polyparse-1.2: docs/haddock/src/Text/ParserCombinators/Poly/Plain.html
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<title>src/Text/ParserCombinators/Poly/Plain.hs</title>
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<pre><a name="line-1"></a><font color=Green><u>module</u></font> Text<font color=Cyan>.</font>ParserCombinators<font color=Cyan>.</font>Poly<font color=Cyan>.</font>Plain
<a name="line-2"></a> <font color=Cyan>(</font> <font color=Blue>-- * The Parser datatype</font>
<a name="line-3"></a> Parser<font color=Cyan>(</font>P<font color=Cyan>)</font> <font color=Blue>-- datatype, instance of: Functor, Monad, PolyParse</font>
<a name="line-4"></a> <font color=Cyan>,</font> Result<font color=Cyan>(</font><font color=Red>..</font><font color=Cyan>)</font> <font color=Blue>-- internal to the Parser Monad.</font>
<a name="line-5"></a> <font color=Cyan>,</font> runParser <font color=Blue>-- :: Parser t a -> [t] -> (Either String a, [t])</font>
<a name="line-6"></a> <font color=Blue>-- ** basic parsers</font>
<a name="line-7"></a> <font color=Cyan>,</font> next <font color=Blue>-- :: Parser t t</font>
<a name="line-8"></a> <font color=Cyan>,</font> satisfy <font color=Blue>-- :: (t->Bool) -> Parser t t</font>
<a name="line-9"></a>
<a name="line-10"></a> <font color=Blue>-- ** re-parsing</font>
<a name="line-11"></a> <font color=Cyan>,</font> reparse <font color=Blue>-- :: [t] -> Parser t ()</font>
<a name="line-12"></a> <font color=Blue>-- * Re-export all more general combinators</font>
<a name="line-13"></a> <font color=Cyan>,</font> <font color=Green><u>module</u></font> Text<font color=Cyan>.</font>ParserCombinators<font color=Cyan>.</font>Poly<font color=Cyan>.</font>Base
<a name="line-14"></a> <font color=Cyan>)</font> <font color=Green><u>where</u></font>
<a name="line-15"></a>
<a name="line-16"></a>
<a name="line-17"></a><font color=Green><u>import</u></font> Text<font color=Cyan>.</font>ParserCombinators<font color=Cyan>.</font>Poly<font color=Cyan>.</font>Base
<a name="line-18"></a>
<a name="line-19"></a><a name="Parser"></a><font color=Blue>-- | This @Parser@ datatype is a fairly generic parsing monad with error</font>
<a name="line-20"></a><a name="Parser"></a><font color=Blue>-- reporting. It can be used for arbitrary token types, not just</font>
<a name="line-21"></a><a name="Parser"></a><font color=Blue>-- String input. (If you require a running state, use module PolyState</font>
<a name="line-22"></a><a name="Parser"></a><font color=Blue>-- instead)</font>
<a name="line-23"></a><a name="Parser"></a><font color=Green><u>newtype</u></font> Parser t a <font color=Red>=</font> P <font color=Cyan>(</font><font color=Red>[</font>t<font color=Red>]</font> <font color=Red>-></font> Result <font color=Red>[</font>t<font color=Red>]</font> a<font color=Cyan>)</font>
<a name="line-24"></a>
<a name="line-25"></a><a name="Result"></a><font color=Blue>-- | A return type like Either, that distinguishes not only between</font>
<a name="line-26"></a><a name="Result"></a><font color=Blue>-- right and wrong answers, but also has commitment, so that a failure</font>
<a name="line-27"></a><a name="Result"></a><font color=Blue>-- cannot be undone. This should only be used for writing very primitive</font>
<a name="line-28"></a><a name="Result"></a><font color=Blue>-- parsers - really it is an internal detail of the library.</font>
<a name="line-29"></a><a name="Result"></a><font color=Green><u>data</u></font> Result z a <font color=Red>=</font> Success z a
<a name="line-30"></a> <font color=Red>|</font> Failure z String
<a name="line-31"></a> <font color=Red>|</font> Committed <font color=Cyan>(</font>Result z a<font color=Cyan>)</font>
