Class: Lisp::Macro

Inherits:
Atom show all
Defined in:
lib/rubylisp/macro.rb

Instance Attribute Summary collapse

Attributes inherited from Atom

#value

Instance Method Summary collapse

Methods inherited from Atom

#alist?, #all?, #car, #cdr, #character?, #class?, #copy, #eq?, #evaluate, #false?, #frame?, #function?, #length, #lisp_object?, #list?, #negative?, #number?, #object?, #pair?, #positive?, #primitive?, #print_string, #quoted, #set!, #special?, #string?, #symbol?, #true?, #vector?, #zero?

Constructor Details

#initialize(name, arguments, doc, body, env) ⇒ Macro

Returns a new instance of Macro.



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# File 'lib/rubylisp/macro.rb', line 22

def initialize(name, arguments, doc, body, env)
  sig = ([name] << arguments.to_a).flatten
  @doc = "(#{(sig.collect {|e| e.to_s}).join(" ")})"
  @name = name
  @arguments = arguments
  @doc = [@doc, doc].join("\n\n") unless doc.nil? || doc.to_s.empty?
  @body = body
  @env = env
  @local_env = nil
  compute_required_argument_count(@arguments)
end

Instance Attribute Details

#doc ⇒ Object (readonly)

Returns the value of attribute doc.



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# File 'lib/rubylisp/macro.rb', line 5

def doc
  @doc
end

Instance Method Details

#apply_to(parameters, env) ⇒ Object 



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# File 'lib/rubylisp/macro.rb', line 73

def apply_to(parameters, env)
  internal_apply_to(parameters, env, false)
end

#apply_to_without_evaluating(parameters, env) ⇒ Object 



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# File 'lib/rubylisp/macro.rb', line 77

def apply_to_without_evaluating(parameters, env)
  internal_apply_to(parameters, env, false)
end

#compute_required_argument_count(args) ⇒ Object 



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# File 'lib/rubylisp/macro.rb', line 7

def compute_required_argument_count(args)
  a = args
  @required_argument_count = 0
  @var_args = false
  while a
    if a.symbol?
      @var_args = true
      return
    else
      @required_argument_count += 1
    end
    a = a.cdr
  end
end

#expand(parameters, env, should_eval) ⇒ Object 



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# File 'lib/rubylisp/macro.rb', line 34

def expand(parameters, env, should_eval)
  if @var_args
    raise "#{@name} expected at least #{@required_argument_count} parameters, received #{parameters.length}." if parameters.length < @required_argument_count
  else
    raise "#{@name} expected #{@required_argument_count} parameters, received #{parameters.length}." unless parameters.length == @required_argument_count        
  end
  
  local_env = EnvironmentFrame.extending(@env, env.frame)
  self_sym = Symbol.named("self")
  if env.frame
    local_env.bind_locally(self_sym, env.frame)
  elsif env.local_binding_for(self_sym)
    local_env.bind_locally(self_sym, env.value_of(self_sym))
  end
  arg = @arguments
  param = parameters
  accumulating_arg = nil
  accumulated_params = []
  while !param.nil?        
    param_value = should_eval ? param.car.evaluate(env) : param.car
    if accumulating_arg
      accumulated_params << param_value
    else
      local_env.bind_locally(arg.car, param_value) unless arg.car.nil?
    end
    param = param.cdr
    arg = arg.cdr unless accumulating_arg
    accumulating_arg = arg if arg.symbol?
  end
  local_env.bind_locally(accumulating_arg, Lisp::ConsCell.array_to_list(accumulated_params)) if accumulating_arg
  
  @body.evaluate(local_env)
end

#internal_apply_to(parameters, env, should_eval) ⇒ Object 



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# File 'lib/rubylisp/macro.rb', line 68

def internal_apply_to(parameters, env, should_eval)
  expanded_macro = expand(parameters, env, should_eval)
  expanded_macro.evaluate(env)
end

#macro? ⇒ Boolean

Returns:



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# File 'lib/rubylisp/macro.rb', line 85

def macro?
  true
end

#to_s ⇒ Object 



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# File 'lib/rubylisp/macro.rb', line 81

def to_s
  "<macro: #{@name}>"
end

#type ⇒ Object 



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# File 'lib/rubylisp/macro.rb', line 89

def type
  :macro
end