hxt-8.3.0: doc/hdoc/src/Text-XML-HXT-RelaxNG-XmlSchema-RegexMatch.html
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<pre><a name="line-1"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-2"></a>
<a name="line-3"></a><span class='comment'>{- |
<a name="line-4"></a> Module : Text.XML.HXT.RelaxNG.XmlSchema.RegexMatch
<a name="line-5"></a> Copyright : Copyright (C) 2005 Uwe Schmidt
<a name="line-6"></a> License : MIT
<a name="line-7"></a>
<a name="line-8"></a> Maintainer : Uwe Schmidt (uwe@fh-wedel.de)
<a name="line-9"></a> Stability : experimental
<a name="line-10"></a> Portability: portable
<a name="line-11"></a>
<a name="line-12"></a> Convenient functions for W3C XML Schema Regular Expression Matcher.
<a name="line-13"></a> For internals see 'Text.XML.HXT.RelaxNG.XmlSchema.Regex'
<a name="line-14"></a>
<a name="line-15"></a> Grammar can be found under <<a href="http://www.w3.org/TR/xmlschema11-2/#regexs">http://www.w3.org/TR/xmlschema11-2/#regexs</a>>
<a name="line-16"></a>
<a name="line-17"></a>-}</span>
<a name="line-18"></a>
<a name="line-19"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-20"></a>
<a name="line-21"></a><span class='keyword'>module</span> <span class='conid'>Text</span><span class='varop'>.</span><span class='conid'>XML</span><span class='varop'>.</span><span class='conid'>HXT</span><span class='varop'>.</span><span class='conid'>RelaxNG</span><span class='varop'>.</span><span class='conid'>XmlSchema</span><span class='varop'>.</span><span class='conid'>RegexMatch</span>
<a name="line-22"></a> <span class='layout'>(</span> <span class='varid'>matchRE</span>
<a name="line-23"></a> <span class='layout'>,</span> <span class='varid'>splitRE</span>
<a name="line-24"></a> <span class='layout'>,</span> <span class='varid'>sedRE</span>
<a name="line-25"></a> <span class='layout'>,</span> <span class='varid'>tokenizeRE</span>
<a name="line-26"></a> <span class='layout'>,</span> <span class='varid'>tokenizeRE'</span>
<a name="line-27"></a> <span class='layout'>,</span> <span class='varid'>match</span>
<a name="line-28"></a> <span class='layout'>,</span> <span class='varid'>tokenize</span>
<a name="line-29"></a> <span class='layout'>,</span> <span class='varid'>tokenize'</span>
<a name="line-30"></a> <span class='layout'>,</span> <span class='varid'>sed</span>
<a name="line-31"></a> <span class='layout'>,</span> <span class='varid'>split</span>
<a name="line-32"></a> <span class='layout'>)</span>
<a name="line-33"></a><span class='keyword'>where</span>
<a name="line-34"></a>
<a name="line-35"></a><span class='keyword'>import</span> <span class='conid'>Data</span><span class='varop'>.</span><span class='conid'>Maybe</span>
<a name="line-36"></a>
<a name="line-37"></a><span class='keyword'>import</span> <span class='conid'>Text</span><span class='varop'>.</span><span class='conid'>XML</span><span class='varop'>.</span><span class='conid'>HXT</span><span class='varop'>.</span><span class='conid'>RelaxNG</span><span class='varop'>.</span><span class='conid'>XmlSchema</span><span class='varop'>.</span><span class='conid'>Regex</span>
<a name="line-38"></a><span class='keyword'>import</span> <span class='conid'>Text</span><span class='varop'>.</span><span class='conid'>XML</span><span class='varop'>.</span><span class='conid'>HXT</span><span class='varop'>.</span><span class='conid'>RelaxNG</span><span class='varop'>.</span><span class='conid'>XmlSchema</span><span class='varop'>.</span><span class='conid'>RegexParser</span>
<a name="line-39"></a>
<a name="line-40"></a><span class='comment'>{-
<a name="line-41"></a>import qualified Debug.Trace as T
<a name="line-42"></a>-}</span>
<a name="line-43"></a>
<a name="line-44"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-45"></a>
<a name="line-46"></a><a name="splitRegex"></a><span class='definition'>splitRegex</span> <span class='keyglyph'>::</span> <span class='conid'>Regex</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='layout'>(</span><span class='conid'>String</span><span class='layout'>,</span> <span class='conid'>String</span><span class='layout'>)</span>
