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RDoc::Parser::C

We attempt to parse C extension files. Basically we look for the standard patterns that you find in extensions: rb_define_class, rb_define_method and so on. We also try to find the corresponding C source for the methods and extract comments, but if we fail we don’t worry too much.

The comments associated with a Ruby method are extracted from the C comment block associated with the routine that implements that method, that is to say the method whose name is given in the rb_define_method call. For example, you might write:

  Returns a new array that is a one-dimensional flattening of this
  array (recursively). That is, for every element that is an array,
  extract its elements into the new array.

     s = [ 1, 2, 3 ]           #=> [1, 2, 3]
     t = [ 4, 5, 6, [7, 8] ]   #=> [4, 5, 6, [7, 8]]
     a = [ s, t, 9, 10 ]       #=> [[1, 2, 3], [4, 5, 6, [7, 8]], 9, 10]
     a.flatten                 #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

static VALUE
rb_ary_flatten(ary)
    VALUE ary;
{
    ary = rb_obj_dup(ary);
    rb_ary_flatten_bang(ary);
    return ary;
}

...

void
Init_Array()
{
  ...
  rb_define_method(rb_cArray, "flatten", rb_ary_flatten, 0);

Here RDoc will determine from the rb_define_method line that there’s a method called “flatten” in class Array, and will look for the implementation in the method rb_ary_flatten. It will then use the comment from that method in the HTML output. This method must be in the same source file as the rb_define_method.

C classes can be diagrammed (see /tc/dl/ruby/ruby/error.c), and RDoc integrates C and Ruby source into one tree

The comment blocks may include special directives:

Document-class: name

This comment block is documentation for the given class. Use this when the Init_xxx method is not named after the class.

Document-method: name

This comment documents the named method. Use when RDoc cannot automatically find the method from it’s declaration

call-seq: text up to an empty line

Because C source doesn’t give descripive names to Ruby-level parameters, you need to document the calling sequence explicitly

In addition, RDoc assumes by default that the C method implementing a Ruby function is in the same source file as the rb_define_method call. If this isn’t the case, add the comment:

rb_define_method(....);  // in: filename

As an example, we might have an extension that defines multiple classes in its Init_xxx method. We could document them using

   Document-class:  MyClass

   Encapsulate the writing and reading of the configuration
   file. ...

/*

   call-seq:
     cfg.read_value(key)            -> value
     cfg.read_value(key} { |key| }  -> value

   Return the value corresponding to +key+ from the configuration.
   In the second form, if the key isn't found, invoke the
   block and return its value.
  /

Public Class Methods

new(top_level, file_name, content, options, stats) click to toggle source

Prepare to parse a C file

 
               # File rdoc/parser/c.rb, line 105
def initialize(top_level, file_name, content, options, stats)
  super

  @known_classes = RDoc::KNOWN_CLASSES.dup
  @content = handle_tab_width handle_ifdefs_in(@content)
  @classes = Hash.new
  @file_dir = File.dirname(@file_name)
end
            

Public Instance Methods

do_aliases() click to toggle source
 
               # File rdoc/parser/c.rb, line 114
def do_aliases
  @content.scan(%r{rb_define_alias\s*\(\s*(\w+),\s*"([^"]+)",\s*"([^"]+)"\s*\)}m) do
    |var_name, new_name, old_name|
    class_name = @known_classes[var_name] || var_name
    class_obj  = find_class(var_name, class_name)

    as = class_obj.add_alias RDoc::Alias.new("", old_name, new_name, "")

    @stats.add_alias as
  end
end
            
do_classes() click to toggle source
 
               # File rdoc/parser/c.rb, line 126
def do_classes
  @content.scan(/(\w+)\s* = \s*rb_define_module\s*\(\s*"(\w+)"\s*\)/mx) do 
    |var_name, class_name|
    handle_class_module(var_name, "module", class_name, nil, nil)
  end

  # The '.' lets us handle SWIG-generated files
  @content.scan(/([\w\.]+)\s* = \s*rb_define_class\s*
            \(
               \s*"(\w+)",
               \s*(\w+)\s*
            \)/mx) do |var_name, class_name, parent|
    handle_class_module(var_name, "class", class_name, parent, nil)
  end

  @content.scan(/(\w+)\s*=\s*boot_defclass\s*\(\s*"(\w+?)",\s*(\w+?)\s*\)/) do
    |var_name, class_name, parent|
    parent = nil if parent == "0"
    handle_class_module(var_name, "class", class_name, parent, nil)
  end

