hxt-8.0.0: doc/hdoc/src/Text-XML-HXT-Arrow-XmlRegex.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.Arrow.XmlRegex
<a name="line-5"></a> Copyright : Copyright (C) 2008 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> Regular Expression Matcher working on lists of XmlTrees
<a name="line-13"></a>
<a name="line-14"></a> It's intendet to import this module with an explicit
<a name="line-15"></a> import declaration for not spoiling the namespace
<a name="line-16"></a> with these somewhat special arrows
<a name="line-17"></a>
<a name="line-18"></a>-}</span>
<a name="line-19"></a>
<a name="line-20"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-21"></a>
<a name="line-22"></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'>Arrow</span><span class='varop'>.</span><span class='conid'>XmlRegex</span>
<a name="line-23"></a> <span class='layout'>(</span> <span class='conid'>XmlRegex</span>
<a name="line-24"></a> <span class='layout'>,</span> <span class='varid'>mkZero</span>
<a name="line-25"></a> <span class='layout'>,</span> <span class='varid'>mkUnit</span>
<a name="line-26"></a> <span class='layout'>,</span> <span class='varid'>mkPrim</span>
<a name="line-27"></a> <span class='layout'>,</span> <span class='varid'>mkPrimA</span>
<a name="line-28"></a> <span class='layout'>,</span> <span class='varid'>mkDot</span>
<a name="line-29"></a> <span class='layout'>,</span> <span class='varid'>mkStar</span>
<a name="line-30"></a> <span class='layout'>,</span> <span class='varid'>mkAlt</span>
<a name="line-31"></a> <span class='layout'>,</span> <span class='varid'>mkSeq</span>
<a name="line-32"></a> <span class='layout'>,</span> <span class='varid'>mkRep</span>
<a name="line-33"></a> <span class='layout'>,</span> <span class='varid'>mkRng</span>
<a name="line-34"></a> <span class='layout'>,</span> <span class='varid'>mkOpt</span>
<a name="line-35"></a> <span class='layout'>,</span> <span class='varid'>nullable</span>
<a name="line-36"></a> <span class='layout'>,</span> <span class='varid'>delta</span>
<a name="line-37"></a> <span class='layout'>,</span> <span class='varid'>matchXmlRegex</span>
<a name="line-38"></a> <span class='layout'>,</span> <span class='varid'>splitXmlRegex</span>
<a name="line-39"></a> <span class='layout'>,</span> <span class='varid'>scanXmlRegex</span>
<a name="line-40"></a> <span class='layout'>,</span> <span class='varid'>matchRegexA</span>
<a name="line-41"></a> <span class='layout'>,</span> <span class='varid'>splitRegexA</span>
<a name="line-42"></a> <span class='layout'>,</span> <span class='varid'>scanRegexA</span>
<a name="line-43"></a> <span class='layout'>)</span>
<a name="line-44"></a><span class='keyword'>where</span>
<a name="line-45"></a>
<a name="line-46"></a><span class='keyword'>import</span> <span class='conid'>Control</span><span class='varop'>.</span><span class='conid'>Arrow</span><span class='varop'>.</span><span class='conid'>ListArrows</span>
<a name="line-47"></a>
<a name="line-48"></a><span class='keyword'>import</span> <span class='conid'>Data</span><span class='varop'>.</span><span class='conid'>Maybe</span>
<a name="line-49"></a>
<a name="line-50"></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'>DOM</span><span class='varop'>.</span><span class='conid'>Interface</span>
<a name="line-51"></a>
<a name="line-52"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-53"></a><span class='comment'>-- the exported regex arrows</span>
<a name="line-54"></a>
<a name="line-55"></a><span class='comment'>-- | check whether a sequence of XmlTrees match an Xml regular expression</span>
<a name="line-56"></a><span class='comment'>--</span>
<a name="line-57"></a><span class='comment'>-- The arrow for 'matchXmlRegex'.</span>
<a name="line-58"></a><span class='comment'>--</span>
<a name="line-59"></a><span class='comment'>-- The expession is build up from simple arrows acting as predicate ('mkPrimA') for</span>
<a name="line-60"></a><span class='comment'>-- an XmlTree and of the usual cobinators for sequence ('mkSeq'), repetition</span>
<a name="line-61"></a><span class='comment'>-- ('mkStar', mkRep', 'mkRng') and choice ('mkAlt', 'mkOpt')</span>
<a name="line-62"></a>
<a name="line-63"></a><a name="matchRegexA"></a><span class='definition'>matchRegexA</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>LA</span> <span class='conid'>XmlTree</span> <span class='conid'>XmlTree</span> <span class='keyglyph'>-></span> <span class='conid'>LA</span> <span class='conid'>XmlTree</span> <span class='conid'>XmlTrees</span>
<a name="line-64"></a><span class='definition'>matchRegexA</span> <span class='varid'>re</span> <span class='varid'>ts</span> <span class='keyglyph'>=</span> <span class='varid'>ts</span> <span class='varop'>>>.</span> <span class='layout'>(</span><span class='keyglyph'>\</span> <span class='varid'>s</span> <span class='keyglyph'>-></span> <span class='varid'>maybe</span> <span class='conid'>[]</span> <span class='layout'>(</span><span class='varid'>const</span> <span class='keyglyph'>[</span><span class='varid'>s</span><span class='keyglyph'>]</span><span class='layout'>)</span> <span class='varop'>.</span> <span class='varid'>matchXmlRegex</span> <span class='varid'>re</span> <span class='varop'>$</span> <span class='varid'>s</span><span class='layout'>)</span>
<a name="line-65"></a>
<a name="line-66"></a><span class='comment'>-- | split the sequence of trees computed by the filter a into</span>
<a name="line-67"></a><span class='comment'>--</span>
<a name="line-68"></a><span class='comment'>-- The arrow for 'splitXmlRegex'.</span>
<a name="line-69"></a><span class='comment'>--</span>
<a name="line-70"></a><span class='comment'>-- a first part matching the regex and a rest,</span>