<a name="line-32"></a>
<a name="line-33"></a><font color=Green><u>instance</u></font> Functor <font color=Cyan>(</font>Result z<font color=Cyan>)</font> <font color=Green><u>where</u></font>
<a name="line-34"></a> fmap f <font color=Cyan>(</font>Success z a<font color=Cyan>)</font> <font color=Red>=</font> Success z <font color=Cyan>(</font>f a<font color=Cyan>)</font>
<a name="line-35"></a> fmap f <font color=Cyan>(</font>Failure z e<font color=Cyan>)</font> <font color=Red>=</font> Failure z e
<a name="line-36"></a> fmap f <font color=Cyan>(</font>Committed r<font color=Cyan>)</font> <font color=Red>=</font> Committed <font color=Cyan>(</font>fmap f r<font color=Cyan>)</font>
<a name="line-37"></a>
<a name="line-38"></a><a name="runParser"></a><font color=Blue>-- | Apply a parser to an input token sequence.</font>
<a name="line-39"></a><font color=Blue>runParser</font> <font color=Red>::</font> Parser t a <font color=Red>-></font> <font color=Red>[</font>t<font color=Red>]</font> <font color=Red>-></font> <font color=Cyan>(</font>Either String a<font color=Cyan>,</font> <font color=Red>[</font>t<font color=Red>]</font><font color=Cyan>)</font>
<a name="line-40"></a><font color=Blue>runParser</font> <font color=Cyan>(</font>P p<font color=Cyan>)</font> <font color=Red>=</font> resultToEither <font color=Cyan>.</font> p
<a name="line-41"></a> <font color=Green><u>where</u></font>
<a name="line-42"></a> resultToEither <font color=Red>::</font> Result z a <font color=Red>-></font> <font color=Cyan>(</font>Either String a<font color=Cyan>,</font> z<font color=Cyan>)</font>
<a name="line-43"></a> resultToEither <font color=Cyan>(</font>Success z a<font color=Cyan>)</font> <font color=Red>=</font> <font color=Cyan>(</font>Right a<font color=Cyan>,</font> z<font color=Cyan>)</font>
<a name="line-44"></a> resultToEither <font color=Cyan>(</font>Failure z e<font color=Cyan>)</font> <font color=Red>=</font> <font color=Cyan>(</font>Left e<font color=Cyan>,</font> z<font color=Cyan>)</font>
<a name="line-45"></a> resultToEither <font color=Cyan>(</font>Committed r<font color=Cyan>)</font> <font color=Red>=</font> resultToEither r
<a name="line-46"></a>
<a name="line-47"></a><font color=Green><u>instance</u></font> Functor <font color=Cyan>(</font>Parser t<font color=Cyan>)</font> <font color=Green><u>where</u></font>
<a name="line-48"></a> fmap f <font color=Cyan>(</font>P p<font color=Cyan>)</font> <font color=Red>=</font> P <font color=Cyan>(</font>fmap f <font color=Cyan>.</font> p<font color=Cyan>)</font>
<a name="line-49"></a>
<a name="line-50"></a><font color=Green><u>instance</u></font> Monad <font color=Cyan>(</font>Parser t<font color=Cyan>)</font> <font color=Green><u>where</u></font>
<a name="line-51"></a> return x <font color=Red>=</font> P <font color=Cyan>(</font><font color=Red>\</font>ts<font color=Red>-></font> Success ts x<font color=Cyan>)</font>
<a name="line-52"></a> fail e <font color=Red>=</font> P <font color=Cyan>(</font><font color=Red>\</font>ts<font color=Red>-></font> Failure ts e<font color=Cyan>)</font>
<a name="line-53"></a> <font color=Cyan>(</font>P f<font color=Cyan>)</font> <font color=Cyan>>>=</font> g <font color=Red>=</font> P <font color=Cyan>(</font>continue <font color=Cyan>.</font> f<font color=Cyan>)</font>
<a name="line-54"></a> <font color=Green><u>where</u></font>
<a name="line-55"></a> continue <font color=Cyan>(</font>Success ts x<font color=Cyan>)</font> <font color=Red>=</font> <font color=Green><u>let</u></font> <font color=Cyan>(</font>P g'<font color=Cyan>)</font> <font color=Red>=</font> g x <font color=Green><u>in</u></font> g' ts
