Class: Feather::Template

Inherits:
Object
  • Object
show all
Defined in:
lib/feather/template.rb

Defined Under Namespace

Classes: ArgumentError, MissingVariable, ParseError, RecursionError, TemplateHash, VariableTracker

Constant Summary collapse

TOKEN_REGEXP =

Constants ============================================================

/((?:[^\{]|\{[^\{]|\{\{\{)+)|\{\{\s*([\&\%\$\.\:\#\^\*\/\=\!]|\?\!?)?([^\}]*)\}\}/.freeze
TOKEN_TRIGGER = 
/\{\{/.freeze

Instance Method Summary collapse

Constructor Details

#initialize(content, options = nil) {|_self| ... } ⇒ Template

Creates a new template with the supplied contens. Options may be specified:

  • :html - Automatically escape fields for HTML

  • :text - Default mode, render all fields literally

Yields:

  • (_self)

Yield Parameters:



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# File 'lib/feather/template.rb', line 33

def initialize(content, options = nil)
  @escape_method = nil

  if (options)
    if (source = options[:escape])
      case (source.to_sym)
      when :html, :html_escape
        @escape_method = :html_escape
      when :text, nil
        # Default, ignored
      else
        raise ArgumentError, "Unknown escape source #{source}"
      end
    end
  end
  
  @content =
    case (content)
    when IO
      content.read
    else
      content.to_s
    end

  yield(self) if (block_given?)
end

Instance Method Details

#compile(options) ⇒ Object

Compiles a template and manipulates the options strucutre passed in. Keys supported are:

  • :escape_method - Defines the default escape method for this template.

  • :templates - Hash to capture the templates referenced in this template.

  • :variables - Hash to capture the variables referenced in this template.

  • :source - String to capture the Ruby equivalent of this template.



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# File 'lib/feather/template.rb', line 155

def compile(options)
  escape_method = options[:escape_method]
  sections = options[:sections]
  templates = options[:templates]
  variables = options[:variables]
  source = options[:source]

  stack = [ [ :base, nil, VariableTracker.new ] ]
  stack_variables = nil
  
  @content.scan(TOKEN_REGEXP).each do |text, tag_type, tag|
    if (text)
      text = text.sub(/\{(\{\{+)/, '\1').sub(/\}(\}\}+)/, '\1')
      
      source and source << "r<<#{text.inspect};"
    else
      tag = tag.strip
      tag = tag.empty? ? nil : tag.to_sym
      
      case (tag_type)
      when '&'
        # HTML escaped
        index = stack[-1][2][tag.inspect]

        source and source << "v&&r<<h.html_escape((v.is_a?(Array)?v[#{index}]:v[#{tag.inspect}]).to_s);"
        
        variables and variables[tag] = true
      when '%'
        # URI escaped
        index = stack[-1][2][tag.inspect]

        source and source << "v&&r<<h.uri_escape(v.is_a?(Array)?v[#{index}]:v[#{tag.inspect}]);"

        variables and variables[tag] = true
      when '$'
        # JavaScript escaped
        index = stack[-1][2][tag.inspect]

        source and source << "v&&r<<h.js_escape(v.is_a?(Array)?v[#{index}]:v[#{tag.inspect}]);"

        variables and variables[tag] = true
      when '.'
        # CSS escaped
        index = stack[-1][2][tag.inspect]

        source and source << "v&&r<<h.css_escape(v.is_a?(Array)?v[#{index}]:v[#{tag.inspect}]);"

        variables and variables[tag] = true
      when ':', '#'
        # Defines start of a :section or #section
        index = stack[-1][2][tag.inspect]

        stack_variables ||= 's=[];'
        stack << [ :section, tag, VariableTracker.new ]

        source and source << "if(v);s<<v;v=v.is_a?(Array)?v[#{index}]:(v.is_a?(Hash)&&v[#{tag.inspect}]);"
        source and source << "h.iterate(v){|_v|;v=h.cast_as_vars(_v, s);"
        
        sections and sections[tag] = true
      when '^'
        # Displays if referenced variable is undefined or empty
        index = stack[-1][2][tag.inspect]

        stack_variables ||= 's=[];'
        stack << [ :empty_section, tag, stack[-1][2] ]

        source and source << "t=v.is_a?(Array)?v[#{index}]:(v.is_a?(Hash)&&v[#{tag.inspect}]);if(!t||t.respond_to?(:empty?)&&t.empty?);"
        
        variables and variables[tag] = true
      when '?', '?!'
        # Defines start of a ?conditional

