replace build system with generated table of contents

Gets rid of `doc/README.mdtoc` and its build script. Since GitHub.com renders anchors for each heading, all we have to do is put a simple table of contents into `README.md` itself, and everything will get linked up nicely. Pros of this approach: * We don't have to point out to people not to edit `README.md` anymore * We don't have to run the build script each time README gets edited Cons of this change: * The "chapter" numbers are lost. They were silly anyway. `doc/mdtoc` renders a Markdown table of contents for a Markdown file. `doc/filter-toc` filters that down to only headings after ToC. This script can be used to easily insert ToC into the current document when editing `README.md` with, e.g., Vim: :read !doc/filter-toc %
13 lat temu · da562ad74c
--- a/README.md
+++ b/README.md
@ -39,27 +39,27 @@ tools that do one thing well.

 ## Table of Contents

   * [1 How It Works](#section_1)
   * [2 Installation](#section_2)
      * [2.1 Basic GitHub Checkout](#section_2.1)
         * [2.1.1 Upgrading](#section_2.1.1)
      * [2.2 Homebrew on Mac OS X](#section_2.2)
      * [2.3 Neckbeard Configuration](#section_2.3)
      * [2.4 Uninstalling Ruby Versions](#section_2.4)
   * [3 Usage](#section_3)
      * [3.1 rbenv global](#section_3.1)
      * [3.2 rbenv local](#section_3.2)
      * [3.3 rbenv shell](#section_3.3)
      * [3.4 rbenv versions](#section_3.4)
      * [3.5 rbenv version](#section_3.5)
      * [3.6 rbenv rehash](#section_3.6)
      * [3.7 rbenv which](#section_3.7)
      * [3.8 rbenv whence](#section_3.8)
   * [4 Development](#section_4)
      * [4.1 Version History](#section_4.1)
      * [4.2 License](#section_4.2)

 ## <a name="section_1"></a> 1 How It Works
 * [How It Works](#how-it-works)
 * [Installation](#installation)
  * [Basic GitHub Checkout](#basic-github-checkout)
    * [Upgrading](#upgrading)
  * [Homebrew on Mac OS X](#homebrew-on-mac-os-x)
  * [Neckbeard Configuration](#neckbeard-configuration)
  * [Uninstalling Ruby Versions](#uninstalling-ruby-versions)
 * [Usage](#usage)
  * [rbenv global](#rbenv-global)
  * [rbenv local](#rbenv-local)
  * [rbenv shell](#rbenv-shell)
  * [rbenv versions](#rbenv-versions)
  * [rbenv version](#rbenv-version)
  * [rbenv rehash](#rbenv-rehash)
  * [rbenv which](#rbenv-which)
  * [rbenv whence](#rbenv-whence)
 * [Development](#development)
  * [Version History](#version-history)
  * [License](#license)

 ## How It Works ##

 rbenv operates on the per-user directory `~/.rbenv`. Version names in
 rbenv correspond to subdirectories of `~/.rbenv/versions`. For
@ -79,14 +79,14 @@ and then execute the corresponding binary.
 Because of the simplicity of the shim approach, all you need to use
 rbenv is `~/.rbenv/shims` in your `$PATH`.

 ## <a name="section_2"></a> 2 Installation
 ## Installation ##

 **Compatibility note**: rbenv is _incompatible_ with rvm. Things will
  appear to work until you try to install a gem. The problem is that
  rvm actually overrides the `gem` command with a shell function!
  Please remove any references to rvm before using rbenv.

 ### <a name="section_2.1"></a> 2.1 Basic GitHub Checkout
 ### Basic GitHub Checkout ###

 This will get you going with the latest version of rbenv and make it
 easy to fork and contribute any changes back upstream.
@ -140,7 +140,7 @@ easy to fork and contribute any changes back upstream.

