc}
* @see kodkod.ast.Expression#accept(kodkod.ast.visitor.ReturnVisitor)
*/
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)
*/
public void accept(VoidVisitor visitor) {
visitor.visit(this);
}
/**
* {@inheritDoc}
* @see kodkod.ast.Node#toString()
*/
public String toString() {
return "(" + left + " " + op + " " + right + ")";
}
}