<?xml version="1.0" encoding="UTF-8"?>
<!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>Language/Haskell/ParseMonad.hs</title>
<link type='text/css' rel='stylesheet' href='hscolour.css' />
</head>
<body>
<pre><a name="line-1"></a><span class='hs-comment'>-- #hide</span>
<a name="line-2"></a><span class='hs-comment'>-----------------------------------------------------------------------------</span>
<a name="line-3"></a><span class='hs-comment'>-- |</span>
<a name="line-4"></a><span class='hs-comment'>-- Module : Language.Haskell.ParseMonad</span>
<a name="line-5"></a><span class='hs-comment'>-- Copyright : (c) The GHC Team, 1997-2000</span>
<a name="line-6"></a><span class='hs-comment'>-- License : BSD-style (see the file libraries/base/LICENSE)</span>
<a name="line-7"></a><span class='hs-comment'>-- </span>
<a name="line-8"></a><span class='hs-comment'>-- Maintainer : libraries@haskell.org</span>
<a name="line-9"></a><span class='hs-comment'>-- Stability : experimental</span>
<a name="line-10"></a><span class='hs-comment'>-- Portability : portable</span>
<a name="line-11"></a><span class='hs-comment'>--</span>
<a name="line-12"></a><span class='hs-comment'>-- Monads for the Haskell parser and lexer.</span>
<a name="line-13"></a><span class='hs-comment'>--</span>
<a name="line-14"></a><span class='hs-comment'>-----------------------------------------------------------------------------</span>
<a name="line-15"></a>
<a name="line-16"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Language</span><span class='hs-varop'>.</span><span class='hs-conid'>Haskell</span><span class='hs-varop'>.</span><span class='hs-conid'>ParseMonad</span><span class='hs-layout'>(</span>
<a name="line-17"></a> <span class='hs-comment'>-- * Parsing</span>
<a name="line-18"></a> <span class='hs-conid'>P</span><span class='hs-layout'>,</span> <span class='hs-conid'>ParseResult</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-varid'>atSrcLoc</span><span class='hs-layout'>,</span> <span class='hs-conid'>LexContext</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span>
<a name="line-19"></a> <span class='hs-conid'>ParseMode</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-varid'>defaultParseMode</span><span class='hs-layout'>,</span>
<a name="line-20"></a> <span class='hs-varid'>runParserWithMode</span><span class='hs-layout'>,</span> <span class='hs-varid'>runParser</span><span class='hs-layout'>,</span>
<a name="line-21"></a> <span class='hs-varid'>getSrcLoc</span><span class='hs-layout'>,</span> <span class='hs-varid'>pushCurrentContext</span><span class='hs-layout'>,</span> <span class='hs-varid'>popContext</span><span class='hs-layout'>,</span>
<a name="line-22"></a> <span class='hs-comment'>-- * Lexing</span>
<a name="line-23"></a> <span class='hs-conid'>Lex</span><span class='hs-layout'>(</span><span class='hs-varid'>runL</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-varid'>getInput</span><span class='hs-layout'>,</span> <span class='hs-varid'>discard</span><span class='hs-layout'>,</span> <span class='hs-varid'>lexNewline</span><span class='hs-layout'>,</span> <span class='hs-varid'>lexTab</span><span class='hs-layout'>,</span> <span class='hs-varid'>lexWhile</span><span class='hs-layout'>,</span>
<a name="line-24"></a> <span class='hs-varid'>alternative</span><span class='hs-layout'>,</span> <span class='hs-varid'>checkBOL</span><span class='hs-layout'>,</span> <span class='hs-varid'>setBOL</span><span class='hs-layout'>,</span> <span class='hs-varid'>startToken</span><span class='hs-layout'>,</span> <span class='hs-varid'>getOffside</span><span class='hs-layout'>,</span>
<a name="line-25"></a> <span class='hs-varid'>pushContextL</span><span class='hs-layout'>,</span> <span class='hs-varid'>popContextL</span>
<a name="line-26"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-27"></a>
<a name="line-28"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Language</span><span class='hs-varop'>.</span><span class='hs-conid'>Haskell</span><span class='hs-varop'>.</span><span class='hs-conid'>Syntax</span><span class='hs-layout'>(</span><span class='hs-conid'>SrcLoc</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-29"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Applicative</span>
<a name="line-30"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Monoid</span>
<a name="line-31"></a>
<a name="line-32"></a><a name="ParseResult"></a><span class='hs-comment'>-- | The result of a parse.</span>
<a name="line-33"></a><a name="ParseResult"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>ParseResult</span> <span class='hs-varid'>a</span>
<a name="line-34"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseOk</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ The parse succeeded, yielding a value.</span>