  @content.scan(/(\w+)\s* = \s*rb_define_module_under\s*
            \(
               \s*(\w+),
               \s*"(\w+)"
            \s*\)/mx) do |var_name, in_module, class_name|
    handle_class_module(var_name, "module", class_name, nil, in_module)
  end

  @content.scan(/([\w\.]+)\s* = \s*rb_define_class_under\s*
            \(
               \s*(\w+),
               \s*"(\w+)",
               \s*([\w\*\s\(\)\.\->]+)\s*  # for SWIG
            \s*\)/mx) do |var_name, in_module, class_name, parent|
    handle_class_module(var_name, "class", class_name, parent, in_module)
  end
end
            
do_constants() click to toggle source
 
               # File rdoc/parser/c.rb, line 165
def do_constants
  @content.scan(%r{\Wrb_define_
                 (
                    variable |
                    readonly_variable |
                    const |
                    global_const |
                  )
             \s*\(
               (?:\s*(\w+),)?
               \s*"(\w+)",
               \s*(.*?)\s*\)\s*;
               }xm) do |type, var_name, const_name, definition|
    var_name = "rb_cObject" if !var_name or var_name == "rb_mKernel"
    handle_constants(type, var_name, const_name, definition)
  end
end
            
do_includes() click to toggle source

Look for includes of the form:

rb_include_module(rb_cArray, rb_mEnumerable);
 
               # File rdoc/parser/c.rb, line 188
def do_includes
  @content.scan(/rb_include_module\s*\(\s*(\w+?),\s*(\w+?)\s*\)/) do |c,m|
    if cls = @classes[c]
      m = @known_classes[m] || m
      cls.add_include RDoc::Include.new(m, "")
    end
  end
end
            
do_methods() click to toggle source
 
               # File rdoc/parser/c.rb, line 197
def do_methods
  @content.scan(%r{rb_define_
                 (
                    singleton_method |
                    method           |
                    module_function  |
                    private_method
                 )
                 \s*\(\s*([\w\.]+),
                   \s*"([^"]+)",
                   \s*(?:RUBY_METHOD_FUNC\(|VALUEFUNC\()?(\w+)\)?,
                   \s*(-?\w+)\s*\)
                 (?:;\s*/[*/]\s+in\s+(\w+?\.[cy]))?
               }xm) do
    |type, var_name, meth_name, meth_body, param_count, source_file|

    # Ignore top-object and weird struct.c dynamic stuff
    next if var_name == "ruby_top_self"
    next if var_name == "nstr"
    next if var_name == "envtbl"
    next if var_name == "argf"   # it'd be nice to handle this one

    var_name = "rb_cObject" if var_name == "rb_mKernel"
    handle_method(type, var_name, meth_name,
                  meth_body, param_count, source_file)
  end

  @content.scan(%r{rb_define_attr\(
                           \s*([\w\.]+),
                           \s*"([^"]+)",
                           \s*(\d+),
                           \s*(\d+)\s*\);
              }xm) do |var_name, attr_name, attr_reader, attr_writer|
    #var_name = "rb_cObject" if var_name == "rb_mKernel"
    handle_attr(var_name, attr_name,
                attr_reader.to_i != 0,
                attr_writer.to_i != 0)
  end

  @content.scan(%r{rb_define_global_function\s*\(
                           \s*"([^"]+)",
                           \s*(?:RUBY_METHOD_FUNC\(|VALUEFUNC\()?(\w+)\)?,
                           \s*(-?\w+)\s*\)
              (?:;\s*/[*/]\s+in\s+(\w+?\.[cy]))?
              }xm) do |meth_name, meth_body, param_count, source_file|
    handle_method("method", "rb_mKernel", meth_name,
                  meth_body, param_count, source_file)
  end

  @content.scan(/define_filetest_function\s*\(
                           \s*"([^"]+)",
                           \s*(?:RUBY_METHOD_FUNC\(|VALUEFUNC\()?(\w+)\)?,
                           \s*(-?\w+)\s*\)/xm) do
    |meth_name, meth_body, param_count|

    handle_method("method", "rb_mFileTest", meth_name, meth_body, param_count)
    handle_method("singleton_method", "rb_cFile", meth_name, meth_body, param_count)
  end
end
            
find_attr_comment(attr_name) click to toggle source
 
               # File rdoc/parser/c.rb, line 257
def find_attr_comment(attr_name)
  if @content =~ %r{((?>/\*.*?\*/\s+))
                 rb_define_attr\((?:\s*(\w+),)?\s*"#{attr_name}"\s*,.*?\)\s*;}xmi
    $1
  elsif @content =~ %r{Document-attr:\s#{attr_name}\s*?\n((?>.*?\*/))}m
    $1
  else
    ''
  end
end
            
find_body(class_name, meth_name, meth_obj, body, quiet = false) click to toggle source

