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12 This is the user's manual for Aspell
14 GNU Aspell is a spell checker designed to eventually replace Ispell.
15 It can either be used as a library or as an independent spell checker.
17 Copyright (C) 2000--2011 Kevin Atkinson.
19 Permission is granted to copy, distribute and/or modify this
20 document under the terms of the GNU Free Documentation License,
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48 <h3 class="section">6.1 Through the C API</h3>
50 <p>The Aspell library contains two main classes and several helper
51 classes. The two main classes are <code>AspellConfig</code> and
52 <code>AspellSpeller</code>. The <code>AspellConfig</code> class is used to set
53 initial defaults and to change spell checker specific options. The
54 <code>AspellSpeller</code> class does most of the real work. The
55 <code>C API</code> is responsible for managing the dictionaries, checking
56 if a word is in the dictionary, and coming up with suggestions among
57 other things. There are many helper classes the important ones are
58 <code>AspellWordList</code>, <code>AspellMutableWordList</code>,
59 <code>Aspell*Enumeration</code>. The <code>AspellWordList</code> classes is used
60 for accessing the suggestion list, as well as the personal and
61 suggestion word list currently in use. The
62 <code>AspellMutableWordList</code> is used to manage the personal, and
63 perhaps other, word lists. The <code>Aspell*Enumeration</code> classes are
64 used for iterating through a list.
66 <h4 class="subsection">6.1.1 Usage</h4>
68 <p>To use Aspell your application should include <samp><span class="file">aspell.h</span></samp>. In
69 order to ensure that all the necessary libraries are linked in libtool
70 should be used to perform the linking. When using libtool simply
71 linking with <code>-laspell</code> should be all that is necessary. When
72 using shared libraries you might be able to simply link
73 <code>-laspell</code>, but this is not recommended. This version of Aspell
74 uses the CVS version of libtool however released versions of libtool
77 <p>When your application first starts you should get a new configuration
78 class with the command:
80 <pre class="smallexample"> AspellConfig * spell_config = new_aspell_config();
82 <p class="noindent">which will create a new <code>AspellConfig</code> class. It is allocated
83 with <samp><span class="command">new</span></samp> and it is your responsibility to delete it with
84 <code>delete_aspell_config</code>. Once you have the config class you
85 should set some variables. The most important one is the language
86 variable. To do so use the command:
88 <pre class="smallexample"> aspell_config_replace(spell_config, "lang", "en_US");
90 <p class="noindent">which will set the default language to use to American English. The
91 language is expected to be the standard two letter ISO 639 language
92 code, with an optional two letter ISO 3166 country code after an
93 underscore. You can set the preferred size via the <samp><span class="option">size</span></samp>
94 option, any extra info via the <samp><span class="option">variety</span></samp> option, and the
95 encoding via the <samp><span class="option">encoding</span></samp> option. Other things you might
96 want to set is the preferred spell checker to use, the search path for
97 dictionaries, and the like — see <a href="The-Options.html#The-Options">The Options</a>, for a list of
98 all available options.
100 <p>Whenever a new document is created a new <code>AspellSpeller</code> class
101 should also be created. There should be one speller class per
102 document. To create a new speller class use the
103 <code>new_aspell_speller</code> and then cast it up using
104 <code>to_aspell_speller</code> like so:
106 <pre class="smallexample"> AspellCanHaveError * possible_err = new_aspell_speller(spell_config);
107 AspellSpeller * spell_checker = 0;
108 if (aspell_error_number(possible_err) != 0)
109 puts(aspell_error_message(possible_err));
111 spell_checker = to_aspell_speller(possible_err);
113 <p class="noindent">which will create a new <code>AspellSpeller</code> class using the defaults
114 found in <code>spell_config</code>. To find out which dictionary is
115 selected the <samp><span class="option">lang</span></samp>, <samp><span class="option">size</span></samp>, and <samp><span class="option">variety</span></samp> options
116 may be examined. To find out the exact name of the dictionary the
117 <samp><span class="option">master</span></samp> option may be examined as well as the
118 <samp><span class="option">master-flags</span></samp> options to see if there were any special flags
119 that were passed on to the module. The <samp><span class="option">module</span></samp> option way
120 also be examined to figure out which speller module was selected, but
121 since there is only one this option will always be the same.
