class Tilt::Template

Base class for template implementations. Subclasses must implement the prepare method and one of the evaluate or precompiled_template methods.

Attributes

default_mime_type[RW]
engine_initialized[RW]
engine_initialized?[RW]
data[R]

Template source; loaded from a file or given directly.

file[R]

The name of the file where the template data was loaded from.

line[R]

The line number in file where template data was loaded from.

options[R]

A Hash of template engine specific options. This is passed directly to the underlying engine and is not used by the generic template interface.

Public Class Methods

new(file=nil, line=1, options={}, &block) click to toggle source

Create a new template with the file, line, and options specified. By default, template data is read from the file. When a block is given, it should read template data and return as a String. When file is nil, a block is required.

All arguments are optional.

# File lib/tilt/template.rb, line 38
def initialize(file=nil, line=1, options={}, &block)
  @file, @line, @options = nil, 1, {}

  [options, line, file].compact.each do |arg|
    case
    when arg.respond_to?(:to_str)  ; @file = arg.to_str
    when arg.respond_to?(:to_int)  ; @line = arg.to_int
    when arg.respond_to?(:to_hash) ; @options = arg.to_hash.dup
    when arg.respond_to?(:path)    ; @file = arg.path
    else raise TypeError
    end
  end

  raise ArgumentError, "file or block required" if (@file || block).nil?

  # call the initialize_engine method if this is the very first time
  # an instance of this class has been created.
  if !self.class.engine_initialized?
    initialize_engine
    self.class.engine_initialized = true
  end

  # used to hold compiled template methods
  @compiled_method = {}

  # used on 1.9 to set the encoding if it is not set elsewhere (like a magic comment)
  # currently only used if template compiles to ruby
  @default_encoding = @options.delete :default_encoding

  # load template data and prepare (uses binread to avoid encoding issues)
  @reader = block || lambda { |t| read_template_file }
  @data = @reader.call(self)

  if @data.respond_to?(:force_encoding)
    @data.force_encoding(default_encoding) if default_encoding

    if !@data.valid_encoding?
      raise Encoding::InvalidByteSequenceError, "#{eval_file} is not valid #{@data.encoding}"
    end
  end

  prepare
end

Public Instance Methods

allows_script?() click to toggle source

Whether or not this template engine allows executing Ruby script within the template. If this is false, scope and locals will generally not be used, nor will the provided block be avaiable via yield. This should be overridden by template subclasses.

# File lib/tilt/template.rb, line 126
def allows_script?
  true
end
basename(suffix='') click to toggle source

The basename of the template file.

# File lib/tilt/template.rb, line 107
def basename(suffix='')
  File.basename(file, suffix) if file
end
default_encoding() click to toggle source

The encoding of the source data. Defaults to the default_encoding-option if present. You may override this method in your template class if you have a better hint of the data’s encoding.

# File lib/tilt/template.rb, line 86
def default_encoding
  @default_encoding
end
eval_file() click to toggle source

The filename used in backtraces to describe the template.

# File lib/tilt/template.rb, line 117
def eval_file
  file || '(__TEMPLATE__)'
end
name() click to toggle source

The template file’s basename with all extensions chomped off.

# File lib/tilt/template.rb, line 112
def name
  basename.split('.', 2).first if basename
end
read_template_file() click to toggle source
# File lib/tilt/template.rb, line 90
def read_template_file
  data = File.open(file, 'rb') { |io| io.read }
  if data.respond_to?(:force_encoding)
    # Set it to the default external (without verifying)
    data.force_encoding(Encoding.default_external) if Encoding.default_external
  end
  data
end
render(scope=Object.new, locals={}, &block) click to toggle source

Render the template in the given scope with the locals specified. If a block is given, it is typically available within the template via yield.

# File lib/tilt/template.rb, line 102
def render(scope=Object.new, locals={}, &block)
  evaluate scope, locals || {}, &block
end

Protected Instance Methods

compiled_method(locals_keys) click to toggle source

The compiled method for the locals keys provided.

