477 lines
14 KiB
Ruby
477 lines
14 KiB
Ruby
# = Introduction
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#
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# SimpleMarkup parses plain text documents and attempts to decompose
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# them into their constituent parts. Some of these parts are high-level:
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# paragraphs, chunks of verbatim text, list entries and the like. Other
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# parts happen at the character level: a piece of bold text, a word in
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# code font. This markup is similar in spirit to that used on WikiWiki
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# webs, where folks create web pages using a simple set of formatting
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# rules.
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#
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# SimpleMarkup itself does no output formatting: this is left to a
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# different set of classes.
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#
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# SimpleMarkup is extendable at runtime: you can add new markup
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# elements to be recognised in the documents that SimpleMarkup parses.
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#
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# SimpleMarkup is intended to be the basis for a family of tools which
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# share the common requirement that simple, plain-text should be
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# rendered in a variety of different output formats and media. It is
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# envisaged that SimpleMarkup could be the basis for formating RDoc
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# style comment blocks, Wiki entries, and online FAQs.
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#
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# = Basic Formatting
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#
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# * SimpleMarkup looks for a document's natural left margin. This is
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# used as the initial margin for the document.
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#
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# * Consecutive lines starting at this margin are considered to be a
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# paragraph.
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#
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# * If a paragraph starts with a "*", "-", or with "<digit>.", then it is
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# taken to be the start of a list. The margin in increased to be the
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# first non-space following the list start flag. Subsequent lines
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# should be indented to this new margin until the list ends. For
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# example:
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#
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# * this is a list with three paragraphs in
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# the first item. This is the first paragraph.
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#
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# And this is the second paragraph.
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#
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# 1. This is an indented, numbered list.
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# 2. This is the second item in that list
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#
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# This is the third conventional paragraph in the
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# first list item.
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#
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# * This is the second item in the original list
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#
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# * You can also construct labeled lists, sometimes called description
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# or definition lists. Do this by putting the label in square brackets
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# and indenting the list body:
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#
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# [cat] a small furry mammal
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# that seems to sleep a lot
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#
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# [ant] a little insect that is known
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# to enjoy picnics
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#
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# A minor variation on labeled lists uses two colons to separate the
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# label from the list body:
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#
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# cat:: a small furry mammal
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# that seems to sleep a lot
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#
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# ant:: a little insect that is known
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# to enjoy picnics
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#
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# This latter style guarantees that the list bodies' left margins are
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# aligned: think of them as a two column table.
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#
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# * Any line that starts to the right of the current margin is treated
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# as verbatim text. This is useful for code listings. The example of a
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# list above is also verbatim text.
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#
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# * A line starting with an equals sign (=) is treated as a
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# heading. Level one headings have one equals sign, level two headings
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# have two,and so on.
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#
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# * A line starting with three or more hyphens (at the current indent)
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# generates a horizontal rule. THe more hyphens, the thicker the rule
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# (within reason, and if supported by the output device)
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#
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# * You can use markup within text (except verbatim) to change the
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# appearance of parts of that text. Out of the box, SimpleMarkup
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# supports word-based and general markup.
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#
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# Word-based markup uses flag characters around individual words:
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#
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# [\*word*] displays word in a *bold* font
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# [\_word_] displays word in an _emphasized_ font
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# [\+word+] displays word in a +code+ font
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#
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# General markup affects text between a start delimiter and and end
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# delimiter. Not surprisingly, these delimiters look like HTML markup.
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#
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# [\<b>text...</b>] displays word in a *bold* font
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# [\<em>text...</em>] displays word in an _emphasized_ font
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# [\<i>text...</i>] displays word in an _emphasized_ font
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# [\<tt>text...</tt>] displays word in a +code+ font
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#
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# Unlike conventional Wiki markup, general markup can cross line
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# boundaries. You can turn off the interpretation of markup by
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# preceding the first character with a backslash, so \\\<b>bold
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# text</b> and \\\*bold* produce \<b>bold text</b> and \*bold
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# respectively.
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#
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# = Using SimpleMarkup
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#
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# For information on using SimpleMarkup programatically,
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# see SM::SimpleMarkup.
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#
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# Author:: Dave Thomas, dave@pragmaticprogrammer.com
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# Version:: 0.0
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# License:: Ruby license
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require 'rdoc/markup/simple_markup/fragments'
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require 'rdoc/markup/simple_markup/lines.rb'
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module SM #:nodoc:
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# == Synopsis
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#
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# This code converts <tt>input_string</tt>, which is in the format
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# described in markup/simple_markup.rb, to HTML. The conversion
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# takes place in the +convert+ method, so you can use the same
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# SimpleMarkup object to convert multiple input strings.