123 <p>If for some reason you want to use different defaults simply clone
124 <code>spell_config</code> and change the setting like so:
126 <pre class="smallexample"> AspellConfig * spell_config2 = aspell_config_clone(spell_config);
127 aspell_config_replace(spell_config2, "lang","nl");
128 possible_err = new_aspell_speller(spell_config2);
129 delete_aspell_config(spell_config2);
131 <p>Once the speller class is created you can use the <code>check</code> method
132 to see if a word in the document is correct like so:
134 <pre class="smallexample"> int correct = aspell_speller_check(spell_checker, <var>word</var>, <var>size</var>);
136 <p class="noindent"><var>word</var> is expected to be a <code>const char *</code> character
137 string. If the encoding is set to be <code>ucs-2</code> or
138 <code>ucs-4</code> <var>word</var> is expected to be a cast
139 from either <code>const u16int *</code> or <code>const u32int *</code>
140 respectively. <code>u16int</code> and <code>u32int</code> are generally
141 <code>unsigned short</code> and <code>unsigned int</code> respectively.
142 <var>size</var> is the length of the string or <code>-1</code> if the string
143 is null terminated. If the string is a cast from <code>const u16int
144 *</code> or <code>const u32int *</code> then <i>size</i> is the amount of
145 space in bytes the string takes up after being cast to <code>const
146 char *</code> and not the true size of the string. <code>sspell_speller_check</code>
147 will return <code>0</code> if it is not found and non-zero otherwise.
149 <p>If the word is not correct, then the <code>suggest</code> method can be used
150 to come up with likely replacements.
152 <pre class="smallexample"> AspellWordList * suggestions = aspell_speller_suggest(spell_checker,
153 <var>word</var>, <var>size</var>);
154 AspellStringEnumeration * elements = aspell_word_list_elements(suggestions);
156 while ( (word = aspell_string_enumeration_next(aspell_elements)) != NULL )
158 // add to suggestion list
160 delete_aspell_string_enumeration(elements);
162 <p>Notice how <code>elements</code> is deleted but <code>suggestions</code> is not.
163 The value returned by <code>suggestions</code> is only valid to the next
164 call to <code>suggest</code>. Once a replacement is made the
165 <code>store_repl</code> method should be used to communicate the replacement
166 pair back to the spell checker (for the reason, see <a href="Notes-on-Storing-Replacement-Pairs.html#Notes-on-Storing-Replacement-Pairs">Notes on Storing Replacement Pairs</a>). Its usage is as follows:
168 <pre class="smallexample"> aspell_speller_store_repl(spell_checker, <var>misspelled_word</var>, <var>size</var>,
169 <var>correctly_spelled_word</var>, <var>size</var>);
171 <p>If the user decided to add the word to the session or personal
172 dictionary the the word can be be added using the
173 <code>add_to_session</code> or <code>add_to_personal</code> methods respectively
176 <pre class="smallexample"> aspell_speller_add_to_session|personal(spell_checker, <i>word</i>, <i>size</i>);
178 <p>It is better to let the spell checker manage these words rather than
179 doing it yourself so that the words have a chance of appearing in the
182 <p>Finally, when the document is closed the <code>AspellSpeller</code> class
183 should be deleted like so:
185 <pre class="smallexample"> delete_aspell_speller(spell_checker);
187 <h4 class="subsection">6.1.2 API Reference</h4>
189 <p>Methods that return a boolean result generally return <code>false</code> on
190 error and <code>true</code> otherwise. To find out what went wrong use the
191 <code>error_number</code> and <code>error_message</code> methods. Unless
192 otherwise stated methods that return a <code>const char *</code> will return
193 <code>NULL</code> on error. In general, the character string returned is
194 only valid until the next method which returns a <code>const char *</code>
197 <p>For the details of the various classes please see the header files.
198 In the future I will generate class references using some automated
201 <h4 class="subsection">6.1.3 Examples</h4>
203 <p>Two simple examples are included in the examples directory. The
204 <code>example-c</code> program demonstrates most of the Aspell library
205 functionality and the <code>list-dicts</code> lists the available
208 <h4 class="subsection">6.1.4 Notes About Thread Safety</h4>
210 <p>Aspell should be thread safe, when used properly, as long as the
211 underlying compiler, C and C++ library is thread safe. Aspell
212 objects, including the AspellSpeller class, should not be used by
213 multiple threads unless they are protected by locks or it is only
214 accessed by read-only methods. A method is read-only only if a
215 <code>const</code> object is passed in. Many methods that seam to be
216 read-only are not because they may store state information in the