module Compiler

  # Compiling is the conversion of the AST into 2 things:
  # - code (ie sequences of Instructions inside Blocks) carried by CompiledMethods
  # - an object graph containing all the Methods, their classes and Constants
  #
  # Some compile methods just add code, some may add structure (ie Blocks) while
  # others instantiate Class and Method objects
  #
  # Everything in ruby is an expression, ie returns a value. So the effect of every compile
  # is that a value is put into the ReturnSlot of the current Message.
  # The compile method (so every compile method) returns the value that it deposits which
  # may be unknown Mystery value.
  #
  # The Compiler.compile uses a visitor patter to dispatch according to the class name of
  # the expression. So a NameExpression is delegated to compile_name etc.
  # This makes the dispatch extensible, ie Expressions may be added by external code,
  # as long as matching compile methods are supplied too.
  #
  def self.compile expression , method
    exp_name = expression.class.name.split("::").last.sub("Expression","").downcase
    #puts "Expression #{exp_name}"
    begin
      self.send "compile_#{exp_name}".to_sym , expression, method
    rescue NoMethodError => e
      puts "No compile method found for " + exp_name
      raise e
    end
  end

end

require_relative "compiler/basic_expressions"
require_relative "compiler/callsite_expression"
require_relative "compiler/compound_expressions"
require_relative "compiler/if_expression"
require_relative "compiler/function_expression"
require_relative "compiler/module_expression"
require_relative "compiler/operator_expressions"
require_relative "compiler/return_expression"
require_relative "compiler/while_expression"
require_relative "compiler/expression_list"