# simple_markup.rb

Path: | rdoc/markup/simple_markup.rb
Last Update: | Tue Oct 25 16:35:29 AUS Eastern Standard Time 2005

# 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

### Required files

rdoc/markup/simple_markup/fragments rdoc/markup/simple_markup/lines.rb

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