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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE RankNTypes #-}</span>
<a name="line-2"></a><span class='hs-comment'>{-# LANGUAGE FlexibleContexts #-}</span>
<a name="line-3"></a><span class='hs-comment'>{-# LANGUAGE TypeFamilies #-}</span>
<a name="line-4"></a><span class='hs-comment'>{-# LANGUAGE CPP #-}</span>
<a name="line-5"></a><span class='hs-comment'>-- | Utilities for constructing and converting 'Source', 'Source' and</span>
<a name="line-6"></a><span class='hs-comment'>-- 'BSource' types. Please see "Data.Conduit.Types.Source" for more information</span>
<a name="line-7"></a><span class='hs-comment'>-- on the base types.</span>
<a name="line-8"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Conduit</span><span class='hs-varop'>.</span><span class='hs-conid'>Util</span><span class='hs-varop'>.</span><span class='hs-conid'>Source</span>
<a name="line-9"></a> <span class='hs-layout'>(</span> <span class='hs-varid'>sourceState</span>
<a name="line-10"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>sourceStateIO</span>
<a name="line-11"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>SourceStateResult</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-12"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>sourceIO</span>
<a name="line-13"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>SourceIOResult</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-14"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-15"></a>
<a name="line-16"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Resource</span>
<a name="line-17"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Conduit</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span>
<a name="line-18"></a>
<a name="line-19"></a><a name="SourceStateResult"></a><span class='hs-comment'>-- | The return value when pulling in the @sourceState@ function. Either</span>
<a name="line-20"></a><a name="SourceStateResult"></a><span class='hs-comment'>-- indicates no more data, or the next value and an updated state.</span>
<a name="line-21"></a><a name="SourceStateResult"></a><span class='hs-comment'>--</span>
<a name="line-22"></a><a name="SourceStateResult"></a><span class='hs-comment'>-- Since 0.3.0</span>
<a name="line-23"></a><a name="SourceStateResult"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>SourceStateResult</span> <span class='hs-varid'>state</span> <span class='hs-varid'>output</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>StateOpen</span> <span class='hs-varid'>state</span> <span class='hs-varid'>output</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>StateClosed</span>
<a name="line-24"></a>
<a name="line-25"></a><a name="sourceState"></a><span class='hs-comment'>-- | Construct a 'Source' with some stateful functions. This function addresses</span>
<a name="line-26"></a><span class='hs-comment'>-- threading the state value for you.</span>
<a name="line-27"></a><span class='hs-comment'>--</span>
<a name="line-28"></a><span class='hs-comment'>-- Since 0.3.0</span>
<a name="line-29"></a><span class='hs-definition'>sourceState</span>
<a name="line-30"></a> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-31"></a> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>state</span> <span class='hs-comment'>-- ^ Initial state</span>
<a name="line-32"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>state</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>SourceStateResult</span> <span class='hs-varid'>state</span> <span class='hs-varid'>output</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ Pull function</span>
<a name="line-33"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Source</span> <span class='hs-varid'>m</span> <span class='hs-varid'>output</span>
<a name="line-34"></a><span class='hs-definition'>sourceState</span> <span class='hs-varid'>state0</span> <span class='hs-varid'>pull0</span> <span class='hs-keyglyph'>=</span>
<a name="line-35"></a> <span class='hs-varid'>src</span> <span class='hs-varid'>state0</span>
<a name="line-36"></a> <span class='hs-keyword'>where</span>
<a name="line-37"></a> <span class='hs-varid'>src</span> <span class='hs-varid'>state</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>PipeM</span> <span class='hs-layout'>(</span><span class='hs-varid'>pull</span> <span class='hs-varid'>state</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-38"></a>
<a name="line-39"></a> <span class='hs-varid'>pull</span> <span class='hs-varid'>state</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-40"></a> <span class='hs-varid'>res</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>pull0</span> <span class='hs-varid'>state</span>