<a name="line-47"></a><span class='definition'>splitRegex</span> <span class='varid'>re</span> <span class='str'>""</span>
<a name="line-48"></a> <span class='keyglyph'>|</span> <span class='varid'>nullable</span> <span class='varid'>re</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='layout'>(</span><span class='str'>""</span><span class='layout'>,</span> <span class='str'>""</span><span class='layout'>)</span>
<a name="line-49"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-50"></a>
<a name="line-51"></a><span class='definition'>splitRegex</span> <span class='varid'>re</span> <span class='varid'>inp</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='varid'>c</span> <span class='conop'>:</span> <span class='varid'>inp'</span><span class='layout'>)</span>
<a name="line-52"></a> <span class='keyglyph'>|</span> <span class='varid'>isZero</span> <span class='varid'>re</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-53"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='varid'>evalRes</span> <span class='varop'>.</span> <span class='varid'>splitRegex</span> <span class='comment'>{- (T.trace (show re') re') -}</span> <span class='varid'>re'</span> <span class='varop'>$</span> <span class='varid'>inp'</span>
<a name="line-54"></a> <span class='keyword'>where</span>
<a name="line-55"></a> <span class='varid'>re'</span> <span class='keyglyph'>=</span> <span class='varid'>delta</span> <span class='varid'>re</span> <span class='varid'>c</span>
<a name="line-56"></a> <span class='varid'>evalRes</span> <span class='conid'>Nothing</span>
<a name="line-57"></a> <span class='keyglyph'>|</span> <span class='varid'>nullable</span> <span class='varid'>re</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='layout'>(</span><span class='str'>""</span><span class='layout'>,</span> <span class='varid'>inp</span><span class='layout'>)</span>
<a name="line-58"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-59"></a>
<a name="line-60"></a> <span class='varid'>evalRes</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='layout'>(</span><span class='varid'>tok</span><span class='layout'>,</span> <span class='varid'>rest</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-61"></a> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='layout'>(</span><span class='varid'>c</span> <span class='conop'>:</span> <span class='varid'>tok</span><span class='layout'>,</span> <span class='varid'>rest</span><span class='layout'>)</span>
<a name="line-62"></a>
<a name="line-63"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-64"></a>
<a name="line-65"></a><span class='comment'>-- | split a string by taking the longest prefix matching a regular expression</span>
<a name="line-66"></a><span class='comment'>--</span>
<a name="line-67"></a><span class='comment'>-- @Nothing@ is returned in case of a syntactically wrong regex string</span>
<a name="line-68"></a><span class='comment'>-- or in case there is no matching prefix, else the pair of prefix and rest is returned</span>
<a name="line-69"></a><span class='comment'>--</span>
<a name="line-70"></a><span class='comment'>-- examples:</span>
<a name="line-71"></a><span class='comment'>--</span>
<a name="line-72"></a><span class='comment'>-- > splitRE "a*b" "abc" = Just ("ab","c")</span>
<a name="line-73"></a><span class='comment'>-- > splitRE "a*" "bc" = Just ("", "bc")</span>
<a name="line-74"></a><span class='comment'>-- > splitRE "a+" "bc" = Nothing</span>
<a name="line-75"></a><span class='comment'>-- > splitRE "[" "abc" = Nothing</span>
<a name="line-76"></a>
<a name="line-77"></a><a name="splitRE"></a><span class='definition'>splitRE</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='layout'>(</span><span class='conid'>String</span><span class='layout'>,</span> <span class='conid'>String</span><span class='layout'>)</span>
<a name="line-78"></a><span class='definition'>splitRE</span> <span class='varid'>re</span> <span class='varid'>input</span>
