Class: BtrieveSearchBuffer

Inherits:
Object
  • Object
show all
Includes:
Btrieve
Defined in:
lib/btrieve/btrieve_extended.rb

Constant Summary collapse

COMPARISON = 
{:equal=>1,:greater_than=>2,:less_than=>3, :not_equal=>4, :greater_than_or_equal=>5, :less_than_or_equal=>6}
BOOLEAN = 
{:and=>1, :or=>2}

Constants included from BtrCodes

BtrCodes::ABORT_TRANSACTION, BtrCodes::ACCELERATED_MODE, BtrCodes::BEGIN_TRANSACTION, BtrCodes::CLOSE, BtrCodes::DELETE, BtrCodes::END_TRANSACTION, BtrCodes::EOF, BtrCodes::EXCEPTION_MESSAGES, BtrCodes::EXCLUSIVE_MODE, BtrCodes::GET_DIRECT, BtrCodes::GET_EQUAL, BtrCodes::GET_EQUAL_KEY, BtrCodes::GET_FIRST, BtrCodes::GET_GREATER_THAN_OR_EQUAL, BtrCodes::GET_LESS_THAN_OR_EQUAL, BtrCodes::GET_NEXT, BtrCodes::GET_NEXT_EXTENDED, BtrCodes::GET_NEXT_KEY, BtrCodes::GET_POSITION, BtrCodes::GET_PREVIOUS, BtrCodes::INSERT, BtrCodes::KEY_NOT_FOUND, BtrCodes::LOCAL_ACCELERATED_MODE, BtrCodes::LOCAL_EXCLUSIVE_MODE, BtrCodes::LOCAL_NORMAL_MODE, BtrCodes::LOCAL_READ_ONLY_MODE, BtrCodes::MAX_DATATYPE, BtrCodes::NORMAL_MODE, BtrCodes::NO_CURRENCY_CHANGE, BtrCodes::NO_LOGICAL_CURRENCY_KEY, BtrCodes::NULL_BUFFER, BtrCodes::NULL_KEY, BtrCodes::OK, BtrCodes::OPEN, BtrCodes::POS_BLOCK_SIZE, BtrCodes::READ_ONLY_MODE, BtrCodes::RECORD_POSITION_SIZE, BtrCodes::REMOTE_ACCELERATED_MODE, BtrCodes::REMOTE_EXCLUSIVE_MODE, BtrCodes::REMOTE_NORMAL_MODE, BtrCodes::REMOTE_READ_ONLY_MODE, BtrCodes::RESET, BtrCodes::STEP_NEXT, BtrCodes::STEP_NEXT_EXTENDED, BtrCodes::STOP, BtrCodes::SYSTEM_LOG_KEY, BtrCodes::UPDATE, BtrCodes::VERIFY_MODE

Instance Method Summary collapse

Methods included from Btrieve

#btr_op, create_string_buffer

Constructor Details

#initialize(table, filter, fields_to_return, records_to_fetch = 10, start_point = :next_record, max_reject_count = 0) ⇒ BtrieveSearchBuffer

Returns a new instance of BtrieveSearchBuffer.



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# File 'lib/btrieve/btrieve_extended.rb', line 6

def initialize(table, filter, fields_to_return, records_to_fetch=10, start_point=:next_record, max_reject_count=0)
  @table=table
  @filter=filter
  @records_to_fetch=records_to_fetch
  @fields_to_return=fields_to_return
  @start_point = start_point == :current_record ? 'UC' : 'EG'
  @max_reject_count=max_reject_count
end

Instance Method Details

#get_encoded_buffer ⇒ Object 



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# File 'lib/btrieve/btrieve_extended.rb', line 15

def get_encoded_buffer
  filter_buff = []
  @filter.each_with_index() do |token, i|
    is_expr = (i%2 == 0)
    if(is_expr)
      column = @table.schema[:columns][token[0]]
      comparison = COMPARISON[token[1]]
      right_operand = nil
      if(is_symbol?(token[2]))
        # We're comparing against a value stored in another field in this record
        comparison += 64
        right_operand=[@table.schema[:columns][token[2]][:offset]].pack('S')
      else
        # We're comparing against a constant in the exact same format as the column itself
        right_operand=@table.pack_value(column, token[2])
        right_operand=right_operand.gsub("\x00",' ') if [0,11,12,21].include?(column[:datatype])
      end
      filter_item = [column[:datatype], column[:size], column[:offset], comparison, 0].pack('CSSCC')
      filter_item << right_operand
      filter_buff << filter_item
    else
      boolean = BOOLEAN[token]
      filter_buff.last[6..6]=[boolean].pack('C')
    end
  end
  num_logical_expressions = filter_buff.size
  result_descriptor=[@records_to_fetch, @fields_to_return.size].pack('SS')
  @fields_to_return.inject(result_descriptor) do |desc, field|
    column = @table.schema[:columns][field]
    desc << [column[:size], column[:offset]].pack('SS')
    desc
  end
  buffer_size=8+result_descriptor.size+filter_buff.join('').size
  search_buffer=[buffer_size, @start_point, @max_reject_count, num_logical_expressions].pack('Sa2SS')
  search_buffer << filter_buff.join('') << result_descriptor
  search_buffer
end