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, offsets)

Source

# File lib/prism/parse_result.rb, line 32
def self.for(source, start_line, 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

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.

Note that if you are calling this method manually, you will need to supply the start_line and offsets parameters. start_line is the line number that the source starts on, which is typically 1 but can be different if this source is a subset of a larger source or if this is an eval. offsets is an array of byte offsets for the start of each line in the source code, which can be calculated by iterating through the source code and recording the byte offset whenever a newline character is encountered.

new (source, start_line, offsets)

Source

# File lib/prism/parse_result.rb, line 67
def initialize(source, start_line, offsets)
  @source = source
  @start_line = start_line # set after parsing is done
  @offsets = offsets # set after parsing is done
end

Create a new source object with the given source code.

Public Instance Methods

byte_offset (line, column)

Source

# File lib/prism/parse_result.rb, line 113
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

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

character_column (byte_offset)

Source

# File lib/prism/parse_result.rb, line 162
def character_column(byte_offset)
  character_offset(byte_offset) - character_offset(line_start(byte_offset))
end

Return the column in characters for the given byte offset.

character_offset (byte_offset)

Source

# File lib/prism/parse_result.rb, line 155
def character_offset(byte_offset)
  (source.byteslice(0, byte_offset) or raise).length
end

Return the character offset for the given byte offset.

code_units_cache (encoding)

Source

# File lib/prism/parse_result.rb, line 194
def code_units_cache(encoding)
  CodeUnitsCache.new(source, encoding)
end

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

code_units_column (byte_offset, encoding)

Source

# File lib/prism/parse_result.rb, line 202
def code_units_column(byte_offset, encoding)
  code_units_offset(byte_offset, encoding) - code_units_offset(line_start(byte_offset), encoding)
end

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

code_units_offset (byte_offset, encoding)

Source

# File lib/prism/parse_result.rb, line 180
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

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.

column (byte_offset)

Source

# File lib/prism/parse_result.rb, line 148
def column(byte_offset)
  byte_offset - line_start(byte_offset)
end

Return the column in bytes for the given byte offset.

deep_freeze ()

Source

# File lib/prism/parse_result.rb, line 209
def deep_freeze
  source.freeze
  offsets.freeze
  freeze
end

Freeze this object and the objects it contains.

encoding ()

Source

# File lib/prism/parse_result.rb, line 91
def encoding
  source.encoding
end

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

line (byte_offset)

Source

# File lib/prism/parse_result.rb, line 125
def line(byte_offset)
  start_line + find_line(byte_offset)
end

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

line_end (byte_offset)

Source

# File lib/prism/parse_result.rb, line 141
def line_end(byte_offset)
  offsets[find_line(byte_offset) + 1] || source.bytesize
end

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

line_start (byte_offset)

Source

# File lib/prism/parse_result.rb, line 133
def line_start(byte_offset)
  offsets[find_line(byte_offset)]
end

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

lines ()

Source

# File lib/prism/parse_result.rb, line 98
def lines
  source.lines
end

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

replace_offsets (offsets)

Source

# File lib/prism/parse_result.rb, line 83
def replace_offsets(offsets)
  @offsets.replace(offsets)
end

Replace the value of offsets with the given value.

replace_start_line (start_line)

Source

# File lib/prism/parse_result.rb, line 76
def replace_start_line(start_line)
  @start_line = start_line
end

Replace the value of start_line with the given value.

slice (byte_offset, length)

Source

# File lib/prism/parse_result.rb, line 106
def slice(byte_offset, length)
  source.byteslice(byte_offset, length) or raise
end

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