<a name="line-79"></a> <span class='keyglyph'>=</span> <span class='varid'>either</span> <span class='layout'>(</span><span class='varid'>const</span> <span class='conid'>Nothing</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>flip</span> <span class='varid'>splitRegex</span> <span class='varid'>input</span><span class='layout'>)</span> <span class='varop'>.</span> <span class='varid'>parseRegex</span> <span class='varop'>$</span> <span class='varid'>re</span>
<a name="line-80"></a>
<a name="line-81"></a><span class='comment'>-- | convenient function for splitRE</span>
<a name="line-82"></a><span class='comment'>--</span>
<a name="line-83"></a><span class='comment'>-- syntax errors in R.E. are interpreted as no matching prefix found</span>
<a name="line-84"></a>
<a name="line-85"></a><a name="split"></a><span class='definition'>split</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='conid'>String</span><span class='layout'>,</span> <span class='conid'>String</span><span class='layout'>)</span>
<a name="line-86"></a><span class='definition'>split</span> <span class='varid'>re</span> <span class='varid'>input</span>
<a name="line-87"></a> <span class='keyglyph'>=</span> <span class='varid'>fromMaybe</span> <span class='layout'>(</span><span class='str'>""</span><span class='layout'>,</span> <span class='varid'>input</span><span class='layout'>)</span> <span class='varop'>.</span> <span class='varid'>splitRE</span> <span class='varid'>re</span> <span class='varop'>$</span> <span class='varid'>input</span>
<a name="line-88"></a>
<a name="line-89"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-90"></a>
<a name="line-91"></a><span class='comment'>-- | split a string into tokens (words) by giving a regular expression</span>
<a name="line-92"></a><span class='comment'>-- which all tokens must match</span>
<a name="line-93"></a><span class='comment'>--</span>
<a name="line-94"></a><span class='comment'>-- This can be used for simple tokenizers.</span>
<a name="line-95"></a><span class='comment'>-- The words in the result list contain at least one char.</span>
<a name="line-96"></a><span class='comment'>-- All none matching chars are discarded. If the given regex contains syntax errors,</span>
<a name="line-97"></a><span class='comment'>-- @Nothing@ is returned</span>
<a name="line-98"></a><span class='comment'>--</span>
<a name="line-99"></a><span class='comment'>-- examples:</span>
<a name="line-100"></a><span class='comment'>--</span>
<a name="line-101"></a><span class='comment'>-- > tokenizeRE "a*b" "" = Just []</span>
<a name="line-102"></a><span class='comment'>-- > tokenizeRE "a*b" "abc" = Just ["ab"]</span>
<a name="line-103"></a><span class='comment'>-- > tokenizeRE "a*b" "abaab ab" = Just ["ab","aab","ab"]</span>
<a name="line-104"></a><span class='comment'>-- ></span>
<a name="line-105"></a><span class='comment'>-- > tokenizeRE "[a-z]{2,}|[0-9]{2,}|[0-9]+[.][0-9]+" "ab123 456.7abc"</span>
<a name="line-106"></a><span class='comment'>-- > = Just ["ab","123","456.7","abc"]</span>
<a name="line-107"></a><span class='comment'>-- ></span>
<a name="line-108"></a><span class='comment'>-- > tokenizeRE "[a-z]*|[0-9]{2,}|[0-9]+[.][0-9]+" "cab123 456.7abc"</span>
<a name="line-109"></a><span class='comment'>-- > = Just ["cab","123","456.7","abc"]</span>
<a name="line-110"></a><span class='comment'>-- ></span>
<a name="line-111"></a><span class='comment'>-- > tokenizeRE "[^ \t\n\r]*" "abc def\t\n\rxyz"</span>
<a name="line-112"></a><span class='comment'>-- > = Just ["abc","def","xyz"]</span>
<a name="line-113"></a><span class='comment'>-- ></span>
<a name="line-114"></a><span class='comment'>-- > tokenizeRE "[^ \t\n\r]*" = words</span>
<a name="line-115"></a>
<a name="line-116"></a><a name="tokenizeRE"></a><span class='definition'>tokenizeRE</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='keyglyph'>[</span><span class='conid'>String</span><span class='keyglyph'>]</span>
<a name="line-117"></a><span class='definition'>tokenizeRE</span> <span class='varid'>regex</span> <span class='varid'>input</span>