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#
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# require 'rdoc/markup/simple_markup'
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# require 'rdoc/markup/simple_markup/to_html'
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#
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# p = SM::SimpleMarkup.new
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# h = SM::ToHtml.new
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#
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# puts p.convert(input_string, h)
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#
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# You can extend the SimpleMarkup parser to recognise new markup
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# sequences, and to add special processing for text that matches a
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# regular epxression. Here we make WikiWords significant to the parser,
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# and also make the sequences {word} and \<no>text...</no> signify
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# strike-through text. When then subclass the HTML output class to deal
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# with these:
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#
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# require 'rdoc/markup/simple_markup'
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# require 'rdoc/markup/simple_markup/to_html'
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#
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# class WikiHtml < SM::ToHtml
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# def handle_special_WIKIWORD(special)
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# "<font color=red>" + special.text + "</font>"
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# end
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# end
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#
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# p = SM::SimpleMarkup.new
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# p.add_word_pair("{", "}", :STRIKE)
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# p.add_html("no", :STRIKE)
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#
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# p.add_special(/\b([A-Z][a-z]+[A-Z]\w+)/, :WIKIWORD)
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#
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# h = WikiHtml.new
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# h.add_tag(:STRIKE, "<strike>", "</strike>")
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#
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# puts "<body>" + p.convert(ARGF.read, h) + "</body>"
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#
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# == Output Formatters
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#
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# _missing_
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#
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#
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class SimpleMarkup
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SPACE = ?\s
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# List entries look like:
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# * text
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# 1. text
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# [label] text
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# label:: text
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#
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# Flag it as a list entry, and
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# work out the indent for subsequent lines
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SIMPLE_LIST_RE = /^(
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( \* (?# bullet)
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|- (?# bullet)
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|\d+\. (?# numbered )
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|[A-Za-z]\. (?# alphabetically numbered )
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)
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\s+
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)\S/x
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LABEL_LIST_RE = /^(
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( \[.*?\] (?# labeled )
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|\S.*:: (?# note )
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)(?:\s+|$)
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)/x
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##
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# take a block of text and use various heuristics to determine
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# it's structure (paragraphs, lists, and so on). Invoke an
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# event handler as we identify significant chunks.
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#
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def initialize
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@am = AttributeManager.new
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@output = nil
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end
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##
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# Add to the sequences used to add formatting to an individual word
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# (such as *bold*). Matching entries will generate attibutes
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# that the output formatters can recognize by their +name+
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def add_word_pair(start, stop, name)
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@am.add_word_pair(start, stop, name)
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end
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##
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# Add to the sequences recognized as general markup
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#
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def add_html(tag, name)
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@am.add_html(tag, name)
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end
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##
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# Add to other inline sequences. For example, we could add
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# WikiWords using something like:
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#
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# parser.add_special(/\b([A-Z][a-z]+[A-Z]\w+)/, :WIKIWORD)
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#
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# Each wiki word will be presented to the output formatter
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# via the accept_special method
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#
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def add_special(pattern, name)
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@am.add_special(pattern, name)
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end
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# We take a string, split it into lines, work out the type of
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# each line, and from there deduce groups of lines (for example
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# all lines in a paragraph). We then invoke the output formatter
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# using a Visitor to display the result
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def convert(str, op)
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@lines = Lines.new(str.split(/\r?\n/).collect { |aLine|
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Line.new(aLine) })
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return "" if @lines.empty?
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@lines.normalize
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assign_types_to_lines
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group = group_lines
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# call the output formatter to handle the result
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# group.to_a.each {|i| p i}
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group.accept(@am, op)
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end
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#######
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private
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#######
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##
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# Look through the text at line indentation. We flag each line as being
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# Blank, a paragraph, a list element, or verbatim text
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#
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def assign_types_to_lines(margin = 0, level = 0)
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while line = @lines.next
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if line.isBlank?
