Class: Linguist::Shebang

Inherits:
Object
  • Object
show all
Defined in:
lib/linguist/shebang.rb

Class Method Summary collapse

Class Method Details

.call(blob, candidates) ⇒ Object

Public: Use shebang to detect language of the blob.

blob - An object that quacks like a blob. candidates - A list of candidate languages.

Examples

Shebang.call(FileBlob.new("path/to/file"))

Returns an array of languages from the candidate list for which the blob’s shebang is valid. Returns an empty list if there is no shebang. If the candidate list is empty, any language is a valid candidate.



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# File 'lib/linguist/shebang.rb', line 17

def self.call(blob, candidates)
  return [] if blob.symlink?

  languages = Language.find_by_interpreter interpreter(blob.data)
  candidates.any? ? candidates & languages : languages
end

.interpreter(data) ⇒ Object

Public: Get the interpreter from the shebang

Returns a String or nil



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# File 'lib/linguist/shebang.rb', line 27

def self.interpreter(data)
  # First line must start with #!
  return unless data.start_with?("#!")

  shebang = data[0, data.index($/) || data.length]

  s = StringScanner.new(shebang)

  # There was nothing after the #!
  return unless path = s.scan(/^#!\s*\S+/)

  # Keep going
  script = path.split('/').last

  # if /usr/bin/env type shebang then walk the string
  if script == 'env'
    s.scan(/\s+/)
    while s.scan(/((-[i0uCSv]*|--\S+)\s+)+/) || # skip over optional arguments e.g. -vS
          s.scan(/(\S+=\S+\s+)+/) # skip over variable arguments e.g. foo=bar
      # do nothing
    end
    script = s.scan(/\S+/)
  end

  # Interpreter was /usr/bin/env with no arguments
  return unless script

  # "python2.6" -> "python2"
  script.sub!(/(\.\d+)$/, '')

  # #! perl -> perl
  script.sub!(/^#!\s*/, '')

  # Check for multiline shebang hacks that call `exec`
  if script == 'sh' &&
    data.lines.first(5).any? { |l| l.match(/exec (\w+).+\$0.+\$@/) }
    script = $1
  end

  # osascript can be called with an optional `-l <language>` argument, which may not be a language with an interpreter.
  # In this case, return and rely on the subsequent strategies to determine the language.
  if script == 'osascript'
    return if s.scan_until(/\-l\s?/)
  end

  File.basename(script)
end