        $ rbenv rehash

 #### <a name="section_2.1.1"></a> 2.1.1 Upgrading
 #### Upgrading ####

 If you've installed rbenv using the instructions above, you can
 upgrade your installation at any time using git.
@ -162,7 +162,7 @@ tag:
    v0.2.0
    $ git checkout v0.2.0

 ### <a name="section_2.2"></a> 2.2 Homebrew on Mac OS X
 ### Homebrew on Mac OS X ###

 You can also install rbenv using the
 [Homebrew](http://mxcl.github.com/homebrew/) package manager on Mac OS
@ -178,7 +178,7 @@ Afterwards you'll still need to add `eval "$(rbenv init -)"` to your
 profile as stated in the caveats. You'll only ever have to do this
 once.

 ### <a name="section_2.3"></a> 2.3 Neckbeard Configuration
 ### Neckbeard Configuration ###

 Skip this section unless you must know what every line in your shell
 profile is doing.
@ -210,7 +210,7 @@ opposed to this idea. Here's what `rbenv init` actually does:
 Run `rbenv init -` for yourself to see exactly what happens under the
 hood.

 ### <a name="section_2.4"></a> 2.4 Uninstalling Ruby Versions
 ### Uninstalling Ruby Versions ###

 As time goes on, ruby versions you install will accumulate in your
 `~/.rbenv/versions` directory.
@ -219,12 +219,12 @@ There is no uninstall or remove command in `rbenv`, so removing old
 versions is a simple matter of `rm -rf` the directory of the relevant
 ruby version you want removed under `~/.rbenv/versions`

 ## <a name="section_3"></a> 3 Usage
 ## Usage ##

 Like `git`, the `rbenv` command delegates to subcommands based on its
 first argument. The most common subcommands are:

 ### <a name="section_3.1"></a> 3.1 rbenv global
 ### rbenv global ###

 Sets the global version of Ruby to be used in all shells by writing
 the version name to the `~/.rbenv/version` file. This version can be
@ -239,7 +239,7 @@ The special version name `system` tells rbenv to use the system Ruby
 When run without a version number, `rbenv global` reports the
 currently configured global version.

 ### <a name="section_3.2"></a> 3.2 rbenv local
 ### rbenv local ###

 Sets a local per-project Ruby version by writing the version name to
 an `.rbenv-version` file in the current directory. This version
@ -254,7 +254,7 @@ configured local version. You can also unset the local version:

    $ rbenv local --unset

 ### <a name="section_3.3"></a> 3.3 rbenv shell
 ### rbenv shell ###

 Sets a shell-specific Ruby version by setting the `RBENV_VERSION`
 environment variable in your shell. This version overrides both
@ -274,7 +274,7 @@ prefer not to use shell integration, you may simply set the

    $ export RBENV_VERSION=jruby-1.7.1

 ### <a name="section_3.4"></a> 3.4 rbenv versions
 ### rbenv versions ###

 Lists all Ruby versions known to rbenv, and shows an asterisk next to
 the currently active version.
@ -287,7 +287,7 @@ the currently active version.
      rbx-1.2.4
      ree-1.8.7-2011.03

 ### <a name="section_3.5"></a> 3.5 rbenv version
 ### rbenv version ###

 Displays the currently active Ruby version, along with information on
 how it was set.
@ -295,7 +295,7 @@ how it was set.
    $ rbenv version
    1.8.7-p352 (set by /Volumes/37signals/basecamp/.rbenv-version)

 ### <a name="section_3.6"></a> 3.6 rbenv rehash
 ### rbenv rehash ###

 Installs shims for all Ruby binaries known to rbenv (i.e.,
 `~/.rbenv/versions/*/bin/*`). Run this command after you install a new
@ -303,7 +303,7 @@ version of Ruby, or install a gem that provides binaries.

