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<pre><a name="line-1"></a><span class='hs-comment'>{- arch-tag: String utilities main file
<a name="line-2"></a>Copyright (C) 2004-2006 John Goerzen <jgoerzen@complete.org>
<a name="line-3"></a>
<a name="line-4"></a>This program is free software; you can redistribute it and\/or modify
<a name="line-5"></a>it under the terms of the GNU General Public License as published by
<a name="line-6"></a>the Free Software Foundation; either version 2 of the License, or
<a name="line-7"></a>(at your option) any later version.
<a name="line-8"></a>
<a name="line-9"></a>This program is distributed in the hope that it will be useful,
<a name="line-10"></a>but WITHOUT ANY WARRANTY; without even the implied warranty of
<a name="line-11"></a>MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
<a name="line-12"></a>GNU General Public License for more details.
<a name="line-13"></a>
<a name="line-14"></a>You should have received a copy of the GNU General Public License
<a name="line-15"></a>along with this program; if not, write to the Free Software
<a name="line-16"></a>Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
<a name="line-17"></a>-}</span>
<a name="line-18"></a>
<a name="line-19"></a><span class='hs-comment'>{- |
<a name="line-20"></a> Module : Data.String.Utils
<a name="line-21"></a> Copyright : Copyright (C) 2004-2008 John Goerzen
<a name="line-22"></a> License : GNU GPL, version 2 or above
<a name="line-23"></a>
<a name="line-24"></a> Maintainer : John Goerzen <jgoerzen@complete.org>
<a name="line-25"></a> Stability : provisional
<a name="line-26"></a> Portability: portable
<a name="line-27"></a>
<a name="line-28"></a>This module provides various helpful utilities for dealing with strings.
<a name="line-29"></a>
<a name="line-30"></a>Written by John Goerzen, jgoerzen\@complete.org
<a name="line-31"></a>-}</span>
<a name="line-32"></a>
<a name="line-33"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>String</span><span class='hs-varop'>.</span><span class='hs-conid'>Utils</span>
<a name="line-34"></a> <span class='hs-layout'>(</span><span class='hs-comment'>-- * Whitespace Removal</span>
<a name="line-35"></a> <span class='hs-varid'>strip</span><span class='hs-layout'>,</span> <span class='hs-varid'>lstrip</span><span class='hs-layout'>,</span> <span class='hs-varid'>rstrip</span><span class='hs-layout'>,</span>
<a name="line-36"></a> <span class='hs-comment'>-- * Tests</span>
<a name="line-37"></a> <span class='hs-comment'>-- | Note: These functions are aliases for functions</span>
<a name="line-38"></a> <span class='hs-comment'>-- in "Data.List.Utils".</span>
<a name="line-39"></a> <span class='hs-varid'>startswith</span><span class='hs-layout'>,</span> <span class='hs-varid'>endswith</span><span class='hs-layout'>,</span>
<a name="line-40"></a> <span class='hs-comment'>-- * Conversions</span>
<a name="line-41"></a> <span class='hs-comment'>-- | Note: Some of these functions are aliases for functions</span>
<a name="line-42"></a> <span class='hs-comment'>-- in "Data.List.Utils".</span>
<a name="line-43"></a> <span class='hs-varid'>join</span><span class='hs-layout'>,</span> <span class='hs-varid'>split</span><span class='hs-layout'>,</span> <span class='hs-varid'>splitWs</span><span class='hs-layout'>,</span> <span class='hs-varid'>replace</span><span class='hs-layout'>,</span> <span class='hs-varid'>escapeRe</span>
<a name="line-44"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-45"></a>
<a name="line-46"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>List</span><span class='hs-varop'>.</span><span class='hs-conid'>Utils</span> <span class='hs-layout'>(</span><span class='hs-varid'>startswith</span><span class='hs-layout'>,</span> <span class='hs-varid'>endswith</span><span class='hs-layout'>,</span> <span class='hs-varid'>join</span><span class='hs-layout'>,</span> <span class='hs-varid'>split</span><span class='hs-layout'>,</span> <span class='hs-varid'>replace</span><span class='hs-layout'>)</span>
<a name="line-47"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Char</span> <span class='hs-layout'>(</span><span class='hs-varid'>isAlpha</span><span class='hs-layout'>,</span> <span class='hs-varid'>isAscii</span><span class='hs-layout'>,</span> <span class='hs-varid'>isDigit</span><span class='hs-layout'>)</span>
<a name="line-48"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Text</span><span class='hs-varop'>.</span><span class='hs-conid'>Regex</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkRegex</span><span class='hs-layout'>,</span> <span class='hs-varid'>splitRegex</span><span class='hs-layout'>)</span>
<a name="line-49"></a>
<a name="line-50"></a><a name="wschars"></a><span class='hs-definition'>wschars</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span>
<a name="line-51"></a><span class='hs-definition'>wschars</span> <span class='hs-keyglyph'>=</span> <span class='hs-str'>" \t\r\n"</span>
<a name="line-52"></a>
<a name="line-53"></a><a name="strip"></a><span class='hs-comment'>{- | Removes any whitespace characters that are present at the start
<a name="line-54"></a>or end of a string. Does not alter the internal contents of a
<a name="line-55"></a>string. If no whitespace characters are present at the start or end
<a name="line-56"></a>of a string, returns the original string unmodified. Safe to use on
<a name="line-57"></a>any string.
