* lib/pp.rb, lib/prettyprint.rb: Documentation for PP and PrettyPrint

  Based on a patch by Vincent Batts [ruby-core:51253] [Bug #7656]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39180 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 256 insertions, 45 deletions

diff --git a/ChangeLog b/ChangeLog
index 006cf5d6b8..5d6a03c4ea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Feb  10 09:10:00 2013  Zachary Scott  <zachary@zacharyscott.net>
+
+	* lib/pp.rb, lib/prettyprint.rb: Documentation for PP and PrettyPrint
+	  Based on a patch by Vincent Batts [ruby-core:51253] [Bug #7656]
+
 Sat Feb  9 21:11:21 2013  Tanaka Akira  <akr@fsij.org>
 
 	* configure.in: move header files check to the beginning of
diff --git a/lib/pp.rb b/lib/pp.rb
index 6e0c797d2e..134991bd71 100644
--- a/lib/pp.rb
+++ b/lib/pp.rb
@@ -1,7 +1,13 @@
 require 'prettyprint'
 
 module Kernel
-  # returns a pretty printed object as a string.
+  # Returns a pretty printed object as a string.
+  #
+  # In order to use this method you must first require the PP module:
+  #
+  #   require 'pp'
+  #
+  # See the PP module for more information.
   def pretty_inspect
     PP.pp(self, '')
   end
@@ -10,23 +16,23 @@ module Kernel
   # prints arguments in pretty form.
   #
   # pp returns argument(s).
-  def pp(*objs) # :doc:
+  def pp(*objs) # :nodoc:
     objs.each {|obj|
       PP.pp(obj)
     }
     objs.size <= 1 ? objs.first : objs
   end
-  module_function :pp
+  module_function :pp # :nodoc:
 end
 
-# == Pretty-printer for Ruby objects.
+# Pretty-printer for Ruby objects.
 #
-# = Which seems better?
+# == Which seems better?
 #
-# non-pretty-printed output by #p is:
+# Standard output by #p like this?
 #   #<PP:0x81fedf0 @genspace=#<Proc:0x81feda0>, @group_queue=#<PrettyPrint::GroupQueue:0x81fed3c @queue=[[#<PrettyPrint::Group:0x81fed78 @breakables=[], @depth=0, @break=false>], []]>, @buffer=[], @newline="\n", @group_stack=[#<PrettyPrint::Group:0x81fed78 @breakables=[], @depth=0, @break=false>], @buffer_width=0, @indent=0, @maxwidth=79, @output_width=2, @output=#<IO:0x8114ee4>>
 #
-# pretty-printed output by #pp is:
+# Or the pretty-printed version:
 #   #<PP:0x81fedf0
 #    @buffer=[],
 #    @buffer_width=0,
@@ -46,25 +52,27 @@ end
 #
 # I like the latter.  If you do too, this library is for you.
 #
-# = Usage
+# == Usage
 #
 #   pp(obj)             #=> obj
 #   pp(obj1, obj2, ...) #=> [obj1, obj2, ...]
 #   pp()                #=> nil
 #
-# output +obj(s)+ to +$>+ in pretty printed format.
+# Output <tt>obj(s)</tt> to <tt>$></tt> in pretty printed format.
 #
-# It returns +obj(s)+.
+# It returns <tt>obj(s)</tt>.
 #
 # = Output Customization
+#
 # To define your customized pretty printing function for your classes,
 # redefine a method #pretty_print(+pp+) in the class.
+#
 # It takes an argument +pp+ which is an instance of the class PP.
-# The method should use PP#text, PP#breakable, PP#nest, PP#group and
-# PP#pp to print the object.
+# The method should use #text, #breakable, #nest, #group and #pp to print the
+# object.
 #
 # = Author
-# Tanaka Akira <akr@m17n.org>
+# Tanaka Akira <akr@fsij.org>
 class PP < PrettyPrint
   # Outputs +obj+ to +out+ in pretty printed format of
   # +width+ columns in width.
@@ -106,6 +114,9 @@ class PP < PrettyPrint
   end
 
   module PPMethods
+
+    # Yields to a block
+    # and preserves the previous set of objects being printed.
     def guard_inspect_key
       if Thread.current[:__recursive_key__] == nil
         Thread.current[:__recursive_key__] = {}.untrust
@@ -125,14 +136,22 @@ class PP < PrettyPrint
       end
     end
 