        # The stack will inherit the variable assignment locations from the
        # existing stack layer.
        stack << [ :conditional, tag, stack[-1][2] ]
        source and source << "#{tag_type=='?' ? 'if' : 'unless'}(v&&v.is_a?(Hash)&&v[#{tag.inspect}]);"

        variables and variables[tag] = true
      when '*'
        source and source << "_t=t&&(t[#{tag.inspect}]||t[#{tag.to_s.inspect}]);r<<(_t.respond_to?(:call)?_t.call(v,t):_t.to_s);"
        
        templates and templates[tag] = true
      when '/'
        # Closes out a section or conditional
        closed = stack.pop
        
        case (closed[0])
        when :section
          if (tag and tag != closed[1])
            raise ParseError, "Template contains unexpected {{#{tag}}}, expected {{#{closed[1]}}}"
          end
          
          source and source << "};v=s.pop;end;"
        when :empty_section
          source and source << "end;"
        when :conditional
          source and source << "end;"
        when :base
          raise ParseError, "Unexpected {{#{tag}}}, too many tags closed"
        end
      when '='
        # Literal insertion
        index = stack[-1][2][tag.inspect]

        source and source << "v&&r<<(v.is_a?(Array)?v[#{index}]:v[#{tag.inspect}]).to_s;"

        variables and variables[tag] = true
      else
        # Contextual insertion
        index = stack[-1][2][tag.inspect]

        subst = "v.is_a?(Array)?v[#{stack[-1][2][tag.inspect]}]:v[#{tag.inspect}]"
        
        if (escape_method)
          source and source << "v&&r<<h.#{escape_method}(#{subst}.to_s);"
        else
          source and source << "v&&r<<(#{subst}).to_s;"
        end

        variables and variables[tag] = true
      end
    end
  end
  
  unless (stack.length == 1)
    case (stack[1][0])
    when :section
      raise ParseError, "Unclosed {{:#{stack[1][1]}}} in template"
    when :conditional
      raise ParseError, "Unclosed {{?#{stack[1][1]}}} in template"
    else
      raise ParseError, "Unclosed {{#{stack[1][1]}}} in template"
    end
  end
  
  if (source)
    source.replace("begin;c=false;h=Feather::Support;lambda{|v,t|raise RecursionError if(c);c=true;#{stack_variables}r='';#{source}c=false;r};end")
  end
  
  true
end

#encode_with(coder) ⇒ Object

For compatibility with YAML



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# File 'lib/feather/template.rb', line 298

def encode_with(coder)
  coder['content'] = @content
  coder['escape_method'] = @escape_method
end

#marshal_dump ⇒ Object

For compatibility with Marshal.dump



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# File 'lib/feather/template.rb', line 317

def marshal_dump
  [ @content, { escape: @escape_method } ]
end

#marshal_load(dump) ⇒ Object

For compatibility with Marshal.load



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# File 'lib/feather/template.rb', line 322

def marshal_load(dump)
  @content, options = dump
  
  @escape_method = options[:escape]
end

#psych_to_yaml(dump) ⇒ Object

For compatibility with the Psych YAML library



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# File 'lib/feather/template.rb', line 304

def psych_to_yaml(dump)
  # Avoid serializing the generated proc by moving it to a temporary
  # variable for the duration of this operation.
  _proc, @_proc = @_proc, nil
  
  super(dump)

  @_proc = _proc
  
  dump
end

#render(variables = nil, templates = nil, parents = nil) ⇒ Object Also known as: call

Render the template with the given variables, templates, and parent chain. The variables are specified in a Hash, Array, or object that supports [](key). templates must be a Hash or [](key) accessible object. The parents chain is defined as an array.



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# File 'lib/feather/template.rb', line 75

def render(variables = nil, templates = nil, parents = nil)
  variables = Feather::Support.variable_stack(variables, true)
  
  if (templates)
    # Unless the template options have already been processed, mapping
    # will need to be performed.
    unless (templates.is_a?(TemplateHash))
      _templates = templates
      templates = TemplateHash.new do |h, k|
        v = _templates[k]
        
        h[k] =
          case (v)
          when Feather::Template, Proc, Array
            v
          when TOKEN_TRIGGER
            self.class.new(v, escape: @escape_method)
          when nil
            nil
          else
            v.to_s
          end
      end
    end
  else
    templates = TemplateHash.new
  end
  
  if (parents)
    case (parents)
    when Array
      _parents = parents.dup
      _parent = _parents.shift
      
      unless (_parent.is_a?(Feather::Template))
        _parent = self.class.new(_parent, escape: @escape_method)
      end
      
      _parent.render(
        variables,
        templates.merge(
          nil => self.to_proc.call(variables, templates)
        ),
        _parents.empty? ? nil : _parents
      )
    when Feather::Template, Proc
      parents.render(
        variables,
        templates.merge(
          nil => self.to_proc.call(variables, templates)
        )
      )
    when String
      _parent = parents
      
      unless (_parent.is_a?(Feather::Template))
        _parent = self.class.new(_parent, :escape => @escape_method)
      end
      
      _parent.render(
        variables,
        templates.merge(
          nil => self.to_proc.call(variables, templates)
        )
      )
    else
      raise ArgumentError, "Invalid options passed in to parents"
    end
  else
    self.to_proc.call(variables, templates)
  end
end

#to_proc ⇒ Object

Returns a function that can be used to evaluate the template.



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# File 'lib/feather/template.rb', line 61

def to_proc
  @_proc ||= begin
    source = ''

    self.compile(source: source, escape_method: @escape_method)

    eval(source)
  end
end