<a name="line-35"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>ParseFailed</span> <span class='hs-conid'>SrcLoc</span> <span class='hs-conid'>String</span>
<a name="line-36"></a> <span class='hs-comment'>-- ^ The parse failed at the specified</span>
<a name="line-37"></a> <span class='hs-comment'>-- source location, with an error message.</span>
<a name="line-38"></a> <span class='hs-keyword'>deriving</span> <span class='hs-conid'>Show</span>
<a name="line-39"></a>
<a name="line-40"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Functor</span> <span class='hs-conid'>ParseResult</span> <span class='hs-keyword'>where</span>
<a name="line-41"></a> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>ParseOk</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseOk</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-varid'>x</span>
<a name="line-42"></a> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>ParseFailed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>msg</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseFailed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>msg</span>
<a name="line-43"></a>
<a name="line-44"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Applicative</span> <span class='hs-conid'>ParseResult</span> <span class='hs-keyword'>where</span>
<a name="line-45"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseOk</span>
<a name="line-46"></a> <span class='hs-conid'>ParseOk</span> <span class='hs-varid'>f</span> <span class='hs-varop'><*></span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varop'><$></span> <span class='hs-varid'>x</span>
<a name="line-47"></a> <span class='hs-conid'>ParseFailed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>msg</span> <span class='hs-varop'><*></span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseFailed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>msg</span>
<a name="line-48"></a>
<a name="line-49"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-conid'>ParseResult</span> <span class='hs-keyword'>where</span>
<a name="line-50"></a> <span class='hs-varid'>return</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseOk</span>
<a name="line-51"></a> <span class='hs-conid'>ParseOk</span> <span class='hs-varid'>x</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>x</span>
<a name="line-52"></a> <span class='hs-conid'>ParseFailed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>msg</span> <span class='hs-varop'>>>=</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseFailed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>msg</span>
<a name="line-53"></a>
<a name="line-54"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monoid</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Monoid</span> <span class='hs-layout'>(</span><span class='hs-conid'>ParseResult</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-55"></a> <span class='hs-varid'>mempty</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseOk</span> <span class='hs-varid'>mempty</span>
<a name="line-56"></a> <span class='hs-conid'>ParseOk</span> <span class='hs-varid'>x</span> <span class='hs-varop'>`mappend`</span> <span class='hs-conid'>ParseOk</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseOk</span> <span class='hs-varop'>$</span> <span class='hs-varid'>x</span> <span class='hs-varop'>`mappend`</span> <span class='hs-varid'>y</span>
<a name="line-57"></a> <span class='hs-conid'>ParseOk</span> <span class='hs-keyword'>_</span> <span class='hs-varop'>`mappend`</span> <span class='hs-varid'>err</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>err</span>
<a name="line-58"></a> <span class='hs-varid'>err</span> <span class='hs-varop'>`mappend`</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>err</span> <span class='hs-comment'>-- left-biased</span>
<a name="line-59"></a>
<a name="line-60"></a><a name="ParseStatus"></a><span class='hs-comment'>-- internal version</span>
<a name="line-61"></a><a name="ParseStatus"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>ParseStatus</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Ok</span> <span class='hs-conid'>ParseState</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Failed</span> <span class='hs-conid'>SrcLoc</span> <span class='hs-conid'>String</span>
<a name="line-62"></a> <span class='hs-keyword'>deriving</span> <span class='hs-conid'>Show</span>
<a name="line-63"></a>
<a name="line-64"></a><a name="LexContext"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>LexContext</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NoLayout</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Layout</span> <span class='hs-conid'>Int</span>
