ForEach


1   
2   
3   /*
4    * The contents of this file are subject to the terms
5    * of the Common Development and Distribution License
6    * (the "License").  You may not use this file except
7    * in compliance with the License.
8    *
9    * You can obtain a copy of the license at
10   * glassfish/bootstrap/legal/CDDLv1.0.txt or
11   * https://glassfish.dev.java.net/public/CDDLv1.0.html.
12   * See the License for the specific language governing
13   * permissions and limitations under the License.
14   *
15   * When distributing Covered Code, include this CDDL
16   * HEADER in each file and include the License file at
17   * glassfish/bootstrap/legal/CDDLv1.0.txt.  If applicable,
18   * add the following below this CDDL HEADER, with the
19   * fields enclosed by brackets "[]" replaced with your
20   * own identifying information: Portions Copyright [yyyy]
21   * [name of copyright owner]
22   *
23   * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
24   *
25   * Portions Copyright Apache Software Foundation.
26   */
27  
28  package org.apache.jasper.tagplugins.jstl;
29  
30  import org.apache.jasper.compiler.tagplugin.*;
31  
32  public final class ForEach implements TagPlugin {
33  
34      private boolean hasVar, hasBegin, hasEnd, hasStep;
35  
36      public void doTag(TagPluginContext ctxt) {
37  
38      String   index = null;
39  
40      boolean hasVarStatus = ctxt.isAttributeSpecified("varStatus");
41      if (hasVarStatus) {
42          ctxt.dontUseTagPlugin();
43          return;
44      }
45  
46      hasVar = ctxt.isAttributeSpecified("var");
47      hasBegin = ctxt.isAttributeSpecified("begin");
48      hasEnd = ctxt.isAttributeSpecified("end");
49      hasStep = ctxt.isAttributeSpecified("step");
50  
51      boolean hasItems = ctxt.isAttributeSpecified("items");
52      if (hasItems) {
53          doCollection(ctxt);
54          return;
55      }
56  
57      // We must have a begin and end attributes
58      index = ctxt.getTemporaryVariableName();
59      ctxt.generateJavaSource("for (int " + index + " = ");
60      ctxt.generateAttribute("begin");
61      ctxt.generateJavaSource("; " + index + " <= ");
62      ctxt.generateAttribute("end");
63      if (hasStep) {
64          ctxt.generateJavaSource("; " + index + "+=");
65          ctxt.generateAttribute("step");
66          ctxt.generateJavaSource(") {");
67      }
68      else {
69          ctxt.generateJavaSource("; " + index + "++) {");
70      }
71  
72      // If var is specified and the body contains an EL, then sycn
73      // the var attribute
74      if (hasVar /* && ctxt.hasEL() */) {
75          ctxt.generateJavaSource("_jspx_page_context.setAttribute(");
76          ctxt.generateAttribute("var");
77          ctxt.generateJavaSource(", String.valueOf(" + index + "));");
78      }
79      ctxt.generateBody();
80      ctxt.generateJavaSource("}");
81      }
82  
83      /**
84       * Generate codes for Collections
85       * The pseudo code is:
86       */
87      private void doCollection(TagPluginContext ctxt) {
88  
89      ctxt.generateImport("java.util.*");
90      generateIterators(ctxt);
91  
92          String   itemsV = ctxt.getTemporaryVariableName();
93          ctxt.generateJavaSource("Object " + itemsV + "= ");
94          ctxt.generateAttribute("items");
95          ctxt.generateJavaSource(";");
96      
97      String   indexV=null, beginV=null, endV=null, stepV=null;
98      if (hasBegin) {
99          beginV = ctxt.getTemporaryVariableName();
100         ctxt.generateJavaSource("int " + beginV + " = ");
101         ctxt.generateAttribute("begin");
102         ctxt.generateJavaSource(";");
103     }
104     if (hasEnd) {
105         indexV = ctxt.getTemporaryVariableName();
106         ctxt.generateJavaSource("int " + indexV + " = 0;");
107         endV = ctxt.getTemporaryVariableName();
108         ctxt.generateJavaSource("int " + endV + " = ");
109         ctxt.generateAttribute("end");
110         ctxt.generateJavaSource(";");
111     }
112     if (hasStep) {
113         stepV = ctxt.getTemporaryVariableName();
114         ctxt.generateJavaSource("int " + stepV + " = ");
115         ctxt.generateAttribute("step");
116         ctxt.generateJavaSource(";");
117     }
118 
119         String   iterV = ctxt.getTemporaryVariableName();
120         ctxt.generateJavaSource("Iterator " + iterV + " = null;");
121     // Object[]
122     ctxt.generateJavaSource("if (" + itemsV + " instanceof Object[])");
123     ctxt.generateJavaSource(iterV + "=toIterator((Object[])" + itemsV + ");");
