com.thesett.aima.logic.fol.wam.builtins.BuiltIn Maven / Gradle / Ivy

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/*
 * Copyright The Sett Ltd, 2005 to 2014.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.thesett.aima.logic.fol.wam.builtins;

import com.thesett.aima.logic.fol.Functor;
import com.thesett.aima.logic.fol.FunctorName;
import com.thesett.aima.logic.fol.wam.compiler.WAMInstruction;
import com.thesett.common.util.SizeableLinkedList;

/**
 * BuiltIn defines the behaviour of Prolog built-in predicates.
 *
 * 
 * 
 * 
 * CRC Card Responsibilities
 * 
 Generate instructions to set up the arguments to a call to a built-in functor.
 Generate instructions to call to a built-in functor.
 *
 * @author Rupert Smith
 */
public interface BuiltIn
{
    /**
     * Compiles the arguments to a call to a body of a clause into an instruction listing in WAM.
     *
     * The name of the clause containing the body, and the position of the body within this clause are passed as
     * arguments, mainly so that these coordinates can be used to help make any labels generated within the generated
     * code unique.
     *
     * @param  expression  The clause body to compile.
     * @param  isFirstBody true iff this is the first body of a program clause.
     * @param  clauseName  The name of the clause within which this body appears.
     * @param  bodyNumber  The body position within the containing clause.
     *
     * @return A listing of the instructions for the clause body in the WAM instruction set.
     */
    SizeableLinkedList compileBodyArguments(Functor expression, boolean isFirstBody,
        FunctorName clauseName, int bodyNumber);

    /**
     * Compiles a call to a body of a clause into an instruction listing in WAM.
     *
     * @param  expression        The body functor to call.
     * @param  isFirstBody       Iff this is the first body in a clause.
     * @param  isLastBody        Iff this is the last body in a clause.
     * @param  chainRule         Iff the clause is a chain rule, so has no environment frame.
     * @param  permVarsRemaining The number of permanent variables remaining at this point in the calling clause. Used
     *                           for environment trimming.
     *
     * @return A list of instructions for the body call.
     */
    SizeableLinkedList compileBodyCall(Functor expression, boolean isFirstBody, boolean isLastBody,
        boolean chainRule, int permVarsRemaining);
}