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1 | /******************************************************************************* |
2 | * Copyright (c) 2005, 2011 IBM Corporation and others. | |
3 | * All rights reserved. This program and the accompanying materials | |
4 | * are made available under the terms of the Eclipse Public License v1.0 | |
5 | * which accompanies this distribution, and is available at | |
6 | * http://www.eclipse.org/legal/epl-v10.html | |
7 | * | |
8 | * Contributors: | |
9 | * IBM Corporation - initial API and implementation | |
10 | *******************************************************************************/ | |
11 | package org.eclipse.jdt.ui.text.java; | |
12 | ||
13 | import org.eclipse.core.runtime.Assert; | |
14 | ||
15 | import org.eclipse.jface.text.BadLocationException; | |
16 | import org.eclipse.jface.text.IDocument; | |
17 | import org.eclipse.jface.text.ITextViewer; | |
18 | ||
19 | /** | |
20 | * Describes the context of an invocation of content assist in a text viewer. The context knows the | |
21 | * document, the invocation offset and can lazily compute the identifier prefix preceding the | |
22 | * invocation offset. It may know the viewer. | |
23 | * <p> | |
24 | * Subclasses may add information to their environment. For example, source code editors may provide | |
25 | * specific context information such as an AST. | |
26 | * </p> | |
27 | * <p> | |
28 | * Clients may instantiate and subclass. | |
29 | * </p> | |
30 | * | |
31 | * @since 3.2 | |
32 | */ | |
33 | public class ContentAssistInvocationContext { | |
34 | ||
35 | /* state */ | |
36 | private final ITextViewer fViewer; | |
37 | private final IDocument fDocument; | |
38 | private final int fOffset; | |
39 | ||
40 | /* cached additional info */ | |
41 | private CharSequence fPrefix; | |
42 | ||
43 | /** | |
44 | * Equivalent to | |
45 | * {@linkplain #ContentAssistInvocationContext(ITextViewer, int) ContentAssistInvocationContext(viewer, viewer.getSelectedRange().x)}. | |
46 | * | |
47 | * @param viewer the text viewer that content assist is invoked in | |
48 | */ | |
49 | public ContentAssistInvocationContext(ITextViewer viewer) { | |
50 | this(viewer, viewer.getSelectedRange().x); | |
51 | } | |
52 | ||
53 | /** | |
54 | * Creates a new context for the given viewer and offset. | |
55 | * | |
56 | * @param viewer the text viewer that content assist is invoked in | |
57 | * @param offset the offset into the viewer's document where content assist is invoked at | |
58 | */ | |
59 | public ContentAssistInvocationContext(ITextViewer viewer, int offset) { | |
60 | Assert.isNotNull(viewer); | |
61 | fViewer= viewer; | |
62 | fDocument= null; | |
63 | fOffset= offset; | |
64 | } | |
65 | ||
66 | /** | |
67 | * Creates a new context with no viewer or invocation offset set. | |
68 | */ | |
69 | protected ContentAssistInvocationContext() { | |
70 | fDocument= null; | |
71 | fViewer= null; | |
72 | fOffset= -1; | |
73 | } | |
74 | ||
75 | /** | |
76 | * Creates a new context for the given document and offset. | |
77 | * | |
78 | * @param document the document that content assist is invoked in | |
79 | * @param offset the offset into the document where content assist is invoked at | |
80 | */ | |
81 | public ContentAssistInvocationContext(IDocument document, int offset) { | |
82 | Assert.isNotNull(document); | |
83 | Assert.isTrue(offset >= 0); | |
84 | fViewer= null; | |
85 | fDocument= document; | |
86 | fOffset= offset; | |
87 | } | |
88 | ||
89 | /** | |
90 | * Returns the invocation offset. | |
91 | * | |
92 | * @return the invocation offset | |
93 | */ | |
