Path: | lib/haml/util.rb |
Last Update: | Wed Jul 28 08:11:07 +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 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