<a name="line-65"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Eq</span><span class='hs-layout'>,</span><span class='hs-conid'>Ord</span><span class='hs-layout'>,</span><span class='hs-conid'>Show</span><span class='hs-layout'>)</span>
<a name="line-66"></a>
<a name="line-67"></a><a name="ParseState"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>ParseState</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>LexContext</span><span class='hs-keyglyph'>]</span>
<a name="line-68"></a>
<a name="line-69"></a><a name="indentOfParseState"></a><span class='hs-definition'>indentOfParseState</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ParseState</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span>
<a name="line-70"></a><span class='hs-definition'>indentOfParseState</span> <span class='hs-layout'>(</span><span class='hs-conid'>Layout</span> <span class='hs-varid'>n</span><span class='hs-conop'>:</span><span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>n</span>
<a name="line-71"></a><span class='hs-definition'>indentOfParseState</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>0</span>
<a name="line-72"></a>
<a name="line-73"></a><span class='hs-comment'>-- | Static parameters governing a parse.</span>
<a name="line-74"></a><span class='hs-comment'>-- More to come later, e.g. literate mode, language extensions.</span>
<a name="line-75"></a>
<a name="line-76"></a><a name="ParseMode"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>ParseMode</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseMode</span> <span class='hs-layout'>{</span>
<a name="line-77"></a> <span class='hs-comment'>-- | original name of the file being parsed</span>
<a name="line-78"></a> <span class='hs-varid'>parseFilename</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span>
<a name="line-79"></a> <span class='hs-layout'>}</span>
<a name="line-80"></a>
<a name="line-81"></a><span class='hs-comment'>-- | Default parameters for a parse,</span>
<a name="line-82"></a><span class='hs-comment'>-- currently just a marker for an unknown filename.</span>
<a name="line-83"></a>
<a name="line-84"></a><a name="defaultParseMode"></a><span class='hs-definition'>defaultParseMode</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ParseMode</span>
<a name="line-85"></a><span class='hs-definition'>defaultParseMode</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ParseMode</span> <span class='hs-layout'>{</span>
<a name="line-86"></a> <span class='hs-varid'>parseFilename</span> <span class='hs-keyglyph'>=</span> <span class='hs-str'>"<unknown>"</span>
<a name="line-87"></a> <span class='hs-layout'>}</span>
<a name="line-88"></a>
<a name="line-89"></a><span class='hs-comment'>-- | Monad for parsing</span>
<a name="line-90"></a>
<a name="line-91"></a><a name="P"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>P</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-layout'>{</span> <span class='hs-varid'>runP</span> <span class='hs-keyglyph'>::</span>
<a name="line-92"></a> <span class='hs-conid'>String</span> <span class='hs-comment'>-- input string</span>
<a name="line-93"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- current column</span>
<a name="line-94"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- current line</span>
<a name="line-95"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SrcLoc</span> <span class='hs-comment'>-- location of last token read</span>
<a name="line-96"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ParseState</span> <span class='hs-comment'>-- layout info.</span>
<a name="line-97"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ParseMode</span> <span class='hs-comment'>-- parse parameters</span>
<a name="line-98"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ParseStatus</span> <span class='hs-varid'>a</span>
<a name="line-99"></a> <span class='hs-layout'>}</span>
<a name="line-100"></a>
<a name="line-101"></a><a name="runParserWithMode"></a><span class='hs-definition'>runParserWithMode</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ParseMode</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ParseResult</span> <span class='hs-varid'>a</span>
<a name="line-102"></a><span class='hs-definition'>runParserWithMode</span> <span class='hs-varid'>mode</span> <span class='hs-layout'>(</span><span class='hs-conid'>P</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>m</span> <span class='hs-varid'>s</span> <span class='hs-num'>0</span> <span class='hs-num'>1</span> <span class='hs-varid'>start</span> <span class='hs-conid'>[]</span> <span class='hs-varid'>mode</span> <span class='hs-keyword'>of</span>
<a name="line-103"></a> <span class='hs-conid'>Ok</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ParseOk</span> <span class='hs-varid'>a</span>
