Class: RBase::Table

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/rbase/table.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#columns ⇒ Object (readonly)

Returns the value of attribute columns.



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# File 'lib/rbase/table.rb', line 113

def columns
  @columns
end

#count ⇒ Object

Returns the value of attribute count.



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# File 'lib/rbase/table.rb', line 113

def count
  @count
end

#language ⇒ Object (readonly)

Returns the value of attribute language.



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# File 'lib/rbase/table.rb', line 113

def language
  @language
end

#last_modified_on ⇒ Object

Returns the value of attribute last_modified_on.



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# File 'lib/rbase/table.rb', line 113

def last_modified_on
  @last_modified_on
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/rbase/table.rb', line 113

def name
  @name
end

Class Method Details

.create(name, schema, options = {}) ⇒ Object

Create new XBase table file. Table file name will be equal to name with “.dbf” suffix.

Allowed options

* :language - language character set used in database. Can be one of LANGUAGE_* constants



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# File 'lib/rbase/table.rb', line 12

def self.create(name, schema, options = {})
  date = Date.today

  record_size = 1+schema.columns.inject(0) { |size, column| size + column.size }

  data = ''
  # data << [0xf5].pack('C') # version
  data << [0x3].pack('C') # version
  data << [date.year % 100, date.month, date.day].pack('CCC') # last modification date
  data << [0].pack('L') # number of records
  # data << [32+schema.columns.size*32+263+1].pack('v') # data size
  data << [32+schema.columns.size*32+1].pack('v') # data size
  data << [record_size].pack('v') # record size
  data << [].pack('x2') # reserved
  data << [].pack('x') # incomplete transaction
  data << [].pack('x') # encyption flag
  data << [].pack('x4') # reserved
  data << [].pack('x8') # reserved
  data << [0].pack('c') # mdx flag
  data << [options[:language]].pack('C') # language driver
  data << [].pack('x2') # reserved

  offset = 1 # take into account 1 byte for deleted flag
  data << schema.columns.collect do |column|
    s = ''
    s << [column.name.to_s[0..9]].pack('a11') # field name
    s << [column.type].pack('a') # field type
    s << [offset].pack('L') # field data offset
    s << [column.size].pack('C') # field size
    s << [column.decimal || 0].pack('C') # decimal count
    s << [].pack('x2') # reserved
    s << [].pack('x') # work area id
    s << [].pack('x2') # reserved
    s << [].pack('x') # flag for SET FIELDS
    s << [].pack('x7') # reserved
    s << [].pack('x') # index field flag
    offset += column.size
    s
  end.join

  data << [13].pack('C') # terminator

  data << [26].pack('C') # end of file

  File.open("#{name}.dbf", 'wb') do |f|
    f.write data
  end
end

.open(name, options = {}) ⇒ Object

Open table with given name. Table name should be like file name without “.dbf” suffix.



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# File 'lib/rbase/table.rb', line 63

def self.open(name, options = {})
  table = new
  table.instance_eval { open("#{name}.dbf", options) }
  if block_given?
    result = yield table
    table.close
    result
  else
    table
  end
end

Instance Method Details

#[]=(index, record) ⇒ Object 



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# File 'lib/rbase/table.rb', line 148

def []=(index, record)
  record.instance_eval { @index = index }
  save(record)
end

#build(attributes = {}) ⇒ Object

Create new record, populate it with given attributes



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# File 'lib/rbase/table.rb', line 126

def build(attributes = {})
  Record.new(self, attributes)
end

#clear ⇒ Object 



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# File 'lib/rbase/table.rb', line 99

def clear
  file_end = @record_offset
  @file.pos = file_end
  @file.write "\x1a"
  @file.truncate file_end+1

  self.count = 0
  update_header
end

#close ⇒ Object 



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# File 'lib/rbase/table.rb', line 109

def close
  @file.close
end

#column(name) ⇒ Object

Return instance of RBase::Column for given column name



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# File 'lib/rbase/table.rb', line 116

def column(name)
  @name_to_columns[name]
end

#create(attributes = {}) ⇒ Object

Create new record, populate it with given attributes and save it



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# File 'lib/rbase/table.rb', line 131

def create(attributes = {})
  record = build(attributes)
  record.save
  record
end

#each ⇒ Object

Iterate through all non-deleted records



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# File 'lib/rbase/table.rb', line 163

def each
  return unless block_given?

  self.each_with_deleted do |record|
    yield record unless record.deleted?
  end
end

#each_with_deleted ⇒ Object

Iterate through all (even deleted) records



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# File 'lib/rbase/table.rb', line 154

def each_with_deleted
  return unless block_given?

  count.times do |i|
    yield load(i)
  end
end

#load(index) ⇒ Object Also known as: []

Load record stored in position ‘index’



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# File 'lib/rbase/table.rb', line 138

def load(index)
  @file.pos = @record_offset + @record_size*index
  data = @file.read(@record_size)
  record = Record.new(self)
  record.instance_eval { load(index, data) }
  record
end

#memo ⇒ Object

Returns instance of MemoFile that is associated with table



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# File 'lib/rbase/table.rb', line 121

def memo
  return @memo_file
end

#pack ⇒ Object

Physically remove records that were marked as deleted from file.



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# File 'lib/rbase/table.rb', line 76

def pack
  packed_count = 0
  count.times do |i|
    @file.pos = @record_offset + @record_size*i
    data = @file.read(@record_size)
    unless data[0, 1]=='*'
      if i!=packed_count
        @file.pos = @record_offset + @record_size*packed_count
        @file.write data
      end
      packed_count += 1
    end
  end

  file_end = @record_offset + @record_size*packed_count
  @file.pos = file_end
  @file.write "\x1a"
  @file.truncate file_end+1

  self.count = packed_count
  update_header
end