Class: RubyLex::BufferedReader

Read an input stream character by character. We allow for unlimited ungetting of characters just read.

We simplify the implementation greatly by reading the entire input into a buffer initially, and then simply traversing it using pointers.

We also have to allow for the here document diversion. This little gem comes about when the lexer encounters a here document. At this point we effectively need to split the input stream into two parts: one to read the body of the here document, the other to read the rest of the input line where the here document was initially encountered. For example, we might have

  do_something(<<-A, <<-B)
    stuff
    for
  A
    stuff
    for
  B

When the lexer encounters the <<A, it reads until the end of the line, and keeps it around for later. It then reads the body of the here document. Once complete, it needs to read the rest of the original line, but then skip the here document body.

Methods

column divert_read_from get_read getc getc_already_read new peek peek_equal ungetc

Attributes

line_num [R]

Public Class methods

new(content)

[Source]

     # File parsers/parse_rb.rb, line 349
349:     def initialize(content)
350:       if /\t/ =~ content
351:         tab_width = Options.instance.tab_width
352:         content = content.split(/\n/).map do |line|
353:           1 while line.gsub!(/\t+/) { ' ' * (tab_width*$&.length - $`.length % tab_width)}  && $~ #`
354:           line
355:         end .join("\n")
356:       end
357:       @content   = content
358:       @content << "\n" unless @content[-1,1] == "\n"
359:       @size      = @content.size
360:       @offset    = 0
361:       @hwm       = 0
362:       @line_num  = 1
363:       @read_back_offset = 0
364:       @last_newline = 0
365:       @newline_pending = false
366:     end

Public Instance methods

column()

[Source]

     # File parsers/parse_rb.rb, line 368
368:     def column
369:       @offset - @last_newline
370:     end

divert_read_from(reserve)

[Source]

     # File parsers/parse_rb.rb, line 422
422:     def divert_read_from(reserve)
423:       @content[@offset, 0] = reserve
424:       @size      = @content.size
425:     end

get_read()

[Source]

     # File parsers/parse_rb.rb, line 403
403:     def get_read
404:       res = @content[@read_back_offset...@offset]
405:       @read_back_offset = @offset
406:       res
407:     end

getc()

[Source]

     # File parsers/parse_rb.rb, line 372
372:     def getc
373:       return nil if @offset >= @size
374:       ch = @content[@offset, 1]
375:       
376:       @offset += 1
377:       @hwm = @offset if @hwm < @offset
378:       
379:       if @newline_pending
380:         @line_num += 1
381:         @last_newline = @offset - 1
382:         @newline_pending = false
383:       end
384:       
385:       if ch == "\n"
386:         @newline_pending = true
387:       end
388:       ch
389:     end

getc_already_read()

[Source]

     # File parsers/parse_rb.rb, line 391
391:     def getc_already_read
392:       getc
393:     end

peek(at)

[Source]

     # File parsers/parse_rb.rb, line 409
409:     def peek(at)
410:       pos = @offset + at
411:       if pos >= @size
412:         nil
413:       else
414:         @content[pos, 1]
415:       end
416:     end

peek_equal(str)

[Source]

     # File parsers/parse_rb.rb, line 418
418:     def peek_equal(str)
419:       @content[@offset, str.length] == str
420:     end

ungetc(ch)

[Source]

     # File parsers/parse_rb.rb, line 395
395:     def ungetc(ch)
396:       raise "unget past beginning of file" if @offset <= 0
397:       @offset -= 1
398:       if @content[@offset] == ?\n
399:         @newline_pending = false
400:       end
401:     end