Module: ProcSource

Defined in:
lib/appengine-mapreduce/proc_source.rb

Overview

:nodoc:

Class Method Summary collapse

Class Method Details

.get_lines(filename, start_line = 0) ⇒ Object 



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# File 'lib/appengine-mapreduce/proc_source.rb', line 7

def get_lines(filename, start_line = 0)
  return nil unless filename

  case filename
    # special "(irb)" descriptor?
    when "(irb)"
      IRB.conf[:MAIN_CONTEXT].io.line(start_line .. -1)
    # special "(eval...)" descriptor?
    when /^\(eval.+\)$/
      EVAL_LINES__[filename][start_line .. -1]
    # regular file
    else
      # Ruby already parsed this file? (see disclaimer above)
      if lines = SCRIPT_LINES__[filename]
        lines[(start_line - 1) .. -1]
        # If the file exists we're going to try reading it in
      elsif File.exist?(filename)
        begin
          File.readlines(filename)[(start_line - 1) .. -1]
        rescue
          nil
        end
      end
  end
end

.handle(proc) ⇒ Object 



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# File 'lib/appengine-mapreduce/proc_source.rb', line 33

def handle(proc)
  filename, line = source_descriptor proc
  lines = get_lines(filename, line) || []

  lexer = RubyLex.new
  lexer.set_input(StringIO.new(lines.join))

  state = :before_constructor
  nesting_level = 1
  start_token, end_token = nil, nil
  found = false
  while token = lexer.token
    # we've not yet found any proc-constructor -- we'll try to find one.
    if [:before_constructor, :check_more].include?(state)
      # checking more and newline? -> done
      if token.is_a?(RubyToken::TkNL) and state == :check_more
        state = :done
        break
      end
      # token is Proc?
      if token.is_a?(RubyToken::TkCONSTANT) and
              token.instance_variable_get(:@name) == "Proc"
        # method call?
        if lexer.token.is_a?(RubyToken::TkDOT)
          method = lexer.token
          # constructor?
          if method.is_a?(RubyToken::TkIDENTIFIER) and
                  method.instance_variable_get(:@name) == "new"
            unless state == :check_more
              # okay, code will follow soon.
              state = :before_code
            else
              # multiple procs on one line
              return
            end
          end
        end
        # token is lambda or proc call?
      elsif token.is_a?(RubyToken::TkIDENTIFIER) and
              %w{proc lambda}.include?(token.instance_variable_get(:@name))
        unless state == :check_more
          # okay, code will follow soon.
          state = :before_code
        else
          # multiple procs on one line
          return
        end
      elsif token.is_a?(RubyToken::TkfLBRACE) or token.is_a?(RubyToken::TkDO)
        # found the code start, update state and remember current token
        state = :in_code
        start_token = token
      end

      # we're waiting for the code start to appear.
    elsif state == :before_code
      if token.is_a?(RubyToken::TkfLBRACE) or token.is_a?(RubyToken::TkDO)
        # found the code start, update state and remember current token
        state = :in_code
        start_token = token
      end

      # okay, we're inside code
    elsif state == :in_code
      if token.is_a?(RubyToken::TkRBRACE) or token.is_a?(RubyToken::TkEND)
        nesting_level -= 1
        if nesting_level == 0
          # we're done!
          end_token = token
          # parse another time to check if there are multiple procs on one line
          # we can't handle that case correctly so we return no source code at all
          state = :check_more
        end
      elsif token.is_a?(RubyToken::TkfLBRACE) or token.is_a?(RubyToken::TkDO) or
              token.is_a?(RubyToken::TkBEGIN) or token.is_a?(RubyToken::TkCASE) or
              token.is_a?(RubyToken::TkCLASS) or token.is_a?(RubyToken::TkDEF) or
              token.is_a?(RubyToken::TkFOR) or token.is_a?(RubyToken::TkIF) or
              token.is_a?(RubyToken::TkMODULE) or token.is_a?(RubyToken::TkUNLESS) or
              token.is_a?(RubyToken::TkUNTIL) or token.is_a?(RubyToken::TkWHILE) or
              token.is_a?(RubyToken::TklBEGIN)
        nesting_level += 1
      end
    end
  end

  if start_token and end_token
    start_line, end_line = start_token.line_no - 1, end_token.line_no - 1
    source = lines[start_line .. end_line]
    start_offset = start_token.char_no
    start_offset += 1 if start_token.is_a?(RubyToken::TkDO)
    end_offset = -(source.last.length - end_token.char_no)
    source.first.slice!(0 .. start_offset)
    source.last.slice!(end_offset .. -1)

    # Can't use .strip because newline at end of code might be important
    # (Stuff would break when somebody does proc { ... #foo\n})
    source.join.gsub(/^ | $/, "")
  end
end

.source_descriptor(p) ⇒ Object 



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# File 'lib/appengine-mapreduce/proc_source.rb', line 132

def source_descriptor p
  if md = /^#<Proc:0x[0-9A-Fa-f]+@(.+):(\d+)>$/.match(p.inspect)
    filename, line = md.captures
    return filename, line.to_i
  end
end