hxt-8.0.0: doc/hdoc/src/Data-NavTree.html
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<pre><a name="line-1"></a><span class='comment'>-- |</span>
<a name="line-2"></a><span class='comment'>-- Navigable tree structure which allow a program to traverse</span>
<a name="line-3"></a><span class='comment'>-- up the tree as well as down.</span>
<a name="line-4"></a><span class='comment'>-- copied and modified from HXML (<<a href="http://www.flightlab.com/~joe/hxml/">http://www.flightlab.com/~joe/hxml/</a>>)</span>
<a name="line-5"></a><span class='comment'>--</span>
<a name="line-6"></a>
<a name="line-7"></a><span class='keyword'>module</span> <span class='conid'>Data</span><span class='varop'>.</span><span class='conid'>NavTree</span>
<a name="line-8"></a> <span class='layout'>(</span> <span class='keyword'>module</span> <span class='conid'>Data</span><span class='varop'>.</span><span class='conid'>NavTree</span>
<a name="line-9"></a> <span class='layout'>,</span> <span class='keyword'>module</span> <span class='conid'>Data</span><span class='varop'>.</span><span class='conid'>Tree</span><span class='varop'>.</span><span class='conid'>NTree</span><span class='varop'>.</span><span class='conid'>TypeDefs</span>
<a name="line-10"></a> <span class='layout'>)</span>
<a name="line-11"></a><span class='keyword'>where</span>
<a name="line-12"></a>
<a name="line-13"></a><span class='keyword'>import</span> <span class='conid'>Data</span><span class='varop'>.</span><span class='conid'>Tree</span><span class='varop'>.</span><span class='conid'>NTree</span><span class='varop'>.</span><span class='conid'>TypeDefs</span>
<a name="line-14"></a><span class='keyword'>import</span> <span class='conid'>Data</span><span class='varop'>.</span><span class='conid'>Maybe</span>
<a name="line-15"></a>
<a name="line-16"></a><span class='comment'>-- -----------------------------------------------------------------------------</span>
<a name="line-17"></a>
<a name="line-18"></a><span class='comment'>-- NavTree</span>
<a name="line-19"></a><span class='comment'>--</span>
<a name="line-20"></a><span class='comment'>-- | navigable tree with nodes of type node</span>
<a name="line-21"></a><span class='comment'>--</span>
<a name="line-22"></a><span class='comment'>-- a navigable tree consists of a n-ary tree for the current fragment tree,</span>
<a name="line-23"></a><span class='comment'>-- a navigable tree for all ancestors, and two n-ary trees for</span>
<a name="line-24"></a><span class='comment'>-- the previous- and following siblings</span>
<a name="line-25"></a>
<a name="line-26"></a><a name="NavTree"></a><span class='keyword'>data</span> <span class='conid'>NavTree</span> <span class='varid'>a</span> <span class='keyglyph'>=</span> <span class='conid'>NT</span>
<a name="line-27"></a> <span class='layout'>(</span><span class='conid'>NTree</span> <span class='varid'>a</span><span class='layout'>)</span> <span class='comment'>-- self</span>
<a name="line-28"></a> <span class='keyglyph'>[</span><span class='conid'>NavTree</span> <span class='varid'>a</span><span class='keyglyph'>]</span> <span class='comment'>-- ancestors</span>
<a name="line-29"></a> <span class='keyglyph'>[</span><span class='conid'>NTree</span> <span class='varid'>a</span><span class='keyglyph'>]</span> <span class='comment'>-- previous siblings (in reverse order)</span>
<a name="line-30"></a> <span class='keyglyph'>[</span><span class='conid'>NTree</span> <span class='varid'>a</span><span class='keyglyph'>]</span> <span class='comment'>-- following siblings</span>
<a name="line-31"></a> <span class='keyword'>deriving</span> <span class='layout'>(</span><span class='conid'>Show</span><span class='layout'>,</span> <span class='conid'>Eq</span><span class='layout'>,</span> <span class='conid'>Ord</span><span class='layout'>)</span>
<a name="line-32"></a>
<a name="line-33"></a>
<a name="line-34"></a><span class='comment'>-- -----------------------------------------------------------------------------</span>
<a name="line-35"></a>
<a name="line-36"></a>
<a name="line-37"></a><span class='comment'>-- |</span>
<a name="line-38"></a><span class='comment'>-- converts a n-ary tree in a navigable tree</span>
<a name="line-39"></a>
<a name="line-40"></a><a name="ntree"></a><span class='definition'>ntree</span> <span class='keyglyph'>::</span> <span class='conid'>NTree</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>NavTree</span> <span class='varid'>a</span>
<a name="line-41"></a><span class='definition'>ntree</span> <span class='varid'>nd</span>
