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

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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
This commit is contained in:
zzak 2013-02-10 00:10:11 +00:00
parent cf2da37701
commit 3952de50bf
3 changed files with 256 additions and 45 deletions
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205
lib/prettyprint.rb
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@ -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