Class Haml::Engine
In: lib/haml/engine.rb
Parent: Object

This is the frontend for using Haml programmatically. It can be directly used by the user by creating a new instance and calling \{render} to render the template. For example:

    template = File.read('templates/really_cool_template.haml')
    haml_engine = Haml::Engine.new(template)
    output = haml_engine.render
    puts output

Methods

Included Modules

Precompiler

Attributes

indentation  [RW]  The indentation used in the Haml document, or `nil` if the indentation is ambiguous (for example, for a single-level document).

@return [String]

options  [RW]  The options hash. See {file:HAML_REFERENCE.md#haml_options the Haml options documentation}.

@return [{Symbol => Object}]

Public Class methods

Precompiles the Haml template.

@param template [String] The Haml template @param options [{Symbol => Object}] An options hash;

  see {file:HAML_REFERENCE.md#haml_options the Haml options documentation}

@raise [Haml::Error] if there‘s a Haml syntax error in the template

[Source]

     # File lib/haml/engine.rb, line 72
 72:     def initialize(template, options = {})
 73:       @options = {
 74:         :suppress_eval => false,
 75:         :attr_wrapper => "'",
 76: 
 77:         # Don't forget to update the docs in doc-src/HAML_REFERENCE.md
 78:         # if you update these
 79:         :autoclose => %w[meta img link br hr input area param col base],
 80:         :preserve => %w[textarea pre code],
 81: 
 82:         :filename => '(haml)',
 83:         :line => 1,
 84:         :ugly => false,
 85:         :format => :xhtml,
 86:         :escape_html => false,
 87:       }
 88:       unless ruby1_8?
 89:         @options[:encoding] = Encoding.default_internal || "utf-8"
 90:       end
 91:       @options.merge! options.reject {|k, v| v.nil?}
 92:       @index = 0
 93: 
 94:       unless [:xhtml, :html4, :html5].include?(@options[:format])
 95:         raise Haml::Error, "Invalid format #{@options[:format].inspect}"
 96:       end
 97: 
 98:       if @options[:encoding] && @options[:encoding].is_a?(Encoding)
 99:         @options[:encoding] = @options[:encoding].name
100:       end
101: 
102:       # :eod is a special end-of-document marker
103:       @template = (template.rstrip).split(/\r\n|\r|\n/) + [:eod, :eod]
104:       @template_index = 0
105:       @to_close_stack = []
106:       @output_tabs = 0
107:       @template_tabs = 0
108:       @flat = false
109:       @newlines = 0
110:       @precompiled = ''
111:       @to_merge = []
112:       @tab_change  = 0
113: 
114:       precompile
115:     rescue Haml::Error => e
116:       e.backtrace.unshift "#{@options[:filename]}:#{(e.line ? e.line + 1 : @index) + @options[:line] - 1}" if @index
117:       raise
118:     end

Public Instance methods

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_`).

@param object [Object, Module] The object on which to define the method @param name [String, Symbol] The name of the method to define @param local_names [Array<Symbol>] The names of the locals that can be passed to the proc

[Source]

     # File lib/haml/engine.rb, line 263
263:     def def_method(object, name, *local_names)
264:       method = object.is_a?(Module) ? :module_eval : :instance_eval
265: 
266:       object.send(method, "def #{name}(_haml_locals = {}); #{precompiled_with_ambles(local_names)}; end",
267:                   @options[:filename], @options[:line])
268:     end

@return [Boolean] Whether or not the format is HTML4.

[Source]

    # File lib/haml/engine.rb, line 44
44:     def html4?
45:       @options[:format] == :html4
46:     end

@return [Boolean] Whether or not the format is HTML5.

[Source]

    # File lib/haml/engine.rb, line 49
49:     def html5?
50:       @options[:format] == :html5
51:     end

@return [Boolean] Whether or not the format is any flavor of HTML.

[Source]

    # File lib/haml/engine.rb, line 39
39:     def html?
40:       html4? or html5?
41:     end

The source code that is evaluated to produce the Haml document.

In Ruby 1.9, this is automatically converted to the correct encoding (see {file:HAML_REFERENCE.md#encoding-option the `:encoding` option}).

@return [String]

[Source]

    # File lib/haml/engine.rb, line 59
59:     def precompiled
60:       return @precompiled if ruby1_8?
61:       encoding = Encoding.find(@options[:encoding])
62:       return @precompiled.force_encoding(encoding) if encoding == Encoding::BINARY
63:       return @precompiled.encode(encoding)
64:     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.respond_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.

@param scope [Binding, Proc, Object] The context in which the template is evaluated @param locals [{Symbol => Object}] Local variables that will be made available

  to the template

@param block [to_proc] A block that can be yielded to within the template @return [String] The rendered template

[Source]

     # File lib/haml/engine.rb, line 161
161:     def render(scope = Object.new, locals = {}, &block)
162:       buffer = Haml::Buffer.new(scope.instance_variable_get('@haml_buffer'), options_for_buffer)
163: 
164:       if scope.is_a?(Binding) || scope.is_a?(Proc)
165:         scope_object = eval("self", scope)
166:         scope = scope_object.instance_eval{binding} if block_given?
167:       else
168:         scope_object = scope
169:         scope = scope_object.instance_eval{binding}
170:       end
171: 
172:       set_locals(locals.merge(:_hamlout => buffer, :_erbout => buffer.buffer), scope, scope_object)
173: 
174:       scope_object.instance_eval do
175:         extend Haml::Helpers
176:         @haml_buffer = buffer
177:       end
178: 
179:       eval(precompiled + ";" + precompiled_method_return_value,
180:         scope, @options[:filename], @options[:line])
181:     ensure
182:       # Get rid of the current buffer
183:       scope_object.instance_eval do
184:         @haml_buffer = buffer.upper
185:       end
186:     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.

@param scope [Binding, Proc, Object] The context in which the template is evaluated @param local_names [Array<Symbol>] The names of the locals that can be passed to the proc @return [Proc] The proc that will run the template

[Source]

     # File lib/haml/engine.rb, line 213
213:     def render_proc(scope = Object.new, *local_names)
214:       if scope.is_a?(Binding) || scope.is_a?(Proc)
215:         scope_object = eval("self", scope)
216:       else
217:         scope_object = scope
218:         scope = scope_object.instance_eval{binding}
219:       end
220: 
221:       eval("Proc.new { |*_haml_locals| _haml_locals = _haml_locals[0] || {};" +
222:            precompiled_with_ambles(local_names) + "}\n", scope, @options[:filename], @options[:line])
223:     end
to_html(scope = Object.new, locals = {}, &block)

Alias for render

@return [Boolean] Whether or not the format is XHTML.

[Source]

    # File lib/haml/engine.rb, line 34
34:     def xhtml?
35:       not html?
36:     end

Protected Instance methods

Returns a subset of \{options}: those that {Haml::Buffer} cares about. All of the values here are such that when `inspect` is called on the hash, it can be `Kernel#eval`ed to get the same result back.

See {file:HAML_REFERENCE.md#haml_options the Haml options documentation}.

@return [{Symbol => Object}] The options hash

[Source]

     # File lib/haml/engine.rb, line 279
279:     def options_for_buffer
280:       {
281:         :autoclose => @options[:autoclose],
282:         :preserve => @options[:preserve],
283:         :attr_wrapper => @options[:attr_wrapper],
284:         :ugly => @options[:ugly],
285:         :format => @options[:format],
286:         :encoding => @options[:encoding],
287:         :escape_html => @options[:escape_html],
288:       }
289:     end

[Validate]