<a name="line-42"></a> <span class='keyglyph'>=</span> <span class='conid'>NT</span> <span class='varid'>nd</span> <span class='conid'>[]</span> <span class='conid'>[]</span> <span class='conid'>[]</span>
<a name="line-43"></a>
<a name="line-44"></a><span class='comment'>-- |</span>
<a name="line-45"></a><span class='comment'>-- converts a navigable tree in a n-ary tree</span>
<a name="line-46"></a>
<a name="line-47"></a><a name="subtreeNT"></a><span class='definition'>subtreeNT</span> <span class='keyglyph'>::</span> <span class='conid'>NavTree</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>NTree</span> <span class='varid'>a</span>
<a name="line-48"></a><span class='definition'>subtreeNT</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='varid'>nd</span> <span class='keyword'>_</span> <span class='keyword'>_</span> <span class='keyword'>_</span><span class='layout'>)</span>
<a name="line-49"></a> <span class='keyglyph'>=</span> <span class='varid'>nd</span>
<a name="line-50"></a>
<a name="line-51"></a>
<a name="line-52"></a><span class='comment'>-- |</span>
<a name="line-53"></a><span class='comment'>-- function for selecting the value of the current fragment tree</span>
<a name="line-54"></a>
<a name="line-55"></a><a name="dataNT"></a><span class='definition'>dataNT</span> <span class='keyglyph'>::</span> <span class='conid'>NavTree</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='varid'>a</span>
<a name="line-56"></a><span class='definition'>dataNT</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='layout'>(</span><span class='conid'>NTree</span> <span class='varid'>a</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyword'>_</span> <span class='keyword'>_</span> <span class='keyword'>_</span><span class='layout'>)</span>
<a name="line-57"></a> <span class='keyglyph'>=</span> <span class='varid'>a</span>
<a name="line-58"></a>
<a name="line-59"></a>
<a name="line-60"></a><span class='comment'>-- -----------------------------------------------------------------------------</span>
<a name="line-61"></a>
<a name="line-62"></a><span class='comment'>-- functions for traversing up, down, left and right in a navigable tree</span>
<a name="line-63"></a>
<a name="line-64"></a><a name="upNT"></a><span class='definition'>upNT</span>
<a name="line-65"></a> <span class='layout'>,</span> <span class='varid'>downNT</span>
<a name="line-66"></a> <span class='layout'>,</span> <span class='varid'>leftNT</span>
<a name="line-67"></a> <span class='layout'>,</span> <span class='varid'>rightNT</span> <span class='keyglyph'>::</span> <span class='conid'>NavTree</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='layout'>(</span><span class='conid'>NavTree</span> <span class='varid'>a</span><span class='layout'>)</span>
<a name="line-68"></a>
<a name="line-69"></a><span class='definition'>upNT</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='keyword'>_</span> <span class='layout'>(</span><span class='varid'>p</span><span class='conop'>:</span><span class='keyword'>_</span><span class='layout'>)</span> <span class='keyword'>_</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='varid'>p</span>
<a name="line-70"></a><span class='definition'>upNT</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='keyword'>_</span> <span class='conid'>[]</span> <span class='keyword'>_</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-71"></a><a name="downNT"></a><span class='definition'>downNT</span> <span class='varid'>t</span><span class='keyglyph'>@</span><span class='layout'>(</span><span class='conid'>NT</span> <span class='layout'>(</span><span class='conid'>NTree</span> <span class='keyword'>_</span> <span class='layout'>(</span><span class='varid'>c</span><span class='conop'>:</span><span class='varid'>cs</span><span class='layout'>)</span><span class='layout'>)</span> <span class='varid'>u</span> <span class='keyword'>_</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='varid'>c</span> <span class='layout'>(</span><span class='varid'>t</span><span class='conop'>:</span><span class='varid'>u</span><span class='layout'>)</span> <span class='conid'>[]</span> <span class='varid'>cs</span><span class='layout'>)</span>
