class Prism::Source

This represents a source of Ruby code that has been parsed. It is used in conjunction with locations to allow them to resolve line numbers and source ranges.

Attributes

offsets[R]

The list of newline byte offsets in the source code.

source[R]

The source code that this source object represents.

start_line[R]

The line number where this source starts.

Public Class Methods

for(source, start_line = 1, offsets = []) click to toggle source

Create a new source object with the given source code. This method should be used instead of new and it will return either a Source or a specialized and more performant ASCIISource if no multibyte characters are present in the source code.

# File lib/prism/parse_result.rb, line 13
def self.for(source, start_line = 1, offsets = [])
  if source.ascii_only?
    ASCIISource.new(source, start_line, offsets)
  elsif source.encoding == Encoding::BINARY
    source.force_encoding(Encoding::UTF_8)

    if source.valid_encoding?
      new(source, start_line, offsets)
    else
      # This is an extremely niche use case where the file is marked as
      # binary, contains multi-byte characters, and those characters are not
      # valid UTF-8. In this case we'll mark it as binary and fall back to
      # treating everything as a single-byte character. This _may_ cause
      # problems when asking for code units, but it appears to be the
      # cleanest solution at the moment.
      source.force_encoding(Encoding::BINARY)
      ASCIISource.new(source, start_line, offsets)
    end
  else
    new(source, start_line, offsets)
  end
end

new(source, start_line = 1, offsets = []) click to toggle source

Create a new source object with the given source code.

# File lib/prism/parse_result.rb, line 46
def initialize(source, start_line = 1, offsets = [])
  @source = source
  @start_line = start_line # set after parsing is done
  @offsets = offsets # set after parsing is done
end

Public Instance Methods

byte_offset(line, column) click to toggle source

Converts the line number and column in bytes to a byte offset.

# File lib/prism/parse_result.rb, line 80
def byte_offset(line, column)
  normal = line - @start_line
  raise IndexError if normal < 0
  offsets.fetch(normal) + column
rescue IndexError
  raise ArgumentError, "line #{line} is out of range"
end

character_column(byte_offset) click to toggle source

Return the column number in characters for the given byte offset.

# File lib/prism/parse_result.rb, line 117
def character_column(byte_offset)
  character_offset(byte_offset) - character_offset(line_start(byte_offset))
end

character_offset(byte_offset) click to toggle source

Return the character offset for the given byte offset.

# File lib/prism/parse_result.rb, line 112
def character_offset(byte_offset)
  (source.byteslice(0, byte_offset) or raise).length
end

code_units_cache(encoding) click to toggle source

Generate a cache that targets a specific encoding for calculating code unit offsets.

# File lib/prism/parse_result.rb, line 145
def code_units_cache(encoding)
  CodeUnitsCache.new(source, encoding)
end

code_units_column(byte_offset, encoding) click to toggle source

Returns the column number in code units for the given encoding for the given byte offset.

# File lib/prism/parse_result.rb, line 151
def code_units_column(byte_offset, encoding)
  code_units_offset(byte_offset, encoding) - code_units_offset(line_start(byte_offset), encoding)
end

code_units_offset(byte_offset, encoding) click to toggle source

Returns the offset from the start of the file for the given byte offset counting in code units for the given encoding.

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

We purposefully replace invalid and undefined characters with replacement characters in this conversion. This happens for two reasons. First, it's possible that the given byte offset will not occur on a character boundary. Second, it's possible that the source code will contain a character that has no equivalent in the given encoding.

# File lib/prism/parse_result.rb, line 133
def code_units_offset(byte_offset, encoding)
  byteslice = (source.byteslice(0, byte_offset) or raise).encode(encoding, invalid: :replace, undef: :replace)

  if encoding == Encoding::UTF_16LE || encoding == Encoding::UTF_16BE
    byteslice.bytesize / 2
  else
    byteslice.length
  end
end

column(byte_offset) click to toggle source

Return the column number for the given byte offset.

# File lib/prism/parse_result.rb, line 107
def column(byte_offset)
  byte_offset - line_start(byte_offset)
end

deep_freeze() click to toggle source

Freeze this object and the objects it contains.

# File lib/prism/parse_result.rb, line 156
def deep_freeze
  source.freeze
  offsets.freeze
  freeze
end

encoding() click to toggle source

Returns the encoding of the source code, which is set by parameters to the parser or by the encoding magic comment.

# File lib/prism/parse_result.rb, line 64
def encoding
  source.encoding
end

line(byte_offset) click to toggle source

Binary search through the offsets to find the line number for the given byte offset.

# File lib/prism/parse_result.rb, line 90
def line(byte_offset)
  start_line + find_line(byte_offset)
end

line_end(byte_offset) click to toggle source

Returns the byte offset of the end of the line corresponding to the given byte offset.

# File lib/prism/parse_result.rb, line 102
def line_end(byte_offset)
  offsets[find_line(byte_offset) + 1] || source.bytesize
end

line_start(byte_offset) click to toggle source

Return the byte offset of the start of the line corresponding to the given byte offset.

# File lib/prism/parse_result.rb, line 96
def line_start(byte_offset)
  offsets[find_line(byte_offset)]
end

lines() click to toggle source

Returns the lines of the source code as an array of strings.

# File lib/prism/parse_result.rb, line 69
def lines
  source.lines
end

replace_offsets(offsets) click to toggle source

Replace the value of offsets with the given value.

# File lib/prism/parse_result.rb, line 58
def replace_offsets(offsets)
  @offsets.replace(offsets)
end

replace_start_line(start_line) click to toggle source

Replace the value of start_line with the given value.

# File lib/prism/parse_result.rb, line 53
def replace_start_line(start_line)
  @start_line = start_line
end

slice(byte_offset, length) click to toggle source

Perform a byteslice on the source code using the given byte offset and byte length.

# File lib/prism/parse_result.rb, line 75
def slice(byte_offset, length)
  source.byteslice(byte_offset, length) or raise
end

Private Instance Methods

find_line(byte_offset) click to toggle source

Binary search through the offsets to find the line number for the given byte offset.

# File lib/prism/parse_result.rb, line 166
def find_line(byte_offset)
  index = offsets.bsearch_index { |offset| offset > byte_offset } || offsets.length
  index - 1
end