<a name="line-118"></a> <span class='keyglyph'>=</span> <span class='varid'>either</span> <span class='layout'>(</span><span class='varid'>const</span> <span class='conid'>Nothing</span><span class='layout'>)</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='varop'>.</span> <span class='varid'>flip</span> <span class='varid'>token'</span> <span class='varid'>input</span><span class='layout'>)</span> <span class='varop'>$</span> <span class='varid'>parseRegex</span> <span class='varid'>regex</span>
<a name="line-119"></a> <span class='keyword'>where</span>
<a name="line-120"></a> <span class='varid'>token'</span> <span class='keyglyph'>::</span> <span class='conid'>Regex</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='conid'>String</span><span class='keyglyph'>]</span>
<a name="line-121"></a> <span class='varid'>token'</span> <span class='varid'>re</span> <span class='varid'>inp</span>
<a name="line-122"></a> <span class='keyglyph'>|</span> <span class='varid'>null</span> <span class='varid'>inp</span> <span class='keyglyph'>=</span> <span class='conid'>[]</span>
<a name="line-123"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='varid'>evalRes</span> <span class='varop'>.</span> <span class='varid'>splitRegex</span> <span class='varid'>re</span> <span class='varop'>$</span> <span class='varid'>inp</span>
<a name="line-124"></a> <span class='keyword'>where</span>
<a name="line-125"></a> <span class='varid'>token''</span> <span class='keyglyph'>=</span> <span class='varid'>token'</span> <span class='varid'>re</span>
<a name="line-126"></a> <span class='varid'>evalRes</span> <span class='conid'>Nothing</span> <span class='keyglyph'>=</span> <span class='varid'>token''</span> <span class='layout'>(</span><span class='varid'>tail</span> <span class='varid'>inp</span><span class='layout'>)</span> <span class='comment'>-- re does not match any prefix</span>
<a name="line-127"></a> <span class='varid'>evalRes</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='layout'>(</span><span class='varid'>tok</span><span class='layout'>,</span> <span class='varid'>rest</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-128"></a> <span class='keyglyph'>|</span> <span class='varid'>null</span> <span class='varid'>tok</span> <span class='keyglyph'>=</span> <span class='varid'>token''</span> <span class='layout'>(</span><span class='varid'>tail</span> <span class='varid'>rest</span><span class='layout'>)</span> <span class='comment'>-- re is nullable and only the empty prefix matches</span>
<a name="line-129"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='varid'>tok</span> <span class='conop'>:</span> <span class='varid'>token''</span> <span class='varid'>rest</span> <span class='comment'>-- token found, tokenize the rest</span>
<a name="line-130"></a>
<a name="line-131"></a><span class='comment'>-- | convenient function for tokenizeRE a string</span>
<a name="line-132"></a><span class='comment'>--</span>
<a name="line-133"></a><span class='comment'>-- syntax errors in R.E. result in an empty list</span>
<a name="line-134"></a>
<a name="line-135"></a><a name="tokenize"></a><span class='definition'>tokenize</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='conid'>String</span><span class='keyglyph'>]</span>
<a name="line-136"></a><span class='definition'>tokenize</span> <span class='varid'>re</span>
<a name="line-137"></a> <span class='keyglyph'>=</span> <span class='varid'>fromMaybe</span> <span class='conid'>[]</span> <span class='varop'>.</span> <span class='varid'>tokenizeRE</span> <span class='varid'>re</span>
<a name="line-138"></a>
<a name="line-139"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-140"></a>
<a name="line-141"></a><span class='comment'>-- | split a string into tokens and delimierter by giving a regular expression</span>
<a name="line-142"></a><span class='comment'>-- wich all tokens must match</span>
<a name="line-143"></a><span class='comment'>--</span>
<a name="line-144"></a><span class='comment'>-- This is a generalisation of the above 'tokenizeRE' functions.</span>
<a name="line-145"></a><span class='comment'>-- The none matching char sequences are marked with @Left@, the matching ones are marked with @Right@</span>