Find the C code corresponding to a Ruby method

 
               # File rdoc/parser/c.rb, line 271
  def find_body(class_name, meth_name, meth_obj, body, quiet = false)
    case body
    when %r((?>/\*.*?\*/\s*))(?:(?:static|SWIGINTERN)\s+)?(?:intern\s+)?VALUE\s+#{meth_name}
            \s*(\([^)]*\))([^;]|$)"xm
      comment, params = $1, $2
      body_text = $&

      remove_private_comments(comment) if comment

      # see if we can find the whole body

      re = Regexp.escape(body_text) + '[^(]*^\{.*?^\}'
      body_text = $& if /#{re}/m =~ body

      # The comment block may have been overridden with a 'Document-method'
      # block. This happens in the interpreter when multiple methods are
      # vectored through to the same C method but those methods are logically
      # distinct (for example Kernel.hash and Kernel.object_id share the same
      # implementation

      override_comment = find_override_comment(class_name, meth_obj.name)
      comment = override_comment if override_comment

      find_modifiers(comment, meth_obj) if comment

#        meth_obj.params = params
      meth_obj.start_collecting_tokens
      meth_obj.add_token(RDoc::RubyToken::Token.new(1,1).set_text(body_text))
      meth_obj.comment = mangle_comment(comment)
    when %r{((?>/\*.*?\*/\s*))^\s*\#\s*define\s+#{meth_name}\s+(\w+)}m
      comment = $1
      find_body(class_name, $2, meth_obj, body, true)
      find_modifiers(comment, meth_obj)
      meth_obj.comment = mangle_comment(comment) + meth_obj.comment
    when %r{^\s*\#\s*define\s+#{meth_name}\s+(\w+)}m
      unless find_body(class_name, $1, meth_obj, body, true)
        warn "No definition for #{meth_name}" unless @options.quiet
        return false
      end
    else

      # No body, but might still have an override comment
      comment = find_override_comment(class_name, meth_obj.name)

      if comment
        find_modifiers(comment, meth_obj)
        meth_obj.comment = mangle_comment(comment)
      else
        warn "No definition for #{meth_name}" unless @options.quiet
        return false
      end
    end
    true
  end
            
find_class(raw_name, name) click to toggle source
 
               # File rdoc/parser/c.rb, line 326
def find_class(raw_name, name)
  unless @classes[raw_name]
    if raw_name =~ /^rb_m/
      container = @top_level.add_module RDoc::NormalModule, name
    else
      container = @top_level.add_class RDoc::NormalClass, name, nil
    end

    container.record_location @top_level
    @classes[raw_name] = container
  end
  @classes[raw_name]
end
            
find_class_comment(class_name, class_meth) click to toggle source

Look for class or module documentation above Init_+class_name+(void), in a Document-class class_name (or module) comment or above an rb_define_class (or module). If a comment is supplied above a matching Init_ and a rb_define_class the Init_ comment is used.

   This is a comment for Foo

Init_Foo(void) {
    VALUE cFoo = rb_define_class("Foo", rb_cObject);
}

   Document-class: Foo
   This is a comment for Foo

Init_foo(void) {
    VALUE cFoo = rb_define_class("Foo", rb_cObject);
}

/*
   This is a comment for Foo
  /
VALUE cFoo = rb_define_class("Foo", rb_cObject);
 
               # File rdoc/parser/c.rb, line 366
def find_class_comment(class_name, class_meth)
  comment = nil
  if @content =~ %r{((?>/\*.*?\*/\s+))
                 (static\s+)?void\s+Init_#{class_name}\s*(?:_\(\s*)?\(\s*(?:void\s*)\)}xmi then
    comment = $1
  elsif @content =~ %r{Document-(?:class|module):\s#{class_name}\s*?(?:<\s+[:,\w]+)?\n((?>.*?\*/))}m
    comment = $1
  else
    if @content =~ /rb_define_(class|module)/m then
      class_name = class_name.split("::").last
      comments = []
      @content.split(/(\/\*.*?\*\/)\s*?\n/m).each_with_index do |chunk, index|
        comments[index] = chunk
        if chunk =~ /rb_define_(class|module).*?"(#{class_name})"/m then
          comment = comments[index-1]
          break
        end
      end
    end
  end
  class_meth.comment = mangle_comment(comment) if comment
end
            
find_const_comment(type, const_name) click to toggle source

Finds a comment matching type and const_name either above the comment or in the matching Document- section.

