| Path: | lib/haml/util.rb |
| Last Update: | Wed Jul 28 03:11:07 -0500 2010 |
This is used for methods in {Haml::Buffer} that need to be very fast, and take a lot of boolean parameters that are known at compile-time. Instead of passing the parameters in normally, a separate method is defined for every possible combination of those parameters; these are then called using \{static_method_name}.
To define a static method, an ERB template for the method is provided. All conditionals based on the static parameters are done as embedded Ruby within this template. For example:
def_static_method(Foo, :my_static_method, [:foo, :bar], :baz, :bang, <<RUBY)
<% if baz && bang %>
return foo + bar
<% elsif baz || bang %>
return foo - bar
<% else %>
return 17
<% end %>
RUBY
\{static_method_name} can be used to call static methods.
@overload def_static_method(klass, name, args, *vars, erb) @param klass [Module] The class on which to define the static method @param name [to_s] The (base) name of the static method @param args [Array<Symbol>] The names of the arguments to the defined methods
(**not** to the ERB template)
@param vars [Array<Symbol>] The names of the static boolean variables
to be made available to the ERB template
@param erb [String] The template for the method code
# File lib/haml/util.rb, line 672
672: def def_static_method(klass, name, args, *vars)
673: erb = vars.pop
674: info = caller_info
675: powerset(vars).each do |set|
676: context = StaticConditionalContext.new(set).instance_eval {binding}
677: klass.class_eval("def \#{static_method_name(name, *vars.map {|v| set.include?(v)})}(\#{args.join(', ')})\n \#{ERB.new(erb).result(context)}\nend\n", info[0], info[1])
678: end
679: end
A version of `Enumerable#enum_cons` that works in Ruby 1.8 and 1.9.
@param enum [Enumerable] The enumerable to get the enumerator for @param n [Fixnum] The size of each cons @return [Enumerator] The consed enumerator
# File lib/haml/util.rb, line 568
568: def enum_cons(enum, n)
569: ruby1_8? ? enum.enum_cons(n) : enum.each_cons(n)
570: end
A version of `Enumerable#enum_slice` that works in Ruby 1.8 and 1.9.
@param enum [Enumerable] The enumerable to get the enumerator for @param n [Fixnum] The size of each slice @return [Enumerator] The consed enumerator
# File lib/haml/util.rb, line 577
577: def enum_slice(enum, n)
578: ruby1_8? ? enum.enum_slice(n) : enum.each_slice(n)
579: end
A version of `Enumerable#enum_with_index` that works in Ruby 1.8 and 1.9.
@param enum [Enumerable] The enumerable to get the enumerator for @return [Enumerator] The with-index enumerator
# File lib/haml/util.rb, line 559
559: def enum_with_index(enum)
560: ruby1_8? ? enum.enum_with_index : enum.each_with_index
561: end
Flattens the first `n` nested arrays in a cross-version manner.
@param arr [Array] The array to flatten @param n [Fixnum] The number of levels to flatten @return [Array] The flattened array
# File lib/haml/util.rb, line 594
594: def flatten(arr, n)
595: return arr.flatten(n) unless ruby1_8_6?
596: return arr if n == 0
597: arr.inject([]) {|res, e| e.is_a?(Array) ? res.concat(flatten(e, n - 1)) : res << e}
598: end
Checks to see if a class has a given method. For example:
Haml::Util.has?(:public_instance_method, String, :gsub) #=> true
Method collections like `Class#instance_methods` return strings in Ruby 1.8 and symbols in Ruby 1.9 and on, so this handles checking for them in a compatible way.
@param attr [to_s] The (singular) name of the method-collection method
(e.g. `:instance_methods`, `:private_methods`)
@param klass [Module] The class to check the methods of which to check @param method [String, Symbol] The name of the method do check for @return [Boolean] Whether or not the given collection has the given method
# File lib/haml/util.rb, line 551
551: def has?(attr, klass, method)
552: klass.send("#{attr}s").include?(ruby1_8? ? method.to_s : method.to_sym)
553: end
Returns the ASCII code of the given character.
@param c [String] All characters but the first are ignored. @return [Fixnum] The ASCII code of `c`.
