REBOL [
    Title: "Text to HTML Converter"
    Date: 29-Feb-2000
    File: %texthtml.r
    Author: "Carl Sassenrath"
    Usage: {
        The first line of the text file is the title of the
        document.  All lines that are flush left will be
        treated as paragraphs.  A blank line will separate
        paragraphs. Indented lines are examples. They are
        indented and printed in monospaced bold font.
        Sections and sub-sections of a document are separated
        with a line that begins with === or --- and the text
        that follows them is shown in a special font.
    }
    Purpose: {A useful doc formatting language. Converts text to HTML with titles, sections, sub-sections, and code. Is used to create all REBOL How-to documents.}
    History: [orig 12-Oct-1999]
    library: [
        level: 'intermediate 
        platform: 'all 
        type: 'Tool 
        domain: [markup text-processing file-handling] 
        tested-under: none 
        support: none 
        license: none 
        see-also: none
    ]
    Version: 1.0.0
]

text-to-html: make object! [
    html: make string! 10000
    emit: func [data] [append html reduce data]

    space: charset " ^-"
    chars: complement charset " ^-^/"

    font: 

    escape-html: func [
        "Format a code example" code
    ][
        replace/all code "&" "&"
        replace/all code "<" "<"
        replace/all code ">" ">"
        insert code [
]
        append code reduce [ newline]
    ]

    ;--- Text Format Language:
    rules: [title some parts done]
    title: [text-line 
        (emit [font
text
])]
    parts: [newline | "===" section | "---" subsect | "###" to end |
         example | paragraph]
    section: [text-line
        (emit [
font
trim text
]) newline]
    subsect: [text-line
        (emit [
font
trim text
]) newline]
    example: [copy code some [indented | some newline indented]
        (emit escape-html code)]
    paragraph: [copy para some [chars thru newline] (emit [para
])]
    done: [(emit [])]
    text-line: [copy text thru newline]
    indented: [some space thru newline]
    convert: func [data] [parse/all detab data rules  html]
]

file: to-file ask "Filename? "
if not find file "." [append file ".txt"]
data: text-to-html/convert read file
write head change find file "." ".html" data
;quit