    $ rbenv rehash

 ### <a name="section_3.7"></a> 3.7 rbenv which
 ### rbenv which ###

 Displays the full path to the binary that rbenv will execute when you
 run the given command.
@ -311,7 +311,7 @@ run the given command.
    $ rbenv which irb
    /Users/sam/.rbenv/versions/1.9.3-p327/bin/irb

 ### <a name="section_3.8"></a> 3.8 rbenv whence
 ### rbenv whence ###

 Lists all Ruby versions with the given command installed.

@ -320,7 +320,7 @@ Lists all Ruby versions with the given command installed.
    jruby-1.7.1
    ree-1.8.7-2011.03

 ## <a name="section_4"></a> 4 Development
 ## Development ##

 The rbenv source code is [hosted on
 GitHub](https://github.com/sstephenson/rbenv). It's clean, modular,
@ -329,7 +329,7 @@ and easy to understand, even if you're not a shell hacker.
 Please feel free to submit pull requests and file bugs on the [issue
 tracker](https://github.com/sstephenson/rbenv/issues).

 ### <a name="section_4.1"></a> 4.1 Version History
 ### Version History ###

 **0.3.0** (December 25, 2011)

@ -405,7 +405,7 @@ tracker](https://github.com/sstephenson/rbenv/issues).

 * Initial public release.

 ### <a name="section_4.2"></a> 4.2 License
 ### License ###

 (The MIT license)

--- a/doc/README.mdtoc
+++ b/doc/README.mdtoc
@ -1,411 +0,0 @@
 # Simple Ruby Version Management: rbenv

 rbenv lets you easily switch between multiple versions of Ruby. It's
 simple, unobtrusive, and follows the UNIX tradition of single-purpose
 tools that do one thing well.

 <img src="http://i.sstephenson.us/rbenv2.png" width="894" height="464">

 ### rbenv _does…_

 * Let you **change the global Ruby version** on a per-user basis.
 * Provide support for **per-project Ruby versions**.
 * Allow you to **override the Ruby version** with an environment
  variable.

 ### In contrast with rvm, rbenv _does not…_

 * **Need to be loaded into your shell.** Instead, rbenv's shim
    approach works by adding a directory to your `$PATH`.
 * **Override shell commands like `cd`.** That's dangerous and
    error-prone.
 * **Have a configuration file.** There's nothing to configure except
    which version of Ruby you want to use.
 * **Install Ruby.** You can build and install Ruby yourself, or use
    [ruby-build](https://github.com/sstephenson/ruby-build) to
    automate the process.
 * **Manage gemsets.** [Bundler](http://gembundler.com/) is a better
    way to manage application dependencies. If you have projects that
    are not yet using Bundler you can install the
    [rbenv-gemset](https://github.com/jamis/rbenv-gemset) plugin.
 * **Require changes to Ruby libraries for compatibility.** The
    simplicity of rbenv means as long as it's in your `$PATH`,
    [nothing](https://rvm.io/integration/bundler/)
    [else](https://rvm.io/integration/capistrano/)
    needs to know about it.
 * **Prompt you with warnings when you switch to a project.** Instead
    of executing arbitrary code, rbenv reads just the version name
    from each project. There's nothing to "trust."

 ## Table of Contents

 ## How It Works ##

 rbenv operates on the per-user directory `~/.rbenv`. Version names in
 rbenv correspond to subdirectories of `~/.rbenv/versions`. For
 example, you might have `~/.rbenv/versions/1.8.7-p354` and
 `~/.rbenv/versions/1.9.3-p327`.

 Each version is a working tree with its own binaries, like
 `~/.rbenv/versions/1.8.7-p354/bin/ruby` and
 `~/.rbenv/versions/1.9.3-p327/bin/irb`. rbenv makes _shim binaries_
 for every such binary across all installed versions of Ruby.

 These shims are simple wrapper scripts that live in `~/.rbenv/shims`
 and detect which Ruby version you want to use. They insert the
 directory for the selected version at the beginning of your `$PATH`
 and then execute the corresponding binary.

 Because of the simplicity of the shim approach, all you need to use
 rbenv is `~/.rbenv/shims` in your `$PATH`.