# File lib/haml/util.rb, line 585
585: def ord(c)
586: ruby1_8? ? c[0] : c.ord
587: end
Tests the hash-equality of two sets in a cross-version manner. Aggravatingly, this is order-dependent in Ruby 1.8.6.
@param set1 [Set] @param set2 [Set] @return [Boolean] Whether or not the sets are hashcode equal
# File lib/haml/util.rb, line 616
616: def set_eql?(set1, set2)
617: return set1.eql?(set2) unless ruby1_8_6?
618: set1.to_a.uniq.sort_by {|e| e.hash}.eql?(set2.to_a.uniq.sort_by {|e| e.hash})
619: end
Returns the hash code for a set in a cross-version manner. Aggravatingly, this is order-dependent in Ruby 1.8.6.
@param set [Set] @return [Fixnum] The order-independent hashcode of `set`
# File lib/haml/util.rb, line 605
605: def set_hash(set)
606: return set.hash unless ruby1_8_6?
607: set.map {|e| e.hash}.uniq.sort.hash
608: end
Computes the name for a method defined via \{def_static_method}.
@param name [String] The base name of the static method @param vars [Array<Boolean>] The static variable assignment @return [String] The real name of the static method
# File lib/haml/util.rb, line 691
691: def static_method_name(name, *vars)
692: "#{name}_#{vars.map {|v| !!v}.join('_')}"
693: end
Computes a single longest common subsequence for arrays x and y. Algorithm from [Wikipedia](en.wikipedia.org/wiki/Longest_common_subsequence_problem#Reading_out_an_LCS)
# File lib/haml/util.rb, line 718
718: def lcs_backtrace(c, x, y, i, j, &block)
719: return [] if i == 0 || j == 0
720: if v = yield(x[i], y[j])
721: return lcs_backtrace(c, x, y, i-1, j-1, &block) << v
722: end
723:
724: return lcs_backtrace(c, x, y, i, j-1, &block) if c[i][j-1] > c[i-1][j]
725: return lcs_backtrace(c, x, y, i-1, j, &block)
726: end
Calculates the memoization table for the Least Common Subsequence algorithm. Algorithm from [Wikipedia](en.wikipedia.org/wiki/Longest_common_subsequence_problem#Computing_the_length_of_the_LCS)
# File lib/haml/util.rb, line 699
699: def lcs_table(x, y)
700: c = Array.new(x.size) {[]}
701: x.size.times {|i| c[i][0] = 0}
702: y.size.times {|j| c[0][j] = 0}
703: (1...x.size).each do |i|
704: (1...y.size).each do |j|
705: c[i][j] =
706: if yield x[i], y[j]
707: c[i-1][j-1] + 1
708: else
709: [c[i][j-1], c[i-1][j]].max
710: end
711: end
712: end
713: return c
714: end
Parses a magic comment at the beginning of a Haml file. The parsing rules are basically the same as Ruby‘s.
@return [(Boolean, String or nil)]
Whether the document begins with a UTF-8 BOM, and the declared encoding of the document (or nil if none is declared)
# File lib/haml/util.rb, line 734
734: def parse_haml_magic_comment(str)
735: scanner = StringScanner.new(str.dup.force_encoding("BINARY"))
736: bom = scanner.scan(/\xEF\xBB\xBF/n)
737: return bom unless scanner.scan(/-\s*#\s*/n)
738: if coding = try_parse_haml_emacs_magic_comment(scanner)
739: return bom, coding
740: end
741:
742: return bom unless scanner.scan(/.*?coding[=:]\s*([\w-]+)/in)
743: return bom, scanner[1]
744: end
# File lib/haml/util.rb, line 746
746: def try_parse_haml_emacs_magic_comment(scanner)
747: pos = scanner.pos
748: return unless scanner.scan(/.*?-\*-\s*/n)
749: # From Ruby's parse.y
750: return unless scanner.scan(/([^\s'":;]+)\s*:\s*("(?:\\.|[^"])*"|[^"\s;]+?)[\s;]*-\*-/n)
751: name, val = scanner[1], scanner[2]
752: return unless name =~ /(en)?coding/in
753: val = $1 if val =~ /^"(.*)"$/n
754: return val
755: ensure
756: scanner.pos = pos
757: end