polyparse-1.1: docs/haddock/src/Text/ParserCombinators/Poly/NoLeak/Lazy.html
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<pre><a name="(line1)"></a><font color=Green><u>module</u></font> Text<font color=Cyan>.</font>ParserCombinators<font color=Cyan>.</font>Poly<font color=Cyan>.</font>NoLeak<font color=Cyan>.</font>Lazy
<a name="(line2)"></a> <font color=Cyan>(</font> <font color=Blue>-- * The Parser datatype</font>
<a name="(line3)"></a> Parser<font color=Cyan>(</font>P<font color=Cyan>)</font> <font color=Blue>-- datatype, instance of: Functor, Monad, PolyParse</font>
<a name="(line4)"></a> <font color=Cyan>,</font> runParser <font color=Blue>-- :: Parser t a -> [t] -> (Either String a, [t])</font>
<a name="(line5)"></a> <font color=Blue>-- ** basic parsers</font>
<a name="(line6)"></a> <font color=Cyan>,</font> next <font color=Blue>-- :: Parser t t</font>
<a name="(line7)"></a> <font color=Cyan>,</font> satisfy <font color=Blue>-- :: (t->Bool) -> Parser t t</font>
<a name="(line8)"></a>
<a name="(line9)"></a> <font color=Blue>-- ** re-parsing</font>
<a name="(line10)"></a> <font color=Cyan>,</font> reparse <font color=Blue>-- :: [t] -> Parser t ()</font>
<a name="(line11)"></a> <font color=Blue>-- * Re-export all more general combinators</font>
<a name="(line12)"></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="(line13)"></a> <font color=Cyan>)</font> <font color=Green><u>where</u></font>
<a name="(line14)"></a>
<a name="(line15)"></a>
<a name="(line16)"></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="(line17)"></a>
<a name="(line18)"></a><font color=Magenta><em>#if __GLASGOW_HASKELL__</em></font>
<a name="(line19)"></a><font color=Green><u>import</u></font> Control<font color=Cyan>.</font>Exception hiding <font color=Cyan>(</font>bracket<font color=Cyan>)</font>
<a name="(line20)"></a><a name="throwE"></a>throwE <font color=Red>::</font> String <font color=Red>-></font> a
<a name="(line21)"></a>throwE msg <font color=Red>=</font> throw <font color=Cyan>(</font>ErrorCall msg<font color=Cyan>)</font>
<a name="(line22)"></a><font color=Magenta><em>#else</em></font>
<a name="(line23)"></a>throwE <font color=Red>::</font> String <font color=Red>-></font> a
<a name="(line24)"></a>throwE msg <font color=Red>=</font> error msg
<a name="(line25)"></a><font color=Magenta><em>#endif</em></font>
<a name="(line26)"></a>
<a name="(line27)"></a>
<a name="(line28)"></a><a name="Parser"></a><font color=Blue>-- | This @Parser@ datatype is a fairly generic parsing monad with error</font>
<a name="(line29)"></a><a name="Parser"></a><font color=Blue>-- reporting. It can be used for arbitrary token types, not just</font>
<a name="(line30)"></a><a name="Parser"></a><font color=Blue>-- String input. (If you require a running state, use module PolyState</font>
<a name="(line31)"></a><a name="Parser"></a><font color=Blue>-- instead)</font>
<a name="(line32)"></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="(line33)"></a>
<a name="(line34)"></a><a name="Result"></a><font color=Blue>-- A return type like Either, that distinguishes not only between</font>
<a name="(line35)"></a><a name="Result"></a><font color=Blue>-- right and wrong answers, but also has gradations of wrongness.</font>
<a name="(line36)"></a><a name="Result"></a><font color=Green><u>data</u></font> Result z a <font color=Red>=</font> Success z a
<a name="(line37)"></a> <font color=Red>|</font> Failure z String
<a name="(line38)"></a> <font color=Red>|</font> Committed <font color=Cyan>(</font>Result z a<font color=Cyan>)</font> <font color=Blue>-- still needed</font>
<a name="(line39)"></a>
<a name="(line40)"></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="(line41)"></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="(line42)"></a> fmap f <font color=Cyan>(</font>Failure z e<font color=Cyan>)</font> <font color=Red>=</font> Failure z e
<a name="(line43)"></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="(line44)"></a>
<a name="(line45)"></a><a name="runParser"></a><font color=Blue>-- | Apply a parser to an input token sequence.</font>
<a name="(line46)"></a>runParser <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>a<font color=Cyan>,</font> <font color=Red>[</font>t<font color=Red>]</font><font color=Cyan>)</font>
<a name="(line47)"></a>runParser <font color=Cyan>(</font>P p<font color=Cyan>)</font> <font color=Red>=</font> fromResult <font color=Cyan>.</font> p
<a name="(line48)"></a> <font color=Green><u>where</u></font>
<a name="(line49)"></a> fromResult <font color=Red>::</font> Result z a <font color=Red>-></font> <font color=Cyan>(</font>a<font color=Cyan>,</font> z<font color=Cyan>)</font>
<a name="(line50)"></a> fromResult <font color=Cyan>(</font>Success z a<font color=Cyan>)</font> <font color=Red>=</font> <font color=Cyan>(</font>a<font color=Cyan>,</font> z<font color=Cyan>)</font>
<a name="(line51)"></a> fromResult <font color=Cyan>(</font>Failure z e<font color=Cyan>)</font> <font color=Red>=</font> throwE e
<a name="(line52)"></a> fromResult <font color=Cyan>(</font>Committed r<font color=Cyan>)</font> <font color=Red>=</font> fromResult r
<a name="(line53)"></a>
<a name="(line54)"></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="(line55)"></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="(line56)"></a>
<a name="(line57)"></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="(line58)"></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="(line59)"></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="(line60)"></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="(line61)"></a> <font color=Green><u>where</u></font>
