Class: CSV::Parser::InputsScanner

Inherits:
Object
  • Object
show all
Defined in:
lib/csv/parser.rb

Overview

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 “”.

Instance Method Summary collapse

Constructor Details

#initialize(inputs, encoding, chunk_size: 8192) ⇒ InputsScanner

Returns a new instance of InputsScanner.



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# 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

Instance Method Details

#each_line(row_separator) {|buffer| ... } ⇒ Object

Yields:

  • (buffer) 


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# 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? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/csv/parser.rb', line 163

def eos?
  @scanner.eos?
end

#keep_back ⇒ Object 



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# 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 ⇒ Object 



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# File 'lib/csv/parser.rb', line 197

def keep_drop
  @keeps.pop
end

#keep_end ⇒ Object 



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# 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 ⇒ Object 



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# File 'lib/csv/parser.rb', line 167

def keep_start
  @keeps.push([@scanner.pos, nil])
end

#rest ⇒ Object 



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# File 'lib/csv/parser.rb', line 201

def rest
  @scanner.rest
end

#scan(pattern) ⇒ Object 



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# 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) ⇒ Object 



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# 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