1 /*
2 * Grapht, an open source dependency injector.
3 * Copyright 2014-2015 various contributors (see CONTRIBUTORS.txt)
4 * Copyright 2010-2014 Regents of the University of Minnesota
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser General Public License as
8 * published by the Free Software Foundation; either version 2.1 of the
9 * License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
14 * details.
15 *
16 * You should have received a copy of the GNU General Public License along with
17 * this program; if not, write to the Free Software Foundation, Inc., 51
18 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
19 */
20 package org.grouplens.grapht.solver;
21
22 import org.grouplens.grapht.CachePolicy;
23 import org.grouplens.grapht.util.Preconditions;
24
25 import javax.annotation.Nonnull;
26 import java.util.Arrays;
27 import java.util.Collections;
28 import java.util.LinkedList;
29 import java.util.List;
30
31 /**
32 * A builder for {@link DependencySolver}s.
33 *
34 * @see org.grouplens.grapht.solver.DependencySolver#newBuilder()
35 * @since 0.6
36 * @author <a href="http://grouplens.org">GroupLens Research</a>
37 */
38 public class DependencySolverBuilder {
39 private List<BindingFunction> bindingFunctions = new LinkedList<BindingFunction>();
40 private List<BindingFunction> triggerFunctions = new LinkedList<BindingFunction>();
41 private CachePolicy defaultPolicy = CachePolicy.NO_PREFERENCE;
42 private int maxDepth = 100;
43
44 /**
45 * Get the current list of binding functions.
46 * @return The current list of binding functions.
47 */
48 public List<BindingFunction> getBindingFunctions() {
49 return Collections.unmodifiableList(bindingFunctions);
50 }
51
52 /**
53 * Get the current list of trigger binding functions. These are the binding functions for which
54 * {@code canTriggerRewrite} is {@code true} in {@link #addBindingFunction(BindingFunction,boolean)}.
55 *
56 * @return The current list of trigger binding functions.
57 */
58 public List<BindingFunction> getTriggerFunctions() {
59 return Collections.unmodifiableList(triggerFunctions);
60 }
61
62 /**
63 * Add a binding function to the dependency solver.
64 * @param func The binding function.
65 * @return The builder (for chaining).
66 */
67 public DependencySolverBuilder addBindingFunction(@Nonnull BindingFunction func) {
68 return addBindingFunction(func, true);
69 }
70
71 /**
72 * Add a binding function to the dependency solver.
73 * @param func The binding function.
74 * @param canTriggerRewrite Controls whether this binding function can activate re-resolution
75 * when doing a graph rewrite. If {@code true} (the value passed by
76 * all other binding function adders), this binding function returning
77 * a binding will cause a graph rewrite; if {@code false}, it will be
78 * ignored during rewrites until the rewrite has been triggered by some
79 * other binding function. Register the default binding function with
80 * {@code false} here to keep default bindings from triggering rewrites.
81 * @return The builder (for chaining).
82 */
83 public DependencySolverBuilder addBindingFunction(@Nonnull BindingFunction func,
84 boolean canTriggerRewrite) {
85 Preconditions.notNull("binding function", func);
86 bindingFunctions.add(func);
87 if (canTriggerRewrite) {
88 triggerFunctions.add(func);
89 }
90 return this;
91 }
92
93 /**
94 * Add multiple binding function to the dependency solver.
95 * @param funcs The binding functions.
96 * @return The builder (for chaining).
97 */
98 public DependencySolverBuilder addBindingFunctions(@Nonnull BindingFunction... funcs) {
99 return addBindingFunctions(Arrays.asList(funcs));
100 }
101
102 /**
103 * Add multiple binding function to the dependency solver.
104 * @param funcs The binding functions.
105 * @return The builder (for chaining).
106 */
107 public DependencySolverBuilder addBindingFunctions(@Nonnull Iterable<BindingFunction> funcs) {
108 for (BindingFunction fn: funcs) {
109 addBindingFunction(fn);
110 }
111 return this;
112 }
113
114 /**
115 * Get the current default policy.
116 * @return The builder's current default policy.
117 */
118 public CachePolicy getDefaultPolicy() {
119 return defaultPolicy;
120 }
121
122 /**
123 * Set the default policy for the solver. This policy will be used when a satisfaction has a
124 * policy of {@link CachePolicy#NO_PREFERENCE}. The default is {@link CachePolicy#NO_PREFERENCE},
125 * so the injector will make final caching decisions.
126 * @param policy The default policy for the solver.
127 * @return The builder (for chaining).
128 */
129 public DependencySolverBuilder setDefaultPolicy(CachePolicy policy) {
130 defaultPolicy = policy;
131 return this;
132 }
133
134 /**
135 * Get the maximum depth.
136 * @return The maximum object graph depth.
137 */
138 public int getMaxDepth() {
139 return maxDepth;
140 }
141
142 /**
143 * Set the maximum object graph depth, for cycle detection.
144 * @param depth The maximum object graph depth that the solver is allowed to produce.
145 * @return The builder (for chaining).
146 */
147 public DependencySolverBuilder setMaxDepth(int depth) {
148 if (depth < 1) {
149 throw new IllegalArgumentException("max depth must be at least 1");
150 }
151 maxDepth = depth;
152 return this;
153 }
154
155 /**
156 * Build a dependency solver.
157 * @return The dependency solver.
158 */
159 public DependencySolver build() {
160 return new DependencySolver(bindingFunctions, triggerFunctions, defaultPolicy, maxDepth);
161 }
162 }