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发表于 2015-6-15 21:02:58
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taroxd 发表于 2015-6-15 17:24
参考Ruby标准库的pp(pretty print)。没记错的话是纯Ruby实现,应该可以直接拿来用 ...
我倒是找到prettyprint.rb了,但对其脚本中的方法没什么头绪。希望前辈能再指点指点- # prettyprint.rb
- # 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 <[email protected]>
- #
- 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
- # first? is a predicate to test the call is a first call to first? with
- # current group.
- #
- # It is useful to format comma separated values as:
- #
- # q.group(1, '[', ']') {
- # xxx.each {|yyy|
- # unless q.first?
- # q.text ','
- # q.breakable
- # end
- # ... pretty printing yyy ...
- # }
- # }
- #
- # first? is obsoleted in 1.8.2.
- #
- def first?
- warn "PrettyPrint#first? is obsoleted at 1.8.2."
- current_group.first?
- 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 [email protected]? && 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
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