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line.stamp(Line::BLANK, level)
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next
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end
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# if a line contains non-blanks before the margin, then it must belong
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# to an outer level
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text = line.text
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for i in 0...margin
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if text[i] != SPACE
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@lines.unget
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return
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end
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end
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active_line = text[margin..-1]
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# Rules (horizontal lines) look like
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#
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# --- (three or more hyphens)
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#
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# The more hyphens, the thicker the rule
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#
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if /^(---+)\s*$/ =~ active_line
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line.stamp(Line::RULE, level, $1.length-2)
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next
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end
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# Then look for list entries. First the ones that have to have
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# text following them (* xxx, - xxx, and dd. xxx)
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if SIMPLE_LIST_RE =~ active_line
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offset = margin + $1.length
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prefix = $2
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prefix_length = prefix.length
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flag = case prefix
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when "*","-" then ListBase::BULLET
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when /^\d/ then ListBase::NUMBER
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when /^[A-Z]/ then ListBase::UPPERALPHA
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when /^[a-z]/ then ListBase::LOWERALPHA
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else raise "Invalid List Type: #{self.inspect}"
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end
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line.stamp(Line::LIST, level+1, prefix, flag)
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text[margin, prefix_length] = " " * prefix_length
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assign_types_to_lines(offset, level + 1)
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next
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end
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if LABEL_LIST_RE =~ active_line
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offset = margin + $1.length
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prefix = $2
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prefix_length = prefix.length
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next if handled_labeled_list(line, level, margin, offset, prefix)
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end
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# Headings look like
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# = Main heading
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# == Second level
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# === Third
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#
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# Headings reset the level to 0
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if active_line[0] == ?= and active_line =~ /^(=+)\s*(.*)/
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prefix_length = $1.length
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prefix_length = 6 if prefix_length > 6
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line.stamp(Line::HEADING, 0, prefix_length)
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line.strip_leading(margin + prefix_length)
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next
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end
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# If the character's a space, then we have verbatim text,
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# otherwise
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if active_line[0] == SPACE
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line.strip_leading(margin) if margin > 0
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line.stamp(Line::VERBATIM, level)
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else
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line.stamp(Line::PARAGRAPH, level)
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end
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end
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end
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# Handle labeled list entries, We have a special case
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# to deal with. Because the labels can be long, they force
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# the remaining block of text over the to right:
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#
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# this is a long label that I wrote:: and here is the
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# block of text with
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# a silly margin
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#
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# So we allow the special case. If the label is followed
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# by nothing, and if the following line is indented, then
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# we take the indent of that line as the new margin
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#
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# this is a long label that I wrote::
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# here is a more reasonably indented block which
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# will ab attached to the label.
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#
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def handled_labeled_list(line, level, margin, offset, prefix)
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prefix_length = prefix.length
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text = line.text
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flag = nil
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case prefix
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when /^\[/
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flag = ListBase::LABELED
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prefix = prefix[1, prefix.length-2]
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when /:$/
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flag = ListBase::NOTE
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prefix.chop!
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else raise "Invalid List Type: #{self.inspect}"
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end
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# body is on the next line
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if text.length <= offset
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original_line = line
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line = @lines.next
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return(false) unless line
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text = line.text
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for i in 0..margin
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if text[i] != SPACE
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@lines.unget
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return false
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end
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end
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i = margin
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i += 1 while text[i] == SPACE
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if i >= text.length
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@lines.unget
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return false
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else
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offset = i
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prefix_length = 0
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@lines.delete(original_line)
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end
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end
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line.stamp(Line::LIST, level+1, prefix, flag)
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text[margin, prefix_length] = " " * prefix_length
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assign_types_to_lines(offset, level + 1)
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return true
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end
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# Return a block consisting of fragments which are
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# paragraphs, list entries or verbatim text. We merge consecutive
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# lines of the same type and level together. We are also slightly
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# tricky with lists: the lines following a list introduction
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# look like paragraph lines at the next level, and we remap them
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# into list entries instead
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def group_lines
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@lines.rewind
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inList = false
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wantedType = wantedLevel = nil
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block = LineCollection.new
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group = nil
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while line = @lines.next
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if line.level == wantedLevel and line.type == wantedType
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group.add_text(line.text)
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else
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group = block.fragment_for(line)
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block.add(group)
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if line.type == Line::LIST
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wantedType = Line::PARAGRAPH
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else
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wantedType = line.type
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end
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wantedLevel = line.type == Line::HEADING ? line.param : line.level
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end
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end
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block.normalize
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block
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end
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## for debugging, we allow access to our line contents as text
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def content
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@lines.as_text
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end
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public :content
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## for debugging, return the list of line types
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def get_line_types
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@lines.line_types
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end
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public :get_line_types
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end
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end
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