124     // boolean[]
125     ctxt.generateJavaSource("else if (" + itemsV + " instanceof boolean[])");
126     ctxt.generateJavaSource(iterV + "=toIterator((boolean[])" + itemsV + ");");
127     // byte[]
128     ctxt.generateJavaSource("else if (" + itemsV + " instanceof byte[])");
129     ctxt.generateJavaSource(iterV + "=toIterator((byte[])" + itemsV + ");");
130     // char[]
131     ctxt.generateJavaSource("else if (" + itemsV + " instanceof char[])");
132     ctxt.generateJavaSource(iterV + "=toIterator((char[])" + itemsV + ");");
133     // short[]
134     ctxt.generateJavaSource("else if (" + itemsV + " instanceof short[])");
135     ctxt.generateJavaSource(iterV + "=toIterator((short[])" + itemsV + ");");
136     // int[]
137     ctxt.generateJavaSource("else if (" + itemsV + " instanceof int[])");
138     ctxt.generateJavaSource(iterV + "=toIterator((int[])" + itemsV + ");");
139     // long[]
140     ctxt.generateJavaSource("else if (" + itemsV + " instanceof long[])");
141     ctxt.generateJavaSource(iterV + "=toIterator((long[])" + itemsV + ");");
142     // float[]
143     ctxt.generateJavaSource("else if (" + itemsV + " instanceof float[])");
144     ctxt.generateJavaSource(iterV + "=toIterator((float[])" + itemsV + ");");
145     // double[]
146     ctxt.generateJavaSource("else if (" + itemsV + " instanceof double[])");
147     ctxt.generateJavaSource(iterV + "=toIterator((double[])" + itemsV + ");");
148 
149         // Collection
150         ctxt.generateJavaSource("else if (" + itemsV + " instanceof Collection)");
151         ctxt.generateJavaSource(iterV + "=((Collection)" + itemsV + ").iterator();");
152 
153         // Iterator
154         ctxt.generateJavaSource("else if (" + itemsV + " instanceof Iterator)");
155         ctxt.generateJavaSource(iterV + "=(Iterator)" + itemsV + ";");
156 
157     // Enumeration
158     ctxt.generateJavaSource("else if (" + itemsV + " instanceof Enumeration)");
159     ctxt.generateJavaSource(iterV + "=toIterator((Enumeration)" + itemsV + ");");
160 
161         // Map
162         ctxt.generateJavaSource("else if (" + itemsV + " instanceof Map)");
163         ctxt.generateJavaSource(iterV + "=((Map)" + itemsV + ").entrySet().iterator();");
164 
165     if (hasBegin) {
166             String   tV = ctxt.getTemporaryVariableName();
167         ctxt.generateJavaSource("for (int " + tV + "=" + beginV + ";" +
168             tV + ">0 && " + iterV + ".hasNext(); " +
169             tV + "--)");
170         ctxt.generateJavaSource(iterV + ".next();");
171     }
172 
173     ctxt.generateJavaSource("while (" + iterV + ".hasNext()){");
174     if (hasVar) {
175         ctxt.generateJavaSource("_jspx_page_context.setAttribute(");
176         ctxt.generateAttribute("var");
177         ctxt.generateJavaSource(", " + iterV + ".next());");
178     }
179 
180     ctxt.generateBody();
181 
182     if (hasStep) {
183         String   tV = ctxt.getTemporaryVariableName();
184         ctxt.generateJavaSource("for (int " + tV + "=" + stepV + "-1;" +
185             tV + ">0 && " + iterV + ".hasNext(); " +
186             tV + "--)");
187         ctxt.generateJavaSource(iterV + ".next();");
188     }
189     if (hasEnd) {
190         if (hasStep) {
191         ctxt.generateJavaSource(indexV + "+=" + stepV + ";");
192         }
193         else {
194         ctxt.generateJavaSource(indexV + "++;");
195         }
196         if (hasBegin) {
197         ctxt.generateJavaSource("if(" + beginV + "+" + indexV +
198             ">"+ endV + ")");
199         }
200         else {
201         ctxt.generateJavaSource("if(" + indexV + ">" + endV + ")");
202         }
203         ctxt.generateJavaSource("break;");
204     }
205     ctxt.generateJavaSource("}");   // while
206     }
207 
208     /**
209      * Generate iterators for data types supported in items
210      */
211     private void generateIterators(TagPluginContext ctxt) {
212 
213     // Object[]
214     ctxt.generateDeclaration("ObjectArrayIterator", 
215         "private Iterator toIterator(final Object[] a){\n" +
216         "  return (new Iterator() {\n" +
217         "    int index=0;\n" +
218         "    public boolean hasNext() {\n" +
219         "      return index < a.length;}\n" +
220         "    public Object next() {\n" +
221         "      return a[index++];}\n" +
222         "    public void remove() {}\n" +
223         "  });\n" +
224         "}"
225     );
226 
227     // boolean[]
228     ctxt.generateDeclaration("booleanArrayIterator", 
229         "private Iterator toIterator(final boolean[] a){\n" +