<a name="line-71"></a><span class='comment'>-- if a prefix of the input sequence does not match the regex, the arrow fails</span>
<a name="line-72"></a><span class='comment'>-- else the pair containing the result lists is returned</span>
<a name="line-73"></a>
<a name="line-74"></a><a name="splitRegexA"></a><span class='definition'>splitRegexA</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>LA</span> <span class='conid'>XmlTree</span> <span class='conid'>XmlTree</span> <span class='keyglyph'>-></span> <span class='conid'>LA</span> <span class='conid'>XmlTree</span> <span class='layout'>(</span><span class='conid'>XmlTrees</span><span class='layout'>,</span> <span class='conid'>XmlTrees</span><span class='layout'>)</span>
<a name="line-75"></a><span class='definition'>splitRegexA</span> <span class='varid'>re</span> <span class='varid'>ts</span> <span class='keyglyph'>=</span> <span class='varid'>ts</span> <span class='varop'>>>.</span> <span class='layout'>(</span><span class='varid'>maybeToList</span> <span class='varop'>.</span> <span class='varid'>splitXmlRegex</span> <span class='varid'>re</span><span class='layout'>)</span>
<a name="line-76"></a>
<a name="line-77"></a><span class='comment'>-- | scan the input sequence with a regex and give the result as a list of lists of trees back</span>
<a name="line-78"></a><span class='comment'>-- the regex must at least match one input tree, so the empty sequence should not match the regex</span>
<a name="line-79"></a><span class='comment'>--</span>
<a name="line-80"></a><span class='comment'>-- The arrow for 'scanXmlRegex'.</span>
<a name="line-81"></a>
<a name="line-82"></a><a name="scanRegexA"></a><span class='definition'>scanRegexA</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>LA</span> <span class='conid'>XmlTree</span> <span class='conid'>XmlTree</span> <span class='keyglyph'>-></span> <span class='conid'>LA</span> <span class='conid'>XmlTree</span> <span class='conid'>XmlTrees</span>
<a name="line-83"></a><span class='definition'>scanRegexA</span> <span class='varid'>re</span> <span class='varid'>ts</span> <span class='keyglyph'>=</span> <span class='varid'>ts</span> <span class='varop'>>>.</span> <span class='layout'>(</span><span class='varid'>fromMaybe</span> <span class='conid'>[]</span> <span class='varop'>.</span> <span class='varid'>scanXmlRegex</span> <span class='varid'>re</span><span class='layout'>)</span>
<a name="line-84"></a>
<a name="line-85"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-86"></a>
<a name="line-87"></a><a name="XmlRegex"></a><span class='keyword'>data</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>=</span> <span class='conid'>Zero</span> <span class='conid'>String</span>
<a name="line-88"></a> <span class='keyglyph'>|</span> <span class='conid'>Unit</span>
<a name="line-89"></a> <span class='keyglyph'>|</span> <span class='conid'>Sym</span> <span class='layout'>(</span><span class='conid'>XmlTree</span> <span class='keyglyph'>-></span> <span class='conid'>Bool</span><span class='layout'>)</span>
<a name="line-90"></a> <span class='keyglyph'>|</span> <span class='conid'>Dot</span>
<a name="line-91"></a> <span class='keyglyph'>|</span> <span class='conid'>Star</span> <span class='conid'>XmlRegex</span>
<a name="line-92"></a> <span class='keyglyph'>|</span> <span class='conid'>Alt</span> <span class='conid'>XmlRegex</span> <span class='conid'>XmlRegex</span>
<a name="line-93"></a> <span class='keyglyph'>|</span> <span class='conid'>Seq</span> <span class='conid'>XmlRegex</span> <span class='conid'>XmlRegex</span>
<a name="line-94"></a> <span class='keyglyph'>|</span> <span class='conid'>Rep</span> <span class='conid'>Int</span> <span class='conid'>XmlRegex</span> <span class='comment'>-- 1 or more repetitions</span>
<a name="line-95"></a> <span class='keyglyph'>|</span> <span class='conid'>Rng</span> <span class='conid'>Int</span> <span class='conid'>Int</span> <span class='conid'>XmlRegex</span> <span class='comment'>-- n..m repetitions</span>
<a name="line-96"></a>
<a name="line-97"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-98"></a>
<a name="line-99"></a><span class='comment'>{- just for documentation
<a name="line-100"></a>
<a name="line-101"></a>class Inv a where
<a name="line-102"></a> inv :: a -> Bool
<a name="line-103"></a>
<a name="line-104"></a>instance Inv XmlRegex where
<a name="line-105"></a> inv (Zero _) = True
<a name="line-106"></a> inv Unit = True
<a name="line-107"></a> inv (Sym p) = p holds for some XmlTrees
<a name="line-108"></a> inv Dot = True
<a name="line-109"></a> inv (Star e) = inv e
<a name="line-110"></a> inv (Alt e1 e2) = inv e1 &&
<a name="line-111"></a> inv e2
<a name="line-112"></a> inv (Seq e1 e2) = inv e1 &&
<a name="line-113"></a> inv e2
<a name="line-114"></a> inv (Rep i e) = i > 0 && inv e
<a name="line-115"></a> inv (Rng i j e) = (i < j || (i == j && i > 1)) &&
<a name="line-116"></a> inv e
<a name="line-117"></a>-}</span>
<a name="line-118"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-119"></a><span class='comment'>--</span>
<a name="line-120"></a><span class='comment'>-- smart constructors</span>
<a name="line-121"></a>
<a name="line-122"></a><a name="mkZero"></a><span class='definition'>mkZero</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-123"></a><span class='definition'>mkZero</span> <span class='keyglyph'>=</span> <span class='conid'>Zero</span>
<a name="line-124"></a>
<a name="line-125"></a><a name="mkUnit"></a><span class='definition'>mkUnit</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span>
<a name="line-126"></a><span class='definition'>mkUnit</span> <span class='keyglyph'>=</span> <span class='conid'>Unit</span>
<a name="line-127"></a>
