<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <head> <!-- Generated by HsColour, http://www.cs.york.ac.uk/fp/darcs/hscolour/ --> <title>Network/MPD/Utils.hs</title> <link type='text/css' rel='stylesheet' href='hscolour.css' /> </head> <body> <pre><a name="line-1"></a><span class='hs-comment'>-- | Module : Network.MPD.Utils</span> <a name="line-2"></a><span class='hs-comment'>-- Copyright : (c) Ben Sinclair 2005-2009, Joachim Fasting 2010</span> <a name="line-3"></a><span class='hs-comment'>-- License : LGPL (see LICENSE)</span> <a name="line-4"></a><span class='hs-comment'>-- Maintainer : Joachim Fasting <joachim.fasting@gmail.com></span> <a name="line-5"></a><span class='hs-comment'>-- Stability : alpha</span> <a name="line-6"></a><span class='hs-comment'>--</span> <a name="line-7"></a><span class='hs-comment'>-- Utilities.</span> <a name="line-8"></a> <a name="line-9"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Network</span><span class='hs-varop'>.</span><span class='hs-conid'>MPD</span><span class='hs-varop'>.</span><span class='hs-conid'>Utils</span> <span class='hs-layout'>(</span> <a name="line-10"></a> <span class='hs-varid'>parseDate</span><span class='hs-layout'>,</span> <span class='hs-varid'>parseNum</span><span class='hs-layout'>,</span> <span class='hs-varid'>parseBool</span><span class='hs-layout'>,</span> <span class='hs-varid'>showBool</span><span class='hs-layout'>,</span> <a name="line-11"></a> <span class='hs-varid'>breakChar</span><span class='hs-layout'>,</span> <span class='hs-varid'>toAssoc</span><span class='hs-layout'>,</span> <span class='hs-varid'>toAssocList</span><span class='hs-layout'>,</span> <span class='hs-varid'>splitGroups</span> <a name="line-12"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span> <a name="line-13"></a> <a name="line-14"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Char</span> <span class='hs-layout'>(</span><span class='hs-varid'>isDigit</span><span class='hs-layout'>)</span> <a name="line-15"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-varid'>fromMaybe</span><span class='hs-layout'>)</span> <a name="line-16"></a> <a name="line-17"></a><a name="breakChar"></a><span class='hs-comment'>-- Break a string by character, removing the separator.</span> <a name="line-18"></a><span class='hs-definition'>breakChar</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Char</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>String</span><span class='hs-layout'>,</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span> <a name="line-19"></a><span class='hs-definition'>breakChar</span> <span class='hs-varid'>c</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>break</span> <span class='hs-layout'>(</span><span class='hs-varop'>==</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-varid'>s</span> <span class='hs-keyword'>in</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span> <span class='hs-varid'>drop</span> <span class='hs-num'>1</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <a name="line-20"></a> <a name="line-21"></a><a name="parseDate"></a><span class='hs-comment'>-- XXX: need a more robust date parser.</span> <a name="line-22"></a><span class='hs-comment'>-- Parse a date value.</span> <a name="line-23"></a><span class='hs-comment'>-- > parseDate "2008" = Just 2008</span> <a name="line-24"></a><span class='hs-comment'>-- > parseDate "2008-03-01" = Just 2008</span> <a name="line-25"></a><span class='hs-definition'>parseDate</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-conid'>Int</span> <a name="line-26"></a><span class='hs-definition'>parseDate</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parseNum</span> <span class='hs-varop'>.</span> <span class='hs-varid'>takeWhile</span> <span class='hs-varid'>isDigit</span> <a name="line-27"></a> <a name="line-28"></a><a name="parseNum"></a><span class='hs-comment'>-- Parse a positive or negative integer value, returning 'Nothing' on failure.</span> <a name="line-29"></a><span class='hs-definition'>parseNum</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Read</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Integral</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-varid'>a</span> <a name="line-30"></a><span class='hs-definition'>parseNum</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <a name="line-31"></a> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span> <span class='hs-str'>""</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>reads</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <a name="line-32"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>x</span> <a name="line-33"></a> <a name="line-34"></a><a name="showBool"></a><span class='hs-comment'>-- Inverts 'parseBool'.</span> <a name="line-35"></a><span class='hs-definition'>showBool</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Bool</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span> <a name="line-36"></a><span class='hs-definition'>showBool</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>then</span> <span class='hs-str'>"1"</span> <span class='hs-keyword'>else</span> <span class='hs-str'>"0"</span> <a name="line-37"></a> <a name="line-38"></a><a name="parseBool"></a><span class='hs-comment'>-- Parse a boolean response value.