Spreadsheet::Excel::Reader::Biff8

This Module collects reader methods such as read_string that are specific to Biff8. This Module is likely to be expanded as Support for older Versions of Excel grows and methods get moved here for disambiguation.

Public Instance Methods

continue_sst(work, oppos, len) click to toggle source

Read more data into the Shared String Table. (see also: read_sst) This method only evaluates the header, the actual work is done in #_read_sst

# File lib/spreadsheet/excel/reader/biff8.rb, line 55
def continue_sst work, oppos, len
  pos = 0
  if @incomplete_sst
    pos = continue_string_header work, oppos
  elsif !@incomplete_skip.nil?
    pos =  @incomplete_skip
    @incomplete_skip = nil
  end
  @sst_offset[1] += len
  _read_sst work, oppos, pos
end
continue_string(work, incomplete_string=@incomplete_string) click to toggle source

When a String is too long for one Opcode, it is continued in a Continue Opcode. Excel may reconsider compressing the remainder of the string. This method appends the available remainder (decompressed if necessary) to the incomplete string.

# File lib/spreadsheet/excel/reader/biff8.rb, line 15
def continue_string work, incomplete_string=@incomplete_string
  opts, _ = work.unpack 'C'
  wide = opts & 1
  head, chars = incomplete_string
  owing = chars - head.size / 2
  size = owing * (wide + 1)
  string = work[1, size]
  if wide == 0
    string = wide string
  end
  head << string
  if head.size >= chars * 2
    @incomplete_string = nil
  end
  size + 1
end
continue_string_header(work, oppos) click to toggle source

When a String is too long for one Opcode, it is continued in a Continue Opcode. Excel may reconsider compressing the remainder of the string. This method only evaluates the header and registers the address of the continuation with the previous SstEntry.

# File lib/spreadsheet/excel/reader/biff8.rb, line 36
def continue_string_header work, oppos
  opts, _ = work.unpack 'C'
  wide = opts & 1
  owing = @incomplete_sst.continued_chars
  size = [work.size, owing * (1 + wide) + 1].min
  chars = (size - 1) / (1 + wide)
  skip = size
  @incomplete_sst.continue oppos + OPCODE_SIZE, size, chars
  unless @incomplete_sst.continued?
    @workbook.add_shared_string @incomplete_sst
    skip += @incomplete_skip
    @incomplete_sst = nil
    @incomplete_skip = nil
  end
  skip
end
read_extsst(work, pos, len) click to toggle source

Store the offset of extsst, so we can write a new extsst when the sst has changed

# File lib/spreadsheet/excel/reader/biff8.rb, line 73
def read_extsst work, pos, len
  @workbook.offsets.store :extsst, [pos, len]
end
read_range_address_list(work, len) click to toggle source
# File lib/spreadsheet/excel/reader/biff8.rb, line 165
def read_range_address_list work, len
  # Cell range address, BIFF8:
  # Offset  Size  Contents
  # 0       2     Index to first row
  # 2       2     Index to last row
  # 4       2     Index to first column
  # 6       2     Index to last column
  # ! In several cases, BIFF8 still writes the BIFF2-BIFF5 format of a cell range address
  # (using 8-bit values for the column indexes). This will be mentioned at the respective place.
  #
  offset = 0, results = []
  return results if len < 2
  count = work[0..1].unpack('v').first
  offset = 2
  count.times do |i|
    results << work[offset...offset+8].unpack('v4')
    offset += 8
  end
  results
end
read_sst(work, pos, len) click to toggle source

Read the Shared String Table present in all Biff8 Files. This method only evaluates the header, the actual work is done in #_read_sst

# File lib/spreadsheet/excel/reader/biff8.rb, line 79
def read_sst work, pos, len
  # Offset  Size  Contents
  #      0     4  Total number of strings in the workbook (see below)
  #      4     4  Number of following strings (nm)
  #      8  var.  List of nm Unicode strings, 16-bit string length (➜ 3.4)
  total, @sst_size = work.unpack 'V2'
  @sst_offset = [pos, len]
  @workbook.offsets.store :sst, @sst_offset
  _read_sst work, pos, 8
end
read_string(work, count_length=1) click to toggle source