<a name="line-56"></a> continue <font color=Cyan>(</font>Committed <font color=Cyan>(</font>Committed r<font color=Cyan>)</font><font color=Cyan>)</font> <font color=Red>=</font> continue <font color=Cyan>(</font>Committed r<font color=Cyan>)</font>
<a name="line-57"></a> continue <font color=Cyan>(</font>Committed r<font color=Cyan>)</font> <font color=Red>=</font> Committed <font color=Cyan>(</font>continue r<font color=Cyan>)</font>
<a name="line-58"></a> continue <font color=Cyan>(</font>Failure ts e<font color=Cyan>)</font> <font color=Red>=</font> Failure ts e
<a name="line-59"></a>
<a name="line-60"></a><font color=Green><u>instance</u></font> PolyParse <font color=Cyan>(</font>Parser t<font color=Cyan>)</font> <font color=Green><u>where</u></font>
<a name="line-61"></a> commit <font color=Cyan>(</font>P p<font color=Cyan>)</font> <font color=Red>=</font> P <font color=Cyan>(</font>Committed <font color=Cyan>.</font> p<font color=Cyan>)</font>
<a name="line-62"></a> <font color=Cyan>(</font>P p<font color=Cyan>)</font> <font color=Cyan>`adjustErr`</font> f <font color=Red>=</font> P <font color=Cyan>(</font>adjust <font color=Cyan>.</font> p<font color=Cyan>)</font>
<a name="line-63"></a> <font color=Green><u>where</u></font>
<a name="line-64"></a> adjust <font color=Cyan>(</font>Failure z e<font color=Cyan>)</font> <font color=Red>=</font> Failure z <font color=Cyan>(</font>f e<font color=Cyan>)</font>
<a name="line-65"></a> adjust <font color=Cyan>(</font>Committed r<font color=Cyan>)</font> <font color=Red>=</font> Committed <font color=Cyan>(</font>adjust r<font color=Cyan>)</font>
<a name="line-66"></a> adjust good <font color=Red>=</font> good
<a name="line-67"></a>
<a name="line-68"></a> <font color=Cyan>(</font>P p<font color=Cyan>)</font> <font color=Cyan>`onFail`</font> <font color=Cyan>(</font>P q<font color=Cyan>)</font> <font color=Red>=</font> P <font color=Cyan>(</font><font color=Red>\</font>ts<font color=Red>-></font> continue ts <font color=Cyan>$</font> p ts<font color=Cyan>)</font>
<a name="line-69"></a> <font color=Green><u>where</u></font>
<a name="line-70"></a> continue ts <font color=Cyan>(</font>Failure z e<font color=Cyan>)</font> <font color=Red>=</font> q ts
<a name="line-71"></a> <font color=Blue>-- continue _ (Committed r) = r -- no, remain Committed</font>
<a name="line-72"></a> continue <font color=Green><u>_</u></font> r <font color=Red>=</font> r
<a name="line-73"></a>
<a name="line-74"></a> oneOf' <font color=Red>=</font> accum []
<a name="line-75"></a> <font color=Green><u>where</u></font> accum errs [] <font color=Red>=</font>
<a name="line-76"></a> fail <font color=Cyan>(</font><font color=Magenta>"failed to parse any of the possible choices:\n"</font>
<a name="line-77"></a> <font color=Cyan>++</font>indent <font color=Magenta>2</font> <font color=Cyan>(</font>concatMap showErr <font color=Cyan>(</font>reverse errs<font color=Cyan>)</font><font color=Cyan>)</font><font color=Cyan>)</font>
<a name="line-78"></a> accum errs <font color=Cyan>(</font><font color=Cyan>(</font>e<font color=Cyan>,</font>P p<font color=Cyan>)</font><font color=Red><b>:</b></font>ps<font color=Cyan>)</font> <font color=Red>=</font>
<a name="line-79"></a> P <font color=Cyan>(</font><font color=Red>\</font>ts<font color=Red>-></font> <font color=Green><u>case</u></font> p ts <font color=Green><u>of</u></font>
<a name="line-80"></a> Failure <font color=Green><u>_</u></font> err <font color=Red>-></font>