<a name="line-128"></a><a name="mkPrim"></a><span class='definition'>mkPrim</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='conid'>XmlTree</span> <span class='keyglyph'>-></span> <span class='conid'>Bool</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-129"></a><span class='definition'>mkPrim</span> <span class='keyglyph'>=</span> <span class='conid'>Sym</span>
<a name="line-130"></a>
<a name="line-131"></a><a name="mkPrimA"></a><span class='definition'>mkPrimA</span> <span class='keyglyph'>::</span> <span class='conid'>LA</span> <span class='conid'>XmlTree</span> <span class='conid'>XmlTree</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-132"></a><span class='definition'>mkPrimA</span> <span class='varid'>a</span> <span class='keyglyph'>=</span> <span class='varid'>mkPrim</span> <span class='layout'>(</span><span class='varid'>not</span> <span class='varop'>.</span> <span class='varid'>null</span> <span class='varop'>.</span> <span class='varid'>runLA</span> <span class='varid'>a</span><span class='layout'>)</span>
<a name="line-133"></a>
<a name="line-134"></a><a name="mkDot"></a><span class='definition'>mkDot</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span>
<a name="line-135"></a><span class='definition'>mkDot</span> <span class='keyglyph'>=</span> <span class='conid'>Dot</span>
<a name="line-136"></a>
<a name="line-137"></a><a name="mkStar"></a><span class='definition'>mkStar</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-138"></a><span class='definition'>mkStar</span> <span class='layout'>(</span><span class='conid'>Zero</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>mkUnit</span> <span class='comment'>-- {}* == ()</span>
<a name="line-139"></a><span class='definition'>mkStar</span> <span class='varid'>e</span><span class='keyglyph'>@</span><span class='conid'>Unit</span> <span class='keyglyph'>=</span> <span class='varid'>e</span> <span class='comment'>-- ()* == ()</span>
<a name="line-140"></a><span class='definition'>mkStar</span> <span class='varid'>e</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Star</span> <span class='sel'>_e1</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>e</span> <span class='comment'>-- (r*)* == r*</span>
<a name="line-141"></a><span class='definition'>mkStar</span> <span class='layout'>(</span><span class='conid'>Rep</span> <span class='num'>1</span> <span class='varid'>e1</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>mkStar</span> <span class='varid'>e1</span> <span class='comment'>-- (r+)* == r*</span>
<a name="line-142"></a><span class='definition'>mkStar</span> <span class='varid'>e</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Alt</span> <span class='keyword'>_</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Star</span> <span class='layout'>(</span><span class='varid'>rmStar</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='comment'>-- (a*|b)* == (a|b)*</span>
<a name="line-143"></a><span class='definition'>mkStar</span> <span class='varid'>e</span> <span class='keyglyph'>=</span> <span class='conid'>Star</span> <span class='varid'>e</span>
<a name="line-144"></a>
<a name="line-145"></a><a name="rmStar"></a><span class='definition'>rmStar</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-146"></a><span class='definition'>rmStar</span> <span class='layout'>(</span><span class='conid'>Alt</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>mkAlt</span> <span class='layout'>(</span><span class='varid'>rmStar</span> <span class='varid'>e1</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>rmStar</span> <span class='varid'>e2</span><span class='layout'>)</span>
<a name="line-147"></a><span class='definition'>rmStar</span> <span class='layout'>(</span><span class='conid'>Star</span> <span class='varid'>e1</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>rmStar</span> <span class='varid'>e1</span>
<a name="line-148"></a><span class='definition'>rmStar</span> <span class='layout'>(</span><span class='conid'>Rep</span> <span class='num'>1</span> <span class='varid'>e1</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>rmStar</span> <span class='varid'>e1</span>
<a name="line-149"></a><span class='definition'>rmStar</span> <span class='varid'>e1</span> <span class='keyglyph'>=</span> <span class='varid'>e1</span>
<a name="line-150"></a>
<a name="line-151"></a><a name="mkAlt"></a><span class='definition'>mkAlt</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-152"></a><span class='definition'>mkAlt</span> <span class='varid'>e1</span> <span class='layout'>(</span><span class='conid'>Zero</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>e1</span> <span class='comment'>-- e1 u {} = e1</span>
<a name="line-153"></a><span class='definition'>mkAlt</span> <span class='layout'>(</span><span class='conid'>Zero</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='varid'>e2</span> <span class='keyglyph'>=</span> <span class='varid'>e2</span> <span class='comment'>-- {} u e2 = e2</span>
<a name="line-154"></a><span class='definition'>mkAlt</span> <span class='varid'>e1</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Star</span> <span class='conid'>Dot</span><span class='layout'>)</span> <span class='sel'>_e2</span> <span class='keyglyph'>=</span> <span class='varid'>e1</span> <span class='comment'>-- A* u e1 = A*</span>
<a name="line-155"></a><span class='definition'>mkAlt</span> <span class='sel'>_e1</span> <span class='varid'>e2</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Star</span> <span class='conid'>Dot</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>e2</span> <span class='comment'>-- e1 u A* = A*</span>
