Class: Innodb::Page::Index::RecordCursor

Inherits:
Object
  • Object
show all
Defined in:
lib/innodb/page/index.rb

Overview

A class for cursoring through records starting from an arbitrary point.

Instance Method Summary collapse

Constructor Details

#initialize(page, offset) ⇒ RecordCursor

Returns a new instance of RecordCursor.



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# File 'lib/innodb/page/index.rb', line 568

def initialize(page, offset)
  @page   = page
  @offset = offset
end

Instance Method Details

#record ⇒ Object

Return the next record, and advance the cursor. Return nil when the end of records is reached.



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# File 'lib/innodb/page/index.rb', line 575

def record
  return nil unless @offset

  record = @page.record(@offset)

  if record == @page.supremum
    # We've reached the end of the linked list at supremum.
    @offset = nil
  elsif record.next == @offset
    # The record links to itself; go ahead and return it (once), but set
    # the next offset to nil to end the loop.
    @offset = nil
    record
  else
    @offset = record.next
    record
  end
end