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Java > Open Source Codes > jfun > parsec > DefaultShowError


1 /*****************************************************************************
2  * Copyright (C) Zephyr Business Solutions Corp. All rights reserved. *
3  * ------------------------------------------------------------------------- *
4  * The software in this package is published under the terms of the BSD *
5  * style license a copy of which has been included with this distribution in *
6  * the LICENSE.txt file. *
7  *****************************************************************************/
8 /*
9  * Created on Nov 18, 2004
10  *
11  * Author Ben Yu
12  */
13 package jfun.parsec;
14 import java.util.Arrays JavaDoc;
15 import java.util.TreeSet JavaDoc;
16
17
18 /**
19  * This class gives the default behavior of reporting parser errors.
20  * @author Ben Yu
21  *
22  * Nov 18, 2004
23  */
24 final class DefaultShowError implements java.io.Serializable JavaDoc{
25
26   /*
27    * @see jfun.parsec.ShowError#show(jfun.parsec.ParseError)
28    */
29   static String JavaDoc show(final ParseError err, final Pos pos) {
30     return toErrorStr(err, pos);
31   }
32   private static String JavaDoc toErrorStr(final ParseError err, final Pos pos){
33     final StringBuffer JavaDoc buf = new StringBuffer JavaDoc();
34     if(pos != null)
35       buf.append("line " + pos.getLineNo() + ", column " + pos.getColumnNo());
36     if(err!=null){
37       buf.append(":\n");
38       showExpecting(buf, err.getExpecting());
39       showUnexpected(buf, err.getUnexpected());
40       showMessages(buf, err.getMessages());
41       showEncountered(buf, err.getEncountered());
42     }
43     return buf.toString();
44   }
45   private static void showEncountered(final StringBuffer JavaDoc buf, final String JavaDoc s){
46     if(s==null) return;
47     buf.append(s).append(" encountered.\n");
48   }
49   private static String JavaDoc[] unique(final String JavaDoc[] msgs){
50     if(msgs.length <= 1) return msgs;
51     final TreeSet JavaDoc set = new TreeSet JavaDoc(Arrays.asList(msgs));
52     final String JavaDoc[] umsgs = new String JavaDoc[set.size()];
53     set.toArray(umsgs);
54     return umsgs;
55   }
56   private static void showList(final StringBuffer JavaDoc buf, final String JavaDoc[] msgs){
57     if(msgs.length==0) return;
58     for(int i=0; i<msgs.length-1; i++){
59       buf.append(msgs[i]).append(' ');
60     }
61     if(msgs.length > 1) buf.append("or ");
62     buf.append(msgs[msgs.length-1]);
63   }
64   private static void showExpecting(final StringBuffer JavaDoc buf, final String JavaDoc[] msgs) {
65     if(msgs==null || msgs.length == 0) return;
66     final String JavaDoc[] umsgs = unique(msgs);
67     buf.append("expecting ");
68     showList(buf, umsgs);
69     buf.append(".\n");
70   }
71   private static void showUnexpected(final StringBuffer JavaDoc buf, final String JavaDoc[] msgs) {
72     if(msgs==null || msgs.length == 0) return;
73     showList(buf, unique(msgs));
74     buf.append(" unexpected.\n");
75   }
76   private static void showMessages(final StringBuffer JavaDoc buf, final String JavaDoc[] msgs){
77     if(msgs==null || msgs.length == 0) return;
78     buf.append(msgs[0]);
79     for(int i=1; i<msgs.length; i++){
80       buf.append(" or \n").append(msgs[i]);
81     }
82     buf.append("\n");
83   }
84   private DefaultShowError(){}
85 }
86
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