<a name="line-72"></a><span class='definition'>downNT</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='layout'>(</span><span class='conid'>NTree</span> <span class='keyword'>_</span> <span class='conid'>[]</span> <span class='layout'>)</span> <span class='keyword'>_</span> <span class='keyword'>_</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-73"></a><a name="leftNT"></a><span class='definition'>leftNT</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='varid'>s</span> <span class='varid'>u</span> <span class='layout'>(</span><span class='varid'>l</span><span class='conop'>:</span><span class='varid'>ls</span><span class='layout'>)</span> <span class='varid'>r</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='varid'>l</span> <span class='varid'>u</span> <span class='varid'>ls</span> <span class='layout'>(</span><span class='varid'>s</span><span class='conop'>:</span><span class='varid'>r</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-74"></a><span class='definition'>leftNT</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='keyword'>_</span> <span class='keyword'>_</span> <span class='conid'>[]</span> <span class='keyword'>_</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-75"></a><a name="rightNT"></a><span class='definition'>rightNT</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='varid'>s</span> <span class='varid'>u</span> <span class='varid'>l</span> <span class='layout'>(</span><span class='varid'>r</span><span class='conop'>:</span><span class='varid'>rs</span><span class='layout'>)</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='varid'>r</span> <span class='varid'>u</span> <span class='layout'>(</span><span class='varid'>s</span><span class='conop'>:</span><span class='varid'>l</span><span class='layout'>)</span> <span class='varid'>rs</span><span class='layout'>)</span>
<a name="line-76"></a><span class='definition'>rightNT</span> <span class='layout'>(</span><span class='conid'>NT</span> <span class='keyword'>_</span> <span class='keyword'>_</span> <span class='keyword'>_</span> <span class='conid'>[]</span> <span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-77"></a>
<a name="line-78"></a>
<a name="line-79"></a><span class='comment'>-- preorderNT t = t : concatMap preorderNT (children t)</span>
<a name="line-80"></a><span class='comment'>-- where children = maybe [] (maybeStar rightNT) . downNT</span>
<a name="line-81"></a>
<a name="line-82"></a><a name="preorderNT"></a><span class='definition'>preorderNT</span> <span class='keyglyph'>::</span> <span class='conid'>NavTree</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='conid'>NavTree</span> <span class='varid'>a</span><span class='keyglyph'>]</span>
<a name="line-83"></a><span class='definition'>preorderNT</span>
<a name="line-84"></a> <span class='keyglyph'>=</span> <span class='varid'>visit</span> <span class='conid'>[]</span>
<a name="line-85"></a> <span class='keyword'>where</span>
<a name="line-86"></a> <span class='varid'>visit</span> <span class='varid'>k</span> <span class='varid'>t</span> <span class='keyglyph'>=</span> <span class='varid'>t</span> <span class='conop'>:</span> <span class='varid'>maybe</span> <span class='varid'>k</span> <span class='layout'>(</span><span class='varid'>visit'</span> <span class='varid'>k</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>downNT</span> <span class='varid'>t</span><span class='layout'>)</span>
<a name="line-87"></a> <span class='varid'>visit'</span> <span class='varid'>k</span> <span class='varid'>t</span> <span class='keyglyph'>=</span> <span class='varid'>visit</span> <span class='layout'>(</span><span class='varid'>maybe</span> <span class='varid'>k</span> <span class='layout'>(</span><span class='varid'>visit'</span> <span class='varid'>k</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>rightNT</span> <span class='varid'>t</span><span class='layout'>)</span><span class='layout'>)</span> <span class='varid'>t</span>
<a name="line-88"></a>
<a name="line-89"></a><a name="revPreorderNT"></a><span class='definition'>revPreorderNT</span> <span class='keyglyph'>::</span> <span class='conid'>NavTree</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='conid'>NavTree</span> <span class='varid'>a</span><span class='keyglyph'>]</span>
<a name="line-90"></a><span class='definition'>revPreorderNT</span> <span class='varid'>t</span>
<a name="line-91"></a> <span class='keyglyph'>=</span> <span class='varid'>t</span> <span class='conop'>:</span> <span class='varid'>concatMap</span> <span class='varid'>revPreorderNT</span> <span class='layout'>(</span><span class='varid'>reverse</span> <span class='layout'>(</span><span class='varid'>children</span> <span class='varid'>t</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-92"></a> <span class='keyword'>where</span>