<a name="line-58"></a>
<a name="line-59"></a>Note that this may differ from some other similar
<a name="line-60"></a>functions from other authors in that:
<a name="line-61"></a>
<a name="line-62"></a>1. If multiple whitespace
<a name="line-63"></a>characters are present all in a row, they are all removed;
<a name="line-64"></a>
<a name="line-65"></a>2. If no
<a name="line-66"></a>whitespace characters are present, nothing is done.
<a name="line-67"></a>-}</span>
<a name="line-68"></a><span class='hs-definition'>strip</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span>
<a name="line-69"></a><span class='hs-definition'>strip</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lstrip</span> <span class='hs-varop'>.</span> <span class='hs-varid'>rstrip</span>
<a name="line-70"></a>
<a name="line-71"></a><a name="lstrip"></a><span class='hs-comment'>-- | Same as 'strip', but applies only to the left side of the string.</span>
<a name="line-72"></a><span class='hs-definition'>lstrip</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span>
<a name="line-73"></a><span class='hs-definition'>lstrip</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>s</span> <span class='hs-keyword'>of</span>
<a name="line-74"></a> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>[]</span>
<a name="line-75"></a> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>if</span> <span class='hs-varid'>elem</span> <span class='hs-varid'>x</span> <span class='hs-varid'>wschars</span>
<a name="line-76"></a> <span class='hs-keyword'>then</span> <span class='hs-varid'>lstrip</span> <span class='hs-varid'>xs</span>
<a name="line-77"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>s</span>
<a name="line-78"></a>
<a name="line-79"></a><a name="rstrip"></a><span class='hs-comment'>-- | Same as 'strip', but applies only to the right side of the string.</span>
<a name="line-80"></a><span class='hs-definition'>rstrip</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span>
<a name="line-81"></a><span class='hs-definition'>rstrip</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>reverse</span> <span class='hs-varop'>.</span> <span class='hs-varid'>lstrip</span> <span class='hs-varop'>.</span> <span class='hs-varid'>reverse</span>
<a name="line-82"></a>
<a name="line-83"></a><a name="splitWs"></a><span class='hs-comment'>{- | Splits a string around whitespace. Empty elements in the result
<a name="line-84"></a>list are automatically removed. -}</span>
<a name="line-85"></a><span class='hs-definition'>splitWs</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>String</span><span class='hs-keyglyph'>]</span>
<a name="line-86"></a><span class='hs-definition'>splitWs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>filter</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x</span> <span class='hs-varop'>/=</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span> <span class='hs-varop'>.</span> <span class='hs-varid'>splitRegex</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkRegex</span> <span class='hs-str'>"[ \t\n\r\v\f]+"</span><span class='hs-layout'>)</span>
<a name="line-87"></a>
<a name="line-88"></a><a name="escapeRe"></a><span class='hs-comment'>{- | Escape all characters in the input pattern that are not alphanumeric.
<a name="line-89"></a>
<a name="line-90"></a>Does not make special allowances for NULL, which isn't valid in a
<a name="line-91"></a>Haskell regular expression pattern. -}</span>
<a name="line-92"></a><span class='hs-definition'>escapeRe</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span>
<a name="line-93"></a><span class='hs-definition'>escapeRe</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>[]</span>
<a name="line-94"></a><span class='hs-definition'>escapeRe</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span>
<a name="line-95"></a> <span class='hs-comment'>-- Chars that we never escape</span>
<a name="line-96"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>x</span> <span class='hs-varop'>`elem`</span> <span class='hs-keyglyph'>[</span><span class='hs-chr'>'\''</span><span class='hs-layout'>,</span> <span class='hs-chr'>'`'</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>x</span> <span class='hs-conop'>:</span> <span class='hs-varid'>escapeRe</span> <span class='hs-varid'>xs</span>
<a name="line-97"></a> <span class='hs-comment'>-- General rules for chars we never escape</span>
<a name="line-98"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isDigit</span> <span class='hs-varid'>x</span> <span class='hs-varop'>||</span> <span class='hs-layout'>(</span><span class='hs-varid'>isAscii</span> <span class='hs-varid'>x</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>isAlpha</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-varop'>||</span> <span class='hs-varid'>x</span> <span class='hs-varop'>`elem`</span> <span class='hs-keyglyph'>[</span><span class='hs-chr'>'<'</span><span class='hs-layout'>,</span> <span class='hs-chr'>'>'</span><span class='hs-keyglyph'>]</span>
<a name="line-99"></a> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>x</span> <span class='hs-conop'>:</span> <span class='hs-varid'>escapeRe</span> <span class='hs-varid'>xs</span>
<a name="line-100"></a> <span class='hs-comment'>-- Escape everything else</span>
<a name="line-101"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-chr'>'\\'</span> <span class='hs-conop'>:</span> <span class='hs-varid'>x</span> <span class='hs-conop'>:</span> <span class='hs-varid'>escapeRe</span> <span class='hs-varid'>xs</span>
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