<a name="(line62)"></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="(line63)"></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="(line64)"></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="(line65)"></a> continue <font color=Cyan>(</font>Failure ts e<font color=Cyan>)</font> <font color=Red>=</font> Failure ts e
<a name="(line66)"></a>
<a name="(line67)"></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="(line68)"></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="(line69)"></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="(line70)"></a> <font color=Green><u>where</u></font>
<a name="(line71)"></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="(line72)"></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="(line73)"></a> adjust good <font color=Red>=</font> good
<a name="(line74)"></a>
<a name="(line75)"></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="(line76)"></a> <font color=Green><u>where</u></font>
<a name="(line77)"></a> continue ts <font color=Cyan>(</font>Failure z e<font color=Cyan>)</font> <font color=Red>=</font> q ts
<a name="(line78)"></a> <font color=Blue>-- continue _ (Committed r) = r -- no, remain Committed</font>
<a name="(line79)"></a> continue <font color=Green><u>_</u></font> r <font color=Red>=</font> r
<a name="(line80)"></a>
<a name="(line81)"></a> oneOf' <font color=Red>=</font> accum []
<a name="(line82)"></a> <font color=Green><u>where</u></font> accum errs [] <font color=Red>=</font>
<a name="(line83)"></a> fail <font color=Cyan>(</font><font color=Magenta>"failed to parse any of the possible choices:\n"</font>
<a name="(line84)"></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="(line85)"></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="(line86)"></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="(line87)"></a> Failure <font color=Green><u>_</u></font> err <font color=Red>-></font>
<a name="(line88)"></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="(line89)"></a> <font color=Green><u>in</u></font> p ts
<a name="(line90)"></a> r<font color=Red>@</font><font color=Cyan>(</font>Success z a<font color=Cyan>)</font> <font color=Red>-></font> r
<a name="(line91)"></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="(line92)"></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="(line93)"></a>
<a name="(line94)"></a> <font color=Blue>-- Apply a parsed function to a parsed value. This version</font>
<a name="(line95)"></a> <font color=Blue>-- is strict in the result of the function parser, but</font>
<a name="(line96)"></a> <font color=Blue>-- lazy in the result of the argument parser. (Argument laziness is</font>
<a name="(line97)"></a> <font color=Blue>-- the distinctive feature over other implementations.)</font>
<a name="(line98)"></a> <font color=Cyan>(</font>P pf<font color=Cyan>)</font> <font color=Cyan>`apply`</font> px <font color=Red>=</font> P <font color=Cyan>(</font>continue <font color=Cyan>.</font> pf<font color=Cyan>)</font>
<a name="(line99)"></a> <font color=Green><u>where</u></font>
<a name="(line100)"></a> continue <font color=Cyan>(</font>Success z f<font color=Cyan>)</font> <font color=Red>=</font> <font color=Green><u>let</u></font> <font color=Cyan>(</font>x<font color=Cyan>,</font>z'<font color=Cyan>)</font> <font color=Red>=</font> runParser px z
<a name="(line101)"></a> <font color=Green><u>in</u></font> Success z' <font color=Cyan>(</font>f x<font color=Cyan>)</font>
<a name="(line102)"></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="(line103)"></a> continue <font color=Cyan>(</font>Failure z e<font color=Cyan>)</font> <font color=Red>=</font> Failure z e
<a name="(line104)"></a>
<a name="(line105)"></a>
<a name="(line106)"></a><a name="next"></a><font color=Blue>------------------------------------------------------------------------</font>
<a name="(line107)"></a>next <font color=Red>::</font> Parser t t
<a name="(line108)"></a>next <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="(line109)"></a> [] <font color=Red>-></font> Failure [] <font color=Magenta>"Ran out of input (EOF)"</font>
<a name="(line110)"></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="(line111)"></a>
<a name="(line112)"></a><a name="satisfy"></a>satisfy <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="(line113)"></a>satisfy pred <font color=Red>=</font> <font color=Green><u>do</u></font> <font color=Cyan>{</font> x <font color=Red><-</font> next
<a name="(line114)"></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="(line115)"></a> <font color=Cyan>}</font>
<a name="(line116)"></a>
<a name="(line117)"></a><a name="reparse"></a><font color=Blue>------------------------------------------------------------------------</font>
<a name="(line118)"></a><font color=Blue>-- | Push some tokens back onto the front of the input stream and reparse.</font>
<a name="(line119)"></a><font color=Blue>-- This is useful e.g. for recursively expanding macros. When the</font>
<a name="(line120)"></a><font color=Blue>-- user-parser recognises a macro use, it can lookup the macro</font>
<a name="(line121)"></a><font color=Blue>-- expansion from the parse state, lex it, and then stuff the</font>
<a name="(line122)"></a><font color=Blue>-- lexed expansion back down into the parser.</font>
<a name="(line123)"></a>reparse <font color=Red>::</font> <font color=Red>[</font>t<font color=Red>]</font> <font color=Red>-></font> Parser t ()
<a name="(line124)"></a>reparse 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="(line125)"></a>
<a name="(line126)"></a><font color=Blue>------------------------------------------------------------------------</font>
</pre>
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