Allow to switch used Jade/Pug version!

.gitignore

@@ -5,3 +5,5 @@ pkg/
 tmp/
 /.idea/
 /node_modules/
+/.yardoc/
+/doc/

.rubocop.yml

@@ -0,0 +1,65 @@
+Style/StringLiterals:
+  EnforcedStyle: double_quotes
+
+Metrics/LineLength:
+  Enabled: false
+  Max: 110
+
+Style/FileName:
+  Regex: !ruby/regexp /\A[-a-z0-9]+\z/
+
+Layout/CaseIndentation:
+  EnforcedStyle: end
+
+Layout/AccessModifierIndentation:
+  EnforcedStyle: outdent
+
+Layout/SpaceInsideArrayPercentLiteral:
+  Enabled: false
+
+Layout/EmptyLinesAroundClassBody:
+  Enabled: false
+
+Style/PerlBackrefs:
+  Enabled: false
+
+Bundler/OrderedGems:
+  Enabled: false
+
+Metrics/BlockLength:
+  Enabled: false
+
+Style/EmptyMethod:
+  Enabled: false
+
+Lint/UselessAssignment:
+  Enabled: false
+
+Lint/EndAlignment:
+  EnforcedStyleAlignWith: variable
+
+Lint/UnusedBlockArgument:
+  Enabled: false
+
+Metrics/MethodLength:
+  Max: 20
+
+Layout/ExtraSpacing:
+  Enabled:                 false
+  AllowForAlignment:       true
+  ForceEqualSignAlignment: true
+
+Style/PercentLiteralDelimiters:
+ PreferredDelimiters:
+   default: '[]'
+   '%i':    '[]'
+   '%':     '{}'
+
+Layout/AlignParameters:
+  Enabled: false
+
+Lint/UnusedMethodArgument:
+  Enabled: false
+
+Style/StringLiteralsInInterpolation:
+  EnforcedStyle: double_quotes

.yardopts

@@ -0,0 +1,4 @@
+--protected
+--private
+-
+lib/**/*.rb

Gemfile

@@ -1,8 +1,8 @@
 # encoding: UTF-8
 # frozen_string_literal: true
 
-source 'https://rubygems.org'
+source "https://rubygems.org"
 
 gemspec
 
-gem 'test-unit', '~> 3.1', require: 'test/unit'
+gem "test-unit", "~> 3.1", require: "test/unit"

Gemfile.lock

@@ -2,12 +2,18 @@ PATH
   remote: .
   specs:
     pug-ruby (1.0.2)
+      execjs (~> 2.0)
+      memoist (~> 0.15)
+      regexp-match-polyfill (~> 1.0)
 
 GEM
   remote: https://rubygems.org/
   specs:
+    execjs (2.7.0)
+    memoist (0.16.0)
     power_assert (1.0.2)
     rake (10.5.0)
+    regexp-match-polyfill (1.0.1)
     test-unit (3.2.5)
       power_assert
 

Rakefile

@@ -13,9 +13,9 @@ namespace "javascripts" do
     require "open3"
 
     def run(*args)
-      puts *args
+      puts(*args)
       stdout, stderr, exit_status = Open3.capture3(*args)
-      fail stderr.strip.empty? ? stdout : stderr  unless exit_status.success?
+      fail stderr.strip.empty? ? stdout : stderr unless exit_status.success?
       stdout
     end
 

lib/jade-pug/base.rb

@@ -0,0 +1,116 @@
+# encoding: UTF-8
+# frozen_string_literal: true
+
+require "memoist"
+
+module JadePug
+  extend Memoist
+
+  #
+  # Compiles the template.
+  #
+  # @param source [String, #read]
+  # @param options [Hash]
+  # @return [String]
+  def compile(source, options = {})
+    compiler(@version).compile(source, options)
+  end
+
+  #
+  # Returns engine compiler for given version.
+  # Compilers are cached.
+  #
+  # @param version [String, :system]
+  # @return [Jade::SystemCompiler, Jade::ShippedCompiler, Pug::SystemCompiler, Pug::ShippedCompiler]
+  def compiler(version = @version)
+    (@compilers ||= {})["#{name}-#{version}"] ||= begin
+      case version
+        when :system then self::SystemCompiler.new
+        else              self::ShippedCompiler.new(version)
+      end
+    end
+  end
+
+  #
+  # Switches compiler version.
+  #
+  # - If you want to switch compiler to one of that shipped with gem simple pass version as a string.
+  # - If you want to switch compiler to system pass :system as a version.
+  #
+  # Pass block to temporarily switch the version. Without block the version is switched permanently.
+  #
+  # @param wanted_version [String, :system]
+  # @return [void]
+  def use(wanted_version)
+    previous_version = @version
+    @version         = wanted_version
+    did_switch_version(previous_version, wanted_version)
+
+    if block_given?
+      begin
+        yield
+      ensure
+        @version = previous_version
+        did_switch_version(wanted_version, previous_version)
+      end
+    end
+  end
+
+  #
+  # Executed after compiler version switched.
+  # Outputs some useful information about version being used.
+  #
+  # @param version_from [String, :system]
+  # @param version_to [String, :system]
+  # @return [void]
+  def did_switch_version(version_from, version_to)
+    if version_from != version_to
+      if Symbol === version_to
+        puts "Using #{version_to} #{name}."
+      else
+        puts "Using #{name} #{version_to}. NOTE: Advanced features like includes, extends and blocks will not work."
+      end
+    end
+    nil
+  end
+
+  #
+  # Returns the list of all available engine compiler versions shipped with gem.
+  #
+  # @return [Array<String>]
+  def versions
+    Dir[File.expand_path("../../../vendor/assets/javascripts/**/#{name.downcase}-*.js", __FILE__)].map do |path|
+      File.basename(path).match(/\A#{name.downcase}-(?!runtime-)(?<v>.+)\.min\.js\z/)&.send(:[], :v)
+    end.compact.sort
+  end
+  memoize :versions
+
+  #
+  # Returns the list of all available engine runtime versions shipped with gem.
+  #
+  # @return [Array<String>]
+  def runtime_versions
+    Dir[File.expand_path("../../../vendor/assets/javascripts/**/#{name.downcase}-*.js", __FILE__)].map do |path|
+      File.basename(path).match(/\A#{name.downcase}-runtime-(?<v>.+)\.js\z/)&.send(:[], :v)
+    end.compact.sort
+  end
+  memoize :runtime_versions
+
+  #
+  # Returns version for system-wide installed engine compiler.
+  #
+  # @return [String]
+  def system_version
+    compiler(:system).version
+  end
+
+  #
+  # Returns config object for engine.
+  # Executed only once per engine (return value is memoized).
+  #
+  # @return [Jade::Config, Pug::Config]
+  def config
+    self::Config.new
+  end
+  memoize :config
+end

