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PDF::TechBook

PDF::TechBook

The TechBook class is a markup language interpreter. This will read a file containing the “TechBook” markukp, described below, and create a PDF document from it. This is intended as a complete document language, but it does have a number of limitations.

The TechBook markup language and class are used to format the PDF::Writer manual, represented in the distrubtion by the file “manual.pwd”.

The TechBook markup language is primarily stream-oriented with awareness of lines. That is to say that the document will be read and generated from beginning to end in the order of the markup stream.

TechBook Markup

TechBook markup is relatively simple. The simplest markup is no markup at all (flowed paragraphs). This means that two lines separated by a single line separator will be treaed as part of the same paragraph and formatted appropriately by PDF::Writer. Paragaphs are terminated by empty lines, valid line markup directives, or valid headings.

Certain XML entitites will need to be escaped as they would in normal XML usage, that is, < must be written as <; > must be written as >; and & must be written as &.

Comments, headings, and directives are line-oriented where the first mandatory character is in the first column of the document and take up the whole line. Styling and callback tags may appear anywhere in the text.

Comments

Comments begin with the hash-mark (‘#’) at the beginning of the line. Comment lines are ignored.

Styling and Callback Tags

Within normal, preserved, or code text, or in headings, HTML-like markup may be used for bold (&lt;b&gt;) and italic (&lt;i&gt;) text. TechBook supports standard PDF::Writer callback tags (<c:alink>, <c:ilink>, <C:bullet/>, and <C:disc/>) and adds two new ones (<r:xref/>, <C:tocdots/>).

&lt;r:xref/>

Creates an internal document link to the named cross-reference destination. Works with the heading format (see below). See tag_xref_replace for more information.

&lt;C:tocdots/>

This is used internally to create and display a row of dots between a table of contents entry and the page number to which it refers. This is used internally by TechBook.

Directives

Directives begin with a period (‘.’) and are followed by a letter (‘a’..‘z’) and then any combination of word characters (‘a’..‘z’, ‘0’..‘9’, and ‘_’). Directives are case-insensitive. A directive may have arguments; if there are arguments, they must follow the directive name after whitespace. After the arguments for a directive, if any, all other text is ignored and may be considered a comment.

.newpage [force]

The .newpage directive starts a new page. If multicolumn mode is on, a new column will be started if the current column is not the last column. If the optional argument force follows the .newpage directive, a new page will be started even if multicolumn mode is on.

.newpage
.newpage force

.pre, .endpre

The .pre and .endpre directives enclose a block of text with preserved newlines. This is similar to normal text, but the lines in the .pre block are not flowed together. This is useful for poetic forms or other text that must end when each line ends. .pre blocks may not be nested in any other formatting block. When an .endpre directive is encountered, the text format will be returned to normal (flowed text) mode.

.pre
The Way that can be told of is not the eternal Way;
The name that can be named is not the eternal name.
The Nameless is the origin of Heaven and Earth;
The Named is the mother of all things.
Therefore let there always be non-being,
  so we may see their subtlety,
And let there always be being,
  so we may see their outcome.
The two are the same,
But after they are produced,
  they have different names.
.endpre

.code, .endcode

The .code and .endcode directives enclose a block of text with preserved newlines. In addition, the font is changed from the normal techbook_textfont to techbook_codefont. The techbook_codefont is normally a fixed pitched font and defaults to Courier. At the end of the code block, the text state is restored to its prior state, which will either be .pre or normal.

.code
require 'pdf/writer'
PDF::Writer.prepress # US Letter, portrait, 1.3, prepress
.endcode

.blist, .endblist

These directives enclose a bulleted list block. Lists may be nested within other text states. If lists are nested, each list will be appropriately indented. Each line in the list block will be treated as a single list item with a bullet inserted in front using either the <C:bullet/> or <C:disc/> callbacks. Nested lists are successively indented. .blist directives accept one optional argument, the name of the type of bullet callback desired (e.g., ‘bullet’ for <C:bullet/> and ‘disc’ for <C:disc/>).

.blist
Item 1
.blist disc
Item 1.1
.endblist
.endblist

.eval, .endeval

With these directives, the block enclosed will collected and passed to Ruby’s Kernel#eval. .eval blocks may be present within normal text, .pre, .code, and .blist blocks. No other block may be embedded within an .eval block.

.eval
puts "Hello"
.endeval

.columns

Multi-column output is controlled with this directive, which accepts one or two parameters. The first parameter is mandatory and is either the number of columns (2 or more) or the word ‘off’ (turning off multi-column output). When starting multi-column output, a second parameter with the gutter size may be specified.