 
               # File rdoc/parser/c.rb, line 393
def find_const_comment(type, const_name)
  if @content =~ %r{((?>^\s*/\*.*?\*/\s+))
                 rb_define_#{type}\((?:\s*(\w+),)?\s*"#{const_name}"\s*,.*?\)\s*;}xmi
    $1
  elsif @content =~ %r{Document-(?:const|global|variable):\s#{const_name}\s*?\n((?>.*?\*/))}m
    $1
  else
    ''
  end
end
            
new click to toggle source
new(10)

If the comment block contains a section that looks like:

use it for the parameters.

 
               # File rdoc/parser/c.rb, line 413
def find_modifiers(comment, meth_obj)
  if comment.sub!(/:nodoc:\s*^\s*\*?\s*$/m, '') or
     comment.sub!(/\A\/\*\s*:nodoc:\s*\*\/\Z/, '')
    meth_obj.document_self = false
  end
  if comment.sub!(/call-seq:(.*?)^\s*\*?\s*$/m, '') or
     comment.sub!(/\A\/\*\s*call-seq:(.*?)\*\/\Z/, '')
    seq = $1
    seq.gsub!(/^\s*\*\s*/, '')
    meth_obj.call_seq = seq
  end
end
            
find_override_comment(class_name, meth_name) click to toggle source
 
               # File rdoc/parser/c.rb, line 426
def find_override_comment(class_name, meth_name)
  name = Regexp.escape(meth_name)
  if @content =~ %r{Document-method:\s+#{class_name}(?:\.|::|#)#{name}\s*?\n((?>.*?\*/))}m then
    $1
  elsif @content =~ %r{Document-method:\s#{name}\s*?\n((?>.*?\*/))}m then
    $1
  end
end
            
handle_attr(var_name, attr_name, reader, writer) click to toggle source
 
               # File rdoc/parser/c.rb, line 435
def handle_attr(var_name, attr_name, reader, writer)
  rw = ''
  if reader
    #@stats.num_methods += 1
    rw << 'R'
  end
  if writer
    #@stats.num_methods += 1
    rw << 'W'
  end

  class_name = @known_classes[var_name]

  return unless class_name

  class_obj  = find_class(var_name, class_name)

  if class_obj
    comment = find_attr_comment(attr_name)
    unless comment.empty?
      comment = mangle_comment(comment)
    end
    att = RDoc::Attr.new '', attr_name, rw, comment
    class_obj.add_attribute(att)
  end
end
            
handle_class_module(var_name, class_mod, class_name, parent, in_module) click to toggle source
 
               # File rdoc/parser/c.rb, line 462
def handle_class_module(var_name, class_mod, class_name, parent, in_module)
  parent_name = @known_classes[parent] || parent

  if in_module
    enclosure = @classes[in_module] || @@enclosure_classes[in_module]
    unless enclosure
      if enclosure = @known_classes[in_module]
        handle_class_module(in_module, (/^rb_m/ =~ in_module ? "module" : "class"),
                            enclosure, nil, nil)
        enclosure = @classes[in_module]
      end
    end
    unless enclosure
      warn("Enclosing class/module '#{in_module}' for " +
            "#{class_mod} #{class_name} not known")
      return
    end
  else
    enclosure = @top_level
  end

  if class_mod == "class" then
    full_name = enclosure.full_name.to_s + "::#{class_name}"
    if @content =~ %r{Document-class:\s+#{full_name}\s*<\s+([:,\w]+)} then
      parent_name = $1
    end
    cm = enclosure.add_class RDoc::NormalClass, class_name, parent_name
    @stats.add_class cm
  else
    cm = enclosure.add_module RDoc::NormalModule, class_name
    @stats.add_module cm
  end

  cm.record_location(enclosure.toplevel)

  find_class_comment(cm.full_name, cm)
  @classes[var_name] = cm
  @@enclosure_classes[var_name] = cm
  @known_classes[var_name] = cm.full_name
end
            
handle_constants(type, var_name, const_name, definition) click to toggle source

Adds constant comments. By providing some_value: at the start ofthe comment you can override the C value of the comment to give a friendly definition.

   300: The perfect score in bowling   
rb_define_const(cFoo, "PERFECT", INT2FIX(300);

Will override +INT2FIX(300)+ with the value 300 in the output RDoc. Values may include quotes and escaped colons (:).