<a name="line-104"></a> <span class='hs-conid'>Failed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>msg</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ParseFailed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>msg</span>
<a name="line-105"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>start</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>SrcLoc</span> <span class='hs-layout'>{</span>
<a name="line-106"></a> <span class='hs-varid'>srcFilename</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parseFilename</span> <span class='hs-varid'>mode</span><span class='hs-layout'>,</span>
<a name="line-107"></a> <span class='hs-varid'>srcLine</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>1</span><span class='hs-layout'>,</span>
<a name="line-108"></a> <span class='hs-varid'>srcColumn</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>1</span>
<a name="line-109"></a> <span class='hs-layout'>}</span>
<a name="line-110"></a>
<a name="line-111"></a><a name="runParser"></a><span class='hs-definition'>runParser</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>P</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ParseResult</span> <span class='hs-varid'>a</span>
<a name="line-112"></a><span class='hs-definition'>runParser</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>runParserWithMode</span> <span class='hs-varid'>defaultParseMode</span>
<a name="line-113"></a>
<a name="line-114"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-conid'>P</span> <span class='hs-keyword'>where</span>
<a name="line-115"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-sel'>_i</span> <span class='hs-sel'>_x</span> <span class='hs-sel'>_y</span> <span class='hs-sel'>_l</span> <span class='hs-varid'>s</span> <span class='hs-sel'>_m</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Ok</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span>
<a name="line-116"></a> <span class='hs-conid'>P</span> <span class='hs-varid'>m</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>i</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>l</span> <span class='hs-varid'>s</span> <span class='hs-varid'>mode</span> <span class='hs-keyglyph'>-></span>
<a name="line-117"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>m</span> <span class='hs-varid'>i</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>l</span> <span class='hs-varid'>s</span> <span class='hs-varid'>mode</span> <span class='hs-keyword'>of</span>
<a name="line-118"></a> <span class='hs-conid'>Failed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>msg</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Failed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>msg</span>
<a name="line-119"></a> <span class='hs-conid'>Ok</span> <span class='hs-varid'>s'</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>k</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>i</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>l</span> <span class='hs-varid'>s'</span> <span class='hs-varid'>mode</span>
<a name="line-120"></a> <span class='hs-varid'>fail</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-sel'>_r</span> <span class='hs-sel'>_col</span> <span class='hs-sel'>_line</span> <span class='hs-varid'>loc</span> <span class='hs-sel'>_stk</span> <span class='hs-sel'>_m</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Failed</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>s</span>
<a name="line-121"></a>
<a name="line-122"></a><a name="atSrcLoc"></a><span class='hs-definition'>atSrcLoc</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>P</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>SrcLoc</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varid'>a</span>
<a name="line-123"></a><span class='hs-conid'>P</span> <span class='hs-varid'>m</span> <span class='hs-varop'>`atSrcLoc`</span> <span class='hs-varid'>loc</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>i</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-sel'>_l</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>i</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span>
<a name="line-124"></a>
<a name="line-125"></a><a name="getSrcLoc"></a><span class='hs-definition'>getSrcLoc</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>P</span> <span class='hs-conid'>SrcLoc</span>
<a name="line-126"></a><span class='hs-definition'>getSrcLoc</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-sel'>_i</span> <span class='hs-sel'>_x</span> <span class='hs-sel'>_y</span> <span class='hs-varid'>l</span> <span class='hs-varid'>s</span> <span class='hs-sel'>_m</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Ok</span> <span class='hs-varid'>s</span> <span class='hs-varid'>l</span>
