The Generator is in charge of taking an array of Mustache tokens, usually assembled by the Parser, and generating an interpolatable Ruby string. This string is considered the “compiled” template because at that point we’re relying on Ruby to do the parsing and run our code.

For example, let’s take this template:

  Hi {{thing}}!

If we run this through the Parser we’ll get these tokens:

  [:multi,
    [:static, "Hi "],
    [:mustache, :etag, "thing"],
    [:static, "!\n"]]

Now let’s hand that to the Generator:

>> puts Mustache::Generator.new.compile(tokens) “Hi #{CGI.escapeHTML(ctx[:thing].to_s)}!n“

You can see the generated Ruby string for any template with the mustache(1) command line tool:

  $ mustache --compile test.mustache
  "Hi #{CGI.escapeHTML(ctx[:thing].to_s)}!\n"
Methods
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Class Public methods
new(options = {})

Options are unused for now but may become useful in the future.

# File lib/mustache/generator.rb, line 31
    def initialize(options = {})
      @options = options
    end
Instance Public methods
compile(exp)

Given an array of tokens, returns an interpolatable Ruby string.

# File lib/mustache/generator.rb, line 36
    def compile(exp)
      "\"#{compile!(exp)}\""
    end
compile!(exp)

Given an array of tokens, converts them into Ruby code. In particular there are three types of expressions we are concerned with:

  :multi
    Mixed bag of :static, :mustache, and whatever.

  :static
    Normal HTML, the stuff outside of {{mustaches}}.

  :mustache
    Any Mustache tag, from sections to partials.

To give you an idea of what you’ll be dealing with take this template:

  Hello {{name}}
  You have just won ${{value}}!
  {{#in_ca}}
  Well, ${{taxed_value}}, after taxes.
  {{/in_ca}}

If we run this through the Parser, we’ll get back this array of tokens:

  [:multi,
   [:static, "Hello "],
   [:mustache, :etag, "name"],
   [:static, "\nYou have just won $"],
   [:mustache, :etag, "value"],
   [:static, "!\n"],
   [:mustache,
    :section,
    "in_ca",
    [:multi,
     [:static, "Well, $"],
     [:mustache, :etag, "taxed_value"],
     [:static, ", after taxes.\n"]]]]
# File lib/mustache/generator.rb, line 78
    def compile!(exp)
      case exp.first
      when :multi
        exp[1..-1].map { |e| compile!(e) }.join
      when :static
        str(exp[1])
      when :mustache
        send("on_#{exp[1]}", *exp[2..-1])
      else
        raise "Unhandled exp: #{exp.first}"
      end
    end
ev(s)

An interpolation-friendly version of a string, for use within a Ruby string.

# File lib/mustache/generator.rb, line 150
    def ev(s)
      "#\{#{s}}"
    end
on_etag(name)

An escaped tag.

# File lib/mustache/generator.rb, line 144
    def on_etag(name)
      ev("CGI.escapeHTML(ctx[#{name.to_sym.inspect}].to_s)")
    end
on_inverted_section(name, content)

Fired when we find an inverted section. Just like `on_section`, we’re passed the inverted section name and the array of tokens.

# File lib/mustache/generator.rb, line 115
    def on_inverted_section(name, content)
      # Convert the tokenized content of this section into a Ruby
      # string we can use.
      code = compile(content)

      # Compile the Ruby for this inverted section now that we know
      # what's inside.
      ev("v = ctx[\#{name.to_sym.inspect}]\nif v.nil? || v == false || v.respond_to?(:empty?) && v.empty?\n\#{code}\nend\n")
    end
on_partial(name)

Fired when the compiler finds a partial. We want to return code which calls a partial at runtime instead of expanding and including the partial’s body to allow for recursive partials.

# File lib/mustache/generator.rb, line 134
    def on_partial(name)
      ev("ctx.partial(#{name.to_sym.inspect})")
    end
on_section(name, content)

Callback fired when the compiler finds a section token. We’re passed the section name and the array of tokens.

# File lib/mustache/generator.rb, line 93
    def on_section(name, content)
      # Convert the tokenized content of this section into a Ruby
      # string we can use.
      code = compile(content)

      # Compile the Ruby for this section now that we know what's
      # inside the section.
      ev("if v = ctx[\#{name.to_sym.inspect}]\nif v == true\n\#{code}\nelse\nv = [v] unless v.is_a?(Array) # shortcut when passed non-array\nv.map { |h| ctx.push(h); r = \#{code}; ctx.pop; r }.join\nend\nend\n")
    end
on_utag(name)

An unescaped tag.

# File lib/mustache/generator.rb, line 139
    def on_utag(name)
      ev("ctx[#{name.to_sym.inspect}]")
    end
str(s)
# File lib/mustache/generator.rb, line 154
    def str(s)
      s.inspect[1..-2]
    end