Class: RecordSearch::Search

Inherits:
Object
  • Object
show all
Defined in:
lib/recordsearch/search.rb

Constant Summary collapse

INDEX_SIZE =

TODO is there a sizeof(long) ?

4

Instance Method Summary collapse

Constructor Details

#initialize(db, db_idx = nil) ⇒ Search

Returns a new Search object. db is the file having the data used for your searches. db_idx is the index created with RecordSearch#index if it’s nil, it will construct a filename appending ‘.idx’ to the value db has.



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# File 'lib/recordsearch/search.rb', line 11

def initialize(db, db_idx=nil)
  @db = File.open(db, 'r')
  db_idx = db + '.idx' if db_idx.nil?
  @db_idx = File.open(db_idx, 'r')
  @db_size = File.stat(db_idx).size / INDEX_SIZE
  @db_pos = 0
end

Instance Method Details

#close ⇒ Object

Close the files.



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# File 'lib/recordsearch/search.rb', line 20

def close
  @db.close
  @db_idx.close
  @db = @db_idx = nil
end

#search(key) ⇒ Object

Searches object key in the file using binary search. If found returns what your implementation of parse returned, nil otherwise.



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# File 'lib/recordsearch/search.rb', line 28

def search(key)
  from = 0
  to = @db_size - 1

  pivot = nil
  while from < to
    middle = ((from + to) / 2).to_i

    pivot = read(middle)

    if lt(key, pivot)
      to = middle
      next
    elsif gt(key, pivot)
      from = middle + 1
      next
    end

    result = nil
    result = pivot if eq(key, pivot)
    return result
  end

  if from == to
    pivot = read(from)
    return pivot if eq(pivot, pivot)
  end
end