| Path: | lib/haml/util.rb |
| Last Update: | Tue Jun 01 04:09:49 +0000 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 680
680: def def_static_method(klass, name, args, *vars)
681: erb = vars.pop
682: info = caller_info
683: powerset(vars).each do |set|
684: context = StaticConditionalContext.new(set).instance_eval {binding}
685: 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])
686: end
687: 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 576
576: def enum_cons(enum, n)
577: ruby1_8? ? enum.enum_cons(n) : enum.each_cons(n)
578: 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 585
585: def enum_slice(enum, n)
586: ruby1_8? ? enum.enum_slice(n) : enum.each_slice(n)
587: 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 567
567: def enum_with_index(enum)
568: ruby1_8? ? enum.enum_with_index : enum.each_with_index
569: 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 602
602: def flatten(arr, n)
603: return arr.flatten(n) unless ruby1_8_6?
604: return arr if n == 0
605: arr.inject([]) {|res, e| e.is_a?(Array) ? res.concat(flatten(e, n - 1)) : res << e}
606: 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 559
559: def has?(attr, klass, method)
560: klass.send("#{attr}s").include?(ruby1_8? ? method.to_s : method.to_sym)
561: 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 593
593: def ord(c)
594: ruby1_8? ? c[0] : c.ord
595: 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 624
624: def set_eql?(set1, set2)
625: return set1.eql?(set2) unless ruby1_8_6?
626: set1.to_a.uniq.sort_by {|e| e.hash}.eql?(set2.to_a.uniq.sort_by {|e| e.hash})
627: 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 613
613: def set_hash(set)
614: return set.hash unless ruby1_8_6?
615: set.map {|e| e.hash}.uniq.sort.hash
616: 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 699
699: def static_method_name(name, *vars)
700: "#{name}_#{vars.map {|v| !!v}.join('_')}"
701: 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 726
726: def lcs_backtrace(c, x, y, i, j, &block)
727: return [] if i == 0 || j == 0
728: if v = yield(x[i], y[j])
729: return lcs_backtrace(c, x, y, i-1, j-1, &block) << v
730: end
731:
732: return lcs_backtrace(c, x, y, i, j-1, &block) if c[i][j-1] > c[i-1][j]
733: return lcs_backtrace(c, x, y, i-1, j, &block)
734: 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 707
707: def lcs_table(x, y)
708: c = Array.new(x.size) {[]}
709: x.size.times {|i| c[i][0] = 0}
710: y.size.times {|j| c[0][j] = 0}
711: (1...x.size).each do |i|
712: (1...y.size).each do |j|
713: c[i][j] =
714: if yield x[i], y[j]
715: c[i-1][j-1] + 1
716: else
717: [c[i][j-1], c[i-1][j]].max
718: end
719: end
720: end
721: return c
722: 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 742
742: def parse_haml_magic_comment(str)
743: scanner = StringScanner.new(str.dup.force_encoding("BINARY"))
744: bom = scanner.scan(/\xEF\xBB\xBF/n)
745: return bom unless scanner.scan(/-\s*#\s*/n)
746: if coding = try_parse_haml_emacs_magic_comment(scanner)
747: return bom, coding
748: end
749:
750: return bom unless scanner.scan(/.*?coding[=:]\s*([\w-]+)/in)
751: return bom, scanner[1]
752: end
# File lib/haml/util.rb, line 754
754: def try_parse_haml_emacs_magic_comment(scanner)
755: pos = scanner.pos
756: return unless scanner.scan(/.*?-\*-\s*/n)
757: # From Ruby's parse.y
758: return unless scanner.scan(/([^\s'":;]+)\s*:\s*("(?:\\.|[^"])*"|[^"\s;]+?)[\s;]*-\*-/n)
759: name, val = scanner[1], scanner[2]
760: return unless name =~ /(en)?coding/in
761: val = $1 if val =~ /^"(.*)"$/n
762: return val
763: ensure
764: scanner.pos = pos
765: end