Class: Glimmer::DSL::Engine

Inherits:
Object
  • Object
show all
Defined in:
lib/glimmer/dsl/engine.rb

Overview

Glimmer DSL Engine

Follows Interpreter and Chain of Responsibility Design Patterns

When DSL engine interprets an expression, it attempts to handle with ordered expression array specified via ‘.expressions=` method.

Class Method Summary collapse

Class Method Details

.add_content(parent, expression, &block) ⇒ Object

Adds content block to parent UI object

This allows evaluating parent UI object properties and children

For example, a shell widget would get properties set and children added



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# File 'lib/glimmer/dsl/engine.rb', line 120

def add_content(parent, expression, &block)
  time = Time.now.to_f
  dsl_stack.push(expression.class.dsl)
  parent_stack.push(parent) if expression.is_a?(ParentExpression)
  expression.add_content(parent, &block) if block_given?
  parent_stack.pop if expression.is_a?(ParentExpression)
  dsl_stack.pop
end

.add_dynamic_expressions(dsl_namespace, expression_names) ⇒ Object

Sets an ordered array of DSL expressions to support

Every expression has an underscored name corresponding to an upper camelcase AbstractExpression subclass name in glimmer/dsl

They are used in order following the Chain of Responsibility Design Pattern when interpretting a DSL expression



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# File 'lib/glimmer/dsl/engine.rb', line 44

def add_dynamic_expressions(dsl_namespace, expression_names)
  dsl = dsl_namespace.name.split("::").last.downcase.to_sym
  dynamic_expression_chains_of_responsibility[dsl] = expression_names.reverse.map do |expression_name|
    expression_class(dsl_namespace, expression_name).new
  end.reduce(nil) do |last_expresion_handler, expression|
    Glimmer.logger&.debug "Adding dynamic expression: #{expression.class.name}"
    expression_handler = ExpressionHandler.new(expression)
    expression_handler.next = last_expresion_handler if last_expresion_handler
    expression_handler
  end
end

.add_static_expression(static_expression) ⇒ Object 



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# File 'lib/glimmer/dsl/engine.rb', line 56

def add_static_expression(static_expression)
  Glimmer.logger&.debug "Adding static expression: #{static_expression.class.name}"
  keyword = static_expression.class.keyword
  static_expression_dsl = static_expression.class.dsl
  static_expressions[keyword] ||= {}
  static_expressions[keyword][static_expression_dsl] = static_expression
  Glimmer.define_method(keyword) do |*args, &block|
    begin
      retrieved_static_expression = Glimmer::DSL::Engine.static_expressions[keyword][Glimmer::DSL::Engine.dsl]            
      static_expression_dsl = Glimmer::DSL::Engine.static_expressions[keyword].keys.first if retrieved_static_expression.nil?
      if retrieved_static_expression.nil? && Glimmer::DSL::Engine.dsl && (static_expression_dsl.nil? || !Glimmer::DSL::Engine.static_expressions[keyword][static_expression_dsl].is_a?(TopLevelExpression))
        begin
          return Glimmer::DSL::Engine.interpret(keyword, *args, &block)
        rescue => e 
          raise e if static_expression_dsl.nil?
        end
      end
      raise Glimmer::Error, "Unsupported keyword: #{keyword}" unless static_expression_dsl || retrieved_static_expression
      Glimmer::DSL::Engine.dsl_stack.push(static_expression_dsl || Glimmer::DSL::Engine.dsl)
      static_expression = Glimmer::DSL::Engine.static_expressions[keyword][Glimmer::DSL::Engine.dsl]
      if !static_expression.can_interpret?(Glimmer::DSL::Engine.parent, keyword, *args, &block)
        raise Error, "Invalid use of Glimmer keyword #{keyword} with args #{args} under parent #{Glimmer::DSL::Engine.parent}"
      else
        Glimmer.logger&.debug "#{static_expression.class.name} will handle expression keyword #{keyword}"
        return static_expression.interpret(Glimmer::DSL::Engine.parent, keyword, *args, &block).tap do |ui_object|
          Glimmer::DSL::Engine.add_content(ui_object, static_expression, &block) unless block.nil?
          Glimmer::DSL::Engine.dsl_stack.pop
        end
      end
    rescue => e
      Glimmer::DSL::Engine.dsl_stack.pop
      raise e
    end
  end
end

.dsl ⇒ Object 



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# File 'lib/glimmer/dsl/engine.rb', line 23

def dsl
  dsl_stack.last
end

.dsl=(dsl_name) ⇒ Object 



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# File 'lib/glimmer/dsl/engine.rb', line 14

def dsl=(dsl_name)
  dsl_name = dsl_name&.to_sym
  if dsl_name
    dsl_stack.push(dsl_name)
  else
    dsl_stack.clear
  end
end

.dsl_stack ⇒ Object

Enables multiple DSLs to play well with each other when mixing together



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# File 'lib/glimmer/dsl/engine.rb', line 146

def dsl_stack
  @dsl_stack ||= []
end

.dynamic_expression_chains_of_responsibility ⇒ Object

Dynamic expression chains of responsibility indexed by dsl



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# File 'lib/glimmer/dsl/engine.rb', line 28

def dynamic_expression_chains_of_responsibility
  @dynamic_expression_chains_of_responsibility ||= {}
end

.expression_class(dsl_namespace, expression_name) ⇒ Object 



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# File 'lib/glimmer/dsl/engine.rb', line 92

def expression_class(dsl_namespace, expression_name)
  dsl_namespace.const_get(expression_class_name(expression_name).to_sym)
end

.expression_class_name(expression_name) ⇒ Object 



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# File 'lib/glimmer/dsl/engine.rb', line 96

def expression_class_name(expression_name)
  "#{expression_name}_expression".camelcase(:upper)
end

.interpret(keyword, *args, &block) ⇒ Object

Interprets Glimmer dynamic DSL expression consisting of keyword, args, and block (e.g. shell(:no_resize) { … })



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# File 'lib/glimmer/dsl/engine.rb', line 101

def interpret(keyword, *args, &block)
  keyword = keyword.to_s
  dynamic_expression_dsl = dynamic_expression_chains_of_responsibility.keys.first if dsl.nil?
  dsl_stack.push(dynamic_expression_dsl || dsl)
  expression = dynamic_expression_chains_of_responsibility[dsl].handle(parent, keyword, *args, &block)
  expression.interpret(parent, keyword, *args, &block).tap do |ui_object|            
    add_content(ui_object, expression, &block)
    dsl_stack.pop
  end
rescue => e
  dsl_stack.pop
  raise e
end

.parent ⇒ Object

Current parent while evaluating Glimmer DSL (nil if just started or done evaluatiing)

Parents are maintained in a stack while evaluating Glimmer DSL to ensure properly ordered interpretation of DSL syntax



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# File 'lib/glimmer/dsl/engine.rb', line 133

def parent
  parent_stack.last
end

.parent_stack ⇒ Object 



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# File 'lib/glimmer/dsl/engine.rb', line 137

def parent_stack
  parent_stacks[dsl] ||= []
end

.parent_stacks ⇒ Object 



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# File 'lib/glimmer/dsl/engine.rb', line 141

def parent_stacks
  @parent_stacks ||= {}
end

.static_expressions ⇒ Object

Static expressions indexed by keyword and dsl



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# File 'lib/glimmer/dsl/engine.rb', line 33

def static_expressions
  @static_expressions ||= {}
end