<a name="line-146"></a><span class='comment'>--</span>
<a name="line-147"></a><span class='comment'>-- If the regular expression contains syntax errors @Nothing@ is returned</span>
<a name="line-148"></a><span class='comment'>--</span>
<a name="line-149"></a><span class='comment'>-- The following Law holds:</span>
<a name="line-150"></a><span class='comment'>--</span>
<a name="line-151"></a><span class='comment'>-- > concat . map (either id id) . fromJust . tokenizeRE' re == id</span>
<a name="line-152"></a>
<a name="line-153"></a><a name="tokenizeRE'"></a><span class='definition'>tokenizeRE'</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='keyglyph'>[</span><span class='conid'>Either</span> <span class='conid'>String</span> <span class='conid'>String</span><span class='keyglyph'>]</span>
<a name="line-154"></a><span class='definition'>tokenizeRE'</span> <span class='varid'>regex</span> <span class='varid'>input</span>
<a name="line-155"></a> <span class='keyglyph'>=</span> <span class='varid'>either</span> <span class='layout'>(</span><span class='varid'>const</span> <span class='conid'>Nothing</span><span class='layout'>)</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='varop'>.</span> <span class='varid'>flip</span> <span class='varid'>token'</span> <span class='varid'>input</span><span class='layout'>)</span> <span class='varop'>$</span> <span class='varid'>parseRegex</span> <span class='varid'>regex</span>
<a name="line-156"></a> <span class='keyword'>where</span>
<a name="line-157"></a> <span class='varid'>token'</span> <span class='keyglyph'>::</span> <span class='conid'>Regex</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='conid'>Either</span> <span class='conid'>String</span> <span class='conid'>String</span><span class='keyglyph'>]</span>
<a name="line-158"></a> <span class='varid'>token'</span> <span class='varid'>re</span>
<a name="line-159"></a> <span class='keyglyph'>=</span> <span class='varid'>tok2</span> <span class='str'>""</span>
<a name="line-160"></a> <span class='keyword'>where</span>
<a name="line-161"></a> <span class='varid'>tok2</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='conid'>Either</span> <span class='conid'>String</span> <span class='conid'>String</span><span class='keyglyph'>]</span>
<a name="line-162"></a> <span class='varid'>tok2</span> <span class='varid'>noMatchPrefix</span> <span class='varid'>inp</span>
<a name="line-163"></a> <span class='keyglyph'>|</span> <span class='varid'>null</span> <span class='varid'>inp</span> <span class='keyglyph'>=</span> <span class='varid'>addNoMatch</span> <span class='conid'>[]</span>
<a name="line-164"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='varid'>evalRes</span> <span class='varop'>.</span> <span class='varid'>splitRegex</span> <span class='varid'>re</span> <span class='varop'>$</span> <span class='varid'>inp</span>
<a name="line-165"></a> <span class='keyword'>where</span>
<a name="line-166"></a> <span class='varid'>addNoMatch</span> <span class='varid'>res</span>
<a name="line-167"></a> <span class='keyglyph'>|</span> <span class='varid'>null</span> <span class='varid'>noMatchPrefix</span> <span class='keyglyph'>=</span> <span class='varid'>res</span>
<a name="line-168"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='conid'>Left</span> <span class='varop'>.</span> <span class='varid'>reverse</span> <span class='varop'>$</span> <span class='varid'>noMatchPrefix</span><span class='layout'>)</span> <span class='conop'>:</span> <span class='varid'>res</span>
<a name="line-169"></a>
<a name="line-170"></a> <span class='varid'>evalRes</span> <span class='conid'>Nothing</span> <span class='keyglyph'>=</span> <span class='varid'>tok2</span> <span class='layout'>(</span><span class='varid'>head</span> <span class='varid'>inp</span> <span class='conop'>:</span> <span class='varid'>noMatchPrefix</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>tail</span> <span class='varid'>inp</span><span class='layout'>)</span> <span class='comment'>-- re does not match any prefix</span>