<a name="line-127"></a>
<a name="line-128"></a><span class='hs-comment'>-- Enter a new layout context. If we are already in a layout context,</span>
<a name="line-129"></a><span class='hs-comment'>-- ensure that the new indent is greater than the indent of that context.</span>
<a name="line-130"></a><span class='hs-comment'>-- (So if the source loc is not to the right of the current indent, an</span>
<a name="line-131"></a><span class='hs-comment'>-- empty list {} will be inserted.)</span>
<a name="line-132"></a>
<a name="line-133"></a><a name="pushCurrentContext"></a><span class='hs-definition'>pushCurrentContext</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>P</span> <span class='hs-conid'>()</span>
<a name="line-134"></a><span class='hs-definition'>pushCurrentContext</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-135"></a> <span class='hs-varid'>loc</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>getSrcLoc</span>
<a name="line-136"></a> <span class='hs-varid'>indent</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>currentIndent</span>
<a name="line-137"></a> <span class='hs-varid'>pushContext</span> <span class='hs-layout'>(</span><span class='hs-conid'>Layout</span> <span class='hs-layout'>(</span><span class='hs-varid'>max</span> <span class='hs-layout'>(</span><span class='hs-varid'>indent</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>srcColumn</span> <span class='hs-varid'>loc</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-138"></a>
<a name="line-139"></a><a name="currentIndent"></a><span class='hs-definition'>currentIndent</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>P</span> <span class='hs-conid'>Int</span>
<a name="line-140"></a><span class='hs-definition'>currentIndent</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-sel'>_r</span> <span class='hs-sel'>_x</span> <span class='hs-sel'>_y</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>stk</span> <span class='hs-sel'>_mode</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Ok</span> <span class='hs-varid'>stk</span> <span class='hs-layout'>(</span><span class='hs-varid'>indentOfParseState</span> <span class='hs-varid'>stk</span><span class='hs-layout'>)</span>
<a name="line-141"></a>
<a name="line-142"></a><a name="pushContext"></a><span class='hs-definition'>pushContext</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>LexContext</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-conid'>()</span>
<a name="line-143"></a><span class='hs-definition'>pushContext</span> <span class='hs-varid'>ctxt</span> <span class='hs-keyglyph'>=</span>
<a name="line-144"></a><span class='hs-comment'>--trace ("pushing lexical scope: " ++ show ctxt ++"\n") $</span>
<a name="line-145"></a> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-sel'>_i</span> <span class='hs-sel'>_x</span> <span class='hs-sel'>_y</span> <span class='hs-sel'>_l</span> <span class='hs-varid'>s</span> <span class='hs-sel'>_m</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Ok</span> <span class='hs-layout'>(</span><span class='hs-varid'>ctxt</span><span class='hs-conop'>:</span><span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-conid'>()</span>
<a name="line-146"></a>
<a name="line-147"></a><a name="popContext"></a><span class='hs-definition'>popContext</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>P</span> <span class='hs-conid'>()</span>
<a name="line-148"></a><span class='hs-definition'>popContext</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-sel'>_i</span> <span class='hs-sel'>_x</span> <span class='hs-sel'>_y</span> <span class='hs-sel'>_l</span> <span class='hs-varid'>stk</span> <span class='hs-sel'>_m</span> <span class='hs-keyglyph'>-></span>
<a name="line-149"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>stk</span> <span class='hs-keyword'>of</span>
<a name="line-150"></a> <span class='hs-layout'>(</span><span class='hs-keyword'>_</span><span class='hs-conop'>:</span><span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-comment'>--trace ("popping lexical scope, context now "++show s ++ "\n") $</span>
<a name="line-151"></a> <span class='hs-conid'>Ok</span> <span class='hs-varid'>s</span> <span class='hs-conid'>()</span>
<a name="line-152"></a> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>error</span> <span class='hs-str'>"Internal error: empty context in popContext"</span>
<a name="line-153"></a>
<a name="line-154"></a><span class='hs-comment'>-- Monad for lexical analysis:</span>
<a name="line-155"></a><span class='hs-comment'>-- a continuation-passing version of the parsing monad</span>
<a name="line-156"></a>
