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authorakr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2001-12-24 17:38:33 +0000
committerakr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2001-12-24 17:38:33 +0000
commita2ba32fab9b2bc0d968cfd77f62385beff67042d (patch)
tree6509e67f3b25a24630f75800e75d7c6bb994a86c /lib/prettyprint.rb
parent428269821916bf8ed7c058340640edd8105cf599 (diff)
downloadruby-a2ba32fab9b2bc0d968cfd77f62385beff67042d.tar.gz
lib/pp.rb lib/prettyprint.rb: new file.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@1936 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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-rw-r--r--lib/prettyprint.rb681
1 files changed, 681 insertions, 0 deletions
diff --git a/lib/prettyprint.rb b/lib/prettyprint.rb
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+# $Id$
+
+=begin
+= PrettyPrint
+The class implements 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 situasions
+by giving suitable arguments for some methods:
+newline object and space generation block for (({PrettyPrint.new})),
+optional width argument for (({PrettyPrint#text})),
+(({PrettyPrint#breakable})), etc.
+There are several candidates to use them:
+text formatting using proportional fonts,
+multibyte characters which has columns diffrent to number of bytes,
+non-string formatting, etc.
+
+== class methods
+--- PrettyPrint.new([newline]) [{|width| ...}]
+ creates a buffer for pretty printing.
+
+ ((|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.
+
+== methods
+--- text(obj[, width])
+ adds ((|obj|)) as a text of ((|width|)) columns in width.
+
+ If ((|width|)) is not specified, (({((|obj|)).length})) is used.
+
+--- breakable([sep[, width]])
+ 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.
+
+--- nest(indent) {...}
+ increases left margin after newline with ((|indent|)) for line breaks added in the block.
+
+--- group {...}
+ groups line break hints added in the block.
+
+--- format(out[, width])
+ outputs buffered data to ((|out|)).
+ It tries to restrict the line length to ((|width|)) but it may
+ overflow.
+
+ If ((|width|)) is not specified, 79 is assumed.
+
+ ((|out|)) must have a method named (({<<})) which accepts
+ a first argument ((|obj|)) of (({PrettyPrint#text})),
+ a first argument ((|sep|)) of (({PrettyPrint#breakable})),
+ a first argument ((|newline|)) of (({PrettyPrint.new})),
+ and
+ a result of a given block for (({PrettyPrint.new})).
+
+== Bugs
+* Line breaks in a group is constrained to whether all line break hints are
+ to be breaked or not. Maybe, non-constrained version of
+ PrettyPrint#group should be provided to filling multi lines.
+
+* Box based formatting?
+
+== References
+Strictly Pretty, Christian Lindig, March 2000,
+((<URL:http://www.gaertner.de/~lindig/papers/strictly-pretty.html>))
+
+A prettier printer, Philip Wadler, March 1998,
+((<URL:http://cm.bell-labs.com/cm/cs/who/wadler/topics/recent.html#prettier>))
+
+=end
+
+class PrettyPrint
+ def initialize(newline="\n", &genspace)
+ @newline = newline
+ @genspace = genspace || lambda {|n| ' ' * n}
+ @buf = Group.new