.columns 3
Column 1
.newpage
Column 2
.newpage
Column 3
.columns off

.toc

This directive is used to tell TechBook to generate a table of contents after the first page (assumed to be a title page). If this is not present, then a table of contents will not be generated.

.author, .title, .subject, .keywords

Sets values in the PDF information object. The arguments – to the end of the line – are used to populate the values.

.done

Stops the processing of the document at this point.

Headings

Headings begin with a number followed by the rest of the heading format. This format is “#<heading-text>” or “#<heading-text>xref_name”. TechBook supports five levels of headings. Headings may include markup, but should not exceed a single line in size; those headings which have boxes as part of their layout are not currently configured to work with multiple lines of heading output. If an xref_name is specified, then the &lt;r:xref> tag can use this name to find the target for the heading. If xref_name is not specified, then the “name” associated with the heading is the index of the order of insertion. The xref_name is case sensitive.

1<Chapter>xChapter
2<Section>Section23
3<Subsection>
4<Subsection>
5<Subsection>

Heading Level 1

First level headings are generally chapters. As such, the standard implementation of the heading level 1 method (#__heading1), will be rendered as “chapter#. heading-text” in centered white on a black background, at 26 point (H1_STYLE). First level headings are added to the table of contents.

Heading Level 2

Second level headings are major sections in chapters. The headings are rendered by default as black on 80% grey, left-justified at 18 point (H2_STYLE). The text is unchanged (#__heading2). Second level headings are added to the table of contents.

Heading Level 3, 4, and 5

The next three heading levels are used for varying sections within second level chapter sections. They are rendered by default in black on the background (there is no bar) at 18, 14, and 12 points, respectively (H3_STYLE, H4_STYLE, and H5_STYLE). Third level headings are bold-faced (#__heading3); fourth level headings are italicised (#__heading4), and fifth level headings are underlined (#__heading5).

Attributes

chapter_number[RW]
table_of_contents[RW]
xref_table[R]

Public Instance Methods

__heading1(heading) click to toggle source
# File lib/pdf/techbook.rb, line 433
def __heading1(heading)
  @chapter_number ||= 0
  @chapter_number = @chapter_number.succ
  "#{chapter_number}. #{heading}"
end
__heading2(heading) click to toggle source
# File lib/pdf/techbook.rb, line 438
def __heading2(heading)
  heading
end
__heading3(heading) click to toggle source
# File lib/pdf/techbook.rb, line 441
def __heading3(heading)
  "<b>#{heading}</b>"
end
__heading4(heading) click to toggle source
# File lib/pdf/techbook.rb, line 444
def __heading4(heading)
  "<i>#{heading}</i>"
end
__heading5(heading) click to toggle source
# File lib/pdf/techbook.rb, line 447
def __heading5(heading)
  "<c:uline>#{heading}</c:uline>"
end
techbook_parse(document, progress = nil) click to toggle source
# File lib/pdf/techbook.rb, line 517
  def techbook_parse(document, progress = nil)
    @table_of_contents = []

    @toc_title          = "Table of Contents"
    @gen_toc            = false
    @techbook_code      = ""
    @techbook_para      = ""
    @techbook_fontsize  = 12
    @techbook_textopt   = { :justification => :full }
    @techbook_lastmode  = @techbook_mode = :normal

    @techbook_textfont  = "Times-Roman"
    @techbook_codefont  = "Courier"

    @blist_info         = []

    @techbook_line__    = 0

    __build_xref_table(document)

    document.each do |line|
    begin
      progress.inc if progress
      @techbook_line__ += 1

      next if line =~ %{^#}o

      directive, args = techbook_find_directive(line)
      if directive
          # Just try to call the method/directive. It will be far more
          # common to *find* the method than not to.
        res = __send__("techbook_directive_#{directive}", args) rescue nil
        break if :break == res 
        next
      end

      case @techbook_mode
      when :eval
        @techbook_code << line << "\n"
        next
      when :code
        techbook_text(line)
        next
      when :blist
        line = "<C:#{@blist_info[-1][:style]}/>#{line}"
        techbook_text(line)
        next
      end

      next if techbook_heading(line)

      if :preserved == @techbook_mode
        techbook_text(line)
        next
      end

      line.chomp!