Read a string from the Spreadsheet, such as a Worksheet- or Font-Name, or a Number-Format. See also read_string_header and read_string_body

# File lib/spreadsheet/excel/reader/biff8.rb, line 92
def read_string work, count_length=1
  #   Offset    Size  Contents
  #        0  1 or 2  Length of the string (character count, ln)
  #   1 or 2       1  Option flags:
  #                   Bit  Mask  Contents
  #                     0  0x01  Character compression (ccompr):
  #                              0 = Compressed (8-bit characters)
  #                              1 = Uncompressed (16-bit characters)
  #                     2  0x04  Asian phonetic settings (phonetic):
  #                              0 = Does not contain Asian phonetic settings
  #                              1 = Contains Asian phonetic settings
  #                     3  0x08  Rich-Text settings (richtext):
  #                              0 = Does not contain Rich-Text settings
  #                              1 = Contains Rich-Text settings
  # [2 or 3]       2  (optional, only if richtext=1)
  #                   Number of Rich-Text formatting runs (rt)
  #   [var.]       4  (optional, only if phonetic=1)
  #                   Size of Asian phonetic settings block (in bytes, sz)
  #     var.      ln  Character array (8-bit characters
  #          or 2∙ln               or 16-bit characters, dependent on ccompr)
  #   [var.]    4∙rt  (optional, only if richtext=1)
  #                   List of rt formatting runs (➜ 3.2)
  #   [var.]      sz  (optional, only if phonetic=1)
  #                   Asian Phonetic Settings Block (➜ 3.4.2)
  chars, offset, wide, phonetic, richtext, available, owing, skip        = read_string_header work, count_length
  string, data = read_string_body work, offset, available, wide > 0
  if owing > 0
    @incomplete_string = [string, chars]
  end
  string
end
read_string_body(work, offset, available, wide) click to toggle source

Read the body of a string. Returns the String (decompressed if necessary) and the available data (unchanged).

# File lib/spreadsheet/excel/reader/biff8.rb, line 127
def read_string_body work, offset, available, wide
  data = work[offset, available]
  string = wide ? data : wide(data)
  [string, data]
end
read_string_header(work, count_length=1, offset=0) click to toggle source

Read the header of a string. Returns the following information in an Array:

  • The total number of characters in the string

  • The offset of the actual string data (= the length of this header in bytes)

  • Whether or not the string was compressed (0/1)

  • Whether or not the string contains asian phonetic settings (0/1)

  • Whether or not the string contains richtext formatting (0/1)

  • The number of bytes containing characters in this chunk of data

  • The number of characters missing from this chunk of data and expected to follow in a Continue Opcode

# File lib/spreadsheet/excel/reader/biff8.rb, line 142
def read_string_header work, count_length=1, offset=0
  fmt = count_length == 1 ? 'C2' : 'vC'
  chars, opts = work[offset, 1 + count_length].unpack fmt
  wide      = opts & 1
  phonetic  = (opts >> 2) & 1
  richtext  = (opts >> 3) & 1
  size      = chars * (wide + 1)
  skip = 0
  if richtext > 0
    runs, = work[offset + 1 + count_length, 2].unpack 'v'
    skip = 4 * runs
  end
  if phonetic > 0
    psize, = work[offset + 1 + count_length + richtext * 2, 4].unpack 'V'
    skip += psize
  end
  flagsize  = 1 + count_length + richtext * 2 + phonetic * 4
  avbl      = [work.size - offset, flagsize + size].min
  have_chrs = (avbl - flagsize) / (1 + wide)
  owing     = chars - have_chrs
  [chars, flagsize, wide, phonetic, richtext, avbl, owing, skip]
end
wide(string) click to toggle source

Insert null-characters into a compressed UTF-16 string

# File lib/spreadsheet/excel/reader/biff8.rb, line 187
def wide string
  data = ''
  string.each_byte do |byte| data << byte.chr << 0.chr end
  data
end

[Validate]

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