+    # Check whether the object_id +id+ is in the current buffer of objects
+    # to be pretty printed. Used to break cycles in chains of objects to be
+    # pretty printed.
     def check_inspect_key(id)
       Thread.current[:__recursive_key__] &&
       Thread.current[:__recursive_key__][:inspect] &&
       Thread.current[:__recursive_key__][:inspect].include?(id)
     end
+
+    # Adds the object_id +id+ to the set of objects being pretty printed, so
+    # as to not repeat objects.
     def push_inspect_key(id)
       Thread.current[:__recursive_key__][:inspect][id] = true
     end
+
+    # Removes an object from the set of objects being pretty printed.
     def pop_inspect_key(id)
       Thread.current[:__recursive_key__][:inspect].delete id
     end
@@ -165,15 +184,19 @@ class PP < PrettyPrint
       group(1, '#<' + obj.class.name, '>', &block)
     end
 
+    # A mask used in formating object_id's into a hexadecimal id
     PointerMask = (1 << ([""].pack("p").size * 8)) - 1
 
     case Object.new.inspect
     when /\A\#<Object:0x([0-9a-f]+)>\z/
+      # String Formating for hexadecimal id
       PointerFormat = "%0#{$1.length}x"
     else
       PointerFormat = "%x"
     end
 
+    # A convenience method, like object_group, but also reformats the Object's
+    # object_id.
     def object_address_group(obj, &block)
       id = PointerFormat % (obj.object_id * 2 & PointerMask)
       group(1, "\#<#{obj.class}:0x#{id}", '>', &block)
@@ -225,6 +248,7 @@ class PP < PrettyPrint
       }
     end
 
+    # A present standard failsafe for pretty printing any given Object
     def pp_object(obj)
       object_address_group(obj) {
         seplist(obj.pretty_print_instance_variables, lambda { text ',' }) {|v|
@@ -240,6 +264,7 @@ class PP < PrettyPrint
       }
     end
 
+    # A pretty print for a Hash
     def pp_hash(obj)
       group(1, '{', '}') {
         seplist(obj, nil, :each_pair) {|k, v|
@@ -258,7 +283,7 @@ class PP < PrettyPrint
 
   include PPMethods
 
-  class SingleLine < PrettyPrint::SingleLine
+  class SingleLine < PrettyPrint::SingleLine # :nodoc:
     include PPMethods
   end
 
@@ -324,8 +349,8 @@ class PP < PrettyPrint
   end
 end
 
-class Array
-  def pretty_print(q)
+class Array # :nodoc:
+  def pretty_print(q) # :nodoc:
     q.group(1, '[', ']') {
       q.seplist(self) {|v|
         q.pp v
@@ -333,23 +358,23 @@ class Array
     }
   end
 
-  def pretty_print_cycle(q)
+  def pretty_print_cycle(q) # :nodoc:
     q.text(empty? ? '[]' : '[...]')
   end
 end
 
-class Hash
-  def pretty_print(q)
+class Hash # :nodoc:
+  def pretty_print(q) # :nodoc:
     q.pp_hash self
   end
 
-  def pretty_print_cycle(q)
+  def pretty_print_cycle(q) # :nodoc:
     q.text(empty? ? '{}' : '{...}')
   end
 end
 
-class << ENV
-  def pretty_print(q)
+class << ENV # :nodoc:
+  def pretty_print(q) # :nodoc:
     h = {}
     ENV.keys.sort.each {|k|
       h[k] = ENV[k]
@@ -358,8 +383,8 @@ class << ENV
   end
 end
 
-class Struct
-  def pretty_print(q)
+class Struct # :nodoc:
+  def pretty_print(q) # :nodoc:
     q.group(1, sprintf("#<struct %s", PP.mcall(self, Kernel, :class).name), '>') {
       q.seplist(PP.mcall(self, Struct, :members), lambda { q.text "," }) {|member|
         q.breakable
@@ -373,13 +398,13 @@ class Struct
     }
   end
 
-  def pretty_print_cycle(q)
+  def pretty_print_cycle(q) # :nodoc:
     q.text sprintf("#<struct %s:...>", PP.mcall(self, Kernel, :class).name)
   end
 end
 