      if line.empty?
        __render_paragraph
        techbook_text("\n")
      else
        @techbook_para << " " unless @techbook_para.empty?
        @techbook_para << line
      end
    rescue Exception => ex
      $stderr.puts PDF::Writer::Lang[:techbook_exception] % [ ex, @techbook_line ]
      raise
    end
    end
  end

  def techbook_toc(progress = nil)
    insert_mode :on
    insert_position :after
    insert_page 1
    start_new_page

    style = H1_STYLE
    save_state

    if style[:bar]
      fill_color    style[:background]
      fh = font_height(style[:font_size]) * 1.01
      fd = font_descender(style[:font_size]) * 1.01
      x = absolute_left_margin
      w = absolute_right_margin - absolute_left_margin
      rectangle(x, y - fh + fd, w, fh).fill
    end

    fill_color  style[:foreground]
    text(@toc_title, :font_size => style[:font_size],
         :justification => style[:justification])

    restore_state

    self.y += font_descender(style[:font_size])#* 0.5

    right = absolute_right_margin

      # TODO -- implement tocdots as a replace tag and a single drawing tag.
    @table_of_contents.each do |entry|
      progress.inc if progress

      info =  "<c:ilink dest='#{entry[:xref]}'>#{entry[:title]}</c:ilink>"
      info << "<C:tocdots level='#{entry[:level]}' page='#{entry[:page]}' xref='#{entry[:xref]}'/>"

      case entry[:level]
      when 1
        text info, :font_size => 16, :absolute_right => right
      when 2
        text info, :font_size => 12, :left => 50, :absolute_right => right
      end
    end
  end

  attr_accessor :techbook_codefont
  attr_accessor :techbook_textfont
  attr_accessor :techbook_encoding
  attr_accessor :techbook_fontsize

    # Start a new page: .newpage
  def techbook_directive_newpage(args)
    __render_paragraph

    if args =~ /^force/
      start_new_page true
    else
      start_new_page
    end
  end

    # Preserved newlines: .pre
  def techbook_directive_pre(args)
    __render_paragraph
    @techbook_mode = :preserved
  end

    # End preserved newlines: .endpre
  def techbook_directive_endpre(args)
    @techbook_mode = :normal
  end

    # Code: .code
  def techbook_directive_code(args)
    __render_paragraph
    select_font @techbook_codefont, @techbook_encoding
    @techbook_lastmode, @techbook_mode = @techbook_mode, :code
    @techbook_textopt  = { :justification => :left, :left => 20, :right => 20 }
    @techbook_fontsize = 10
  end

    # End Code: .endcode
  def techbook_directive_endcode(args)
    select_font @techbook_textfont, @techbook_encoding
    @techbook_lastmode, @techbook_mode = @techbook_mode, @techbook_lastmode
    @techbook_textopt  = { :justification => :full }
    @techbook_fontsize = 12
  end

    # Eval: .eval
  def techbook_directive_eval(args)
    __render_paragraph
    @techbook_lastmode, @techbook_mode = @techbook_mode, :eval
  end

    # End Eval: .endeval
  def techbook_directive_endeval(args)
    save_state

    thread = Thread.new do
      begin
        @techbook_code.untaint
        pdf = self
        eval @techbook_code
      rescue Exception => ex
        err = PDF::Writer::Lang[:techbook_eval_exception]
        $stderr.puts err % [ @techbook_line__, ex, ex.backtrace.join("\n") ]
        raise ex
      end
    end
    thread.abort_on_exception = true
    thread.join

    restore_state
    select_font @techbook_textfont, @techbook_encoding

    @techbook_code = ""
    @techbook_mode, @techbook_lastmode = @techbook_lastmode, @techbook_mode
  end

    # Done. Stop parsing: .done
  def techbook_directive_done(args)
    unless @techbook_code.empty?
      $stderr.puts PDF::Writer::Lang[:techbook_code_not_empty]
      $stderr.puts @techbook_code
    end
    __render_paragraph
    :break
  end

    # Columns. .columns <number-of-columns>|off
  def techbook_directive_columns(args)
    av = /^(\d+|off)(?: (\d+))?(?: .*)?$/o.match(args)
    unless av
      $stderr.puts PDF::Writer::Lang[:techbook_bad_columns_directive] % args
      raise ArgumentError
    end
    cols = av.captures[0]

      # Flush the paragraph cache.
    __render_paragraph

    if cols == "off" or cols.to_i < 2
      stop_columns
    else
      if av.captures[1]
        start_columns(cols.to_i, av.captures[1].to_i)
      else
        start_columns(cols.to_i)
      end
    end
  end

  def techbook_directive_toc(args)
    @toc_title  = args unless args.empty?
    @gen_toc    = true
  end

  def techbook_directive_author(args)
    info.author = args
  end
  
  def techbook_directive_title(args)
    info.title  = args
  end

  def techbook_directive_subject(args)
    info.subject  = args
  end

  def techbook_directive_keywords(args)
    info.keywords = args
  end

  LIST_ITEM_STYLES = %w(bullet disc)

  def techbook_directive_blist(args)
    __render_paragraph
    sm = /^(\w+).*$/o.match(args)
    style = sm.captures[0] if sm
    style = "bullet" unless LIST_ITEM_STYLES.include?(style)