lib/jade-pug/compiler.rb

@@ -0,0 +1,91 @@
+# encoding: UTF-8
+# frozen_string_literal: true
+
+module JadePug
+  #
+  # Abstraction layer for engine compiler.
+  #
+  class Compiler
+
+    #
+    # Returns the engine module.
+    #
+    # Used in such cases:
+    # - used to compute the name for engine
+    # - used to refer to the error classes
+    #
+    # @return [Jade, Pug]
+    attr_reader :engine
+
+    #
+    # Returns the version of engine compiler.
+    #
+    # @return [String]
+    attr_reader :version
+
+    #
+    # @param engine [Jade, Pug]
+    # @param version [String]
+    def initialize(engine, version)
+      @engine  = engine
+      @version = version
+    end
+
+    #
+    # Compiles template.
+    #
+    # By default does nothing.
+    #
+    # @abstract Derived compilers must implement it.
+    # @param source [String, #read]
+    #   The template source code or any object which responds to #read and returns string.
+    # @param options [Hash]
+    # @return [String]
+    def compile(source, options = {})
+
+    end
+
+  protected
+
+    #
+    # Reads the template source code.
+    # Responds for pre-processing source code.
+    # Actually, it just checks if source code responds to #read and if so
+    #
+    # @param source [String, #read]
+    # @return [String]
+    def prepare_source(source)
+      source.respond_to?(:read) ? source.read : source
+    end
+
+    #
+    # Responds for preparing compilation options.
+    #
+    # The next steps are executed:
+    # - is merges options into the engine config
+    # - it camelizes and symbolizes every option key
+    # - it removes nil values from the options
+    #
+    # @param options [Hash]
+    # @return [Hash]
+    def prepare_options(options)
+      options = engine.config.to_hash.merge(options)
+      options.keys.each { |k, v| options[k.to_s.gsub(/_([a-z])/) { $1.upcase }.to_sym] = options[k] }
+      options.delete_if { |k, v| v.nil? }
+    end
+
+    #
+    # Responds for post-processing compilation result.
+    #
+    # By default returns the result without any processing.
+    # Derived compilers may override it for it's own special behaviors.
+    #
+    # @param source [String] The source code of template.
+    # @param result [String] The compiled code of template.
+    # @param options [Hash] The compilation options.
+    # @return [String]
+    def process_result(source, result, options)
+      result
+    end
+  end
+end

lib/jade-pug/config.rb

@@ -0,0 +1,56 @@
+# encoding: UTF-8
+# frozen_string_literal: true
+
+require "regexp-match-polyfill"
+
+module JadePug
+  #
+  # Defines template engine compiler configuration.
+  #
+  class Config
+    #
+    # Allows to dynamically set config attributes.
+    #
+    def method_missing(name, *args, &block)
+      return super if block
+
+      case args.size
+        when 0
+
+          # config.client?
+          if name =~ /\A(\w+)\?\z/
+            !!(respond_to?($1) ? send($1) : instance_variable_get("@#{$1}"))
+
+          # config.client
+          elsif name =~ /\A(\w+)\z/
+            instance_variable_get("@#{$1}")
+
+          else
+            super
+          end
+
+        when 1
+          # config.client=
+          if name =~ /\A(\w+)=\z/
+            instance_variable_set("@#{$1}", args.first)
+          else
+            super
+          end
+        else
+          super
+      end
+    end
+
+    def respond_to_missing?(name, include_all)
+      name.match?(/\A\w+[=?]?\z/)
+    end
+
+    #
+    # Transforms config to the hash with all keys symbolized.
+    #
+    # @return [Hash]
+    def to_hash
+      instance_variables.map { |var| [var[1..-1].to_sym, instance_variable_get(var)] }.to_h
+    end
+  end
+end

lib/jade-pug/errors/compilation-error.rb

@@ -0,0 +1,14 @@
+# encoding: UTF-8
+# frozen_string_literal: true
+
+module JadePug
+  #
+  # Used for template compilation errors, for example:
+  # - any template engine errors
+  # - syntax errors in template
+  # - any JavaScript exceptions (they are caught by ExecJS)
+  #
+  class CompilationError < StandardError
+
+  end
+end