<a name="line-156"></a><span class='definition'>mkAlt</span> <span class='layout'>(</span><span class='conid'>Sym</span> <span class='varid'>p1</span><span class='layout'>)</span> <span class='layout'>(</span><span class='conid'>Sym</span> <span class='varid'>p2</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>mkPrim</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='varid'>p1</span> <span class='varid'>x</span> <span class='varop'>||</span> <span class='varid'>p2</span> <span class='varid'>x</span> <span class='comment'>-- melting of predicates</span>
<a name="line-157"></a><span class='definition'>mkAlt</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Sym</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>mkAlt</span> <span class='varid'>e2</span> <span class='varid'>e1</span> <span class='comment'>-- symmetry: predicates always first</span>
<a name="line-158"></a><span class='definition'>mkAlt</span> <span class='varid'>e1</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Sym</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='layout'>(</span><span class='conid'>Alt</span> <span class='varid'>e2</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Sym</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='varid'>e3</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>mkAlt</span> <span class='layout'>(</span><span class='varid'>mkAlt</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='varid'>e3</span> <span class='comment'>-- prepare melting of predicates</span>
<a name="line-159"></a><span class='definition'>mkAlt</span> <span class='layout'>(</span><span class='conid'>Alt</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='varid'>e3</span> <span class='keyglyph'>=</span> <span class='varid'>mkAlt</span> <span class='varid'>e1</span> <span class='layout'>(</span><span class='varid'>mkAlt</span> <span class='varid'>e2</span> <span class='varid'>e3</span><span class='layout'>)</span> <span class='comment'>-- associativity</span>
<a name="line-160"></a><span class='definition'>mkAlt</span> <span class='varid'>e1</span> <span class='varid'>e2</span> <span class='keyglyph'>=</span> <span class='conid'>Alt</span> <span class='varid'>e1</span> <span class='varid'>e2</span>
<a name="line-161"></a>
<a name="line-162"></a><a name="mkSeq"></a><span class='definition'>mkSeq</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-163"></a><span class='definition'>mkSeq</span> <span class='varid'>e1</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Zero</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='sel'>_e2</span> <span class='keyglyph'>=</span> <span class='varid'>e1</span>
<a name="line-164"></a><span class='definition'>mkSeq</span> <span class='sel'>_e1</span> <span class='varid'>e2</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Zero</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>e2</span>
<a name="line-165"></a><span class='definition'>mkSeq</span> <span class='conid'>Unit</span> <span class='varid'>e2</span> <span class='keyglyph'>=</span> <span class='varid'>e2</span>
<a name="line-166"></a><span class='definition'>mkSeq</span> <span class='varid'>e1</span> <span class='conid'>Unit</span> <span class='keyglyph'>=</span> <span class='varid'>e1</span>
<a name="line-167"></a><span class='definition'>mkSeq</span> <span class='layout'>(</span><span class='conid'>Seq</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='varid'>e3</span> <span class='keyglyph'>=</span> <span class='varid'>mkSeq</span> <span class='varid'>e1</span> <span class='layout'>(</span><span class='varid'>mkSeq</span> <span class='varid'>e2</span> <span class='varid'>e3</span><span class='layout'>)</span>
<a name="line-168"></a><span class='definition'>mkSeq</span> <span class='varid'>e1</span> <span class='varid'>e2</span> <span class='keyglyph'>=</span> <span class='conid'>Seq</span> <span class='varid'>e1</span> <span class='varid'>e2</span>
<a name="line-169"></a>
<a name="line-170"></a><a name="mkRep"></a><span class='definition'>mkRep</span> <span class='keyglyph'>::</span> <span class='conid'>Int</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-171"></a><span class='definition'>mkRep</span> <span class='num'>0</span> <span class='varid'>e</span> <span class='keyglyph'>=</span> <span class='varid'>mkStar</span> <span class='varid'>e</span>
<a name="line-172"></a><span class='definition'>mkRep</span> <span class='keyword'>_</span> <span class='varid'>e</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Zero</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>e</span>
<a name="line-173"></a><span class='definition'>mkRep</span> <span class='keyword'>_</span> <span class='varid'>e</span><span class='keyglyph'>@</span><span class='conid'>Unit</span> <span class='keyglyph'>=</span> <span class='varid'>e</span>
<a name="line-174"></a><span class='definition'>mkRep</span> <span class='varid'>i</span> <span class='varid'>e</span> <span class='keyglyph'>=</span> <span class='conid'>Rep</span> <span class='varid'>i</span> <span class='varid'>e</span>
<a name="line-175"></a>
<a name="line-176"></a><a name="mkRng"></a><span class='definition'>mkRng</span> <span class='keyglyph'>::</span> <span class='conid'>Int</span> <span class='keyglyph'>-></span> <span class='conid'>Int</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-177"></a><span class='definition'>mkRng</span> <span class='num'>0</span> <span class='num'>0</span> <span class='sel'>_e</span> <span class='keyglyph'>=</span> <span class='varid'>mkUnit</span>
<a name="line-178"></a><span class='definition'>mkRng</span> <span class='num'>1</span> <span class='num'>1</span> <span class='varid'>e</span> <span class='keyglyph'>=</span> <span class='varid'>e</span>
<a name="line-179"></a><span class='definition'>mkRng</span> <span class='varid'>lb</span> <span class='varid'>ub</span> <span class='sel'>_e</span>