<a name="line-157"></a><a name="Lex"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>r</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-layout'>{</span> <span class='hs-varid'>runL</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varid'>r</span> <span class='hs-layout'>}</span>
<a name="line-158"></a>
<a name="line-159"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lex</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-160"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>k</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>k</span> <span class='hs-varid'>a</span>
<a name="line-161"></a> <span class='hs-conid'>Lex</span> <span class='hs-varid'>v</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>k</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>v</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runL</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>k</span><span class='hs-layout'>)</span>
<a name="line-162"></a> <span class='hs-conid'>Lex</span> <span class='hs-varid'>v</span> <span class='hs-varop'>>></span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>w</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>k</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>v</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>w</span> <span class='hs-varid'>k</span><span class='hs-layout'>)</span>
<a name="line-163"></a> <span class='hs-varid'>fail</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>fail</span> <span class='hs-varid'>s</span>
<a name="line-164"></a>
<a name="line-165"></a><span class='hs-comment'>-- Operations on this monad</span>
<a name="line-166"></a>
<a name="line-167"></a><a name="getInput"></a><span class='hs-definition'>getInput</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>r</span> <span class='hs-conid'>String</span>
<a name="line-168"></a><span class='hs-definition'>getInput</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span>
<a name="line-169"></a>
<a name="line-170"></a><span class='hs-comment'>-- | Discard some input characters (these must not include tabs or newlines).</span>
<a name="line-171"></a>
<a name="line-172"></a><a name="discard"></a><span class='hs-definition'>discard</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>r</span> <span class='hs-conid'>()</span>
<a name="line-173"></a><span class='hs-definition'>discard</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>drop</span> <span class='hs-varid'>n</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-varop'>+</span><span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-174"></a>
<a name="line-175"></a><span class='hs-comment'>-- | Discard the next character, which must be a newline.</span>
<a name="line-176"></a>
<a name="line-177"></a><a name="lexNewline"></a><span class='hs-definition'>lexNewline</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-conid'>()</span>
<a name="line-178"></a><span class='hs-definition'>lexNewline</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-keyword'>_</span><span class='hs-conop'>:</span><span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-sel'>_x</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-num'>1</span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span>
<a name="line-179"></a>
<a name="line-180"></a><span class='hs-comment'>-- | Discard the next character, which must be a tab.</span>
<a name="line-181"></a>
<a name="line-182"></a><a name="lexTab"></a><span class='hs-definition'>lexTab</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-conid'>()</span>
<a name="line-183"></a><span class='hs-definition'>lexTab</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-keyword'>_</span><span class='hs-conop'>:</span><span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-layout'>(</span><span class='hs-varid'>nextTab</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-184"></a>
<a name="line-185"></a><a name="nextTab"></a><span class='hs-definition'>nextTab</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span>
<a name="line-186"></a><span class='hs-definition'>nextTab</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>x</span> <span class='hs-varop'>+</span> <span class='hs-layout'>(</span><span class='hs-varid'>tAB_LENGTH</span> <span class='hs-comment'>-</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-comment'>-</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varop'>`mod`</span> <span class='hs-varid'>tAB_LENGTH</span><span class='hs-layout'>)</span>
<a name="line-187"></a>
<a name="line-188"></a><a name="tAB_LENGTH"></a><span class='hs-definition'>tAB_LENGTH</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span>
<a name="line-189"></a><span class='hs-definition'>tAB_LENGTH</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>8</span>