+ @nest = [0]
+ @stack = []
+ end
+
+ def text(obj, width=obj.length)
+ @buf << Text.new(obj, width)
+ end
+
+ def breakable(sep=' ', width=sep.length)
+ @buf << Breakable.new(sep, width, @nest.last, @newline, @genspace)
+ end
+
+ def nest(indent)
+ nest_enter(indent)
+ begin
+ yield
+ ensure
+ nest_leave
+ end
+ end
+
+ def nest_enter(indent)
+ @nest << @nest.last + indent
+ end
+
+ def nest_leave
+ @nest.pop
+ end
+
+ def group
+ group_enter
+ begin
+ yield
+ ensure
+ group_leave
+ end
+ end
+
+ def group_enter
+ g = Group.new
+ @buf << g
+ @stack << @buf
+ @buf = g
+ end
+
+ def group_leave
+ @buf = @stack.pop
+ end
+
+ def format(out, width=79)
+ tails = [[-1, 0]]
+ @buf.update_tails(tails, 0)
+ @buf.multiline_output(out, 0, 0, width)
+ end
+
+ class Text
+ def initialize(text, width)
+ @text = text
+ @width = width
+ end
+
+ def update_tails(tails, group)
+ tails[-1][1] += @width
+ end
+
+ def singleline_width
+ return @width
+ end
+
+ def singleline_output(out)
+ out << @text
+ end
+
+ def multiline_output(out, group, margin, width)
+ singleline_output(out)
+ return margin + singleline_width
+ end
+ end
+
+ class Breakable
+ def initialize(sep, width, indent, newline, genspace)
+ @sep = sep
+ @width = width
+ @indent = indent
+ @newline = newline
+ @genspace = genspace
+ end
+
+ def update_tails(tails, group)
+ if group == tails[-1][0]
+ tails[-2][1] += @width + tails[-1][1]
+ tails[-1][1] = 0
+ else
+ tails[-1][1] += @width
+ tails << [group, 0]
+ end
+ end
+
+ def singleline_width
+ return @width
+ end
+
+ def singleline_output(out)
+ out << @sep
+ end
+
+ def multiline_output(out, group, margin, width)
+ out << @newline
+ out << @genspace.call(@indent)
+ return @indent
+ end
+ end
+
+ class Group
+ def initialize
+ @buf = []
+ @singleline_width = nil
+ end
+
+ def <<(obj)
+ @buf << obj
+ end
+
+ def update_tails(tails, group)
+ @tail = tails.empty? ? 0 : tails[-1][1]
+ len = 0
+ @buf.reverse_each {|obj|
+ obj.update_tails(tails, group + 1)
+ len += obj.singleline_width
+ }
+ @singleline_width = len
+ while !tails.empty? && group <= tails[-1][0]
+ tails[-2][1] += tails[-1][1]
+ tails.pop
+ end
+ end
+
+ def singleline_width
+ return @singleline_width
+ end
+
+ def singleline_output(out)
+ @buf.each {|obj| obj.singleline_output(out)}
+ end
+
+ def multiline_output(out, group, margin, width)
+ if margin + singleline_width + @tail <= width
+ singleline_output(out)
+ margin += singleline_width
+ else
+ @buf.each {|obj|
+ margin = obj.multiline_output(out, group + 1, margin, width)
+ }
+ end
+ return margin
+ end
+ end
+end
+
+if __FILE__ == $0
+ require 'runit/testcase'
+ require 'runit/cui/testrunner'
+
+ class WadlerExample < RUNIT::TestCase
+ def setup
+ @hello = PrettyPrint.new
+ @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'
+ }
+
+ @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 test_hello_00_06
+ expected = <<'End'.chomp
+hello
+a
+b
+c
+d
+End
+ @hello.format(out='', 0); assert_equal(expected, out)
+ @hello.format(out='', 6); assert_equal(expected, out)
+ end
+
+ def test_hello_07_08
+ expected = <<'End'.chomp
+hello a
+b
+c
+d