 ## Installation ##

 **Compatibility note**: rbenv is _incompatible_ with rvm. Things will
  appear to work until you try to install a gem. The problem is that
  rvm actually overrides the `gem` command with a shell function!
  Please remove any references to rvm before using rbenv.

 ### Basic GitHub Checkout ###

 This will get you going with the latest version of rbenv and make it
 easy to fork and contribute any changes back upstream.

 1. Check out rbenv into `~/.rbenv`.

        $ git clone git://github.com/sstephenson/rbenv.git ~/.rbenv

 2. Add `~/.rbenv/bin` to your `$PATH` for access to the `rbenv`
   command-line utility.

        $ echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bash_profile

    **Zsh note**: Modify your `~/.zshenv` file instead of `~/.bash_profile`.

    **Ubuntu note**: Ubuntu uses `~/.profile` for enabling certain path 
    changes. This file won't be read if you create a `~/.bash_profile`. 
    Therefore, it's recommended that you add this line and the one in 
    point 3 below to your `~/.profile`. This has the added advantage 
    of working under both bash and zsh.

 3. Add rbenv init to your shell to enable shims and autocompletion.

        $ echo 'eval "$(rbenv init -)"' >> ~/.bash_profile

    **Zsh note**: Modify your `~/.zshenv` file instead of `~/.bash_profile`.
    
    **Ubuntu note**: Same as Ubuntu note for point 2 above.

 4. Restart your shell as a login shell so the path changes take effect. 
    You can now begin using rbenv.

        $ exec $SHELL -l

 5. Install Ruby versions into `~/.rbenv/versions`. For example, to
   install Ruby 1.9.3-p327, download and unpack the source, then run:

        $ ./configure --prefix=$HOME/.rbenv/versions/1.9.3-p327
        $ make
        $ make install

    The [ruby-build](https://github.com/sstephenson/ruby-build) project
    provides an `rbenv install` command that simplifies the process of
    installing new Ruby versions to:

        $ rbenv install 1.9.3-p327

 6. Rebuild the shim binaries. You should do this any time you install
   a new Ruby binary (for example, when installing a new Ruby version,
   or when installing a gem that provides a binary).

        $ rbenv rehash

 #### Upgrading ####

 If you've installed rbenv using the instructions above, you can
 upgrade your installation at any time using git.

 To upgrade to the latest development version of rbenv, use `git pull`:

    $ cd ~/.rbenv
    $ git pull

 To upgrade to a specific release of rbenv, check out the corresponding
 tag:

    $ cd ~/.rbenv
    $ git fetch
    $ git tag
    v0.1.0
    v0.1.1
    v0.1.2
    v0.2.0
    $ git checkout v0.2.0

 ### Homebrew on Mac OS X ###

 You can also install rbenv using the
 [Homebrew](http://mxcl.github.com/homebrew/) package manager on Mac OS
 X.

    $ brew update
    $ brew install rbenv
    $ brew install ruby-build

 The same commands can be used for upgrading.

 Afterwards you'll still need to add `eval "$(rbenv init -)"` to your
 profile as stated in the caveats. You'll only ever have to do this
 once.

 ### Neckbeard Configuration ###

 Skip this section unless you must know what every line in your shell
 profile is doing.

 `rbenv init` is the only command that crosses the line of loading
 extra commands into your shell. Coming from rvm, some of you might be
 opposed to this idea. Here's what `rbenv init` actually does:

 1. Sets up your shims path. This is the only requirement for rbenv to
   function properly. You can do this by hand by prepending
   `~/.rbenv/shims` to your `$PATH`.

 2. Installs autocompletion. This is entirely optional but pretty
   useful. Sourcing `~/.rbenv/completions/rbenv.bash` will set that
   up. There is also a `~/.rbenv/completions/rbenv.zsh` for Zsh
   users.

