diff options
Diffstat (limited to 'lib/prettyprint.rb')
| -rw-r--r-- | lib/prettyprint.rb | 272 |
1 files changed, 236 insertions, 36 deletions
diff --git a/lib/prettyprint.rb b/lib/prettyprint.rb index 2c1fff3258..44ca5e816f 100644 --- a/lib/prettyprint.rb +++ b/lib/prettyprint.rb @@ -1,3 +1,5 @@ +# frozen_string_literal: true +# # This class implements a pretty printing algorithm. It finds line breaks and # nice indentations for grouped structure. # @@ -17,18 +19,23 @@ # * 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 +# https://lindig.github.io/papers/strictly-pretty-2000.pdf # # Philip Wadler, A prettier printer, March 1998, -# http://homepages.inf.ed.ac.uk/wadler/topics/language-design.html#prettier +# https://homepages.inf.ed.ac.uk/wadler/topics/language-design.html#prettier # # == Author -# Tanaka Akira <akr@m17n.org> +# Tanaka Akira <akr@fsij.org> # class PrettyPrint + # The version string + VERSION = "0.2.0" + # This is a convenience method which is same as follows: # # begin @@ -38,7 +45,7 @@ class PrettyPrint # output # end # - def PrettyPrint.format(output='', maxwidth=79, newline="\n", genspace=lambda {|n| ' ' * n}) + def PrettyPrint.format(output=''.dup, maxwidth=79, newline="\n", genspace=lambda {|n| ' ' * n}) q = PrettyPrint.new(output, maxwidth, newline, &genspace) yield q q.flush @@ -52,7 +59,7 @@ class PrettyPrint # 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) + def PrettyPrint.singleline_format(output=''.dup, maxwidth=nil, newline=nil, genspace=nil) q = SingleLine.new(output) yield q output @@ -75,7 +82,7 @@ class PrettyPrint # The block is used to generate spaces. {|width| ' ' * width} is used if it # is not given. # - def initialize(output='', maxwidth=79, newline="\n", &genspace) + def initialize(output=''.dup, maxwidth=79, newline="\n", &genspace) @output = output @maxwidth = maxwidth @newline = newline @@ -90,35 +97,69 @@ class PrettyPrint @group_queue = GroupQueue.new(root_group) @indent = 0 end - attr_reader :output, :maxwidth, :newline, :genspace - attr_reader :indent, :group_queue - def current_group - @group_stack.last - end + # The output object. + # + # This defaults to '', and should accept the << method + attr_reader :output - # first? is a predicate to test the call is a first call to first? with - # current group. + # The maximum width of a line, before it is separated in to a newline # - # It is useful to format comma separated values as: + # This defaults to 79, and should be an Integer + attr_reader :maxwidth + + # The value that is appended to +output+ to add a new line. # - # q.group(1, '[', ']') { - # xxx.each {|yyy| - # unless q.first? - # q.text ',' - # q.breakable - # end - # ... pretty printing yyy ... - # } - # } + # This defaults to "\n", and should be String + attr_reader :newline + + # A lambda or Proc, that takes one argument, of an Integer, and returns + # the corresponding number of spaces. # - # first? is obsoleted in 1.8.2. + # 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. # - def first? - warn "PrettyPrint#first? is obsoleted at 1.8.2." - current_group.first? + # 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 @@ -155,11 +196,27 @@ class PrettyPrint 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 tells "you can break a line here if necessary", and a +width+\-column + # 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. @@ -202,6 +259,7 @@ 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 @@ -238,25 +296,55 @@ 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 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 - 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 separator + # * +width+ Integer width of the +sep+ + # * +q+ parent PrettyPrint object, to base from def initialize(sep, width, q) @obj = sep @width = width @@ -265,8 +353,24 @@ class PrettyPrint @group = q.current_group @group.breakables.push self end - attr_reader :obj, :width, :indent + # 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? @@ -281,22 +385,45 @@ 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 @@ -307,18 +434,33 @@ 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| @@ -334,29 +476,76 @@ 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 + # * #fill_breakable + # * #nest + # * #group + # * #group_sub + # * #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 - def nest(indent) + # Appends +sep+ to the text to be output. By default +sep+ is ' ' + # + # +width+ argument is here for compatibility. It is a noop argument. + def fill_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 @@ -365,9 +554,20 @@ class PrettyPrint @first.pop end - def flush + # Yields to a block for compatibility. + def group_sub # :nodoc: + yield + end + + # Method present for compatibility, but is a noop + def break_outmost_groups # :nodoc: + 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 |