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tilt.rb
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tilt.rb
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module Tilt
VERSION = '0.4'
@template_mappings = {}
# Hash of template path pattern => template implementation
# class mappings.
def self.mappings
@template_mappings
end
# Register a template implementation by file extension.
def self.register(ext, template_class)
ext = ext.to_s.sub(/^\./, '')
mappings[ext.downcase] = template_class
end
# Create a new template for the given file using the file's extension
# to determine the the template mapping.
def self.new(file, line=nil, options={}, &block)
if template_class = self[file]
template_class.new(file, line, options, &block)
else
fail "No template engine registered for #{File.basename(file)}"
end
end
# Lookup a template class given for the given filename or file
# extension. Return nil when no implementation is found.
def self.[](file)
if @template_mappings.key?(pattern = file.to_s.downcase)
@template_mappings[pattern]
elsif @template_mappings.key?(pattern = File.basename(pattern))
@template_mappings[pattern]
else
while !pattern.empty?
if @template_mappings.key?(pattern)
return @template_mappings[pattern]
else
pattern = pattern.sub(/^[^.]*\.?/, '')
end
end
nil
end
end
# Base class for template implementations. Subclasses must implement
# the #compile! method and one of the #evaluate or #template_source
# methods.
class Template
# Template source; loaded from a file or given directly.
attr_reader :data
# The name of the file where the template data was loaded from.
attr_reader :file
# The line number in #file where template data was loaded from.
attr_reader :line
# A Hash of template engine specific options. This is passed directly
# to the underlying engine and is not used by the generic template
# interface.
attr_reader :options
# Create a new template with the file, line, and options specified. By
# default, template data is read from the file specified. When a block
# is given, it should read template data and return as a String. When
# file is nil, a block is required.
#
# The #initialize_engine method is called if this is the very first
# time this template subclass has been initialized.
def initialize(file=nil, line=1, options={}, &block)
raise ArgumentError, "file or block required" if file.nil? && block.nil?
options, line = line, 1 if line.is_a?(Hash)
@file = file
@line = line || 1
@options = options || {}
@reader = block || lambda { |t| File.read(file) }
if !self.class.engine_initialized
initialize_engine
self.class.engine_initialized = true
end
end
# 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.
def initialize_engine
end
@engine_initialized = false
class << self ; attr_accessor :engine_initialized ; end
# Load template source and compile the template. The template is
# loaded and compiled the first time this method is called; subsequent
# calls are no-ops.
def compile
if @data.nil?
@data = @reader.call(self)
compile!
end
end
# 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+.
def render(scope=Object.new, locals={}, &block)
compile
evaluate scope, locals || {}, &block
end
# The basename of the template file.
def basename(suffix='')
File.basename(file, suffix) if file
end
# The template file's basename with all extensions chomped off.
def name
basename.split('.', 2).first if basename
end
# The filename used in backtraces to describe the template.
def eval_file
file || '(__TEMPLATE__)'
end
protected
# Do whatever preparation is necessary to "compile" the template.
# 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.
def compile!
raise NotImplementedError
end
# Process the template and return the result. Subclasses should override
# this method unless they implement the #template_source.
def evaluate(scope, locals, &block)
source, offset = local_assignment_code(locals)
source = [source, template_source].join("\n")
scope.instance_eval source, eval_file, line - offset
end
# Return a string containing the (Ruby) source code for the template. The
# default Template#evaluate implementation requires this method be
# defined.
def template_source
raise NotImplementedError
end
private
def local_assignment_code(locals)
return ['', 1] if locals.empty?
source = locals.collect { |k,v| "#{k} = locals[:#{k}]" }
[source.join("\n"), source.length]
end
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
end
# Extremely simple template cache implementation. Calling applications
# create a Tilt::Cache instance and use #fetch with any set of hashable
# arguments (such as those to Tilt.new):
# cache = Tilt::Cache.new
# cache.fetch(path, line, options) { Tilt.new(path, line, options) }
#
# Subsequent invocations return the already compiled template object.
class Cache
def initialize
@cache = {}
end
def fetch(*key)
@cache[key] ||= yield
end
def clear
@cache = {}
end
end
# Template Implementations ================================================
# The template source is evaluated as a Ruby string. The #{} interpolation
# syntax can be used to generated dynamic output.
class StringTemplate < Template
def compile!
