Class: Sexpistol::Parser

Inherits:
StringScanner
  • Object
show all
Defined in:
lib/sexpistol/parser.rb

Constant Summary collapse

PARANTHESES = 
/[()]/.freeze
STRING = 
/"([^"\\]|\\.)*"/.freeze
FLOAT = 
/[\-+]? [0-9]+ ((e[0-9]+) | (\.[0-9]+(e[0-9]+)?)) [\s()]/x.freeze
INTEGER = 
/[\-+]?[0-9]+[\s()]/.freeze
SYMBOL = 
/[^0-9()\s]+[^()\s]*/.freeze

Instance Method Summary collapse

Constructor Details

#initialize(string) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/sexpistol/parser.rb', line 13

def initialize(string)
  raise 'String given is not an s-expression' if string.strip[0] != '('
  raise 'Invalid s-expression' if string.count('(') != string.count(')')

  super(string.strip)
end

Instance Method Details

#fetch_token ⇒ Object 



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# File 'lib/sexpistol/parser.rb', line 37

def fetch_token
  skip(/\s+/)

  return matched        if scan(PARANTHESES)
  return matched.undump if scan(STRING)
  return matched.to_f   if scan(FLOAT)
  return matched.to_i   if scan(INTEGER)
  return matched.to_sym if scan(SYMBOL)

  raise "Invalid token at position #{pos} near '#{scan(/.{0,20}/)}'."
end

#parse(level = 0, exp = []) ⇒ Object 



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# File 'lib/sexpistol/parser.rb', line 20

def parse(level = 0, exp = [])
  until eos?
    case token = fetch_token
    when ')' then break
    when '(' then exp << parse(level + 1)
    when String, Integer, Float, Symbol then exp << token
    end
  end

  if level.zero?
    exp = exp.first if exp.first.is_a?(Array) && exp.length == 1
    exp = Sexpistol::SExpressionArray.new(exp) if exp.all? { |item| item.is_a?(Array) }
  end

  exp
end