<a name="line-180"></a> <span class='keyglyph'>|</span> <span class='varid'>lb</span> <span class='varop'>></span> <span class='varid'>ub</span> <span class='keyglyph'>=</span> <span class='conid'>Zero</span> <span class='varop'>$</span>
<a name="line-181"></a> <span class='str'>"illegal range "</span> <span class='varop'>++</span>
<a name="line-182"></a> <span class='varid'>show</span> <span class='varid'>lb</span> <span class='varop'>++</span> <span class='str'>".."</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>ub</span>
<a name="line-183"></a><span class='definition'>mkRng</span> <span class='sel'>_l</span> <span class='sel'>_u</span> <span class='varid'>e</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Zero</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>e</span>
<a name="line-184"></a><span class='definition'>mkRng</span> <span class='sel'>_l</span> <span class='sel'>_u</span> <span class='varid'>e</span><span class='keyglyph'>@</span><span class='conid'>Unit</span> <span class='keyglyph'>=</span> <span class='varid'>e</span>
<a name="line-185"></a><span class='definition'>mkRng</span> <span class='varid'>lb</span> <span class='varid'>ub</span> <span class='varid'>e</span> <span class='keyglyph'>=</span> <span class='conid'>Rng</span> <span class='varid'>lb</span> <span class='varid'>ub</span> <span class='varid'>e</span>
<a name="line-186"></a>
<a name="line-187"></a><a name="mkOpt"></a><span class='definition'>mkOpt</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-188"></a><span class='definition'>mkOpt</span> <span class='keyglyph'>=</span> <span class='varid'>mkRng</span> <span class='num'>0</span> <span class='num'>1</span>
<a name="line-189"></a>
<a name="line-190"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-191"></a>
<a name="line-192"></a><span class='keyword'>instance</span> <span class='conid'>Show</span> <span class='conid'>XmlRegex</span> <span class='keyword'>where</span>
<a name="line-193"></a> <span class='varid'>show</span> <span class='layout'>(</span><span class='conid'>Zero</span> <span class='varid'>s</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='str'>"{err:"</span> <span class='varop'>++</span> <span class='varid'>s</span> <span class='varop'>++</span> <span class='str'>"}"</span>
<a name="line-194"></a> <span class='varid'>show</span> <span class='conid'>Unit</span> <span class='keyglyph'>=</span> <span class='str'>"()"</span>
<a name="line-195"></a> <span class='varid'>show</span> <span class='layout'>(</span><span class='conid'>Sym</span> <span class='sel'>_p</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='str'>"{single tree pred}"</span>
<a name="line-196"></a> <span class='varid'>show</span> <span class='conid'>Dot</span> <span class='keyglyph'>=</span> <span class='str'>"."</span>
<a name="line-197"></a> <span class='varid'>show</span> <span class='layout'>(</span><span class='conid'>Star</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='str'>"("</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>e</span> <span class='varop'>++</span> <span class='str'>")*"</span>
<a name="line-198"></a> <span class='varid'>show</span> <span class='layout'>(</span><span class='conid'>Alt</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='str'>"("</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>e1</span> <span class='varop'>++</span> <span class='str'>"|"</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>e2</span> <span class='varop'>++</span> <span class='str'>")"</span>
<a name="line-199"></a> <span class='varid'>show</span> <span class='layout'>(</span><span class='conid'>Seq</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>show</span> <span class='varid'>e1</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>e2</span>
<a name="line-200"></a> <span class='varid'>show</span> <span class='layout'>(</span><span class='conid'>Rep</span> <span class='num'>1</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='str'>"("</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>e</span> <span class='varop'>++</span> <span class='str'>")+"</span>
<a name="line-201"></a> <span class='varid'>show</span> <span class='layout'>(</span><span class='conid'>Rep</span> <span class='varid'>i</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='str'>"("</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>e</span> <span class='varop'>++</span> <span class='str'>"){"</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>i</span> <span class='varop'>++</span> <span class='str'>",}"</span>
<a name="line-202"></a> <span class='varid'>show</span> <span class='layout'>(</span><span class='conid'>Rng</span> <span class='num'>0</span> <span class='num'>1</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='str'>"("</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>e</span> <span class='varop'>++</span> <span class='str'>")?"</span>
<a name="line-203"></a> <span class='varid'>show</span> <span class='layout'>(</span><span class='conid'>Rng</span> <span class='varid'>i</span> <span class='varid'>j</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='str'>"("</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>e</span> <span class='varop'>++</span> <span class='str'>"){"</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>i</span> <span class='varop'>++</span> <span class='str'>","</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>j</span> <span class='varop'>++</span> <span class='str'>"}"</span>
<a name="line-204"></a>
<a name="line-205"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-206"></a>
<a name="line-207"></a><a name="nullable"></a><span class='definition'>nullable</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>Bool</span>
<a name="line-208"></a><span class='definition'>nullable</span> <span class='layout'>(</span><span class='conid'>Zero</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>False</span>