<a name="line-190"></a>
<a name="line-191"></a><span class='hs-comment'>-- Consume and return the largest string of characters satisfying p</span>
<a name="line-192"></a>
<a name="line-193"></a><a name="lexWhile"></a><span class='hs-definition'>lexWhile</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Char</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-conid'>String</span>
<a name="line-194"></a><span class='hs-definition'>lexWhile</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span>
<a name="line-195"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>cs</span><span class='hs-layout'>,</span><span class='hs-varid'>rest</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>span</span> <span class='hs-varid'>p</span> <span class='hs-varid'>r</span> <span class='hs-keyword'>in</span>
<a name="line-196"></a> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-varid'>cs</span><span class='hs-layout'>)</span> <span class='hs-varid'>rest</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varop'>+</span> <span class='hs-varid'>length</span> <span class='hs-varid'>cs</span><span class='hs-layout'>)</span>
<a name="line-197"></a>
<a name="line-198"></a><span class='hs-comment'>-- An alternative scan, to which we can return if subsequent scanning</span>
<a name="line-199"></a><span class='hs-comment'>-- is unsuccessful.</span>
<a name="line-200"></a>
<a name="line-201"></a><a name="alternative"></a><span class='hs-definition'>alternative</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-varid'>v</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span>
<a name="line-202"></a><span class='hs-definition'>alternative</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lex</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>-></span>
<a name="line-203"></a> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont'</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-sel'>_r</span> <span class='hs-sel'>_x</span> <span class='hs-sel'>_y</span> <span class='hs-keyglyph'>-></span>
<a name="line-204"></a> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>v</span> <span class='hs-varid'>cont'</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span>
<a name="line-205"></a>
<a name="line-206"></a><span class='hs-comment'>-- The source location is the coordinates of the previous token,</span>
<a name="line-207"></a><span class='hs-comment'>-- or, while scanning a token, the start of the current token.</span>
<a name="line-208"></a>
<a name="line-209"></a><span class='hs-comment'>-- col is the current column in the source file.</span>
<a name="line-210"></a><span class='hs-comment'>-- We also need to remember between scanning tokens whether we are</span>
<a name="line-211"></a><span class='hs-comment'>-- somewhere at the beginning of the line before the first token.</span>
<a name="line-212"></a><span class='hs-comment'>-- This could be done with an extra Bool argument to the P monad,</span>
<a name="line-213"></a><span class='hs-comment'>-- but as a hack we use a col value of 0 to indicate this situation.</span>
<a name="line-214"></a>
<a name="line-215"></a><span class='hs-comment'>-- Setting col to 0 is used in two places: just after emitting a virtual</span>
<a name="line-216"></a><span class='hs-comment'>-- close brace due to layout, so that next time through we check whether</span>
<a name="line-217"></a><span class='hs-comment'>-- we also need to emit a semi-colon, and at the beginning of the file,</span>
<a name="line-218"></a><span class='hs-comment'>-- by runParser, to kick off the lexer.</span>
<a name="line-219"></a><span class='hs-comment'>-- Thus when col is zero, the true column can be taken from the loc.</span>
<a name="line-220"></a>
<a name="line-221"></a><a name="checkBOL"></a><span class='hs-definition'>checkBOL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-conid'>Bool</span>
<a name="line-222"></a><span class='hs-definition'>checkBOL</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span> <span class='hs-keyglyph'>-></span>
<a name="line-223"></a> <span class='hs-keyword'>if</span> <span class='hs-varid'>x</span> <span class='hs-varop'>==</span> <span class='hs-num'>0</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-conid'>True</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-layout'>(</span><span class='hs-varid'>srcColumn</span> <span class='hs-varid'>loc</span><span class='hs-layout'>)</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span>
<a name="line-224"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-conid'>False</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span>
<a name="line-225"></a>
<a name="line-226"></a><a name="setBOL"></a><span class='hs-definition'>setBOL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-conid'>()</span>