@code = "%Q{#{data}}"
end
def template_source
@code
end
end
register 'str', StringTemplate
# ERB template implementation. See:
# http://www.ruby-doc.org/stdlib/libdoc/erb/rdoc/classes/ERB.html
class ERBTemplate < Template
def initialize_engine
require_template_library 'erb' unless defined? ::ERB
end
def compile!
@engine = ::ERB.new(data, options[:safe], options[:trim], '@_out_buf')
end
def template_source
@engine.src
end
def evaluate(scope, locals, &block)
source, offset = local_assignment_code(locals)
source = [source, template_source].join("\n")
original_out_buf =
scope.instance_variables.any? { |var| var.to_sym == :@_out_buf } &&
scope.instance_variable_get(:@_out_buf)
scope.instance_eval source, eval_file, line - offset
output = scope.instance_variable_get(:@_out_buf)
scope.instance_variable_set(:@_out_buf, original_out_buf)
output
end
private
# ERB generates a line to specify the character coding of the generated
# source in 1.9. Account for this in the line offset.
if RUBY_VERSION >= '1.9.0'
def local_assignment_code(locals)
source, offset = super
[source, offset + 1]
end
end
end
%w[erb rhtml].each { |ext| register ext, ERBTemplate }
# Erubis template implementation. See:
# http://www.kuwata-lab.com/erubis/
class ErubisTemplate < ERBTemplate
def initialize_engine
require_template_library 'erubis' unless defined? ::Erubis
end
def compile!
Erubis::Eruby.class_eval(%Q{def add_preamble(src) src << "@_out_buf = _buf = '';" end})
@engine = ::Erubis::Eruby.new(data, options)
end
private
# Erubis doesn't have ERB's line-off-by-one under 1.9 problem. Override
# and adjust back.
if RUBY_VERSION >= '1.9.0'
def local_assignment_code(locals)
source, offset = super
[source, offset - 1]
end
end
end
register 'erubis', ErubisTemplate
# Haml template implementation. See:
# http://haml.hamptoncatlin.com/
class HamlTemplate < Template
def initialize_engine
require_template_library 'haml' unless defined? ::Haml::Engine
end
def compile!
@engine = ::Haml::Engine.new(data, haml_options)
end
def evaluate(scope, locals, &block)
@engine.render(scope, locals, &block)
end
private
def haml_options
options.merge(:filename => eval_file, :line => line)
end
end
register 'haml', HamlTemplate
# Sass template implementation. See:
# http://haml.hamptoncatlin.com/
#
# Sass templates do not support object scopes, locals, or yield.
class SassTemplate < Template
def initialize_engine
require_template_library 'sass' unless defined? ::Sass::Engine
end
def compile!
@engine = ::Sass::Engine.new(data, sass_options)
end
def evaluate(scope, locals, &block)
@engine.render
end
private
def sass_options
options.merge(:filename => eval_file, :line => line)
end
end
register 'sass', SassTemplate
# Lessscss template implementation. See:
# http://lesscss.org/
#
# Less templates do not support object scopes, locals, or yield.
class LessTemplate < Template
def initialize_engine
require_template_library 'less' unless defined? ::Less::Engine
end
def compile!
@engine = ::Less::Engine.new(data)
end
def evaluate(scope, locals, &block)
@engine.to_css
end
end
register 'less', LessTemplate
# Builder template implementation. See:
# http://builder.rubyforge.org/
class BuilderTemplate < Template
def initialize_engine
require_template_library 'builder' unless defined?(::Builder)
end
def compile!
end
def evaluate(scope, locals, &block)
xml = ::Builder::XmlMarkup.new(:indent => 2)
if data.respond_to?(:to_str)
locals[:xml] = xml
super(scope, locals, &block)
elsif data.kind_of?(Proc)
data.call(xml)
end
xml.target!
end
def template_source
data.to_str
end
end
register 'builder', BuilderTemplate
# Liquid template implementation. See:
# http://liquid.rubyforge.org/
#
# Liquid is designed to be a *safe* template system and threfore
# does not provide direct access to execuatable scopes. In order to
# support a +scope+, the +scope+ must be able to represent itself
# as a hash by responding to #to_h. If the +scope+ does not respond
# to #to_h it will be ignored.
#
# LiquidTemplate does not support yield blocks.
#
# It's suggested that your program require 'liquid' at load
# time when using this template engine.
class LiquidTemplate < Template
def initialize_engine
require_template_library 'liquid' unless defined? ::Liquid::Template
end
def compile!