<a name="line-209"></a><span class='definition'>nullable</span> <span class='conid'>Unit</span> <span class='keyglyph'>=</span> <span class='conid'>True</span>
<a name="line-210"></a><span class='definition'>nullable</span> <span class='layout'>(</span><span class='conid'>Sym</span> <span class='sel'>_p</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>False</span> <span class='comment'>-- assumption: p holds for at least one tree</span>
<a name="line-211"></a><span class='definition'>nullable</span> <span class='conid'>Dot</span> <span class='keyglyph'>=</span> <span class='conid'>False</span>
<a name="line-212"></a><span class='definition'>nullable</span> <span class='layout'>(</span><span class='conid'>Star</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>True</span>
<a name="line-213"></a><span class='definition'>nullable</span> <span class='layout'>(</span><span class='conid'>Alt</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>nullable</span> <span class='varid'>e1</span> <span class='varop'>||</span>
<a name="line-214"></a> <span class='varid'>nullable</span> <span class='varid'>e2</span>
<a name="line-215"></a><span class='definition'>nullable</span> <span class='layout'>(</span><span class='conid'>Seq</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>nullable</span> <span class='varid'>e1</span> <span class='varop'>&&</span>
<a name="line-216"></a> <span class='varid'>nullable</span> <span class='varid'>e2</span>
<a name="line-217"></a><span class='definition'>nullable</span> <span class='layout'>(</span><span class='conid'>Rep</span> <span class='sel'>_i</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>nullable</span> <span class='varid'>e</span>
<a name="line-218"></a><span class='definition'>nullable</span> <span class='layout'>(</span><span class='conid'>Rng</span> <span class='varid'>i</span> <span class='keyword'>_</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>i</span> <span class='varop'>==</span> <span class='num'>0</span> <span class='varop'>||</span>
<a name="line-219"></a> <span class='varid'>nullable</span> <span class='varid'>e</span>
<a name="line-220"></a>
<a name="line-221"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-222"></a>
<a name="line-223"></a><a name="delta"></a><span class='definition'>delta</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlTree</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-224"></a><span class='definition'>delta</span> <span class='varid'>e</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Zero</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyword'>_</span> <span class='keyglyph'>=</span> <span class='varid'>e</span>
<a name="line-225"></a><span class='definition'>delta</span> <span class='conid'>Unit</span> <span class='varid'>c</span> <span class='keyglyph'>=</span> <span class='varid'>mkZero</span> <span class='varop'>$</span>
<a name="line-226"></a> <span class='str'>"unexpected char "</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>c</span>
<a name="line-227"></a><span class='definition'>delta</span> <span class='layout'>(</span><span class='conid'>Sym</span> <span class='varid'>p</span><span class='layout'>)</span> <span class='varid'>c</span>
<a name="line-228"></a> <span class='keyglyph'>|</span> <span class='varid'>p</span> <span class='varid'>c</span> <span class='keyglyph'>=</span> <span class='varid'>mkUnit</span>
<a name="line-229"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='varid'>mkZero</span> <span class='varop'>$</span>
<a name="line-230"></a> <span class='str'>"unexpected tree "</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>c</span>
<a name="line-231"></a><span class='definition'>delta</span> <span class='conid'>Dot</span> <span class='keyword'>_</span> <span class='keyglyph'>=</span> <span class='varid'>mkUnit</span>
<a name="line-232"></a><span class='definition'>delta</span> <span class='varid'>e</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>Star</span> <span class='varid'>e1</span><span class='layout'>)</span> <span class='varid'>c</span> <span class='keyglyph'>=</span> <span class='varid'>mkSeq</span> <span class='layout'>(</span><span class='varid'>delta</span> <span class='varid'>e1</span> <span class='varid'>c</span><span class='layout'>)</span> <span class='varid'>e</span>
<a name="line-233"></a><span class='definition'>delta</span> <span class='layout'>(</span><span class='conid'>Alt</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='varid'>c</span> <span class='keyglyph'>=</span> <span class='varid'>mkAlt</span> <span class='layout'>(</span><span class='varid'>delta</span> <span class='varid'>e1</span> <span class='varid'>c</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>delta</span> <span class='varid'>e2</span> <span class='varid'>c</span><span class='layout'>)</span>
<a name="line-234"></a><span class='definition'>delta</span> <span class='layout'>(</span><span class='conid'>Seq</span> <span class='varid'>e1</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='varid'>c</span>
<a name="line-235"></a> <span class='keyglyph'>|</span> <span class='varid'>nullable</span> <span class='varid'>e1</span> <span class='keyglyph'>=</span> <span class='varid'>mkAlt</span> <span class='layout'>(</span><span class='varid'>mkSeq</span> <span class='layout'>(</span><span class='varid'>delta</span> <span class='varid'>e1</span> <span class='varid'>c</span><span class='layout'>)</span> <span class='varid'>e2</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>delta</span> <span class='varid'>e2</span> <span class='varid'>c</span><span class='layout'>)</span>
