class Prism::ASCIISource

include multibyte characters are represented by the Prism::Source class.
cannot be applied to sources that include multibyte characters. Sources that
characters only. This class is used to apply performance optimizations that
Specialized version of Prism::Source for source code that includes ASCII

def character_column(byte_offset)

Return the column number in characters for the given byte offset. 
def character_column(byte_offset)
  byte_offset - line_start(byte_offset)
end

def character_offset(byte_offset)

Return the character offset for the given byte offset. 
def character_offset(byte_offset)
  byte_offset
end

def code_units_column(byte_offset, encoding)

essentially the same as `Prism::Source#column`.
`code_units_offset`, which is a more expensive operation. This is
Specialized version of `code_units_column` that does not depend on 
def code_units_column(byte_offset, encoding)
  byte_offset - line_start(byte_offset)
end

def code_units_offset(byte_offset, encoding)

encodings, it is not captured here.
concept of code units that differs from the number of characters in other
This method is tested with UTF-8, UTF-16, and UTF-32. If there is the

counting in code units for the given encoding.
Returns the offset from the start of the file for the given byte offset 
def code_units_offset(byte_offset, encoding)
  byte_offset
end