<a name="line-227"></a><span class='hs-definition'>setBOL</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-num'>0</span>
<a name="line-228"></a>
<a name="line-229"></a><span class='hs-comment'>-- Set the loc to the current position</span>
<a name="line-230"></a>
<a name="line-231"></a><a name="startToken"></a><span class='hs-definition'>startToken</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-conid'>()</span>
<a name="line-232"></a><span class='hs-definition'>startToken</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>s</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>stk</span> <span class='hs-varid'>mode</span> <span class='hs-keyglyph'>-></span>
<a name="line-233"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>loc</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>SrcLoc</span> <span class='hs-layout'>{</span>
<a name="line-234"></a> <span class='hs-varid'>srcFilename</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>parseFilename</span> <span class='hs-varid'>mode</span><span class='hs-layout'>,</span>
<a name="line-235"></a> <span class='hs-varid'>srcLine</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>y</span><span class='hs-layout'>,</span>
<a name="line-236"></a> <span class='hs-varid'>srcColumn</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>x</span>
<a name="line-237"></a> <span class='hs-layout'>}</span> <span class='hs-keyword'>in</span>
<a name="line-238"></a> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varid'>s</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>stk</span> <span class='hs-varid'>mode</span>
<a name="line-239"></a>
<a name="line-240"></a><span class='hs-comment'>-- Current status with respect to the offside (layout) rule:</span>
<a name="line-241"></a><span class='hs-comment'>-- LT: we are to the left of the current indent (if any)</span>
<a name="line-242"></a><span class='hs-comment'>-- EQ: we are at the current indent (if any)</span>
<a name="line-243"></a><span class='hs-comment'>-- GT: we are to the right of the current indent, or not subject to layout</span>
<a name="line-244"></a>
<a name="line-245"></a><a name="getOffside"></a><span class='hs-definition'>getOffside</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-conid'>Ordering</span>
<a name="line-246"></a><span class='hs-definition'>getOffside</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>stk</span> <span class='hs-keyglyph'>-></span>
<a name="line-247"></a> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-layout'>(</span><span class='hs-varid'>compare</span> <span class='hs-varid'>x</span> <span class='hs-layout'>(</span><span class='hs-varid'>indentOfParseState</span> <span class='hs-varid'>stk</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>stk</span>
<a name="line-248"></a>
<a name="line-249"></a><a name="pushContextL"></a><span class='hs-definition'>pushContextL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>LexContext</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-conid'>()</span>
<a name="line-250"></a><span class='hs-definition'>pushContextL</span> <span class='hs-varid'>ctxt</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>stk</span> <span class='hs-keyglyph'>-></span>
<a name="line-251"></a> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span> <span class='hs-layout'>(</span><span class='hs-varid'>ctxt</span><span class='hs-conop'>:</span><span class='hs-varid'>stk</span><span class='hs-layout'>)</span>
<a name="line-252"></a>
<a name="line-253"></a><a name="popContextL"></a><span class='hs-definition'>popContextL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Lex</span> <span class='hs-varid'>a</span> <span class='hs-conid'>()</span>
<a name="line-254"></a><span class='hs-definition'>popContextL</span> <span class='hs-varid'>fn</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lex</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>cont</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>stk</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>stk</span> <span class='hs-keyword'>of</span>
<a name="line-255"></a> <span class='hs-layout'>(</span><span class='hs-keyword'>_</span><span class='hs-conop'>:</span><span class='hs-varid'>ctxt</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>cont</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>loc</span> <span class='hs-varid'>ctxt</span>
<a name="line-256"></a> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>error</span> <span class='hs-layout'>(</span><span class='hs-str'>"Internal error: empty context in "</span> <span class='hs-varop'>++</span> <span class='hs-varid'>fn</span><span class='hs-layout'>)</span>
</pre></body>
</html>
