Module: Papercraft::Tags

Included in:
HTML, XML
Defined in:
lib/papercraft/tags.rb

Overview

Markup (HTML/XML) extensions

Constant Summary collapse

S_LT = 
'<'
S_GT = 
'>'
S_LT_SLASH = 
'</'
S_SPACE_LT_SLASH = 
' </'
S_SLASH_GT = 
'/>'
S_GT_LT_SLASH = 
'></'
S_SPACE = 
' '
S_EQUAL_QUOTE = 
'="'
S_QUOTE = 
'"'
S_TAG_METHOD_LINE =

The tag method template below is optimized for performance. Do not touch!

__LINE__ + 2
S_TAG_METHOD = 
<<~EOF
  S_TAG_%<TAG>s_PRE = %<tag_pre>s
  S_TAG_%<TAG>s_CLOSE = %<tag_close>s

  def %<tag>s(text = nil, _for: nil, **attributes, &block)
    return if @render_fragment && @fragment != @render_fragment

    return _for.each { |*a| %<tag>s(text, **attributes) { block.(*a)} } if _for

    if text.is_a?(Hash) && attributes.empty?
      attributes = text
      text = nil
    end

    @buffer << S_TAG_%<TAG>s_PRE
    emit_attributes(attributes) unless attributes.empty?

    if block
      @buffer << S_GT
      instance_eval(&block)
      @buffer << S_TAG_%<TAG>s_CLOSE
    elsif Proc === text
      @buffer << S_GT
      emit(text)
      @buffer << S_TAG_%<TAG>s_CLOSE
    elsif text
      @buffer << S_GT << escape_text(text.to_s) << S_TAG_%<TAG>s_CLOSE
    else
      @buffer << S_GT << S_TAG_%<TAG>s_CLOSE
    end
  end
EOF
S_VOID_TAG_METHOD_LINE = 
__LINE__ + 2
S_VOID_TAG_METHOD = 
<<~EOF
  S_TAG_%<TAG>s_PRE = %<tag_pre>s
  S_TAG_%<TAG>s_CLOSE = %<tag_close>s

  def %<tag>s(text = nil, _for: nil, **attributes, &block)
    return if @render_fragment && @fragment != @render_fragment
    
    return _for.each { |*a| %<tag>s(text, **attributes) { block.(*a)} } if _for

    if text.is_a?(Hash) && attributes.empty?
      attributes = text
      text = nil
    end

    @buffer << S_TAG_%<TAG>s_PRE
    emit_attributes(attributes) unless attributes.empty?

    if block
      @buffer << S_GT
      instance_eval(&block)
      @buffer << S_TAG_%<TAG>s_CLOSE
    elsif Proc === text
      @buffer << S_GT
      emit(text)
      @buffer << S_TAG_%<TAG>s_CLOSE
    elsif text
      @buffer << S_GT << escape_text(text.to_s) << S_TAG_%<TAG>s_CLOSE
    else
      @buffer << S_SLASH_GT
    end
  end
EOF
INITIAL_BUFFER_CAPACITY = 
8192

Instance Method Summary collapse

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(sym, *args, **opts, &block) ⇒ void

This method returns an undefined value.

Catches undefined tag method call and handles it by defining the method.

Parameters:

  • sym (Symbol) —

    tag or component identifier

  • args (Array) —

    method arguments

  • opts (Hash) —

    named method arguments



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# File 'lib/papercraft/tags.rb', line 207

def method_missing(sym, *args, **opts, &block)
  tag = sym.to_s
  if tag =~ /^[A-Z]/ && (Object.const_defined?(tag))
    define_const_tag_method(tag)
  else
    define_tag_method(tag)
  end

  send(sym, *args, **opts, &block)
end

Instance Method Details

#def_tag(tag, &block) ⇒ void

This method returns an undefined value.

Defines a custom tag. This is handy for defining helper or extension methods inside the template body.

Papercraft.html {
  def_tag(:section) { |title, &inner|
    div {
      h1 title
      emit inner
    }
  }

  section('Foo') {
    p 'Bar'
  }
}

Parameters:

  • tag (Symbol, String) —

    tag/method name

  • block (Proc) —

    method body



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# File 'lib/papercraft/tags.rb', line 249

def def_tag(tag, &block)
  self.class.define_method(tag, &block)
end

#defer(&block) ⇒ void

This method returns an undefined value.

