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.
# File rdoc/parser/ruby.rb, line 349 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
# File rdoc/parser/ruby.rb, line 370 def column @offset - @last_newline end
# File rdoc/parser/ruby.rb, line 424 def divert_read_from(reserve) @content[@offset, 0] = reserve @size = @content.size end
# File rdoc/parser/ruby.rb, line 405 def get_read res = @content[@read_back_offset...@offset] @read_back_offset = @offset res end
# File rdoc/parser/ruby.rb, line 374 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
# File rdoc/parser/ruby.rb, line 393 def getc_already_read getc end
# File rdoc/parser/ruby.rb, line 411 def peek(at) pos = @offset + at if pos >= @size nil else @content[pos, 1] end end