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Diffstat (limited to 'ruby_2_2/lib/prettyprint.rb')
| -rw-r--r-- | ruby_2_2/lib/prettyprint.rb | 554 |
1 files changed, 554 insertions, 0 deletions
diff --git a/ruby_2_2/lib/prettyprint.rb b/ruby_2_2/lib/prettyprint.rb new file mode 100644 index 0000000000..7e989374b7 --- /dev/null +++ b/ruby_2_2/lib/prettyprint.rb @@ -0,0 +1,554 @@ +# This class implements a pretty printing algorithm. It finds line breaks and +# nice indentations for grouped structure. +# +# By default, the class assumes that primitive elements are strings and each +# byte in the strings have single column in width. But it can be used for +# other situations by giving suitable arguments for some methods: +# * newline object and space generation block for PrettyPrint.new +# * optional width argument for PrettyPrint#text +# * PrettyPrint#breakable +# +# There are several candidate uses: +# * text formatting using proportional fonts +# * multibyte characters which has columns different to number of bytes +# * non-string formatting +# +# == Bugs +# * 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 +# +# Philip Wadler, A prettier printer, March 1998, +# http://homepages.inf.ed.ac.uk/wadler/topics/language-design.html#prettier +# +# == Author +# Tanaka Akira <akr@fsij.org> +# +class PrettyPrint + + # This is a convenience method which is same as follows: + # + # begin + # q = PrettyPrint.new(output, maxwidth, newline, &genspace) + # ... + # q.flush + # output + # end + # + def PrettyPrint.format(output='', maxwidth=79, newline="\n", genspace=lambda {|n| ' ' * n}) + q = PrettyPrint.new(output, maxwidth, newline, &genspace) + yield q + q.flush + output + end + + # This is similar to PrettyPrint::format but the result has no breaks. + # + # +maxwidth+, +newline+ and +genspace+ are ignored. + # + # The invocation of +breakable+ in the block doesn't break a line and is + # treated as just an invocation of +text+. + # + def PrettyPrint.singleline_format(output='', maxwidth=nil, newline=nil, genspace=nil) + q = SingleLine.new(output) + yield q + output + end + + # Creates a buffer for pretty printing. + # + # +output+ is an output target. If it is not specified, '' is assumed. It + # should have a << method which accepts the first argument +obj+ of + # PrettyPrint#text, the first argument +sep+ of PrettyPrint#breakable, the + # first argument +newline+ of PrettyPrint.new, and the result of a given + # block for PrettyPrint.new. + # + # +maxwidth+ specifies maximum line length. If it is not specified, 79 is + # assumed. However actual outputs may overflow +maxwidth+ if long + # non-breakable texts are provided. + # + # +newline+ is used for line breaks. "\n" is used if it is not specified. + # + # The block is used to generate spaces. {|width| ' ' * width} is used if it + # is not given. + # + def initialize(output='', maxwidth=79, newline="\n", &genspace) + @output = output + @maxwidth = maxwidth + @newline = newline + @genspace = genspace || lambda {|n| ' ' * n} + + @output_width = 0 + @buffer_width = 0 + @buffer = [] + + root_group = Group.new(0) + @group_stack = [root_group] + @group_queue = GroupQueue.new(root_group) + @indent = 0 + end + + # 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 + + # Breaks the buffer into lines that are shorter than #maxwidth + def break_outmost_groups + while @maxwidth < @output_width + @buffer_width + return unless group = @group_queue.deq + until group.breakables.empty? + data = @buffer.shift + @output_width = data.output(@output, @output_width) + @buffer_width -= data.width + end + while !@buffer.empty? && Text === @buffer.first + text = @buffer.shift + @output_width = text.output(@output, @output_width) + @buffer_width -= text.width + end + end + end + + # This adds +obj+ as a text of +width+ columns in width. + # + # If +width+ is not specified, obj.length is used. + # + def text(obj, width=obj.length) + if @buffer.empty? + @output << obj + @output_width += width + else + text = @buffer.last + unless Text === text + text = Text.new + @buffer << text + end + text.add(obj, width) + @buffer_width += width + break_outmost_groups + end + end + + # This is similar to #breakable except + # the decision to break or not is determined individually. + # + # Two #fill_breakable under a group may cause 4 results: + # (break,break), (break,non-break), (non-break,break), (non-break,non-break). + # This is different to #breakable because two #breakable under a group + # may cause 2 results: + # (break,break), (non-break,non-break). + # + # The text +sep+ is inserted if a line is not broken at this point. + # + # If +sep+ is not specified, " " is used. + # + # If +width+ is not specified, +sep.length+ is used. You will have to + # specify this when +sep+ is a multibyte character, for example. + # + def fill_breakable(sep=' ', width=sep.length) + group { breakable sep, width } + end + + # This says "you can break a line here if necessary", and a +width+\-column + # text +sep+ is inserted if a line is not broken at the point. + # + # If +sep+ is not specified, " " is used. + # + # If +width+ is not specified, +sep.length+ is used. You will have to + # specify this when +sep+ is a multibyte character, for example. + # + def breakable(sep=' ', width=sep.length) + group = @group_stack.last + if group.break? + flush + @output << @newline + @output << @genspace.call(@indent) + @output_width = @indent + @buffer_width = 0 + else + @buffer << Breakable.new(sep, width, self) + @buffer_width += width + break_outmost_groups + end + end + + # Groups line break hints added in the block. The line break hints are all + # to be used or not. + # + # If +indent+ is specified, the method call is regarded as nested by + # nest(indent) { ... }. + # + # If +open_obj+ is specified, <tt>text open_obj, open_width</tt> is called + # before grouping. If +close_obj+ is specified, <tt>text close_obj, + # close_width</tt> is called after grouping. + # + def group(indent=0, open_obj='', close_obj='', open_width=open_obj.length, close_width=close_obj.length) + text open_obj, open_width + group_sub { + nest(indent) { + yield + } + } + 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 + @group_queue.enq group + begin + yield + ensure + @group_stack.pop + if group.breakables.empty? + @group_queue.delete group + end + end + end + + # Increases left margin after newline with +indent+ for line breaks added in + # the block. + # + def nest(indent) + @indent += indent + begin + yield + ensure + @indent -= indent + end + end + + # outputs buffered data. + # + def flush + @buffer.each {|data| + @output_width = data.output(@output, @output_width) + } + @buffer.clear + @buffer_width = 0 + end + + # 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 constructor 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 + + # 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 separator + # * +width+ Fixnum width of the +sep+ + # * +q+ parent PrettyPrint object, to base from + def initialize(sep, width, q) + @obj = sep + @width = width + @pp = q + @indent = q.indent + @group = q.current_group + @group.breakables.push self + end + + # Holds the separator 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? + out << @pp.newline + out << @pp.genspace.call(@indent) + @indent + else + @pp.group_queue.delete @group if @group.breakables.empty? + out << @obj + output_width + @width + end + end + end + + # 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 + + # 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 + else + @first = false + true + end + end + end + + # 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| + unless gs[i].breakables.empty? + group = gs.slice!(i, 1).first + group.break + return group + end + } + gs.each {|group| group.break} + gs.clear + } + 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 output. + # + # +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 output. By default +sep+ is ' ' + # + # +width+ argument is here for compatibility. It is a noop argument. + def breakable(sep=' ', width=nil) + @output << sep + end + + # 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 + yield + @output << close_obj + @first.pop + end + + # 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 + result + end + end +end |