/lib/ruby/1.8/prettyprint.rb
Ruby | 896 lines | 706 code | 83 blank | 107 comment | 26 complexity | cedbd04b5d93edf5d0e36dc4b3a72f2b MD5 | raw file
Possible License(s): GPL-3.0, JSON
- # $Id$
- # 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?
- #
- # == 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@m17n.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
- attr_reader :output, :maxwidth, :newline, :genspace
- attr_reader :indent, :group_queue
- 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
- 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
- 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
- # 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
- 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
- class Text
- def initialize
- @objs = []
- @width = 0
- end
- attr_reader :width
- def output(out, output_width)
- @objs.each {|obj| out << obj}
- output_width + @width
- end
- def add(obj, width)
- @objs << obj
- @width += width
- end
- end
- class Breakable
- def initialize(sep, width, q)
- @obj = sep
- @width = width
- @pp = q
- @indent = q.indent
- @group = q.current_group
- @group.breakables.push self
- end
- attr_reader :obj, :width, :indent
- 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
- class Group
- def initialize(depth)
- @depth = depth
- @breakables = []
- @break = false
- end
- attr_reader :depth, :breakables
- def break
- @break = true
- end
- def break?
- @break
- end
- def first?
- if defined? @first
- false
- else
- @first = false
- true
- end
- end
- end
- class GroupQueue
- def initialize(*groups)
- @queue = []
- groups.each {|g| enq g}
- end
- def enq(group)
- depth = group.depth
- @queue << [] until depth < @queue.length
- @queue[depth] << group
- end
- 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
- def delete(group)
- @queue[group.depth].delete(group)
- end
- end
- class SingleLine
- def initialize(output, maxwidth=nil, newline=nil)
- @output = output
- @first = [true]
- end
- def text(obj, width=nil)
- @output << obj
- end
- def breakable(sep=' ', width=nil)
- @output << sep
- end
- def nest(indent)
- yield
- end
- 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
- def flush
- end
- def first?
- result = @first[-1]
- @first[-1] = false
- result
- end
- end
- end
- if __FILE__ == $0
- require 'test/unit'
- class WadlerExample < Test::Unit::TestCase # :nodoc:
- def setup
- @tree = Tree.new("aaaa", Tree.new("bbbbb", Tree.new("ccc"),
- Tree.new("dd")),
- Tree.new("eee"),
- Tree.new("ffff", Tree.new("gg"),
- Tree.new("hhh"),
- Tree.new("ii")))
- end
- def hello(width)
- PrettyPrint.format('', width) {|hello|
- hello.group {
- hello.group {
- hello.group {
- hello.group {
- hello.text 'hello'
- hello.breakable; hello.text 'a'
- }
- hello.breakable; hello.text 'b'
- }
- hello.breakable; hello.text 'c'
- }
- hello.breakable; hello.text 'd'
- }
- }
- end
- def test_hello_00_06
- expected = <<'End'.chomp
- hello
- a
- b
- c
- d
- End
- assert_equal(expected, hello(0))
- assert_equal(expected, hello(6))
- end
- def test_hello_07_08
- expected = <<'End'.chomp
- hello a
- b
- c
- d
- End
- assert_equal(expected, hello(7))
- assert_equal(expected, hello(8))
- end
- def test_hello_09_10
- expected = <<'End'.chomp
- hello a b
- c
- d
- End
- out = hello(9); assert_equal(expected, out)