<a name="line-236"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='varid'>mkSeq</span> <span class='layout'>(</span><span class='varid'>delta</span> <span class='varid'>e1</span> <span class='varid'>c</span><span class='layout'>)</span> <span class='varid'>e2</span>
<a name="line-237"></a><span class='definition'>delta</span> <span class='layout'>(</span><span class='conid'>Rep</span> <span class='varid'>i</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='varid'>c</span> <span class='keyglyph'>=</span> <span class='varid'>mkSeq</span> <span class='layout'>(</span><span class='varid'>delta</span> <span class='varid'>e</span> <span class='varid'>c</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>mkRep</span> <span class='layout'>(</span><span class='varid'>i</span><span class='comment'>-</span><span class='num'>1</span><span class='layout'>)</span> <span class='varid'>e</span><span class='layout'>)</span>
<a name="line-238"></a><span class='definition'>delta</span> <span class='layout'>(</span><span class='conid'>Rng</span> <span class='varid'>i</span> <span class='varid'>j</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='varid'>c</span> <span class='keyglyph'>=</span> <span class='varid'>mkSeq</span> <span class='layout'>(</span><span class='varid'>delta</span> <span class='varid'>e</span> <span class='varid'>c</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>mkRng</span> <span class='layout'>(</span><span class='layout'>(</span><span class='varid'>i</span><span class='comment'>-</span><span class='num'>1</span><span class='layout'>)</span> <span class='varop'>`max`</span> <span class='num'>0</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>j</span><span class='comment'>-</span><span class='num'>1</span><span class='layout'>)</span> <span class='varid'>e</span><span class='layout'>)</span>
<a name="line-239"></a>
<a name="line-240"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-241"></a>
<a name="line-242"></a><a name="delta'"></a><span class='definition'>delta'</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlTrees</span> <span class='keyglyph'>-></span> <span class='conid'>XmlRegex</span>
<a name="line-243"></a><span class='definition'>delta'</span> <span class='keyglyph'>=</span> <span class='varid'>foldl</span> <span class='varid'>delta</span>
<a name="line-244"></a>
<a name="line-245"></a><span class='comment'>-- | match a sequence of XML trees with a regular expression over trees</span>
<a name="line-246"></a><span class='comment'>--</span>
<a name="line-247"></a><span class='comment'>-- If the input matches, the result is Nothing, else Just an error message is returned</span>
<a name="line-248"></a>
<a name="line-249"></a><a name="matchXmlRegex"></a><span class='definition'>matchXmlRegex</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlTrees</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='conid'>String</span>
<a name="line-250"></a><span class='definition'>matchXmlRegex</span> <span class='varid'>e</span>
<a name="line-251"></a> <span class='keyglyph'>=</span> <span class='varid'>res</span> <span class='varop'>.</span> <span class='varid'>delta'</span> <span class='varid'>e</span>
<a name="line-252"></a> <span class='keyword'>where</span>
<a name="line-253"></a> <span class='varid'>res</span> <span class='layout'>(</span><span class='conid'>Zero</span> <span class='varid'>er</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='varid'>er</span>
<a name="line-254"></a> <span class='varid'>res</span> <span class='varid'>re</span>
<a name="line-255"></a> <span class='keyglyph'>|</span> <span class='varid'>nullable</span> <span class='varid'>re</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span> <span class='comment'>-- o.k.</span>
<a name="line-256"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='varop'>$</span> <span class='str'>"input does not match "</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>e</span>
<a name="line-257"></a>
<a name="line-258"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-259"></a>
<a name="line-260"></a><span class='comment'>-- | split a sequence of XML trees into a pair of a a matching prefix and a rest</span>
<a name="line-261"></a><span class='comment'>--</span>
<a name="line-262"></a><span class='comment'>-- If there is no matching prefix, Nothing is returned</span>
<a name="line-263"></a>
<a name="line-264"></a><a name="splitXmlRegex"></a><span class='definition'>splitXmlRegex</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlTrees</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='layout'>(</span><span class='conid'>XmlTrees</span><span class='layout'>,</span> <span class='conid'>XmlTrees</span><span class='layout'>)</span>
<a name="line-265"></a><span class='definition'>splitXmlRegex</span> <span class='varid'>re</span> <span class='keyglyph'>=</span> <span class='varid'>splitXmlRegex'</span> <span class='varid'>re</span> <span class='conid'>[]</span>
<a name="line-266"></a>
<a name="line-267"></a><a name="splitXmlRegex'"></a><span class='definition'>splitXmlRegex'</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlTrees</span> <span class='keyglyph'>-></span> <span class='conid'>XmlTrees</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='layout'>(</span><span class='conid'>XmlTrees</span><span class='layout'>,</span> <span class='conid'>XmlTrees</span><span class='layout'>)</span>
<a name="line-268"></a><span class='definition'>splitXmlRegex'</span> <span class='varid'>re</span> <span class='varid'>res</span> <span class='conid'>[]</span>
<a name="line-269"></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='varid'>reverse</span> <span class='varid'>res</span><span class='layout'>,</span> <span class='conid'>[]</span><span class='layout'>)</span>
<a name="line-270"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-271"></a>