94 | public final int getInvocationOffset() { | |
95 | return fOffset; | |
96 | } | |
97 | ||
98 | /** | |
99 | * Returns the viewer, <code>null</code> if not available. | |
100 | * | |
101 | * @return the viewer, possibly <code>null</code> | |
102 | */ | |
103 | public final ITextViewer getViewer() { | |
104 | return fViewer; | |
105 | } | |
106 | ||
107 | /** | |
108 | * Returns the document that content assist is invoked on, or <code>null</code> if not known. | |
109 | * | |
110 | * @return the document or <code>null</code> | |
111 | */ | |
112 | public IDocument getDocument() { | |
113 | if (fDocument == null) { | |
114 | if (fViewer == null) | |
115 | return null; | |
116 | return fViewer.getDocument(); | |
117 | } | |
118 | return fDocument; | |
119 | } | |
120 | ||
121 | /** | |
122 | * Computes the identifier (as specified by {@link Character#isJavaIdentifierPart(char)}) that | |
123 | * immediately precedes the invocation offset. | |
124 | * | |
125 | * @return the prefix preceding the content assist invocation offset, <code>null</code> if | |
126 | * there is no document | |
127 | * @throws BadLocationException if accessing the document fails | |
128 | */ | |
129 | public CharSequence computeIdentifierPrefix() throws BadLocationException { | |
130 | if (fPrefix == null) { | |
131 | IDocument document= getDocument(); | |
132 | if (document == null) | |
133 | return null; | |
134 | int end= getInvocationOffset(); | |
135 | int start= end; | |
136 | while (--start >= 0) { | |
137 | if (!Character.isJavaIdentifierPart(document.getChar(start))) | |
138 | break; | |
139 | } | |
140 | start++; | |
141 | fPrefix= document.get(start, end - start); | |
142 | } | |
143 | ||
144 | return fPrefix; | |
145 | } | |
146 | ||
147 | /** | |
148 | * Invocation contexts are equal if they describe the same context and are of the same type. | |
149 | * This implementation checks for <code>null</code> values and class equality. Subclasses | |
150 | * should extend this method by adding checks for their context relevant fields (but not | |
151 | * necessarily cached values). | |
152 | * <p> | |
153 | * Example: | |
154 | * | |
155 | * <pre> | |
156 | * class MyContext extends ContentAssistInvocationContext { | |
157 | * private final Object fState; | |
158 | * private Object fCachedInfo; | |
159 | * | |
160 | * ... | |
161 | * | |
162 | * public boolean equals(Object obj) { | |
163 | * if (!super.equals(obj)) | |
164 | * return false; | |
165 | * MyContext other= (MyContext) obj; | |
166 | * return fState.equals(other.fState); | |
167 | * } | |
168 | * } | |
169 | * </pre> | |
170 | * | |
171 | * </p> | |
172 | * <p> | |
173 | * Subclasses should also extend {@link Object#hashCode()}. | |
174 | * </p> | |
175 | * | |
176 | * @param obj {@inheritDoc} | |
177 | * @return {@inheritDoc} | |
178 | */ | |
179 | @Override | |
180 | public boolean equals(Object obj) { | |
181 | if (obj == null) | |
182 | return false; | |
183 | if (!getClass().equals(obj.getClass())) | |
184 | return false; | |
185 | ContentAssistInvocationContext other= (ContentAssistInvocationContext) obj; | |
186 | return (fViewer == null && other.fViewer == null || fViewer != null && fViewer.equals(other.fViewer)) && fOffset == other.fOffset && (fDocument == null && other.fDocument == null || fDocument != null && fDocument.equals(other.fDocument)); | |
187 | } | |
188 | ||
189 | /* | |
190 | * @see java.lang.Object#hashCode() | |
191 | */ | |
192 | @Override | |
193 | public int hashCode() { | |
194 | return 23459213 << 5 | (fViewer == null ? 0 : fViewer.hashCode() << 3) | fOffset; | |
195 | } | |
196 | } |