Class | Haml::Engine |
In: |
lib/haml/engine.rb
|
Parent: | Object |
This is the class where all the parsing and processing of the Haml template is done. It can be directly used by the user by creating a new instance and calling to_html to render the template. For example:
template = File.read('templates/really_cool_template.haml') haml_engine = Haml::Engine.new(template) output = haml_engine.to_html puts output
options | [RW] | Allow reading and writing of the options hash |
precompiled | [RW] | This string contains the source code that is evaluated to produce the Haml document. |
Creates a new instace of Haml::Engine that will compile the given template string when render is called. See README for available options.
# File lib/haml/engine.rb, line 36 36: def initialize(template, options = {}) 37: @options = { 38: :suppress_eval => false, 39: :attr_wrapper => "'", 40: :autoclose => ['meta', 'img', 'link', 'br', 'hr', 'input', 'area'], 41: :filters => { 42: 'sass' => Sass::Engine, 43: 'plain' => Haml::Filters::Plain, 44: 'preserve' => Haml::Filters::Preserve, 45: 'redcloth' => Haml::Filters::RedCloth, 46: 'textile' => Haml::Filters::Textile, 47: 'markdown' => Haml::Filters::Markdown }, 48: :filename => '(haml)' 49: } 50: @options.rec_merge! options 51: 52: unless @options[:suppress_eval] 53: @options[:filters].merge!({ 54: 'erb' => ERB, 55: 'ruby' => Haml::Filters::Ruby 56: }) 57: end 58: @options[:filters].rec_merge! options[:filters] if options[:filters] 59: 60: if @options[:locals] 61: warn "DEPRECATION WARNING:\nThe Haml :locals option is deprecated and will be removed in version 2.0.\nUse the locals option for Haml::Engine#render instead.\n" 62: end 63: 64: @template = template.strip #String 65: @to_close_stack = [] 66: @output_tabs = 0 67: @template_tabs = 0 68: @index = 0 69: @flat_spaces = -1 70: 71: precompile 72: rescue Haml::Error 73: $!.backtrace.unshift "#{@options[:filename]}:#{@index}" 74: raise 75: end
Defines a method on object with the given name that renders the template and returns the result as a string.
If object is a class or module, the method will instead by defined as an instance method. For example:
t = Time.now Haml::Engine.new("%p\n Today's date is\n .date= self.to_s").def_method(t, :render) t.render #=> "<p>\n Today's date is\n <div class='date'>Fri Nov 23 18:28:29 -0800 2007</div>\n</p>\n" Haml::Engine.new(".upcased= upcase").def_method(String, :upcased_div) "foobar".upcased_div #=> "<div class='upcased'>FOOBAR</div>\n"
The first argument of the defined method is a hash of local variable names to values. However, due to an unfortunate Ruby quirk, the local variables which can be assigned must be pre-declared. This is done with the local_names argument. For example:
# This works obj = Object.new Haml::Engine.new("%p= foo").def_method(obj, :render, :foo) obj.render(:foo => "Hello!") #=> "<p>Hello!</p>" # This doesn't obj = Object.new Haml::Engine.new("%p= foo").def_method(obj, :render) obj.render(:foo => "Hello!") #=> NameError: undefined local variable or method `foo'
Note that Haml modifies the evaluation context (either the scope object or the "self" object of the scope binding). It extends Haml::Helpers, and various instance variables are set (all prefixed with "haml").
# File lib/haml/engine.rb, line 218 218: def def_method(object, name, *local_names) 219: method = object.is_a?(Module) ? :module_eval : :instance_eval 220: 221: object.send(method, "def #{name}(_haml_locals = {}); #{precompiled_with_ambles(local_names)}; end", 222: @options[:filename], 0) 223: end
Processes the template and returns the result as a string.
scope is the context in which the template is evaluated. If it‘s a Binding or Proc object, Haml uses it as the second argument to Kernel#eval; otherwise, Haml just uses its instance_eval context.
Note that Haml modifies the evaluation context (either the scope object or the "self" object of the scope binding). It extends Haml::Helpers, and various instance variables are set (all prefixed with "haml"). For example:
s = "foobar" Haml::Engine.new("%p= upcase").render(s) #=> "<p>FOOBAR</p>" # s now extends Haml::Helpers s.responds_to?(:html_attrs) #=> true
locals is a hash of local variables to make available to the template. For example:
Haml::Engine.new("%p= foo").render(Object.new, :foo => "Hello, world!") #=> "<p>Hello, world!</p>"
If a block is passed to render, that block is run when yield is called within the template.
Due to some Ruby quirks, if scope is a Binding or Proc object and a block is given, the evaluation context may not be quite what the user expects. In particular, it‘s equivalent to passing eval("self", scope) as scope. This won‘t have an effect in most cases, but if you‘re relying on local variables defined in the context of scope, they won‘t work.
# File lib/haml/engine.rb, line 117 117: def render(scope = Object.new, locals = {}, &block) 118: locals = (@options[:locals] || {}).merge(locals) 119: buffer = Haml::Buffer.new(options_for_buffer) 120: 121: if scope.is_a?(Binding) || scope.is_a?(Proc) 122: scope_object = eval("self", scope) 123: scope = scope_object.instance_eval{binding} if block_given? 124: else 125: scope_object = scope 126: scope = scope_object.instance_eval{binding} 127: end 128: 129: set_locals(locals.merge(:_hamlout => buffer, :_erbout => buffer.buffer), scope, scope_object) 130: 131: scope_object.instance_eval do 132: extend Haml::Helpers 133: @haml_stack ||= Array.new 134: @haml_stack.push(buffer) 135: @haml_is_haml = true 136: end 137: 138: eval(@precompiled, scope, @options[:filename], 0) 139: 140: # Get rid of the current buffer 141: scope_object.instance_eval do 142: @haml_stack.pop 143: @haml_is_haml = false 144: end 145: 146: buffer.buffer 147: end
Returns a proc that, when called, renders the template and returns the result as a string.
scope works the same as it does for render.
The first argument of the returned proc is a hash of local variable names to values. However, due to an unfortunate Ruby quirk, the local variables which can be assigned must be pre-declared. This is done with the local_names argument. For example:
# This works Haml::Engine.new("%p= foo").render_proc(Object.new, :foo).call :foo => "Hello!" #=> "<p>Hello!</p>" # This doesn't Haml::Engine.new("%p= foo").render_proc.call :foo => "Hello!" #=> NameError: undefined local variable or method `foo'
The proc doesn‘t take a block; any yields in the template will fail.
# File lib/haml/engine.rb, line 171 171: def render_proc(scope = Object.new, *local_names) 172: if scope.is_a?(Binding) || scope.is_a?(Proc) 173: scope_object = eval("self", scope) 174: else 175: scope_object = scope 176: scope = scope_object.instance_eval{binding} 177: end 178: 179: eval("Proc.new { |*_haml_locals| _haml_locals = _haml_locals[0] || {};" + 180: precompiled_with_ambles(local_names) + "}\n", scope, @options[:filename], 0) 181: end