</span> <a name="line-39"></a><span class='hs-definition'>parseBool</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-conid'>Bool</span> <a name="line-40"></a><span class='hs-definition'>parseBool</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>take</span> <span class='hs-num'>1</span> <span class='hs-varid'>s</span> <span class='hs-keyword'>of</span> <a name="line-41"></a> <span class='hs-str'>"1"</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Just</span> <span class='hs-conid'>True</span> <a name="line-42"></a> <span class='hs-str'>"0"</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Just</span> <span class='hs-conid'>False</span> <a name="line-43"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Nothing</span> <a name="line-44"></a> <a name="line-45"></a><a name="toAssoc"></a><span class='hs-comment'>-- Break a string into an key-value pair, separating at the first ':'.</span> <a name="line-46"></a><span class='hs-definition'>toAssoc</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>String</span><span class='hs-layout'>,</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span> <a name="line-47"></a><span class='hs-definition'>toAssoc</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>k</span><span class='hs-layout'>,</span> <span class='hs-varid'>dropWhile</span> <span class='hs-layout'>(</span><span class='hs-varop'>==</span> <span class='hs-chr'>' '</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-varid'>drop</span> <span class='hs-num'>1</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <a name="line-48"></a> <span class='hs-keyword'>where</span> <a name="line-49"></a> <span class='hs-layout'>(</span><span class='hs-varid'>k</span><span class='hs-layout'>,</span><span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>break</span> <span class='hs-layout'>(</span><span class='hs-varop'>==</span> <span class='hs-chr'>':'</span><span class='hs-layout'>)</span> <span class='hs-varid'>x</span> <a name="line-50"></a> <a name="line-51"></a><a name="toAssocList"></a><span class='hs-definition'>toAssocList</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>String</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-conid'>String</span><span class='hs-layout'>,</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <a name="line-52"></a><span class='hs-definition'>toAssocList</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>map</span> <span class='hs-varid'>toAssoc</span> <a name="line-53"></a> <a name="line-54"></a><a name="splitGroups"></a><span class='hs-comment'>-- Takes an assoc. list with recurring keys and groups each cycle of</span> <a name="line-55"></a><span class='hs-comment'>-- keys with their values together. There can be several keys that</span> <a name="line-56"></a><span class='hs-comment'>-- begin cycles, being listed as the first tuple component in the</span> <a name="line-57"></a><span class='hs-comment'>-- first parameter. When a cycle finishes all of its pairs are passed</span> <a name="line-58"></a><span class='hs-comment'>-- to the key's associated function (the second tuple component) and</span> <a name="line-59"></a><span class='hs-comment'>-- the result appended to the resulting list.</span> <a name="line-60"></a><span class='hs-comment'>--</span> <a name="line-61"></a><span class='hs-comment'>-- > splitGroups [(1,id),(5,id)]</span> <a name="line-62"></a><span class='hs-comment'>-- > [(1,'a'),(2,'b'),(5,'c'),(6,'d'),(1,'z'),(2,'y'),(3,'x')] ==</span> <a name="line-63"></a><span class='hs-comment'>-- > [[(1,'a'),(2,'b')],[(5,'c'),(6,'d')],[(1,'z'),(2,'y'),(3,'x')]]</span> <a name="line-64"></a><span class='hs-definition'>splitGroups</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Eq</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span><span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span><span class='hs-varid'>b</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>c</span><span class='hs-keyglyph'>]</span> <a name="line-65"></a><span class='hs-definition'>splitGroups</span> <span class='hs-conid'>[]</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>[]</span> <a name="line-66"></a><span class='hs-definition'>splitGroups</span> <span class='hs-keyword'>_</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>[]</span> <a name="line-67"></a><span class='hs-definition'>splitGroups</span> <span class='hs-varid'>wrappers</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-varid'>k</span><span class='hs-layout'>,</span><span class='hs-keyword'>_</span><span class='hs-layout'>)</span><span class='hs-conop'>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <a name="line-68"></a> <span class='hs-varid'>fromMaybe</span> <span class='hs-layout'>(</span><span class='hs-varid'>splitGroups</span> <span class='hs-varid'>wrappers</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span> <a name="line-69"></a> <span class='hs-varid'>f</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>k</span> <span class='hs-varop'>`lookup`</span> <span class='hs-varid'>wrappers</span> <a name="line-70"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>us</span><span class='hs-layout'>,</span><span class='hs-varid'>vs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>break</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-varid'>k'</span><span class='hs-layout'>,</span><span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>k'</span> <span class='hs-varop'>`elem`</span> <span class='hs-varid'>map</span> <span class='hs-varid'>fst</span> <span class='hs-varid'>wrappers</span><span class='hs-layout'>)</span> <span class='hs-varid'>xs</span> <a name="line-71"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-varid'>us</span><span class='hs-layout'>)</span> <span class='hs-conop'>:</span> <span class='hs-varid'>splitGroups</span> <span class='hs-varid'>wrappers</span> <span class='hs-varid'>vs</span> </pre></body> </html>
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