@engine = ::Liquid::Template.parse(data)
end
def evaluate(scope, locals, &block)
locals = locals.inject({}){ |h,(k,v)| h[k.to_s] = v ; h }
if scope.respond_to?(:to_h)
scope = scope.to_h.inject({}){ |h,(k,v)| h[k.to_s] = v ; h }
locals = scope.merge(locals)
end
# TODO: Is it possible to lazy yield ?
locals['yield'] = block.nil? ? '' : yield
locals['content'] = block.nil? ? '' : yield
@engine.render(locals)
end
end
register 'liquid', LiquidTemplate
# Discount Markdown implementation. See:
# http://github.com/rtomayko/rdiscount
#
# RDiscount is a simple text filter. It does not support +scope+ or
# +locals+. The +:smart+ and +:filter_html+ options may be set true
# to enable those flags on the underlying RDiscount object.
class RDiscountTemplate < Template
def flags
[:smart, :filter_html].select { |flag| options[flag] }
end
def initialize_engine
require_template_library 'rdiscount' unless defined? ::RDiscount
end
def compile!
@engine = RDiscount.new(data, *flags)
end
def evaluate(scope, locals, &block)
@engine.to_html
end
end
register 'markdown', RDiscountTemplate
register 'mkd', RDiscountTemplate
register 'md', RDiscountTemplate
# RedCloth implementation. See:
# http://redcloth.org/
class RedClothTemplate < Template
def initialize_engine
require_template_library 'redcloth' unless defined? ::RedCloth
end
def compile!
@engine = RedCloth.new(data)
end
def evaluate(scope, locals, &block)
@engine.to_html
end
end
register 'textile', RedClothTemplate
# Mustache is written and maintained by Chris Wanstrath. See:
# http://github.com/defunkt/mustache
#
# When a scope argument is provided to MustacheTemplate#render, the
# instance variables are copied from the scope object to the Mustache
# view.
class MustacheTemplate < Template
attr_reader :engine
def initialize_engine
require_template_library 'mustache' unless defined? ::Mustache
end
def compile!
Mustache.view_namespace = options[:namespace]
@engine = options[:view] || Mustache.view_class(name)
options.each do |key, value|
next if %w[view namespace mustaches].include?(key.to_s)
@engine.send("#{key}=", value) if @engine.respond_to? "#{key}="
end
end
def evaluate(scope=nil, locals={}, &block)
instance = @engine.new
# copy instance variables from scope to the view
scope.instance_variables.each do |name|
instance.instance_variable_set(name, scope.instance_variable_get(name))
end
# locals get added to the view's context
locals.each do |local, value|
instance[local] = value
end
# if we're passed a block it's a subview. Sticking it in yield
# lets us use {{yield}} in layout.html to render the actual page.
instance[:yield] = block.call if block
instance.template = data unless instance.compiled?
instance.to_html
end
end
register 'mustache', MustacheTemplate
# RDoc template. See:
# http://rdoc.rubyforge.org/
#
# It's suggested that your program require 'rdoc/markup' and
# 'rdoc/markup/to_html' at load time when using this template
# engine.
class RDocTemplate < Template
def initialize_engine
unless defined?(::RDoc::Markup)
require_template_library 'rdoc/markup'
require_template_library 'rdoc/markup/to_html'
end
end
def compile!
markup = RDoc::Markup::ToHtml.new
@engine = markup.convert(data)
end
def evaluate(scope, locals, &block)
@engine.to_s
end
end
register 'rdoc', RDocTemplate
end