1 /* 2 * #%L 3 * prolobjectlink-jpi 4 * %% 5 * Copyright (C) 2019 Prolobjectlink Project 6 * %% 7 * Permission is hereby granted, free of charge, to any person obtaining a copy 8 * of this software and associated documentation files (the "Software"), to deal 9 * in the Software without restriction, including without limitation the rights 10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 11 * copies of the Software, and to permit persons to whom the Software is 12 * furnished to do so, subject to the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included in 15 * all copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 23 * THE SOFTWARE. 24 * #L% 25 */ 26 package io.github.prolobjectlink.prolog; 27 28 /** 29 * <p> 30 * Represent structured prolog compound term. Prolog structures consist in a 31 * relation the functor (structure name) and arguments enclosed between 32 * parenthesis. 33 * </p> 34 * <p> 35 * The Prolog Provider is the mechanism to create a new Prolog structures 36 * invoking {@link PrologProvider#newStructure(String, PrologTerm...)}. 37 * </p> 38 * <p> 39 * Two structures are equals if and only if are structure and have equals 40 * functor and arguments. Structures terms unify only with same functor and 41 * arguments structures, with free variable or with with structures where your 42 * arguments unify if they have the same functor and arity. 43 * </p> 44 * <p> 45 * Structures have a special property named arity that means the number of 46 * arguments present in the structure. 47 * </p> 48 * <p> 49 * There are two special structures term. They are expressions (Two arguments 50 * structure term with operator functor) and atoms (functor with zero 51 * arguments). For the first special case must be used 52 * {@link PrologProvider#newStructure(PrologTerm, String, PrologTerm)} 53 * specifying operands like arguments and operator like functor. For the second 54 * special case must be used {@link PrologProvider#newAtom(String)} specifying 55 * functor only. 56 * </p> 57 * 58 * @author Jose Zalacain 59 * @since 1.0 60 */ 61 public interface PrologStructure extends PrologTerm { 62 63 /** 64 * Return the operator (structure functor) of the current term if the current 65 * term is an evalueble structure (expression). This method is equivalent to 66 * invoke #{@link #getFunctor()} 67 * 68 * @return return the operator of the current term if the current term is an 69 * (expression). 70 * @since 1.0 71 */ 72 public String getOperator(); 73 74 /** 75 * Return the left operand of the current term if the current term is an 76 * evalueble structure (expression). This method is equivalent to invoke 77 * {@link #getArgument(int)} with integer parameter equals to zero. 78 * 79 * @return return the left operand of the current term if the current term is an 80 * expression. 81 * @since 1.0 82 */ 83 public PrologTerm getLeft(); 84 85 /** 86 * Return the right operand of the current term if the current term is an 87 * evalueble structure (expression). This method is equivalent to invoke 88 * {@link #getArgument(int)} with integer parameter equals to one. 89 * 90 * @return return the right operand of the current term if the current term is 91 * an expression. 92 * @since 1.0 93 */ 94 public PrologTerm getRight(); 95 96 }