-class Range
-  def pretty_print(q)
+class Range # :nodoc:
+  def pretty_print(q) # :nodoc:
     q.pp self.begin
     q.breakable ''
     q.text(self.exclude_end? ? '...' : '..')
@@ -388,9 +413,9 @@ class Range
   end
 end
 
-class File < IO
-  class Stat
-    def pretty_print(q)
+class File < IO # :nodoc:
+  class Stat # :nodoc:
+    def pretty_print(q) # :nodoc:
       require 'etc.so'
       q.object_group(self) {
         q.breakable
@@ -470,8 +495,8 @@ class File < IO
   end
 end
 
-class MatchData
-  def pretty_print(q)
+class MatchData # :nodoc:
+  def pretty_print(q) # :nodoc:
     nc = []
     self.regexp.named_captures.each {|name, indexes|
       indexes.each {|i| nc[i] = name }
@@ -495,7 +520,7 @@ class MatchData
   end
 end
 
-class Object < BasicObject
+class Object < BasicObject # :nodoc:
   include PP::ObjectMixin
 end
 
diff --git a/lib/prettyprint.rb b/lib/prettyprint.rb
index 9a90713a4d..eb498cc70a 100644
--- a/lib/prettyprint.rb
+++ b/lib/prettyprint.rb
@@ -17,6 +17,8 @@
 # * Box based formatting?
 # * Other (better) model/algorithm?
 #
+# Report any bugs at http://bugs.ruby-lang.org
+#
 # == References
 # Christian Lindig, Strictly Pretty, March 2000,
 # http://www.st.cs.uni-sb.de/~lindig/papers/#pretty
@@ -25,7 +27,7 @@
 # http://homepages.inf.ed.ac.uk/wadler/topics/language-design.html#prettier
 #
 # == Author
-# Tanaka Akira <akr@m17n.org>
+# Tanaka Akira <akr@fsij.org>
 #
 class PrettyPrint
 
@@ -90,10 +92,64 @@ class PrettyPrint
     @group_queue = GroupQueue.new(root_group)
     @indent = 0
   end
-  attr_reader :output, :maxwidth, :newline, :genspace
-  attr_reader :indent, :group_queue
+
+  # The output object.
+  #
+  # This defaults to '', and should accept the << method
+  attr_reader :output
+
+  # The maximum width of a line, before it is separated in to a newline
+  #
+  # This defaults to 79, and should be a Fixnum
+  attr_reader :maxwidth
+
+  # The value that is appended to +output+ to add a new line.
+  #
+  # This defaults to "\n", and should be String
+  attr_reader :newline
+
+  # A lambda or Proc, that takes one argument, of a Fixnum, and returns
+  # the corresponding number of spaces.
+  #
+  # By default this is:
+  #   lambda {|n| ' ' * n}
+  attr_reader :genspace
+
+  # The number of spaces to be indented
+  attr_reader :indent
+
+  # The PrettyPrint::GroupQueue of groups in stack to be pretty printed
+  attr_reader :group_queue
 