# File lib/tilt/template.rb, line 238
def compiled_method(locals_keys)
  @compiled_method[locals_keys] ||=
    compile_template_method(locals_keys)
end
evaluate(scope, locals, &block) click to toggle source

Execute the compiled template and return the result string. Template evaluation is guaranteed to be performed in the scope object with the locals specified and with support for yielding to the block.

This method is only used by source generating templates. Subclasses that override render() may not support all features.

# File lib/tilt/template.rb, line 168
def evaluate(scope, locals, &block)
  method = compiled_method(locals.keys)
  method.bind(scope).call(locals, &block)
end
initialize_engine() click to toggle source

Called once and only once for each template subclass the first time the template class is initialized. This should be used to require the underlying template library and perform any initial setup.

# File lib/tilt/template.rb, line 134
def initialize_engine
end
precompiled(locals) click to toggle source

Generates all template source by combining the preamble, template, and postamble and returns a two-tuple of the form: [source, offset], where source is the string containing (Ruby) source code for the template and offset is the integer line offset where line reporting should begin.

Template subclasses may override this method when they need complete control over source generation or want to adjust the default line offset. In most cases, overriding the precompiled_template method is easier and more appropriate.

# File lib/tilt/template.rb, line 182
def precompiled(locals)
  preamble = precompiled_preamble(locals)
  template = precompiled_template(locals)
  postamble = precompiled_postamble(locals)
  source = ''

  # Ensure that our generated source code has the same encoding as the
  # the source code generated by the template engine.
  if source.respond_to?(:force_encoding)
    template_encoding = extract_encoding(template)

    source.force_encoding(template_encoding)
    template.force_encoding(template_encoding)
  end

  # https://github.com/rtomayko/tilt/issues/193
  warn "precompiled_preamble should return String (not Array)" if preamble.is_a?(Array)
  warn "precompiled_postamble should return String (not Array)" if postamble.is_a?(Array)
  source << [preamble, template, postamble].join("\n")

  [source, preamble.count("\n")+1]
end
precompiled_postamble(locals) click to toggle source

Generates postamble code for the precompiled template source. The string returned from this method is appended to the precompiled template source.

# File lib/tilt/template.rb, line 233
def precompiled_postamble(locals)
  ''
end
precompiled_preamble(locals) click to toggle source

Generates preamble code for initializing template state, and performing locals assignment. The default implementation performs locals assignment only. Lines included in the preamble are subtracted from the source line offset, so adding code to the preamble does not effect line reporting in Kernel::caller and backtraces.

# File lib/tilt/template.rb, line 220
def precompiled_preamble(locals)
  locals.map do |k,v|
    if k.to_s =~ /\A[a-z_][a-zA-Z_0-9]*\z/
      "#{k} = locals[#{k.inspect}]"
    else
      raise "invalid locals key: #{k.inspect} (keys must be variable names)"
    end
  end.join("\n")
end
precompiled_template(locals) click to toggle source

A string containing the (Ruby) source code for the template. The default #evaluate implementation requires either this method or the precompiled method be overridden. When defined, the base Template guarantees correct file/line handling, locals support, custom scopes, proper encoding, and support for template compilation.

# File lib/tilt/template.rb, line 211
def precompiled_template(locals)
  raise NotImplementedError
end
prepare() click to toggle source

Do whatever preparation is necessary to setup the underlying template engine. Called immediately after template data is loaded. Instance variables set in this method are available when evaluate is called.

Subclasses must provide an implementation of this method.

# File lib/tilt/template.rb, line 152
def prepare
  if respond_to?(:compile!)
    # backward compat with tilt < 0.6; just in case
    warn 'Tilt::Template#compile! is deprecated; implement #prepare instead.'
    compile!
  else
    raise NotImplementedError
  end
end
require_template_library(name) click to toggle source

Like Kernel#require but issues a warning urging a manual require when running under a threaded environment.

# File lib/tilt/template.rb, line 139
def require_template_library(name)
  if Thread.list.size > 1
    warn "WARN: tilt autoloading '#{name}' in a non thread-safe way; " +
         "explicit require '#{name}' suggested."
  end
  require name
end