- out = hello(10); assert_equal(expected, out)
- end
- def test_hello_11_12
- expected = <<'End'.chomp
- hello a b c
- d
- End
- assert_equal(expected, hello(11))
- assert_equal(expected, hello(12))
- end
- def test_hello_13
- expected = <<'End'.chomp
- hello a b c d
- End
- assert_equal(expected, hello(13))
- end
- def tree(width)
- PrettyPrint.format('', width) {|q| @tree.show(q)}
- end
- def test_tree_00_19
- expected = <<'End'.chomp
- aaaa[bbbbb[ccc,
- dd],
- eee,
- ffff[gg,
- hhh,
- ii]]
- End
- assert_equal(expected, tree(0))
- assert_equal(expected, tree(19))
- end
- def test_tree_20_22
- expected = <<'End'.chomp
- aaaa[bbbbb[ccc, dd],
- eee,
- ffff[gg,
- hhh,
- ii]]
- End
- assert_equal(expected, tree(20))
- assert_equal(expected, tree(22))
- end
- def test_tree_23_43
- expected = <<'End'.chomp
- aaaa[bbbbb[ccc, dd],
- eee,
- ffff[gg, hhh, ii]]
- End
- assert_equal(expected, tree(23))
- assert_equal(expected, tree(43))
- end
- def test_tree_44
- assert_equal(<<'End'.chomp, tree(44))
- aaaa[bbbbb[ccc, dd], eee, ffff[gg, hhh, ii]]
- End
- end
- def tree_alt(width)
- PrettyPrint.format('', width) {|q| @tree.altshow(q)}
- end
- def test_tree_alt_00_18
- expected = <<'End'.chomp
- aaaa[
- bbbbb[
- ccc,
- dd
- ],
- eee,
- ffff[
- gg,
- hhh,
- ii
- ]
- ]
- End
- assert_equal(expected, tree_alt(0))
- assert_equal(expected, tree_alt(18))
- end
- def test_tree_alt_19_20
- expected = <<'End'.chomp
- aaaa[
- bbbbb[ ccc, dd ],
- eee,
- ffff[
- gg,
- hhh,
- ii
- ]
- ]
- End
- assert_equal(expected, tree_alt(19))
- assert_equal(expected, tree_alt(20))
- end
- def test_tree_alt_20_49
- expected = <<'End'.chomp
- aaaa[
- bbbbb[ ccc, dd ],
- eee,
- ffff[ gg, hhh, ii ]
- ]
- End
- assert_equal(expected, tree_alt(21))
- assert_equal(expected, tree_alt(49))
- end
- def test_tree_alt_50
- expected = <<'End'.chomp
- aaaa[ bbbbb[ ccc, dd ], eee, ffff[ gg, hhh, ii ] ]
- End
- assert_equal(expected, tree_alt(50))
- end
- class Tree # :nodoc:
- def initialize(string, *children)
- @string = string
- @children = children
- end
- def show(q)
- q.group {
- q.text @string
- q.nest(@string.length) {
- unless @children.empty?
- q.text '['
- q.nest(1) {
- first = true
- @children.each {|t|
- if first
- first = false
- else
- q.text ','
- q.breakable
- end
- t.show(q)
- }
- }
- q.text ']'
- end
- }
- }
- end
- def altshow(q)
- q.group {
- q.text @string
- unless @children.empty?
- q.text '['
- q.nest(2) {
- q.breakable
- first = true
- @children.each {|t|
- if first
- first = false
- else
- q.text ','
- q.breakable
- end
- t.altshow(q)
- }
- }
- q.breakable
- q.text ']'
- end
- }
- end
- end
- end
- class StrictPrettyExample < Test::Unit::TestCase # :nodoc:
- def prog(width)
- PrettyPrint.format('', width) {|q|
- q.group {
- q.group {q.nest(2) {
- q.text "if"; q.breakable;
- q.group {
- q.nest(2) {
- q.group {q.text "a"; q.breakable; q.text "=="}
- q.breakable; q.text "b"}}}}
- q.breakable
- q.group {q.nest(2) {
- q.text "then"; q.breakable;
- q.group {
- q.nest(2) {
- q.group {q.text "a"; q.breakable; q.text "<<"}
- q.breakable; q.text "2"}}}}
- q.breakable
- q.group {q.nest(2) {
- q.text "else"; q.breakable;
- q.group {
- q.nest(2) {
- q.group {q.text "a"; q.breakable; q.text "+"}
- q.breakable; q.text "b"}}}}}
- }
- end
- def test_00_04
- expected = <<'End'.chomp
- if
- a
- ==
- b
- then
- a
- <<
- 2
- else
- a