   # Returns the group most recently added to the stack.
+  #
+  # Contrived example:
+  #   out = ""
+  #   => ""
+  #   q = PrettyPrint.new(out)
+  #   => #<PrettyPrint:0x82f85c0 @output="", @maxwidth=79, @newline="\n", @genspace=#<Proc:0x82f8368@/home/vbatts/.rvm/rubies/ruby-head/lib/ruby/2.0.0/prettyprint.rb:82 (lambda)>, @output_width=0, @buffer_width=0, @buffer=[], @group_stack=[#<PrettyPrint::Group:0x82f8138 @depth=0, @breakables=[], @break=false>], @group_queue=#<PrettyPrint::GroupQueue:0x82fb7c0 @queue=[[#<PrettyPrint::Group:0x82f8138 @depth=0, @breakables=[], @break=false>]]>, @indent=0>
+  #   q.group {
+  #     q.text q.current_group.inspect
+  #     q.text q.newline
+  #     q.group(q.current_group.depth + 1) {
+  #       q.text q.current_group.inspect
+  #       q.text q.newline
+  #       q.group(q.current_group.depth + 1) {
+  #         q.text q.current_group.inspect
+  #         q.text q.newline
+  #         q.group(q.current_group.depth + 1) {
+  #           q.text q.current_group.inspect
+  #           q.text q.newline
+  #         }
+  #       }
+  #     }
+  #   }
+  #   => 284
+  #    puts out
+  #   #<PrettyPrint::Group:0x8354758 @depth=1, @breakables=[], @break=false>
+  #   #<PrettyPrint::Group:0x8354550 @depth=2, @breakables=[], @break=false>
+  #   #<PrettyPrint::Group:0x83541cc @depth=3, @breakables=[], @break=false>
+  #   #<PrettyPrint::Group:0x8347e54 @depth=4, @breakables=[], @break=false>
   def current_group
     @group_stack.last
   end
@@ -166,7 +222,7 @@ class PrettyPrint
   # may cause 2 results:
   # (break,break), (non-break,non-break).
   #
-  # The text sep+ is inserted if a line is not broken at this point.
+  # The text +sep+ is inserted if a line is not broken at this point.
   #
   # If +sep+ is not specified, " " is used.
   #
@@ -220,6 +276,7 @@ class PrettyPrint
     text close_obj, close_width
   end
 
+  # Takes a block and queues a new group that is indented 1 level further.
   def group_sub
     group = Group.new(@group_stack.last.depth + 1)
     @group_stack.push group
@@ -256,25 +313,55 @@ class PrettyPrint
     @buffer_width = 0
   end
 
-  class Text
+  # The Text class is the means by which to collect strings from objects.
+  #
+  # This class is intended for internal use of the PrettyPrint buffers.
+  class Text # :nodoc:
+
+    # Creates a new text object.
+    #
+    # This contructor takes no arguments.
+    #
+    # The workflow is to append a PrettyPrint::Text object to the buffer, and
+    # being able to call the buffer.last() to reference it.
+    #
+    # As there are objects, use PrettyPrint::Text#add to include the objects
+    # and the width to utilized by the String version of this object.
     def initialize
       @objs = []
       @width = 0
     end
+
+    # The total width of the objects included in this Text object.
     attr_reader :width
 
+    # Render the String text of the objects that have been added to this Text object.
+    #
+    # Output the text to +out+, and increment the width to +output_width+
     def output(out, output_width)
       @objs.each {|obj| out << obj}
       output_width + @width
     end
 
+    # Include +obj+ in the objects to be pretty printed, and increment
+    # this Text object's total width by +width+
     def add(obj, width)
       @objs << obj
       @width += width
     end
   end
 
-  class Breakable
+  # The Breakable class is used for breaking up object information
+  #
+  # This class is intended for internal use of the PrettyPrint buffers.
+  class Breakable # :nodoc:
+
+    # Create a new Breakable object.
+    #
+    # Arguments:
+    # * +sep+ String of the seperator
+    # * +width+ Fixnum width of the +sep+
+    # * +q+ parent PrettyPrint object, to base from
     def initialize(sep, width, q)
       @obj = sep
       @width = width
@@ -283,8 +370,24 @@ class PrettyPrint
       @group = q.current_group
       @group.breakables.push self
     end
-    attr_reader :obj, :width, :indent
 
+    # Holds the seperator String
+    #
+    # The +sep+ argument from ::new
+    attr_reader :obj
+
+    # The width of +obj+ / +sep+
+    attr_reader :width
+
+    # The number of spaces to indent.
+    #
+    # This is inferred from +q+ within PrettyPrint, passed in ::new
+    attr_reader :indent
+
+    # Render the String text of the objects that have been added to this
+    # Breakable object.
+    #
+    # Output the text to +out+, and increment the width to +output_width+
     def output(out, output_width)
       @group.breakables.shift
       if @group.break?
@@ -299,22 +402,45 @@ class PrettyPrint
     end
   end
 
-  class Group
+  # The Group class is used for making indentation easier.
+  #
+  # While this class does neither the breaking into newlines nor indentation,
+  # it is used in a stack (as well as a queue) within PrettyPrint, to group
+  # objects.
+  #
+  # For information on using groups, see PrettyPrint#group
+  #
+  # This class is intended for internal use of the PrettyPrint buffers.
+  class Group # :nodoc:
+    # Create a Group object
+    #
+    # Arguments:
+    # * +depth+ - this group's relation to previous groups
     def initialize(depth)
       @depth = depth
       @breakables = []
       @break = false
     end
-    attr_reader :depth, :breakables
 