 
               # File rdoc/parser/c.rb, line 514
def handle_constants(type, var_name, const_name, definition)
  #@stats.num_constants += 1
  class_name = @known_classes[var_name]

  return unless class_name

  class_obj  = find_class(var_name, class_name)

  unless class_obj
    warn("Enclosing class/module '#{const_name}' for not known")
    return
  end

  comment = find_const_comment(type, const_name)

  # In the case of rb_define_const, the definition and comment are in
  # "/* definition: comment */" form.  The literal ':' and '\' characters
  # can be escaped with a backslash.
  if type.downcase == 'const' then
     elements = mangle_comment(comment).split(':')
     if elements.nil? or elements.empty? then
        con = RDoc::Constant.new(const_name, definition,
                                 mangle_comment(comment))
     else
        new_definition = elements[0..-2].join(':')
        if new_definition.empty? then # Default to literal C definition
           new_definition = definition
        else
           new_definition.gsub!("\:", ":")
           new_definition.gsub!("\\", '\')
        end
        new_definition.sub!(/\A(\s+)/, '')
        new_comment = $1.nil? ? elements.last : "#{$1}#{elements.last.lstrip}"
        con = RDoc::Constant.new(const_name, new_definition,
                                 mangle_comment(new_comment))
     end
  else
     con = RDoc::Constant.new const_name, definition, mangle_comment(comment)
  end

  class_obj.add_constant(con)
end
            
handle_ifdefs_in(body) click to toggle source

Removes ifdefs that would otherwise confuse us

 
               # File rdoc/parser/c.rb, line 560
def handle_ifdefs_in(body)
  body.gsub(/^#ifdef HAVE_PROTOTYPES.*?#else.*?\n(.*?)#endif.*?\n/m, '\1')
end
            
handle_method(type, var_name, meth_name, meth_body, param_count, source_file = nil) click to toggle source
 
               # File rdoc/parser/c.rb, line 564
def handle_method(type, var_name, meth_name, meth_body, param_count,
                  source_file = nil)
  class_name = @known_classes[var_name]

  return unless class_name

  class_obj = find_class var_name, class_name

  if class_obj then
    if meth_name == "initialize" then
      meth_name = "new"
      type = "singleton_method"
    end

    meth_obj = RDoc::AnyMethod.new '', meth_name
    meth_obj.singleton = %w[singleton_method module_function].include? type

    p_count = (Integer(param_count) rescue -1)

    if p_count < 0
      meth_obj.params = "(...)"
    elsif p_count == 0
      meth_obj.params = "()"
    else
      meth_obj.params = "(" + (1..p_count).map{|i| "p#{i}"}.join(", ") + ")"
    end

    if source_file then
      file_name = File.join(@file_dir, source_file)
      body = (@@known_bodies[source_file] ||= File.read(file_name))
    else
      body = @content
    end

    if find_body(class_name, meth_body, meth_obj, body) and meth_obj.document_self then
      class_obj.add_method meth_obj
      @stats.add_method meth_obj
    end
  end
end
            
handle_tab_width(body) click to toggle source
 
               # File rdoc/parser/c.rb, line 605
def handle_tab_width(body)
  if /\t/ =~ body
    tab_width = @options.tab_width
    body.split(/\n/).map do |line|
      1 while line.gsub!(/\t+/) { ' ' * (tab_width*$&.length - $`.length % tab_width)}  && $~ #`
      line
    end .join("\n")
  else
    body
  end
end
            
mangle_comment(comment) click to toggle source

Remove the /*‘s and leading asterisks from C comments

 
               # File rdoc/parser/c.rb, line 620
def mangle_comment(comment)
  comment.sub!(%r{/\*+}) { " " * $&.length }
  comment.sub!(%r{\*+/}) { " " * $&.length }
  comment.gsub!(/^[ \t]*\*/m) { " " * $&.length }
  comment
end
            
remove_commented_out_lines() click to toggle source

Removes lines that are commented out that might otherwise get picked up when scanning for classes and methods

 
               # File rdoc/parser/c.rb, line 631
def remove_commented_out_lines
  @content.gsub!(%r{//.*rb_define_}, '//')
end
            
remove_private_comments(comment) click to toggle source
 
               # File rdoc/parser/c.rb, line 635
def remove_private_comments(comment)
   comment.gsub!(/\/?\*--\n(.*?)\/?\*\+\+/m, '')
   comment.sub!(/\/?\*--\n.*/m, '')
end
            
scan() click to toggle source

Extract the classes/modules and methods from a C file and return the corresponding top-level object

 
               # File rdoc/parser/c.rb, line 644
def scan
  remove_commented_out_lines
  do_classes
  do_constants
  do_methods
  do_includes
  do_aliases
  @top_level
end
            
warn(msg) click to toggle source
 
               # File rdoc/parser/c.rb, line 654
def warn(msg)
  $stderr.puts
  $stderr.puts msg
  $stderr.flush
end
            

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