| 1 | /* |
| 2 | * $Id: StepPredicates.java 562 2010-11-11 00:28:13Z PSpeed $ |
| 3 | * |
| 4 | * The Filament BSD license. |
| 5 | * |
| 6 | * Copyright (c) 2009-2010, the original author or authors |
| 7 | * |
| 8 | * Redistribution and use in source and binary forms, with or without |
| 9 | * modification, are permitted provided that the following conditions |
| 10 | * are met: |
| 11 | * |
| 12 | * 1) Redistributions of source code must retain the above copyright notice, |
| 13 | * this list of conditions and the following disclaimer. |
| 14 | * 2) Redistributions in binary form must reproduce the above copyright |
| 15 | * notice, this list of conditions and the following disclaimer in the |
| 16 | * documentation and/or other materials provided with the distribution. |
| 17 | * 3) Neither the names "Filament", "fgraph.org", "filamentgraph.org", nor the |
| 18 | * names of its contributors may be used to endorse or promote products |
| 19 | * derived from this software without specific prior written permission. |
| 20 | * |
| 21 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| 22 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
| 25 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 26 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 27 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 30 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 31 | * POSSIBILITY OF SUCH DAMAGE. |
| 32 | */ |
| 33 | |
| 34 | package org.fgraph.steps; |
| 35 | |
| 36 | import java.io.Serializable; |
| 37 | import java.util.*; |
| 38 | |
| 39 | import com.google.common.base.Predicate; |
| 40 | |
| 41 | |
| 42 | /** |
| 43 | * Set of utility predicates for the fsteps package. |
| 44 | * |
| 45 | * <p>Unless otherwise specified, all methods return serializable |
| 46 | * predicates as long as they're given serializable parameters.</p> |
| 47 | * |
| 48 | * @version $Revision: 562 $ |
| 49 | * @author Paul Speed |
| 50 | */ |
| 51 | public class StepPredicates |
| 52 | { |
| 53 | /** |
| 54 | * Returns a filter that returns true for steps less than |
| 55 | * or equal to a certain depth. |
| 56 | */ |
| 57 | public static <T extends Step> Predicate<T> maxDepth( int depth ) |
| 58 | { |
| 59 | return new DepthPredicate<T>( depth, 1 ); |
| 60 | } |
| 61 | |
| 62 | /** |
| 63 | * Returns a filter that returns true for steps greater |
| 64 | * than or equal to a certain depth. |
| 65 | */ |
| 66 | public static <T extends Step> Predicate<T> minDepth( int depth ) |
| 67 | { |
| 68 | return new DepthPredicate<T>( depth, -1 ); |
| 69 | } |
| 70 | |
| 71 | /** |
| 72 | * Returns a filter that returns true for steps at the |
| 73 | * specified depth. |
| 74 | */ |
| 75 | public static <T extends Step> Predicate<T> depth( int depth ) |
| 76 | { |
| 77 | return new DepthPredicate<T>( depth, 0 ); |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * Returns a filter that returns true for steps that are descending. |
| 82 | */ |
| 83 | public static <T> Predicate<DepthFirstStep<T>> descending() |
| 84 | { |
| 85 | return new DescentPredicate<T>(true); |
| 86 | } |
| 87 | |
| 88 | /** |
| 89 | * Returns a filter that returns true for steps that are ascending. |
| 90 | */ |
| 91 | public static <T> Predicate<DepthFirstStep<T>> ascending() |
| 92 | { |
| 93 | return new DescentPredicate<T>(false); |
| 94 | } |
| 95 | |
| 96 | private static class DepthPredicate<T extends Step> implements Predicate<T>, Serializable |
| 97 | { |
| 98 | static final long serialVersionUID = 1L; |
| 99 | |
| 100 | private int depth; |
| 101 | private int sign; |
| 102 | |
| 103 | public DepthPredicate( int depth, int sign ) |
| 104 | { |
| 105 | this.depth = depth; |
| 106 | this.sign = sign; |
| 107 | } |
| 108 | |
| 109 | public boolean apply( T step ) |
| 110 | { |
| 111 | long diff = (long)depth - (long)step.getDepth(); |
| 112 | if( sign == 0 ) |
| 113 | return diff == 0; |
| 114 | return (diff * sign) >= 0; |
| 115 | } |
| 116 | |
| 117 | public String toString() |
| 118 | { |
| 119 | String comp = ""; |
| 120 | switch( sign ) |
| 121 | { |
| 122 | case -1: |
| 123 | comp = ">="; |
| 124 | break; |
| 125 | case 1: |
| 126 | comp = "<="; |
| 127 | break; |
| 128 | case 0: |
| 129 | comp = "=="; |
| 130 | break; |
| 131 | /* |
| 132 | This can never happen since this class is |
| 133 | private and only ever called by internal values... |
| 134 | it's impossible to cover in unit tests. |
| 135 | default: |
| 136 | comp = "??"; |
| 137 | break;*/ |
| 138 | } |
| 139 | return "DepthPredicate[" + comp + " " + depth + "]"; |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | private static class DescentPredicate<T> implements Predicate<DepthFirstStep<T>>, Serializable |
| 144 | { |
| 145 | static final long serialVersionUID = 1L; |
| 146 | |
| 147 | private boolean descending; |
| 148 | |
| 149 | public DescentPredicate( boolean descending ) |
| 150 | { |
| 151 | this.descending = descending; |
| 152 | } |
| 153 | |
| 154 | public boolean apply( DepthFirstStep<T> step ) |
| 155 | { |
| 156 | return step.isDescending() == descending; |
| 157 | } |
| 158 | |
| 159 | public String toString() |
| 160 | { |
| 161 | return descending ? "Descending[]" : "Ascending[]"; |
| 162 | } |
| 163 | } |
| 164 | } |