Class: AbstractSyntaxTreeBuilder

Inherits:
Object
  • Object
show all
Defined in:
lib/lamep/abstract_syntax_tree_builder.rb

Instance Method Summary collapse

Constructor Details

#initialize(postfix) ⇒ AbstractSyntaxTreeBuilder

Returns a new instance of AbstractSyntaxTreeBuilder.



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# File 'lib/lamep/abstract_syntax_tree_builder.rb', line 3

def initialize(postfix)
  @postfix = postfix
end

Instance Method Details

#build_tree ⇒ Object 



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# File 'lib/lamep/abstract_syntax_tree_builder.rb', line 7

def build_tree
  until @postfix.length == 1
    operator_index = first_operator_index
    fail NotEnoughOperatorsException if operator_index.nil?
    exp = Operator.factory!(@postfix.slice!(operator_index))
    most_left_child = operator_index - exp::ARITY
    fail NotEnoughOperandsException, expression: exp if most_left_child < 0
    children = @postfix.slice!(most_left_child, exp::ARITY)
    @postfix.insert(most_left_child, exp.new(*children))
  end
  @postfix.first
end