230         "  return (new Iterator() {\n" +
231         "    int index=0;\n" +
232         "    public boolean hasNext() {\n" +
233         "      return index < a.length;}\n" +
234         "    public Object next() {\n" +
235         "      return new Boolean(a[index++]);}\n" +
236         "    public void remove() {}\n" +
237         "  });\n" +
238         "}"
239     );
240 
241     // byte[]
242     ctxt.generateDeclaration("byteArrayIterator", 
243         "private Iterator toIterator(final byte[] a){\n" +
244         "  return (new Iterator() {\n" +
245         "    int index=0;\n" +
246         "    public boolean hasNext() {\n" +
247         "      return index < a.length;}\n" +
248         "    public Object next() {\n" +
249         "      return new Byte(a[index++]);}\n" +
250         "    public void remove() {}\n" +
251         "  });\n" +
252         "}"
253     );
254 
255     // char[]
256     ctxt.generateDeclaration("charArrayIterator", 
257         "private Iterator toIterator(final char[] a){\n" +
258         "  return (new Iterator() {\n" +
259         "    int index=0;\n" +
260         "    public boolean hasNext() {\n" +
261         "      return index < a.length;}\n" +
262         "    public Object next() {\n" +
263         "      return new Character(a[index++]);}\n" +
264         "    public void remove() {}\n" +
265         "  });\n" +
266         "}"
267     );
268 
269     // short[]
270     ctxt.generateDeclaration("shortArrayIterator", 
271         "private Iterator toIterator(final short[] a){\n" +
272         "  return (new Iterator() {\n" +
273         "    int index=0;\n" +
274         "    public boolean hasNext() {\n" +
275         "      return index < a.length;}\n" +
276         "    public Object next() {\n" +
277         "      return new Short(a[index++]);}\n" +
278         "    public void remove() {}\n" +
279         "  });\n" +
280         "}"
281     );
282 
283     // int[]
284     ctxt.generateDeclaration("intArrayIterator", 
285         "private Iterator toIterator(final int[] a){\n" +
286         "  return (new Iterator() {\n" +
287         "    int index=0;\n" +
288         "    public boolean hasNext() {\n" +
289         "      return index < a.length;}\n" +
290         "    public Object next() {\n" +
291         "      return new Integer(a[index++]);}\n" +
292         "    public void remove() {}\n" +
293         "  });\n" +
294         "}"
295     );
296 
297     // long[]
298     ctxt.generateDeclaration("longArrayIterator", 
299         "private Iterator toIterator(final long[] a){\n" +
300         "  return (new Iterator() {\n" +
301         "    int index=0;\n" +
302         "    public boolean hasNext() {\n" +
303         "      return index < a.length;}\n" +
304         "    public Object next() {\n" +
305         "      return new Long(a[index++]);}\n" +
306         "    public void remove() {}\n" +
307         "  });\n" +
308         "}"
309     );
310 
311     // float[]
312     ctxt.generateDeclaration("floatArrayIterator",
313         "private Iterator toIterator(final float[] a){\n" +
314         "  return (new Iterator() {\n" +
315         "    int index=0;\n" +
316         "    public boolean hasNext() {\n" +
317         "      return index < a.length;}\n" +
318         "    public Object next() {\n" +
319         "      return new Float(a[index++]);}\n" +
320         "    public void remove() {}\n" +
321         "  });\n" +
322         "}"
323     );
324 
325     // double[]
326     ctxt.generateDeclaration("doubleArrayIterator",
327         "private Iterator toIterator(final double[] a){\n" +
328         "  return (new Iterator() {\n" +
329         "    int index=0;\n" +
330         "    public boolean hasNext() {\n" +
331         "      return index < a.length;}\n" +
332         "    public Object next() {\n" +
333         "      return new Double(a[index++]);}\n" +
334         "    public void remove() {}\n" +
335         "  });\n" +
336         "}"
337     );
338 
339     // Enumeration
340     ctxt.generateDeclaration("enumIterator",
341         "private Iterator toIterator(final Enumeration e){\n" +
342         "  return (new Iterator() {\n" +
343         "    public boolean hasNext() {\n" +
344         "      return e.hasMoreElements();}\n" +
345         "    public Object next() {\n" +
346         "      return e.nextElement();}\n" +
347         "    public void remove() {}\n" +
348         "  });\n" +
349         "}"
350     );
351 
352     }
353 }
354
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags