class CSV::Parser::InputsScanner - RDoc Documentation

# class CSV::Parser::InputsScanner

CSV::InputsScanner receives `IO` inputs, encoding and the chunk_size. It also controls the life cycle of the object with its methods `keep_start`, `keep_end`, `keep_back`, `keep_drop`.

CSV::InputsScanner.scan() tries to match with pattern at the current position. If there's a match, the scanner advances the “scan pointer” and returns the matched string. Otherwise, the scanner returns nil.

CSV::InputsScanner.rest() returns the “rest” of the string (i.e. everything after the scan pointer). If there is no more data (eos? = true), it returns “”.

### Public Class Methods

new(inputs, encoding, chunk_size: 8192) click to toggle source

    # File lib/csv/parser.rb, line 87
    def initialize(inputs, encoding, chunk_size: 8192)
      @inputs = inputs.dup
      @encoding = encoding
      @chunk_size = chunk_size
      @last_scanner = @inputs.empty?
      @keeps = []
      read_chunk
    end

### Public Instance Methods

each_line(row_separator) { |buffer| ... } click to toggle source

    # File lib/csv/parser.rb, line 96
    def each_line(row_separator)
      buffer = nil
      input = @scanner.rest
      position = @scanner.pos
      offset = 0
      n_row_separator_chars = row_separator.size
      while true
        input.each_line(row_separator) do |line|
          @scanner.pos += line.bytesize
          if buffer
            if n_row_separator_chars == 2 and
              buffer.end_with?(row_separator[0]) and
              line.start_with?(row_separator[1])
              buffer << line[0]
              line = line[1..-1]
              position += buffer.bytesize + offset
              @scanner.pos = position
              offset = 0
              yield(buffer)
              buffer = nil
              next if line.empty?
            else
              buffer << line
              line = buffer
              buffer = nil
            end
          end
          if line.end_with?(row_separator)
            position += line.bytesize + offset
            @scanner.pos = position
            offset = 0
            yield(line)
          else
            buffer = line
          end
        end
        break unless read_chunk
        input = @scanner.rest
        position = @scanner.pos
        offset = -buffer.bytesize if buffer
      end
      yield(buffer) if buffer
    end

eos?() click to toggle source

    # File lib/csv/parser.rb, line 163
    def eos?
      @scanner.eos?
    end

keep_back() click to toggle source

    # File lib/csv/parser.rb, line 181
    def keep_back
      start, buffer = @keeps.pop
      if buffer
        string = @scanner.string
        keep = string.byteslice(start, string.bytesize - start)
        if keep and not keep.empty?
          @inputs.unshift(StringIO.new(keep))
          @last_scanner = false
        end
        @scanner = StringScanner.new(buffer)
      else
        @scanner.pos = start
      end
      read_chunk if @scanner.eos?
    end

keep_drop() click to toggle source

    # File lib/csv/parser.rb, line 197
    def keep_drop
      @keeps.pop
    end

keep_end() click to toggle source

    # File lib/csv/parser.rb, line 171
    def keep_end
      start, buffer = @keeps.pop
      keep = @scanner.string.byteslice(start, @scanner.pos - start)
      if buffer
        buffer << keep
        keep = buffer
      end
      keep
    end

keep_start() click to toggle source

    # File lib/csv/parser.rb, line 167
    def keep_start
      @keeps.push([@scanner.pos, nil])
    end

rest() click to toggle source

    # File lib/csv/parser.rb, line 201
    def rest
      @scanner.rest
    end

scan(pattern) click to toggle source

    # File lib/csv/parser.rb, line 140
    def scan(pattern)
      value = @scanner.scan(pattern)
      return value if @last_scanner

      if value
        read_chunk if @scanner.eos?
        return value
      else
        nil
      end
    end

scan_all(pattern) click to toggle source

    # File lib/csv/parser.rb, line 152
    def scan_all(pattern)
      value = @scanner.scan(pattern)
      return value if @last_scanner

      return nil if value.nil?
      while @scanner.eos? and read_chunk and (sub_value = @scanner.scan(pattern))
        value << sub_value
      end
      value
    end

### Private Instance Methods

read_chunk() click to toggle source

    # File lib/csv/parser.rb, line 206
    def read_chunk
      return false if @last_scanner

      unless @keeps.empty?
        keep = @keeps.last
        keep_start = keep[0]
        string = @scanner.string
        keep_data = string.byteslice(keep_start, @scanner.pos - keep_start)
        if keep_data
          keep_buffer = keep[1]
          if keep_buffer
            keep_buffer << keep_data
          else
            keep[1] = keep_data.dup
          end
        end
        keep[0] = 0
      end

      input = @inputs.first
      case input
      when StringIO
        string = input.read
        raise InvalidEncoding unless string.valid_encoding?
        @scanner = StringScanner.new(string)
        @inputs.shift
        @last_scanner = @inputs.empty?
        true
      else
        chunk = input.gets(nil, @chunk_size)
        if chunk
          raise InvalidEncoding unless chunk.valid_encoding?
          @scanner = StringScanner.new(chunk)
          if input.respond_to?(:eof?) and input.eof?
            @inputs.shift
            @last_scanner = @inputs.empty?
          end
          true
        else
          @scanner = StringScanner.new("".encode(@encoding))
          @inputs.shift
          @last_scanner = @inputs.empty?
          if @last_scanner
            false
          else
            read_chunk
          end
        end
      end
    end