Class: BracketNotation::Evaluator

Inherits:
Object
  • Object
show all
Defined in:
lib/bracket_notation/evaluator.rb

Overview

This class takes a list of Token instances and evaluates them. The result is an abstract tree representation of the syntax of the original string fed to the parser.

Defined Under Namespace

Classes: EvaluationError

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(input) ⇒ Evaluator

Saves the token list for evaluation.



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# File 'lib/bracket_notation/evaluator.rb', line 41

def initialize(input)
  @input = input
  @token_index = -1
  @root = nil
end

Instance Attribute Details

#input ⇒ Object (readonly)

Returns the value of attribute input.



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# File 'lib/bracket_notation/evaluator.rb', line 34

def input
  @input
end

Instance Method Details

#evaluate ⇒ Object

Evaluates a bracketed phrase and returns the Evaluation instance that represents the phrase.



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# File 'lib/bracket_notation/evaluator.rb', line 49

def evaluate
  return @root unless @root.nil?
  
  token = next_token
  unexpected_token_error if token.type != Token::LBRACKET
  @root = evaluate_phrase
  
  unexpected_token_error if next_token.type != Token::EOL
  
  return @root
end