 3. Rehashes shims. From time to time you'll need to rebuild your
   shim files. Doing this on init makes sure everything is up to
   date. You can always run `rbenv rehash` manually.

 4. Installs the sh dispatcher. This bit is also optional, but allows
   rbenv and plugins to change variables in your current shell, making
   commands like `rbenv shell` possible. The sh dispatcher doesn't do
   anything crazy like override `cd` or hack your shell prompt, but if
   for some reason you need `rbenv` to be a real script rather than a
   shell function, you can safely skip it.

 Run `rbenv init -` for yourself to see exactly what happens under the
 hood.

 ### Uninstalling Ruby Versions ###

 As time goes on, ruby versions you install will accumulate in your
 `~/.rbenv/versions` directory.

 There is no uninstall or remove command in `rbenv`, so removing old
 versions is a simple matter of `rm -rf` the directory of the relevant
 ruby version you want removed under `~/.rbenv/versions`

 ## Usage ##

 Like `git`, the `rbenv` command delegates to subcommands based on its
 first argument. The most common subcommands are:

 ### rbenv global ###

 Sets the global version of Ruby to be used in all shells by writing
 the version name to the `~/.rbenv/version` file. This version can be
 overridden by a per-project `.rbenv-version` file, or by setting the
 `RBENV_VERSION` environment variable.

    $ rbenv global 1.9.3-p327

 The special version name `system` tells rbenv to use the system Ruby
 (detected by searching your `$PATH`).

 When run without a version number, `rbenv global` reports the
 currently configured global version.

 ### rbenv local ###

 Sets a local per-project Ruby version by writing the version name to
 an `.rbenv-version` file in the current directory. This version
 overrides the global, and can be overridden itself by setting the
 `RBENV_VERSION` environment variable or with the `rbenv shell`
 command.

    $ rbenv local rbx-1.2.4

 When run without a version number, `rbenv local` reports the currently
 configured local version. You can also unset the local version:

    $ rbenv local --unset

 ### rbenv shell ###

 Sets a shell-specific Ruby version by setting the `RBENV_VERSION`
 environment variable in your shell. This version overrides both
 project-specific versions and the global version.

    $ rbenv shell jruby-1.7.1

 When run without a version number, `rbenv shell` reports the current
 value of `RBENV_VERSION`. You can also unset the shell version:

    $ rbenv shell --unset

 Note that you'll need rbenv's shell integration enabled (step 3 of
 the installation instructions) in order to use this command. If you
 prefer not to use shell integration, you may simply set the
 `RBENV_VERSION` variable yourself:

    $ export RBENV_VERSION=jruby-1.7.1

 ### rbenv versions ###

 Lists all Ruby versions known to rbenv, and shows an asterisk next to
 the currently active version.

    $ rbenv versions
      1.8.7-p352
      1.9.2-p290
    * 1.9.3-p327 (set by /Users/sam/.rbenv/global)
      jruby-1.7.1
      rbx-1.2.4
      ree-1.8.7-2011.03

 ### rbenv version ###

 Displays the currently active Ruby version, along with information on
 how it was set.

    $ rbenv version
    1.8.7-p352 (set by /Volumes/37signals/basecamp/.rbenv-version)

 ### rbenv rehash ###

 Installs shims for all Ruby binaries known to rbenv (i.e.,
 `~/.rbenv/versions/*/bin/*`). Run this command after you install a new
 version of Ruby, or install a gem that provides binaries.

    $ rbenv rehash

 ### rbenv which ###

 Displays the full path to the binary that rbenv will execute when you
 run the given command.

    $ rbenv which irb
    /Users/sam/.rbenv/versions/1.9.3-p327/bin/irb

 ### rbenv whence ###

 Lists all Ruby versions with the given command installed.

    $ rbenv whence rackup
    1.9.3-p327
    jruby-1.7.1
    ree-1.8.7-2011.03

 ## Development ##

 The rbenv source code is [hosted on
 GitHub](https://github.com/sstephenson/rbenv). It's clean, modular,
 and easy to understand, even if you're not a shell hacker.