<a name="line-93"></a> <span class='varid'>children</span> <span class='keyglyph'>=</span> <span class='varid'>maybe</span> <span class='conid'>[]</span> <span class='layout'>(</span><span class='varid'>maybeStar</span> <span class='varid'>rightNT</span><span class='layout'>)</span> <span class='varop'>.</span> <span class='varid'>downNT</span>
<a name="line-94"></a>
<a name="line-95"></a><a name="getChildrenNT"></a><span class='definition'>getChildrenNT</span> <span class='keyglyph'>::</span> <span class='conid'>NavTree</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='conid'>NavTree</span> <span class='varid'>a</span><span class='keyglyph'>]</span>
<a name="line-96"></a><span class='definition'>getChildrenNT</span> <span class='varid'>node</span>
<a name="line-97"></a> <span class='keyglyph'>=</span> <span class='varid'>maybe</span> <span class='conid'>[]</span> <span class='varid'>follow</span> <span class='layout'>(</span><span class='varid'>downNT</span> <span class='varid'>node</span><span class='layout'>)</span>
<a name="line-98"></a> <span class='keyword'>where</span>
<a name="line-99"></a> <span class='varid'>follow</span> <span class='varid'>n</span> <span class='keyglyph'>=</span> <span class='varid'>n</span> <span class='conop'>:</span> <span class='varid'>maybe</span> <span class='conid'>[]</span> <span class='varid'>follow</span> <span class='layout'>(</span><span class='varid'>rightNT</span> <span class='varid'>n</span><span class='layout'>)</span>
<a name="line-100"></a>
<a name="line-101"></a><span class='comment'>-- -----------------------------------------------------------------------------</span>
<a name="line-102"></a><span class='comment'>-- Miscellaneous useful combinators</span>
<a name="line-103"></a>
<a name="line-104"></a><span class='comment'>-- |</span>
<a name="line-105"></a><span class='comment'>-- Kleisli composition:</span>
<a name="line-106"></a>
<a name="line-107"></a><a name="o'"></a><span class='definition'>o'</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='conid'>Monad</span> <span class='varid'>m</span><span class='layout'>)</span> <span class='keyglyph'>=></span> <span class='layout'>(</span><span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='varid'>m</span> <span class='varid'>c</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='varid'>m</span> <span class='varid'>b</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='varid'>m</span> <span class='varid'>c</span><span class='layout'>)</span>
<a name="line-108"></a><a name="o'"></a><span class='definition'>f</span> <span class='varop'>`o'`</span> <span class='varid'>g</span> <span class='keyglyph'>=</span> <span class='keyglyph'>\</span><span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='varid'>g</span> <span class='varid'>x</span> <span class='varop'>>>=</span> <span class='varid'>f</span>
<a name="line-109"></a>
<a name="line-110"></a>
<a name="line-111"></a><span class='comment'>-- Some useful anamorphisms:</span>
<a name="line-112"></a>
<a name="line-113"></a><a name="maybeStar"></a><span class='definition'>maybeStar</span><span class='layout'>,</span> <span class='varid'>maybePlus</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='varid'>a</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='varid'>a</span><span class='keyglyph'>]</span>
<a name="line-114"></a><span class='definition'>maybeStar</span> <span class='varid'>f</span> <span class='varid'>a</span> <span class='keyglyph'>=</span> <span class='varid'>a</span> <span class='conop'>:</span> <span class='varid'>maybe</span> <span class='conid'>[]</span> <span class='layout'>(</span><span class='varid'>maybeStar</span> <span class='varid'>f</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>f</span> <span class='varid'>a</span><span class='layout'>)</span>
<a name="line-115"></a><a name="maybePlus"></a><span class='definition'>maybePlus</span> <span class='varid'>f</span> <span class='varid'>a</span> <span class='keyglyph'>=</span> <span class='varid'>maybe</span> <span class='conid'>[]</span> <span class='layout'>(</span><span class='varid'>maybeStar</span> <span class='varid'>f</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>f</span> <span class='varid'>a</span><span class='layout'>)</span>
<a name="line-116"></a>
<a name="line-117"></a><span class='comment'>-- -----------------------------------------------------------------------------</span>
</pre></body>
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