<a name="line-41"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>res</span> <span class='hs-keyword'>of</span>
<a name="line-42"></a> <span class='hs-conid'>StateOpen</span> <span class='hs-varid'>state'</span> <span class='hs-varid'>val</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>HaveOutput</span> <span class='hs-layout'>(</span><span class='hs-varid'>src</span> <span class='hs-varid'>state'</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varid'>val</span>
<a name="line-43"></a> <span class='hs-conid'>StateClosed</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Done</span> <span class='hs-conid'>Nothing</span> <span class='hs-conid'>()</span>
<a name="line-44"></a>
<a name="line-45"></a><a name="SourceIOResult"></a><span class='hs-comment'>-- | The return value when pulling in the @sourceIO@ function. Either indicates</span>
<a name="line-46"></a><a name="SourceIOResult"></a><span class='hs-comment'>-- no more data, or the next value.</span>
<a name="line-47"></a><a name="SourceIOResult"></a><span class='hs-comment'>--</span>
<a name="line-48"></a><a name="SourceIOResult"></a><span class='hs-comment'>-- Since 0.3.0</span>
<a name="line-49"></a><a name="SourceIOResult"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>SourceIOResult</span> <span class='hs-varid'>output</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOOpen</span> <span class='hs-varid'>output</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>IOClosed</span>
<a name="line-50"></a>
<a name="line-51"></a><a name="sourceIO"></a><span class='hs-comment'>-- | Construct a 'Source' based on some IO actions for alloc/release.</span>
<a name="line-52"></a><span class='hs-comment'>--</span>
<a name="line-53"></a><span class='hs-comment'>-- Since 0.3.0</span>
<a name="line-54"></a><span class='hs-definition'>sourceIO</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadResource</span> <span class='hs-varid'>m</span>
<a name="line-55"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>state</span> <span class='hs-comment'>-- ^ resource and/or state allocation</span>
<a name="line-56"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>state</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ resource and/or state cleanup</span>
<a name="line-57"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>state</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>SourceIOResult</span> <span class='hs-varid'>output</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ Pull function. Note that this should not perform any cleanup.</span>
<a name="line-58"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Source</span> <span class='hs-varid'>m</span> <span class='hs-varid'>output</span>
<a name="line-59"></a><span class='hs-definition'>sourceIO</span> <span class='hs-varid'>alloc</span> <span class='hs-varid'>cleanup</span> <span class='hs-varid'>pull0</span> <span class='hs-keyglyph'>=</span>
<a name="line-60"></a> <span class='hs-conid'>PipeM</span> <span class='hs-layout'>(</span><span class='hs-keyword'>do</span>
<a name="line-61"></a> <span class='hs-layout'>(</span><span class='hs-varid'>key</span><span class='hs-layout'>,</span> <span class='hs-varid'>state</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>allocate</span> <span class='hs-varid'>alloc</span> <span class='hs-varid'>cleanup</span>
<a name="line-62"></a> <span class='hs-varid'>pull</span> <span class='hs-varid'>key</span> <span class='hs-varid'>state</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-63"></a> <span class='hs-keyword'>where</span>
<a name="line-64"></a> <span class='hs-varid'>src</span> <span class='hs-varid'>key</span> <span class='hs-varid'>state</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>PipeM</span> <span class='hs-layout'>(</span><span class='hs-varid'>pull</span> <span class='hs-varid'>key</span> <span class='hs-varid'>state</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>release</span> <span class='hs-varid'>key</span><span class='hs-layout'>)</span>
<a name="line-65"></a>
<a name="line-66"></a> <span class='hs-varid'>pull</span> <span class='hs-varid'>key</span> <span class='hs-varid'>state</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-67"></a> <span class='hs-varid'>res</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>pull0</span> <span class='hs-varid'>state</span>
<a name="line-68"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>res</span> <span class='hs-keyword'>of</span>
<a name="line-69"></a> <span class='hs-conid'>IOClosed</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-70"></a> <span class='hs-varid'>release</span> <span class='hs-varid'>key</span>