+End
+ @hello.format(out='', 7); assert_equal(expected, out)
+ @hello.format(out='', 8); assert_equal(expected, out)
+ end
+
+ def test_hello_09_10
+ expected = <<'End'.chomp
+hello a b
+c
+d
+End
+ @hello.format(out='', 9); assert_equal(expected, out)
+ @hello.format(out='', 10); assert_equal(expected, out)
+ end
+
+ def test_hello_11_12
+ expected = <<'End'.chomp
+hello a b c
+d
+End
+ @hello.format(out='', 11); assert_equal(expected, out)
+ @hello.format(out='', 12); assert_equal(expected, out)
+ end
+
+ def test_hello_13
+ expected = <<'End'.chomp
+hello a b c d
+End
+ @hello.format(out='', 13); assert_equal(expected, out)
+ end
+
+ def test_tree_00_19
+ pp = PrettyPrint.new
+ @tree.show(pp)
+ expected = <<'End'.chomp
+aaaa[bbbbb[ccc,
+ dd],
+ eee,
+ ffff[gg,
+ hhh,
+ ii]]
+End
+ pp.format(out='', 0); assert_equal(expected, out)
+ pp.format(out='', 19); assert_equal(expected, out)
+ end
+
+ def test_tree_20_22
+ pp = PrettyPrint.new
+ @tree.show(pp)
+ expected = <<'End'.chomp
+aaaa[bbbbb[ccc, dd],
+ eee,
+ ffff[gg,
+ hhh,
+ ii]]
+End
+ pp.format(out='', 20); assert_equal(expected, out)
+ pp.format(out='', 22); assert_equal(expected, out)
+ end
+
+ def test_tree_23_43
+ pp = PrettyPrint.new
+ @tree.show(pp)
+ expected = <<'End'.chomp
+aaaa[bbbbb[ccc, dd],
+ eee,
+ ffff[gg, hhh, ii]]
+End
+ pp.format(out='', 23); assert_equal(expected, out)
+ pp.format(out='', 43); assert_equal(expected, out)
+ end
+
+ def test_tree_44
+ pp = PrettyPrint.new
+ @tree.show(pp)
+ pp.format(out='', 44)
+ assert_equal(<<'End'.chomp, out)
+aaaa[bbbbb[ccc, dd], eee, ffff[gg, hhh, ii]]
+End
+ end
+
+ def test_tree_alt_00_18
+ pp = PrettyPrint.new
+ @tree.altshow(pp)
+ expected = <<'End'.chomp
+aaaa[
+ bbbbb[
+ ccc,
+ dd
+ ],
+ eee,
+ ffff[
+ gg,
+ hhh,
+ ii
+ ]
+]
+End
+ pp.format(out='', 0); assert_equal(expected, out)
+ pp.format(out='', 18); assert_equal(expected, out)
+ end
+
+ def test_tree_alt_19_20
+ pp = PrettyPrint.new
+ @tree.altshow(pp)
+ expected = <<'End'.chomp
+aaaa[
+ bbbbb[ ccc, dd ],
+ eee,
+ ffff[
+ gg,
+ hhh,
+ ii
+ ]
+]
+End
+ pp.format(out='', 19); assert_equal(expected, out)
+ pp.format(out='', 20); assert_equal(expected, out)
+ end
+
+ def test_tree_alt_20_49
+ pp = PrettyPrint.new
+ @tree.altshow(pp)
+ expected = <<'End'.chomp
+aaaa[
+ bbbbb[ ccc, dd ],
+ eee,
+ ffff[ gg, hhh, ii ]
+]
+End
+ pp.format(out='', 21); assert_equal(expected, out)
+ pp.format(out='', 49); assert_equal(expected, out)
+ end
+
+ def test_tree_alt_50
+ pp = PrettyPrint.new
+ @tree.altshow(pp)
+ expected = <<'End'.chomp
+aaaa[ bbbbb[ ccc, dd ], eee, ffff[ gg, hhh, ii ] ]
+End
+ pp.format(out='', 50); assert_equal(expected, out)
+ end
+
+ class Tree
+ def initialize(string, *children)
+ @string = string
+ @children = children
+ end
+
+ def show(pp)
+ pp.group {
+ pp.text @string
+ pp.nest(@string.length) {
+ unless @children.empty?
+ pp.text '['
+ pp.nest(1) {
+ first = true
+ @children.each {|t|
+ if first
+ first = false
+ else
+ pp.text ','
+ pp.breakable
+ end
+ t.show(pp)
+ }
+ }
+ pp.text ']'
+ end
+ }
+ }
+ end
+
+ def altshow(pp)
+ pp.group {
+ pp.text @string
+ unless @children.empty?