<a name="line-171"></a> <span class='varid'>evalRes</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='layout'>(</span><span class='varid'>tok</span><span class='layout'>,</span> <span class='varid'>rest</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-172"></a> <span class='keyglyph'>|</span> <span class='varid'>null</span> <span class='varid'>tok</span> <span class='keyglyph'>=</span> <span class='varid'>tok2</span> <span class='layout'>(</span><span class='varid'>head</span> <span class='varid'>rest</span> <span class='conop'>:</span> <span class='varid'>noMatchPrefix</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>tail</span> <span class='varid'>rest</span><span class='layout'>)</span> <span class='comment'>-- re is nullable and only the empty prefix matches</span>
<a name="line-173"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='varid'>addNoMatch</span> <span class='varop'>.</span> <span class='layout'>(</span><span class='conid'>Right</span> <span class='varid'>tok</span> <span class='conop'>:</span><span class='layout'>)</span> <span class='varop'>.</span> <span class='varid'>tok2</span> <span class='str'>""</span> <span class='varop'>$</span> <span class='varid'>rest</span> <span class='comment'>-- token found, tokenize the rest</span>
<a name="line-174"></a>
<a name="line-175"></a><span class='comment'>-- | convenient function for tokenizeRE'</span>
<a name="line-176"></a><span class='comment'>--</span>
<a name="line-177"></a><span class='comment'>-- When the regular expression contains errors @[Left input]@ is returned, that means tokens are found</span>
<a name="line-178"></a>
<a name="line-179"></a><a name="tokenize'"></a><span class='definition'>tokenize'</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='conid'>Either</span> <span class='conid'>String</span> <span class='conid'>String</span><span class='keyglyph'>]</span>
<a name="line-180"></a><span class='definition'>tokenize'</span> <span class='varid'>regex</span> <span class='varid'>input</span>
<a name="line-181"></a> <span class='keyglyph'>=</span> <span class='varid'>fromMaybe</span> <span class='keyglyph'>[</span><span class='conid'>Left</span> <span class='varid'>input</span><span class='keyglyph'>]</span> <span class='varop'>.</span> <span class='varid'>tokenizeRE'</span> <span class='varid'>regex</span> <span class='varop'>$</span> <span class='varid'>input</span>
<a name="line-182"></a>
<a name="line-183"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-184"></a>
<a name="line-185"></a><span class='comment'>-- | sed like editing function</span>
<a name="line-186"></a><span class='comment'>--</span>
<a name="line-187"></a><span class='comment'>-- All matching tokens are edited by the 1. argument, the editing function,</span>
<a name="line-188"></a><span class='comment'>-- all other chars remain as they are</span>
<a name="line-189"></a><span class='comment'>--</span>
<a name="line-190"></a><span class='comment'>-- examples:</span>
<a name="line-191"></a><span class='comment'>--</span>
<a name="line-192"></a><span class='comment'>-- > sedRE (const "b") "a" "xaxax" = Just "xbxbx"</span>
<a name="line-193"></a><span class='comment'>-- > sedRE (\ x -> x ++ x) "a" "xax" = Just "xaax"</span>
<a name="line-194"></a><span class='comment'>-- > sedRE undefined "[" undefined = Nothing</span>
<a name="line-195"></a>
<a name="line-196"></a><a name="sedRE"></a><span class='definition'>sedRE</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='conid'>String</span>
<a name="line-197"></a><span class='definition'>sedRE</span> <span class='varid'>edit</span> <span class='varid'>regex</span> <span class='varid'>input</span>
<a name="line-198"></a> <span class='keyglyph'>=</span> <span class='varid'>maybe</span> <span class='conid'>Nothing</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='varop'>.</span> <span class='varid'>concatMap</span> <span class='layout'>(</span><span class='varid'>either</span> <span class='varid'>id</span> <span class='varid'>edit</span><span class='layout'>)</span><span class='layout'>)</span> <span class='varop'>$</span> <span class='varid'>tokenizeRE'</span> <span class='varid'>regex</span> <span class='varid'>input</span>