 Please feel free to submit pull requests and file bugs on the [issue
 tracker](https://github.com/sstephenson/rbenv/issues).

 ### Version History ###

 **0.3.0** (December 25, 2011)

 * Added an `rbenv root` command which prints the value of
  `$RBENV_ROOT`, or the default root directory if it's unset.
 * Clarified Zsh installation instructions in the readme.
 * Removed some redundant code in `rbenv rehash`.
 * Fixed an issue with calling `readlink` for paths with spaces.
 * Changed Zsh initialization code to install completion hooks only for
  interactive shells.
 * Added preliminary support for ksh.
 * `rbenv rehash` creates or removes shims only when necessary instead
  of removing and re-creating all shims on each invocation.
 * Fixed that `RBENV_DIR`, when specified, would be incorrectly
  expanded to its parent directory.
 * Removed the deprecated `set-default` and `set-local` commands.
 * Added a `--no-rehash` option to `rbenv init` for skipping the
  automatic rehash when opening a new shell.

 **0.2.1** (October 1, 2011)

 * Changed the `rbenv` command to ensure that `RBENV_DIR` is always an
  absolute path. This fixes an issue where Ruby scripts using the
  `ruby-local-exec` wrapper would go into an infinite loop when
  invoked with a relative path from the command line.

 **0.2.0** (September 28, 2011)

 * Renamed `rbenv set-default` to `rbenv global` and `rbenv set-local`
  to `rbenv local`. The `set-` commands are deprecated and will be
  removed in the next major release.
 * rbenv now uses `greadlink` on Solaris.
 * Added a `ruby-local-exec` command which can be used in shebangs in
  place of `#!/usr/bin/env ruby` to properly set the project-specific
  Ruby version regardless of current working directory.
 * Fixed an issue with `rbenv rehash` when no binaries are present.
 * Added support for `rbenv-sh-*` commands, which run inside the
  current shell instead of in a child process.
 * Added an `rbenv shell` command for conveniently setting the
  `$RBENV_VERSION` environment variable.
 * Added support for storing rbenv versions and shims in directories
  other than `~/.rbenv` with the `$RBENV_ROOT` environment variable.
 * Added support for debugging rbenv via `set -x` when the
  `$RBENV_DEBUG` environment variable is set.
 * Refactored the autocompletion system so that completions are now
  built-in to each command and shared between bash and Zsh.
 * Added support for plugin bundles in `~/.rbenv/plugins` as documented
  in [issue #102](https://github.com/sstephenson/rbenv/pull/102).
 * Added `/usr/local/etc/rbenv.d` to the list of directories searched
  for rbenv hooks.
 * Added support for an `$RBENV_DIR` environment variable which
  defaults to the current working directory for specifying where rbenv
  searches for local version files.

 **0.1.2** (August 16, 2011)

 * Fixed rbenv to be more resilient against nonexistent entries in
  `$PATH`.
 * Made the `rbenv rehash` command operate atomically.
 * Modified the `rbenv init` script to automatically run `rbenv
  rehash` so that shims are recreated whenever a new shell is opened.
 * Added initial support for Zsh autocompletion.
 * Removed the dependency on egrep for reading version files.

 **0.1.1** (August 14, 2011)

 * Fixed a syntax error in the `rbenv help` command.
 * Removed `-e` from the shebang in favor of `set -e` at the top of
  each file for compatibility with operating systems that do not
  support more than one argument in the shebang.

 **0.1.0** (August 11, 2011)

 * Initial public release.

