#lang scribble/doc @; THIS FILE IS GENERATED @(require scribble/manual) @(require (for-label (planet neil/html-parsing:1:=0))) @(require (for-label racket)) @title[#:version "0.1"]{@bold{html-parsing}: Permissive Parsing of HTML to SXML/xexp in Racket} @author{Neil Van Dyke} License: @seclink["Legal" #:underline? #f]{LGPL 3} @(hspace 1) Web: @link["http://www.neilvandyke.org/racket-html-parsing/" #:underline? #f]{http://www.neilvandyke.org/racket-html-parsing/} @defmodule[(planet neil/html-parsing:1:=0)] @section{Introduction} The @tt{html-parsing} library provides a permissive HTML parser. The parser is useful for software agent extraction of information from Web pages, for programmatically transforming HTML files, and for implementing interactive Web browsers. @tt{html-parsing} emits @link["http://www.neilvandyke.org/racket-xexp/"]{SXML/@emph{xexp}}, so that conventional invalid HTML may be processed with XML tools such as @link["http://pair.com/lisovsky/query/sxpath/"]{SXPath}. Like Oleg Kiselyov's @link["http://pobox.com/~oleg/ftp/Scheme/xml.html#HTML-parser"]{SSAX-based HTML parser}, @tt{html-parsing} provides a permissive tokenizer, but @tt{html-parsing} extends this by attempting to recover syntactic structure. The @tt{html-parsing} parsing behavior is permissive in that it accepts erroneous HTML, handling several classes of HTML syntax errors gracefully, without yielding a parse error. This is crucial for parsing arbitrary real-world Web pages, since many pages actually contain syntax errors that would defeat a strict or validating parser. @tt{html-parsing}'s handling of errors is intended to generally emulate popular Web browsers' interpretation of the structure of erroneous HTML. We euphemistically term this kind of parse ``pragmatic.'' @tt{html-parsing} also has some support for XHTML, although XML namespace qualifiers are accepted but stripped from the resulting SXML/@emph{xexp}. Note that @emph{valid} XHTML input might be better handled by a validating XML parser like Kiselyov's @link["http://pobox.com/~oleg/ftp/Scheme/xml.html#XML-parser"]{SSAX}. This package will be replacing @link["http://www.neilvandyke.org/racket-xexp/"]{HtmlPrag}. @section{Interface} @defproc[ (html->xexp (input any/c)) any/c]{ Permissively parse HTML from @schemevarfont{input}, which is either an input port or a string, and emit an SXML/@emph{xexp} equivalent or approximation. To borrow and slightly modify an example from Kiselyov's discussion of his HTML parser: @SCHEMEBLOCK[ (html->xexp "whatever link

BLah italic bold enedstill < bold

But not done yet...") ==> (*TOP* (html (head (title) (title "whatever")) (body "\n" (a (\@ (href "url")) "link") (p (\@ (align "center")) (ul (\@ (compact) (style "aa")) "\n")) (p "BLah" (*COMMENT* " comment ") " " (i " italic " (b " bold " (tt " ened"))) "\n" "still < bold ")) (p " But not done yet..."))) ] Note that, in the emitted SXML/@emph{xexp}, the text token @tt{"still < bold"} is @emph{not} inside the @tt{b} element, which represents an unfortunate failure to emulate all the quirks-handling behavior of some popular Web browsers. } @section{History} @itemize[ @item{Version 0.1 --- 2011-08-21 - PLaneT @tt{(1 0)} Part of forked development from HtmlPrag. } ] @section[#:tag "Legal"]{Legal} Copyright (c) 2003--2011 Neil Van Dyke. This program is Free Software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License (LGPL 3), or (at your option) any later version. This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See http://www.gnu.org/licenses/ for details. For other licenses and consulting, please contact the author. @italic{@smaller{Standard Documentation Format Note: The API signatures in this documentation are likely incorrect in some regards, such as indicating type @tt{any/c} for things that are not, and not indicating when arguments are optional. This is due to a transitioning from the Texinfo documentation format to Scribble, which the author intends to finish someday.}}