+    # This group's relation to previous groups
+    attr_reader :depth
+
+    # Array to hold the Breakable objects for this Group
+    attr_reader :breakables
+
+    # Makes a break for this Group, and returns true
     def break
       @break = true
     end
 
+    # Boolean of whether this Group has made a break
     def break?
       @break
     end
 
+    # Boolean of whether this Group has been queried for being first
+    #
+    # This is used as a predicate, and ought to be called first.
     def first?
       if defined? @first
         false
@@ -325,18 +451,33 @@ class PrettyPrint
     end
   end
 
-  class GroupQueue
+  # The GroupQueue class is used for managing the queue of Group to be pretty
+  # printed.
+  #
+  # This queue groups the Group objects, based on their depth.
+  #
+  # This class is intended for internal use of the PrettyPrint buffers.
+  class GroupQueue # :nodoc:
+    # Create a GroupQueue object
+    #
+    # Arguments:
+    # * +groups+ - one or more PrettyPrint::Group objects
     def initialize(*groups)
       @queue = []
       groups.each {|g| enq g}
     end
 
+    # Enqueue +group+
+    #
+    # This does not strictly append the group to the end of the queue,
+    # but instead adds it in line, base on the +group.depth+
     def enq(group)
       depth = group.depth
       @queue << [] until depth < @queue.length
       @queue[depth] << group
     end
 
+    # Returns the outer group of the queue
     def deq
       @queue.each {|gs|
         (gs.length-1).downto(0) {|i|
@@ -352,29 +493,67 @@ class PrettyPrint
       return nil
     end
 
+    # Remote +group+ from this queue
     def delete(group)
       @queue[group.depth].delete(group)
     end
   end
 
+  # PrettyPrint::SingleLine is used by PrettyPrint.singleline_format
+  #
+  # It is passed to be similar to a PrettyPrint object itself, by responding to:
+  # * #text
+  # * #breakable
+  # * #nest
+  # * #group
+  # * #flush
+  # * #first?
+  #
+  # but instead, the output has no line breaks
+  #
   class SingleLine
+    # Create a PrettyPrint::SingleLine object
+    #
+    # Arguments:
+    # * +output+ - String (or similar) to store rendered text. Needs to respond to '<<'
+    # * +maxwidth+ - Argument position expected to be here for compatibility.
+    #                This argument is a noop.
+    # * +newline+ - Argument position expected to be here for compatibility.
+    #               This argument is a noop.
     def initialize(output, maxwidth=nil, newline=nil)
       @output = output
       @first = [true]
     end
 
+    # Add +obj+ to the text to be outputed.
+    #
+    # +width+ argument is here for compatibility. It is a noop argument.
     def text(obj, width=nil)
       @output << obj
     end
 
+    # Appends +sep+ to the text to be outputed. By default +sep+ is ' '
+    #
+    # +width+ argument is here for compatibility. It is a noop argument.
     def breakable(sep=' ', width=nil)
       @output << sep
     end
 
-    def nest(indent)
+    # Takes +indent+ arg, but does nothing with it.
+    #
+    # Yields to a block.
+    def nest(indent) # :nodoc:
       yield
     end
 
+    # Opens a block for grouping objects to be pretty printed.
+    #
+    # Arguments:
+    # * +indent+ - noop argument. Present for compatibility.
+    # * +open_obj+ - text appended before the &blok. Default is ''
+    # * +close_obj+ - text appended after the &blok. Default is ''
+    # * +open_width+ - noop argument. Present for compatibility.
+    # * +close_width+ - noop argument. Present for compatibility.
     def group(indent=nil, open_obj='', close_obj='', open_width=nil, close_width=nil)
       @first.push true
       @output << open_obj
@@ -383,9 +562,11 @@ class PrettyPrint
       @first.pop
     end
 
-    def flush
+    # Method present for compatibility, but is a noop
+    def flush # :nodoc:
     end
 
+    # This is used as a predicate, and ought to be called first.
     def first?
       result = @first[-1]
       @first[-1] = false