- +
- b
- End
- assert_equal(expected, prog(0))
- assert_equal(expected, prog(4))
- end
- def test_05
- expected = <<'End'.chomp
- if
- a
- ==
- b
- then
- a
- <<
- 2
- else
- a +
- b
- End
- assert_equal(expected, prog(5))
- end
- def test_06
- expected = <<'End'.chomp
- if
- a ==
- b
- then
- a <<
- 2
- else
- a +
- b
- End
- assert_equal(expected, prog(6))
- end
- def test_07
- expected = <<'End'.chomp
- if
- a ==
- b
- then
- a <<
- 2
- else
- a + b
- End
- assert_equal(expected, prog(7))
- end
- def test_08
- expected = <<'End'.chomp
- if
- a == b
- then
- a << 2
- else
- a + b
- End
- assert_equal(expected, prog(8))
- end
- def test_09
- expected = <<'End'.chomp
- if a == b
- then
- a << 2
- else
- a + b
- End
- assert_equal(expected, prog(9))
- end
- def test_10
- expected = <<'End'.chomp
- if a == b
- then
- a << 2
- else a + b
- End
- assert_equal(expected, prog(10))
- end
- def test_11_31
- expected = <<'End'.chomp
- if a == b
- then a << 2
- else a + b
- End
- assert_equal(expected, prog(11))
- assert_equal(expected, prog(15))
- assert_equal(expected, prog(31))
- end
- def test_32
- expected = <<'End'.chomp
- if a == b then a << 2 else a + b
- End
- assert_equal(expected, prog(32))
- end
- end
- class TailGroup < Test::Unit::TestCase # :nodoc:
- def test_1
- out = PrettyPrint.format('', 10) {|q|
- q.group {
- q.group {
- q.text "abc"
- q.breakable
- q.text "def"
- }
- q.group {
- q.text "ghi"
- q.breakable
- q.text "jkl"
- }
- }
- }
- assert_equal("abc defghi\njkl", out)
- end
- end
- class NonString < Test::Unit::TestCase # :nodoc:
- def format(width)
- PrettyPrint.format([], width, 'newline', lambda {|n| "#{n} spaces"}) {|q|
- q.text(3, 3)
- q.breakable(1, 1)
- q.text(3, 3)
- }
- end
- def test_6
- assert_equal([3, "newline", "0 spaces", 3], format(6))
- end
- def test_7
- assert_equal([3, 1, 3], format(7))
- end
- end
- class Fill < Test::Unit::TestCase # :nodoc:
- def format(width)
- PrettyPrint.format('', width) {|q|
- q.group {
- q.text 'abc'
- q.fill_breakable
- q.text 'def'
- q.fill_breakable
- q.text 'ghi'
- q.fill_breakable
- q.text 'jkl'
- q.fill_breakable
- q.text 'mno'
- q.fill_breakable
- q.text 'pqr'
- q.fill_breakable
- q.text 'stu'
- }
- }
- end
- def test_00_06
- expected = <<'End'.chomp
- abc
- def
- ghi
- jkl
- mno
- pqr
- stu
- End
- assert_equal(expected, format(0))
- assert_equal(expected, format(6))
- end
- def test_07_10
- expected = <<'End'.chomp
- abc def
- ghi jkl
- mno pqr
- stu
- End
- assert_equal(expected, format(7))
- assert_equal(expected, format(10))
- end
- def test_11_14
- expected = <<'End'.chomp
- abc def ghi
- jkl mno pqr
- stu
- End
- assert_equal(expected, format(11))
- assert_equal(expected, format(14))
- end
- def test_15_18
- expected = <<'End'.chomp
- abc def ghi jkl
- mno pqr stu
- End
- assert_equal(expected, format(15))
- assert_equal(expected, format(18))
- end
- def test_19_22
- expected = <<'End'.chomp
- abc def ghi jkl mno
- pqr stu
- End
- assert_equal(expected, format(19))
- assert_equal(expected, format(22))
- end
- def test_23_26
- expected = <<'End'.chomp
- abc def ghi jkl mno pqr
- stu
- End
- assert_equal(expected, format(23))
- assert_equal(expected, format(26))
- end
- def test_27
- expected = <<'End'.chomp
- abc def ghi jkl mno pqr stu
- End
- assert_equal(expected, format(27))
- end
- end
- end