<a name="line-71"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Done</span> <span class='hs-conid'>Nothing</span> <span class='hs-conid'>()</span>
<a name="line-72"></a> <span class='hs-conid'>IOOpen</span> <span class='hs-varid'>val</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>HaveOutput</span> <span class='hs-layout'>(</span><span class='hs-varid'>src</span> <span class='hs-varid'>key</span> <span class='hs-varid'>state</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>release</span> <span class='hs-varid'>key</span><span class='hs-layout'>)</span> <span class='hs-varid'>val</span>
<a name="line-73"></a>
<a name="line-74"></a><a name="sourceStateIO"></a><span class='hs-comment'>-- | A combination of 'sourceIO' and 'sourceState'.</span>
<a name="line-75"></a><span class='hs-comment'>--</span>
<a name="line-76"></a><span class='hs-comment'>-- Since 0.3.0</span>
<a name="line-77"></a><span class='hs-definition'>sourceStateIO</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadResource</span> <span class='hs-varid'>m</span>
<a name="line-78"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>state</span> <span class='hs-comment'>-- ^ resource and/or state allocation</span>
<a name="line-79"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>state</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ resource and/or state cleanup</span>
<a name="line-80"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>state</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>SourceStateResult</span> <span class='hs-varid'>state</span> <span class='hs-varid'>output</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ Pull function. Note that this need not explicitly perform any cleanup.</span>
<a name="line-81"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Source</span> <span class='hs-varid'>m</span> <span class='hs-varid'>output</span>
<a name="line-82"></a><span class='hs-definition'>sourceStateIO</span> <span class='hs-varid'>alloc</span> <span class='hs-varid'>cleanup</span> <span class='hs-varid'>pull0</span> <span class='hs-keyglyph'>=</span>
<a name="line-83"></a> <span class='hs-conid'>PipeM</span> <span class='hs-layout'>(</span><span class='hs-keyword'>do</span>
<a name="line-84"></a> <span class='hs-layout'>(</span><span class='hs-varid'>key</span><span class='hs-layout'>,</span> <span class='hs-varid'>state</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>allocate</span> <span class='hs-varid'>alloc</span> <span class='hs-varid'>cleanup</span>
<a name="line-85"></a> <span class='hs-varid'>pull</span> <span class='hs-varid'>key</span> <span class='hs-varid'>state</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-86"></a> <span class='hs-keyword'>where</span>
<a name="line-87"></a> <span class='hs-varid'>src</span> <span class='hs-varid'>key</span> <span class='hs-varid'>state</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>PipeM</span> <span class='hs-layout'>(</span><span class='hs-varid'>pull</span> <span class='hs-varid'>key</span> <span class='hs-varid'>state</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>release</span> <span class='hs-varid'>key</span><span class='hs-layout'>)</span>
<a name="line-88"></a>
<a name="line-89"></a> <span class='hs-varid'>pull</span> <span class='hs-varid'>key</span> <span class='hs-varid'>state</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-90"></a> <span class='hs-varid'>res</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>pull0</span> <span class='hs-varid'>state</span>
<a name="line-91"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>res</span> <span class='hs-keyword'>of</span>
<a name="line-92"></a> <span class='hs-conid'>StateClosed</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-93"></a> <span class='hs-varid'>release</span> <span class='hs-varid'>key</span>
<a name="line-94"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Done</span> <span class='hs-conid'>Nothing</span> <span class='hs-conid'>()</span>
<a name="line-95"></a> <span class='hs-conid'>StateOpen</span> <span class='hs-varid'>state'</span> <span class='hs-varid'>val</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>HaveOutput</span> <span class='hs-layout'>(</span><span class='hs-varid'>src</span> <span class='hs-varid'>key</span> <span class='hs-varid'>state'</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>release</span> <span class='hs-varid'>key</span><span class='hs-layout'>)</span> <span class='hs-varid'>val</span>
<a name="line-96"></a>
<a name="line-97"></a><span class='hs-comment'>-- FIXME transPipe</span>
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