Code for paring string

parse_string.rb

$code = ''  # Line for execution
$base = 0   # Master pointer, points the place where functions start parsing

def peek(oft) # Returns symbol from $code by index oft relatively to the $base
	if oft < 0 or oft >= $code.size then return nil end
	return $code[$base + oft]
end
  
def skip_trash # Function skipping whitespaces.
	i = 0 # The pointer
	while $base + i < $code.size and peek(i).match?(/\s/) do # Skipping until it gets non-space character
		i += 1
	end
	$base += i
	return i
end

def parse_string # Returns string content between double quotes
	i = 1 # 1 casue I need to skip first double quote, otherwise it will be treated as last double quote by following while cycle
	str = '' # The actual string content
	while $base + i < $code.size and peek(i) != '"' do # Iterate while current character is not double quote
    # Checking for EOF - End Of File
		if $base + i >= $code.size - 1 then
			raise 'Unexpected EOF: " was Expected'
			return nil
		end
		str += peek(i) # Adding new characted to the string
		i += 1 # Moving pointer i to next character
	end
	$base += str.size + 2
	skip_trash # I call skip_trash in order for elimenate spaces and tabs after parsing the string
  # So, the idea is to make parsing functions skip spaces and tabs 
	return str
end
  
# Example of usage
$code = '"ABCDEF"'
$base = 0
puts "string parsed: #{parse_string}" # Prints out: string parsed: ABCDEF