<a name="line-272"></a><span class='definition'>splitXmlRegex'</span> <span class='layout'>(</span><span class='conid'>Zero</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyword'>_</span> <span class='keyword'>_</span>
<a name="line-273"></a> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-274"></a>
<a name="line-275"></a><span class='definition'>splitXmlRegex'</span> <span class='varid'>re</span> <span class='varid'>res</span> <span class='varid'>xs</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='varid'>x</span><span class='conop'>:</span><span class='varid'>xs'</span><span class='layout'>)</span>
<a name="line-276"></a> <span class='keyglyph'>|</span> <span class='varid'>isJust</span> <span class='varid'>res'</span> <span class='keyglyph'>=</span> <span class='varid'>res'</span>
<a name="line-277"></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='varid'>reverse</span> <span class='varid'>res</span><span class='layout'>,</span> <span class='varid'>xs</span><span class='layout'>)</span>
<a name="line-278"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-279"></a> <span class='keyword'>where</span>
<a name="line-280"></a> <span class='varid'>re'</span> <span class='keyglyph'>=</span> <span class='varid'>delta</span> <span class='varid'>re</span> <span class='varid'>x</span>
<a name="line-281"></a> <span class='varid'>res'</span> <span class='keyglyph'>=</span> <span class='varid'>splitXmlRegex'</span> <span class='varid'>re'</span> <span class='layout'>(</span><span class='varid'>x</span><span class='conop'>:</span><span class='varid'>res</span><span class='layout'>)</span> <span class='varid'>xs'</span>
<a name="line-282"></a>
<a name="line-283"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-284"></a>
<a name="line-285"></a><span class='comment'>-- | scan a sequence of XML trees and split it into parts matching the given regex</span>
<a name="line-286"></a><span class='comment'>--</span>
<a name="line-287"></a><span class='comment'>-- If the parts cannot be split because of a missing match, or because of the</span>
<a name="line-288"></a><span class='comment'>-- empty sequence as match, Nothing is returned</span>
<a name="line-289"></a>
<a name="line-290"></a><a name="scanXmlRegex"></a><span class='definition'>scanXmlRegex</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>XmlTrees</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='keyglyph'>[</span><span class='conid'>XmlTrees</span><span class='keyglyph'>]</span>
<a name="line-291"></a><span class='definition'>scanXmlRegex</span> <span class='varid'>re</span> <span class='varid'>ts</span> <span class='keyglyph'>=</span> <span class='varid'>scanXmlRegex'</span> <span class='varid'>re</span> <span class='layout'>(</span><span class='varid'>splitXmlRegex</span> <span class='varid'>re</span> <span class='varid'>ts</span><span class='layout'>)</span>
<a name="line-292"></a>
<a name="line-293"></a><a name="scanXmlRegex'"></a><span class='definition'>scanXmlRegex'</span> <span class='keyglyph'>::</span> <span class='conid'>XmlRegex</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='layout'>(</span><span class='conid'>XmlTrees</span><span class='layout'>,</span> <span class='conid'>XmlTrees</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='keyglyph'>[</span><span class='conid'>XmlTrees</span><span class='keyglyph'>]</span>
<a name="line-294"></a><span class='definition'>scanXmlRegex'</span> <span class='keyword'>_</span> <span class='conid'>Nothing</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-295"></a><span class='definition'>scanXmlRegex'</span> <span class='keyword'>_</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='layout'>(</span><span class='varid'>rs</span><span class='layout'>,</span> <span class='conid'>[]</span><span class='layout'>)</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='keyglyph'>[</span><span class='varid'>rs</span><span class='keyglyph'>]</span>
<a name="line-296"></a><span class='definition'>scanXmlRegex'</span> <span class='keyword'>_</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='layout'>(</span><span class='conid'>[]</span><span class='layout'>,</span> <span class='keyword'>_</span><span class='layout'>)</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span> <span class='comment'>-- re is nullable (the empty word matches), nothing split off</span>
<a name="line-297"></a> <span class='comment'>-- would give infinite list of empty lists</span>
<a name="line-298"></a><span class='definition'>scanXmlRegex'</span> <span class='varid'>re</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='layout'>(</span><span class='varid'>rs</span><span class='layout'>,</span> <span class='varid'>rest</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-299"></a> <span class='keyglyph'>|</span> <span class='varid'>isNothing</span> <span class='varid'>res</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-300"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='layout'>(</span><span class='varid'>rs</span> <span class='conop'>:</span> <span class='varid'>fromJust</span> <span class='varid'>res</span><span class='layout'>)</span>
<a name="line-301"></a> <span class='keyword'>where</span>
<a name="line-302"></a> <span class='varid'>res</span> <span class='keyglyph'>=</span> <span class='varid'>scanXmlRegex'</span> <span class='varid'>re</span> <span class='layout'>(</span><span class='varid'>splitXmlRegex</span> <span class='varid'>re</span> <span class='varid'>rest</span><span class='layout'>)</span>
<a name="line-303"></a>
<a name="line-304"></a><span class='comment'>-- ------------------------------------------------------------</span>
</pre></body>
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