Class: RubyLex::BufferedReader

Inherits:
Object
  • Object
show all
Defined in:
lib/rdoc-f95/parsers/parse_rb.rb

Overview

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
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.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(content, options) ⇒ BufferedReader

Returns a new instance of BufferedReader.



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# File 'lib/rdoc-f95/parsers/parse_rb.rb', line 346

def initialize(content, options)
  @options = options

  if /\t/ =~ content
    tab_width = @options.tab_width
    content = content.split(/\n/).map do |line|
      1 while line.gsub!(/\t+/) { ' ' * (tab_width*$&.length - $`.length % tab_width)}  && $~ #`
      line
    end .join("\n")
  end
  @content   = content
  @content << "\n" unless @content[-1,1] == "\n"
  @size      = @content.size
  @offset    = 0
  @hwm       = 0
  @line_num  = 1
  @read_back_offset = 0
  @last_newline = 0
  @newline_pending = false
end

Instance Attribute Details

#line_num ⇒ Object (readonly)

Returns the value of attribute line_num.



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# File 'lib/rdoc-f95/parsers/parse_rb.rb', line 344

def line_num
  @line_num
end

Instance Method Details

#column ⇒ Object 



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# File 'lib/rdoc-f95/parsers/parse_rb.rb', line 367

def column
  @offset - @last_newline
end

#divert_read_from(reserve) ⇒ Object 



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# File 'lib/rdoc-f95/parsers/parse_rb.rb', line 421

def divert_read_from(reserve)
  @content[@offset, 0] = reserve
  @size      = @content.size
end

#get_read ⇒ Object 



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# File 'lib/rdoc-f95/parsers/parse_rb.rb', line 402

def get_read
  res = @content[@read_back_offset...@offset]
  @read_back_offset = @offset
  res
end

#getc ⇒ Object 



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# File 'lib/rdoc-f95/parsers/parse_rb.rb', line 371

def getc
  return nil if @offset >= @size
  ch = @content[@offset, 1]

  @offset += 1
  @hwm = @offset if @hwm < @offset

  if @newline_pending
    @line_num += 1
    @last_newline = @offset - 1
    @newline_pending = false
  end

  if ch == "\n"
    @newline_pending = true
  end
  ch
end

#getc_already_read ⇒ Object 



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# File 'lib/rdoc-f95/parsers/parse_rb.rb', line 390

def getc_already_read
  getc
end

#peek(at) ⇒ Object 



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# File 'lib/rdoc-f95/parsers/parse_rb.rb', line 408

def peek(at)
  pos = @offset + at
  if pos >= @size
    nil
  else
    @content[pos, 1]
  end
end

#peek_equal(str) ⇒ Object 



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# File 'lib/rdoc-f95/parsers/parse_rb.rb', line 417

def peek_equal(str)
  @content[@offset, str.length] == str
end

#ungetc(ch) ⇒ Object 



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# File 'lib/rdoc-f95/parsers/parse_rb.rb', line 394

def ungetc(ch)
  raise "unget past beginning of file" if @offset <= 0
  @offset -= 1
  if @content[@offset] == ?\n
    @newline_pending = false
  end
end