+ pp.text '['
+ pp.nest(2) {
+ pp.breakable
+ first = true
+ @children.each {|t|
+ if first
+ first = false
+ else
+ pp.text ','
+ pp.breakable
+ end
+ t.altshow(pp)
+ }
+ }
+ pp.breakable
+ pp.text ']'
+ end
+ }
+ end
+
+ end
+ end
+
+ class StrictPrettyExample < RUNIT::TestCase
+ def setup
+ @pp = PrettyPrint.new
+ @pp.group {
+ @pp.group {@pp.nest(2) {
+ @pp.text "if"; @pp.breakable;
+ @pp.group {
+ @pp.nest(2) {
+ @pp.group {@pp.text "a"; @pp.breakable; @pp.text "=="}
+ @pp.breakable; @pp.text "b"}}}}
+ @pp.breakable
+ @pp.group {@pp.nest(2) {
+ @pp.text "then"; @pp.breakable;
+ @pp.group {
+ @pp.nest(2) {
+ @pp.group {@pp.text "a"; @pp.breakable; @pp.text "<<"}
+ @pp.breakable; @pp.text "2"}}}}
+ @pp.breakable
+ @pp.group {@pp.nest(2) {
+ @pp.text "else"; @pp.breakable;
+ @pp.group {
+ @pp.nest(2) {
+ @pp.group {@pp.text "a"; @pp.breakable; @pp.text "+"}
+ @pp.breakable; @pp.text "b"}}}}}
+ end
+
+ def test_00_04
+ expected = <<'End'.chomp
+if
+ a
+ ==
+ b
+then
+ a
+ <<
+ 2
+else
+ a
+ +
+ b
+End
+ @pp.format(out='', 0); assert_equal(expected, out)
+ @pp.format(out='', 4); assert_equal(expected, out)
+ end
+
+ def test_05
+ expected = <<'End'.chomp
+if
+ a
+ ==
+ b
+then
+ a
+ <<
+ 2
+else
+ a +
+ b
+End
+ @pp.format(out='', 5); assert_equal(expected, out)
+ end
+
+ def test_06
+ expected = <<'End'.chomp
+if
+ a ==
+ b
+then
+ a <<
+ 2
+else
+ a +
+ b
+End
+ @pp.format(out='', 6); assert_equal(expected, out)
+ end
+
+ def test_07
+ expected = <<'End'.chomp
+if
+ a ==
+ b
+then
+ a <<
+ 2
+else
+ a + b
+End
+ @pp.format(out='', 7); assert_equal(expected, out)
+ end
+
+ def test_08
+ expected = <<'End'.chomp
+if
+ a == b
+then
+ a << 2
+else
+ a + b
+End
+ @pp.format(out='', 8); assert_equal(expected, out)
+ end
+
+ def test_09
+ expected = <<'End'.chomp
+if a == b
+then
+ a << 2
+else
+ a + b
+End
+ @pp.format(out='', 9); assert_equal(expected, out)
+ end
+
+ def test_10
+ expected = <<'End'.chomp
+if a == b
+then
+ a << 2
+else a + b
+End
+ @pp.format(out='', 10); assert_equal(expected, out)
+ end
+
+ def test_11_31
+ expected = <<'End'.chomp
+if a == b
+then a << 2
+else a + b
+End
+ @pp.format(out='', 11); assert_equal(expected, out)
+ @pp.format(out='', 15); assert_equal(expected, out)
+ @pp.format(out='', 31); assert_equal(expected, out)
+ end
+
+ def test_32
+ expected = <<'End'.chomp
+if a == b then a << 2 else a + b
+End
+ @pp.format(out='', 32); assert_equal(expected, out)
+ end
+
+ end
+
+ class TailGroup < RUNIT::TestCase
+ def test_1
+ pp = PrettyPrint.new
+ pp.group {
+ pp.group {
+ pp.text "abc"
+ pp.breakable
+ pp.text "def"
+ }
+ pp.group {
+ pp.text "ghi"
+ pp.breakable
+ pp.text "jkl"
+ }
+ }
+ pp.format(out='', 10)
+ assert_equal("abc\ndefghi jkl", out)
+ end
+ end
+
+ class NonString < RUNIT::TestCase
+ def setup
+ @pp = PrettyPrint.new('newline') {|n| "#{n} spaces"}
+ @pp.text(3, 3)
+ @pp.breakable(1, 1)
+ @pp.text(3, 3)
+ end
+
+ def test_6
+ @pp.format(out=[], 6)
+ assert_equal([3, "newline", "0 spaces", 3], out)
+ end
+
+ def test_7
+ @pp.format(out=[], 7)
+ assert_equal([3, 1, 3], out)
+ end
+
+ end
+
+ RUNIT::CUI::TestRunner.run(WadlerExample.suite)
+ RUNIT::CUI::TestRunner.run(StrictPrettyExample.suite)
+ RUNIT::CUI::TestRunner.run(TailGroup.suite)
+ RUNIT::CUI::TestRunner.run(NonString.suite)
+end