 ### License ###

 (The MIT license)

 Copyright (c) 2011 Sam Stephenson

 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
 "Software"), to deal in the Software without restriction, including
 without limitation the rights to use, copy, modify, merge, publish,
 distribute, sublicense, and/or sell copies of the Software, and to
 permit persons to whom the Software is furnished to do so, subject to
 the following conditions:

 The above copyright notice and this permission notice shall be
 included in all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--- a/doc/build
+++ b/doc/build
@ -1,4 +0,0 @@
 #!/bin/sh -e

 ruby mdtoc.rb README.mdtoc > ../README.md

--- a/doc/filter-toc
+++ b/doc/filter-toc
@ -0,0 +1,4 @@
 #!/bin/bash
 # Render Markdown ToC with only headings appearing after "Table of Contents"
 dir="$(dirname "$0")"
 "$dir"/mdtoc "$1" | sed -n '/table-of-contents/,$p' | grep -v table-of-contents
--- a/doc/mdtoc
+++ b/doc/mdtoc
@ -0,0 +1,33 @@
 #!/usr/bin/env ruby
 require 'escape_utils'

 start_at_level = 2

 headers = Hash.new(0)

 anchor = lambda { |title|
  href = title.downcase
  href.gsub!(/[^\w\- ]/, '') # remove punctuation
  href.gsub!(' ', '-') # replace spaces with dash
  href = EscapeUtils.escape_uri(href) # escape extended UTF-8 chars

  uniq = (headers[href] > 0) ? "-#{headers[href]}" : ''
  headers[href] += 1

  href + uniq
 }

 ARGF.each_line do |line|
  if line =~ /^(#+) (.+?)#*$/
    level = $1.size
    next if level < start_at_level
    title = $2.strip
    href  = anchor.call title

    puts "%s* [%s](#%s)" % [
      '  ' * (level - start_at_level),
      title,
      href
    ]
  end
 end
--- a/doc/mdtoc.rb
+++ b/doc/mdtoc.rb
@ -1,82 +0,0 @@
 #!/usr/bin/env ruby

 # A little Markdown filter that scans your document for headings,
 # numbers them, adds anchors, and inserts a table of contents.
 #
 # To use it, make sure the headings you want numbered and linked are
 # in this format:
 #
 #     ### Title ###
 #
 # I.e. they must have an equal number of octothorpes around the title
 # text. (In Markdown, `#` means `h1`, `##` means `h2`, and so on.)
 # The table of contents will be inserted before the first such
 # heading.
 #
 # Released into the public domain.
 # Sam Stephenson <sstephenson@gmail.com>
 # 2011-04-30

 def mdtoc(markdown)
  titles = []
  lines = markdown.split($/)
  start = nil

  # First pass: Scan the Markdown source looking for titles of the
  # format: `### Title ###`. Record the line number, header level
  # (number of octothorpes), and text of each matching title.
  lines.each_with_index do |line, line_no|
    if line.match(/^(\#{1,6})\s+(.+?)\s+\1$/)
      titles << [line_no, $1.length, $2]
      start ||= line_no
    end
  end

  last_section = nil
  last_level = nil

  # Second pass: Iterate over all matched titles and compute their
  # corresponding section numbers. Then replace the titles with
  # annotated anchors.
  titles.each do |title_info|
    line_no, level, text = title_info

    if last_section
      section = last_section.dup

      if last_level < level
        section << 1
      else
        (last_level - level).times { section.pop }
        section[-1] += 1
      end
    else
      section = [1]
    end

    name = section.join(".")
    lines[line_no] = %(#{"#" * level} <a name="section_#{name}"></a> #{name} #{text})

    title_info << section
    last_section = section
    last_level = level
  end

  # Third pass: Iterate over matched titles once more to produce the
  # table of contents. Then insert it immediately above the first
  # matched title.
  if start
    toc = titles.map do |(line_no, level, text, section)|
      name = section.join(".")
      %(#{" " * (section.length * 3)}* [#{name} #{text}](#section_#{name}))
    end + [""]

    lines.insert(start, *toc)
  end

  lines.join("\n")
 end

 if __FILE__ == $0
  puts mdtoc($<.read)
 end