CharArrayIterator


1   package java.awt.font;
2   
3   import java.text.CharacterIterator  ;
4   
5   class CharArrayIterator implements CharacterIterator   {
6   
7       private char[] chars;
8       private int pos;
9       private int begin;
10      
11      CharArrayIterator(char[] chars) {
12          
13          reset(chars, 0);
14      }
15      
16      CharArrayIterator(char[] chars, int begin) {
17          
18          reset(chars, begin);
19      }
20      
21      /**
22       * Sets the position to getBeginIndex() and returns the character at that
23       * position.
24       * @return the first character in the text, or DONE if the text is empty
25       * @see getBeginIndex
26       */
27      public char first() {
28          
29          pos = 0;
30          return current();
31      }
32  
33      /**
34       * Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty)
35       * and returns the character at that position.
36       * @return the last character in the text, or DONE if the text is empty
37       * @see getEndIndex
38       */
39      public char last() {
40          
41          if (chars.length > 0) {
42              pos = chars.length-1;
43          }
44          else {
45              pos = 0;
46          }
47          return current();
48      }
49      
50      /**
51       * Gets the character at the current position (as returned by getIndex()).
52       * @return the character at the current position or DONE if the current
53       * position is off the end of the text.
54       * @see getIndex
55       */
56      public char current() {
57          
58          if (pos >= 0 && pos < chars.length) {
59              return chars[pos];
60          }
61          else {
62              return DONE;
63          }
64      }
65  
66      /**
67       * Increments the iterator's index by one and returns the character
68       * at the new index.  If the resulting index is greater or equal
69       * to getEndIndex(), the current index is reset to getEndIndex() and
70       * a value of DONE is returned.
71       * @return the character at the new position or DONE if the new
72       * position is off the end of the text range.
73       */
74      public char next() {
75         
76          if (pos < chars.length-1) {
77              pos++;
78              return chars[pos];
79          }
80          else {
81              pos = chars.length;
82              return DONE;
83          }
84      }
85  
86      /**
87       * Decrements the iterator's index by one and returns the character
88       * at the new index. If the current index is getBeginIndex(), the index
89       * remains at getBeginIndex() and a value of DONE is returned.
90       * @return the character at the new position or DONE if the current
91       * position is equal to getBeginIndex().
92       */
93      public char previous() {
94          
95          if (pos > 0) {
96              pos--;
97              return chars[pos];
98          }
99          else {
100             pos = 0;
101             return DONE;
102         }
103     }
104 
105     /**
106      * Sets the position to the specified position in the text and returns that
107      * character.
108      * @param position the position within the text.  Valid values range from
109      * getBeginIndex() to getEndIndex().  An IllegalArgumentException is thrown
110      * if an invalid value is supplied.
111      * @return the character at the specified position or DONE if the specified position is equal to getEndIndex()
112      */
113     public char setIndex(int position) {
114         
115         position -= begin;
116         if (position < 0 || position > chars.length) {
117             throw new IllegalArgumentException  ("Invalid index");
118         }
119         pos = position;
120         return current();
121     }
122 
123     /**
124      * Returns the start index of the text.
125      * @return the index at which the text begins.
126      */
127     public int getBeginIndex() {
128         return begin;
129     }
130 
131     /**
132      * Returns the end index of the text.  This index is the index of the first
133      * character following the end of the text.
134      * @return the index after the last character in the text
135      */
136     public int getEndIndex() {
137         return begin+chars.length;
138     }
139 
140     /**
141      * Returns the current index.
142      * @return the current index.
143      */
144     public int getIndex() {
145         return begin+pos;
146     }
147 
148     /**
149      * Create a copy of this iterator
150      * @return A copy of this
151      */
152     public Object   clone() {
153         CharArrayIterator   c = new CharArrayIterator  (chars, begin);
154         c.pos = this.pos;
155         return c;
156     }
157 
158     void reset(char[] chars) {
159         reset(chars, 0);
160     }
161     
162     void reset(char[] chars, int begin) {
163         
164         this.chars = chars;
165         this.begin = begin;
166         pos = 0;
167     }
168 }
169
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