    @blist_factor = @left_margin * 0.10 if @blist_info.empty?

    info = {
      :left_margin  => @left_margin,
      :style        => style
    }
    @blist_info << info
    @left_margin += @blist_factor

    @techbook_lastmode, @techbook_mode = @techbook_mode, :blist if :blist != @techbook_mode
  end

  def techbook_directive_endblist(args)
    self.left_margin = @blist_info.pop[:left_margin]
    @techbook_lastmode, @techbook_mode = @techbook_mode, @techbook_lastmode if @blist_info.empty?
  end

  def generate_table_of_contents?
    @gen_toc
  end

  attr_accessor :techbook_source_dir

  def self.run(args)
    config = OpenStruct.new
    config.regen      = false
    config.cache      = true
    config.compressed = false

    opts = OptionParser.new do |opt|
      opt.banner    = PDF::Writer::Lang[:techbook_usage_banner] % [ File.basename($0) ]
      PDF::Writer::Lang[:techbook_usage_banner_1].each do |ll|
        opt.separator "  #{ll}"
      end
      opt.on('-f', '--force-regen', *PDF::Writer::Lang[:techbook_help_force_regen]) { config.regen = true }
      opt.on('-n', '--no-cache', *PDF::Writer::Lang[:techbook_help_no_cache]) { config.cache = false }
      opt.on('-z', '--compress', *PDF::Writer::Lang[:techbook_help_compress]) { config.compressed = true }
      opt.on_tail ""
      opt.on_tail("--help", *PDF::Writer::Lang[:techbook_help_help]) { $stderr << opt; exit(0) }
    end
    opts.parse!(args)

    config.document = args[0]

    unless config.document
      config.document = "manual.pwd"
      unless File.exist?(config.document)
        dirn = File.dirname(__FILE__)
        config.document = File.join(dirn, File.basename(config.document))
        unless File.exist?(config.document)
          dirn = File.join(dirn, "..")
          config.document = File.join(dirn, File.basename(config.document))
          unless File.exist?(config.document)
            dirn = File.join(dirn, "..")
            config.document = File.join(dirn,
                                        File.basename(config.document))
            unless File.exist?(config.document)
              $stderr.puts PDF::Writer::Lang[:techbook_cannot_find_document]
              exit(1)
            end
          end
        end
      end

      $stderr.puts PDF::Writer::Lang[:techbook_using_default_doc] % config.document
    end

    dirn = File.dirname(config.document)
    extn = File.extname(config.document)
    base = File.basename(config.document, extn)

    files = {
      :document => config.document,
      :cache    => "#{base}._mc",
      :pdf      => "#{base}.pdf"
    }

    unless config.regen
      if File.exist?(files[:cache])
        _tm_doc = File.mtime(config.document)
        _tm_prg = File.mtime(__FILE__)
        _tm_cch = File.mtime(files[:cache])
        
          # If the cached file is newer than either the document or the
          # class program, then regenerate.
        if (_tm_doc < _tm_cch) and (_tm_prg < _tm_cch)
          $stderr.puts PDF::Writer::Lang[:techbook_using_cached_doc] % File.basename(files[:cache])
          pdf = File.open(files[:cache], "rb") { |cf| Marshal.load(cf.read) }
          pdf.save_as(files[:pdf])
          File.open(files[:pdf], "wb") { |pf| pf.write pdf.render }
          exit(0)
        else
          $stderr.puts PDF::Writer::Lang[:techbook_regenerating]
        end
      end
    else
      $stderr.puts PDF::Writer::Lang[:techbook_ignoring_cache] if File.exist?(files[:cache])
    end

      # Create the manual object.
    pdf = PDF::TechBook.new
    pdf.compressed = config.compressed
    pdf.techbook_source_dir = File.expand_path(dirn)

    document = open(files[:document]) { |io| io.read.split($/) }
    progress = ProgressBar.new(base.capitalize, document.size)
    pdf.techbook_parse(document, progress)
    progress.finish

    if pdf.generate_table_of_contents?
      progress = ProgressBar.new("TOC", pdf.table_of_contents.size)
      pdf.techbook_toc(progress)
      progress.finish
    end

    if config.cache
      File.open(files[:cache], "wb") { |f| f.write Marshal.dump(pdf) }
    end

    pdf.save_as(files[:pdf])
  end

  def techbook_text(line)
    opt = @techbook_textopt.dup
    opt[:font_size] = @techbook_fontsize
    text(line, opt)
  end

  instance_methods.grep(/^techbook_directive_/).each do |mname|
    private mname.intern
  end
end

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