Defers the given block to be evaluated later. Deferred evaluation allows Papercraft templates to inject state into sibling components, regardless of the component’s order in the container component. For example, a nested component may set an instance variable used by another component. This is an elegant solution to the problem of setting the XML page’s title, or adding elements to the ‘<head>` section. Here’s how a title can be controlled from a nested component:

layout = Papercraft.html {
  html {
    head {
      defer { title @title }
    }
    body {
      emit_yield
    }
  }
}

html.render {
  @title = 'My super page'
  h1 'content'
}



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# File 'lib/papercraft/tags.rb', line 143

def defer(&block)
  if !@parts
    @parts = [@buffer, block]
  else
    @parts << @buffer unless @buffer.empty?
    @parts << block
  end
  @buffer = String.new(capacity: INITIAL_BUFFER_CAPACITY)
end

#extend(ext) ⇒ Object

Extends the template with the provided module or map of modules. When given a module, the template body will be extended with the module, and will have access to all the module’s methods:

module CustomTags
  def label(text)
    span text, class: 'label'
  end
end

Papercraft.html {
  extend CustomTags
  label('foo')
}

When given a hash, each module in the hash is namespaced, and can be accessed using its key:

Papercraft.html {
  extend custom: CustomTags
  custom.label('foo')
}

Parameters:

  • ext (Module, Hash) —

    extension module or hash mapping symbols to modules

Returns:

  • (Object) —

    self



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# File 'lib/papercraft/tags.rb', line 280

def extend(ext)
  if ext.is_a?(Module)
    orig_extend(ext)
  else
    ext.each do |sym, mod|
      define_extension_method(sym, mod)
    end
  end
end

#initialize(render_fragment = nil, &template) ⇒ Object

Initializes a tag renderer.



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# File 'lib/papercraft/tags.rb', line 92

def initialize(render_fragment = nil, &template)
  @buffer = String.new(capacity: INITIAL_BUFFER_CAPACITY)
  super(render_fragment)
end

#orig_extend ⇒ Object 



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# File 'lib/papercraft/tags.rb', line 253

alias_method :orig_extend, :extend

#tag(sym, text = nil, _for: nil, **attributes, &block) ⇒ void

This method returns an undefined value.

Emits an XML tag with the given content, properties and optional block. This method is an alternative to emitting XML tags using dynamically created methods. This is particularly useful when using extensions that have method names that clash with XML tags, such as ‘button` or `a`, or when you need to override the behaviour of a particular XML tag.

The following two method calls have the same effect:

button ‘text’, id: ‘button1’ tag :button, ‘text’, id: ‘button1’

Parameters:

  • sym (Symbol, String) —

    XML tag

  • text (String, nil) (defaults to: nil) —

    tag content

  • **attributes (Hash) —

    tag attributes



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# File 'lib/papercraft/tags.rb', line 169

def tag(sym, text = nil, _for: nil, **attributes, &block)
  return if @render_fragment && @fragment != @render_fragment
    
  return _for.each { |*a| tag(sym, text, **attributes) { block.(*a)} } if _for

  if text.is_a?(Hash) && attributes.empty?
    attributes = text
    text = nil
  end

  tag = tag_repr(sym)

  @buffer << S_LT << tag
  emit_attributes(attributes) unless attributes.empty?

  if block
    @buffer << S_GT
    instance_eval(&block)
    @buffer << S_LT_SLASH << tag << S_GT
  elsif Proc === text
    @buffer << S_GT
    emit(text)
    @buffer << S_LT_SLASH << tag << S_GT
  elsif text
    @buffer << S_GT << escape_text(text.to_s) << S_LT_SLASH << tag << S_GT
  elsif is_void_element_tag?(sym)
    @buffer << S_SLASH_GT
  else
    @buffer << S_GT_LT_SLASH << tag << S_GT
  end
end

#text(data = nil) ⇒ void

This method returns an undefined value.

Emits text into the rendering buffer, escaping any special characters to the respective XML entities.

Parameters:

  • data (String, nil) (defaults to: nil) —

    text



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# File 'lib/papercraft/tags.rb', line 223

def text(data = nil)
  return if !data
  return if @render_fragment && @fragment != @render_fragment
    
  @buffer << escape_text(data)
end

#to_s ⇒ String

Returns the rendered template.

Returns:

  • (String) 


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# File 'lib/papercraft/tags.rb', line 100

def to_s
  if @parts
    last = @buffer
    @buffer = String.new(capacity: INITIAL_BUFFER_CAPACITY)
    parts = @parts
    @parts = nil
    parts.each do |p|
      if Proc === p
        render_deferred_proc(&p)
      else
        @buffer << p
      end
    end
    @buffer << last unless last.empty?
  end
  @buffer
end