<a name="line-199"></a>
<a name="line-200"></a><span class='comment'>-- | convenient function for sedRE</span>
<a name="line-201"></a><span class='comment'>--</span>
<a name="line-202"></a><span class='comment'>-- When the regular expression contains errors, sed is the identity, else</span>
<a name="line-203"></a><span class='comment'>-- the funtionality is like 'sedRE'</span>
<a name="line-204"></a><span class='comment'>--</span>
<a name="line-205"></a><span class='comment'>-- > sed undefined "[" == id</span>
<a name="line-206"></a>
<a name="line-207"></a><a name="sed"></a><span class='definition'>sed</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span>
<a name="line-208"></a><span class='definition'>sed</span> <span class='varid'>edit</span> <span class='varid'>regex</span> <span class='varid'>input</span>
<a name="line-209"></a> <span class='keyglyph'>=</span> <span class='varid'>fromMaybe</span> <span class='varid'>input</span> <span class='varop'>.</span> <span class='varid'>sedRE</span> <span class='varid'>edit</span> <span class='varid'>regex</span> <span class='varop'>$</span> <span class='varid'>input</span>
<a name="line-210"></a>
<a name="line-211"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-212"></a>
<a name="line-213"></a><span class='comment'>-- | match a string with a regular expression</span>
<a name="line-214"></a><span class='comment'>--</span>
<a name="line-215"></a><span class='comment'>-- First argument is the regex, second the input string,</span>
<a name="line-216"></a><span class='comment'>-- if the regex is not well formed, @Nothing@ is returned,</span>
<a name="line-217"></a><span class='comment'>-- else @Just@ the match result</span>
<a name="line-218"></a><span class='comment'>--</span>
<a name="line-219"></a><span class='comment'>-- Examples:</span>
<a name="line-220"></a><span class='comment'>--</span>
<a name="line-221"></a><span class='comment'>-- > matchRE "x*" "xxx" = Just True</span>
<a name="line-222"></a><span class='comment'>-- > matchRE "x" "xxx" = Just False</span>
<a name="line-223"></a><span class='comment'>-- > matchRE "[" "xxx" = Nothing</span>
<a name="line-224"></a>
<a name="line-225"></a><a name="matchRE"></a><span class='definition'>matchRE</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='conid'>Bool</span>
<a name="line-226"></a><span class='definition'>matchRE</span> <span class='varid'>regex</span> <span class='varid'>input</span>
<a name="line-227"></a> <span class='keyglyph'>=</span> <span class='varid'>either</span> <span class='layout'>(</span><span class='varid'>const</span> <span class='conid'>Nothing</span><span class='layout'>)</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='varop'>.</span> <span class='varid'>isNothing</span> <span class='varop'>.</span> <span class='varid'>flip</span> <span class='varid'>matchWithRE</span> <span class='varid'>input</span><span class='layout'>)</span> <span class='varop'>$</span> <span class='varid'>parseRegex</span> <span class='varid'>regex</span>
<a name="line-228"></a>
<a name="line-229"></a>
<a name="line-230"></a><span class='comment'>-- | convenient function for matchRE</span>
<a name="line-231"></a><span class='comment'>--</span>
<a name="line-232"></a><span class='comment'>-- syntax errors in R.E. are interpreted as no match found</span>
<a name="line-233"></a>
<a name="line-234"></a><a name="match"></a><span class='definition'>match</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>Bool</span>
<a name="line-235"></a><span class='definition'>match</span> <span class='varid'>re</span> <span class='keyglyph'>=</span> <span class='varid'>fromMaybe</span> <span class='conid'>False</span> <span class='varop'>.</span> <span class='varid'>matchRE</span> <span class='varid'>re</span>
<a name="line-236"></a>
<a name="line-237"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-238"></a>
</pre></body>
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