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