<a name="line-81"></a> <font color=Green><u>let</u></font> <font color=Cyan>(</font>P p<font color=Cyan>)</font> <font color=Red>=</font> accum <font color=Cyan>(</font><font color=Cyan>(</font>e<font color=Cyan>,</font>err<font color=Cyan>)</font><font color=Red><b>:</b></font>errs<font color=Cyan>)</font> ps
<a name="line-82"></a> <font color=Green><u>in</u></font> p ts
<a name="line-83"></a> r<font color=Red>@</font><font color=Cyan>(</font>Success z a<font color=Cyan>)</font> <font color=Red>-></font> r
<a name="line-84"></a> r<font color=Red>@</font><font color=Cyan>(</font>Committed <font color=Green><u>_</u></font><font color=Cyan>)</font> <font color=Red>-></font> r <font color=Cyan>)</font>
<a name="line-85"></a> showErr <font color=Cyan>(</font>name<font color=Cyan>,</font>err<font color=Cyan>)</font> <font color=Red>=</font> name<font color=Cyan>++</font><font color=Magenta>":\n"</font><font color=Cyan>++</font>indent <font color=Magenta>2</font> err
<a name="line-86"></a>
<a name="line-87"></a><a name="next"></a><font color=Blue>------------------------------------------------------------------------</font>
<a name="line-88"></a><font color=Blue>next</font> <font color=Red>::</font> Parser t t
<a name="line-89"></a><font color=Blue>next</font> <font color=Red>=</font> P <font color=Cyan>(</font><font color=Red>\</font>ts<font color=Red>-></font> <font color=Green><u>case</u></font> ts <font color=Green><u>of</u></font>
<a name="line-90"></a> [] <font color=Red>-></font> Failure [] <font color=Magenta>"Ran out of input (EOF)"</font>
<a name="line-91"></a> <font color=Cyan>(</font>t<font color=Red><b>:</b></font>ts'<font color=Cyan>)</font> <font color=Red>-></font> Success ts' t <font color=Cyan>)</font>
<a name="line-92"></a>
<a name="line-93"></a><a name="satisfy"></a><font color=Blue>satisfy</font> <font color=Red>::</font> <font color=Cyan>(</font>t<font color=Red>-></font>Bool<font color=Cyan>)</font> <font color=Red>-></font> Parser t t
<a name="line-94"></a><font color=Blue>satisfy</font> pred <font color=Red>=</font> <font color=Green><u>do</u></font> <font color=Cyan>{</font> x <font color=Red><-</font> next
<a name="line-95"></a> <font color=Cyan>;</font> <font color=Green><u>if</u></font> pred x <font color=Green><u>then</u></font> return x <font color=Green><u>else</u></font> fail <font color=Magenta>"Parse.satisfy: failed"</font>
<a name="line-96"></a> <font color=Cyan>}</font>
<a name="line-97"></a>
<a name="line-98"></a><a name="reparse"></a><font color=Blue>------------------------------------------------------------------------</font>
<a name="line-99"></a><font color=Blue>-- | Push some tokens back onto the front of the input stream and reparse.</font>
<a name="line-100"></a><font color=Blue>-- This is useful e.g. for recursively expanding macros. When the</font>
<a name="line-101"></a><font color=Blue>-- user-parser recognises a macro use, it can lookup the macro</font>
<a name="line-102"></a><font color=Blue>-- expansion from the parse state, lex it, and then stuff the</font>
<a name="line-103"></a><font color=Blue>-- lexed expansion back down into the parser.</font>
<a name="line-104"></a><font color=Blue>reparse</font> <font color=Red>::</font> <font color=Red>[</font>t<font color=Red>]</font> <font color=Red>-></font> Parser t ()
<a name="line-105"></a><font color=Blue>reparse</font> ts <font color=Red>=</font> P <font color=Cyan>(</font><font color=Red>\</font>inp<font color=Red>-></font> Success <font color=Cyan>(</font>ts<font color=Cyan>++</font>inp<font color=Cyan>)</font> ()<font color=Cyan>)</font>
<a name="line-106"></a>
<a name="line-107"></a><font color=Blue>------------------------------------------------------------------------</font>
</pre>
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