Class: Baikal::Cursor

Inherits:
Object
  • Object
show all
Defined in:
lib/baikal/cursor.rb

Overview

Represents an offset into a byte pool, permitting traversing the byte pool in a linear manner.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(pool, offset = 0) ⇒ Cursor

Creates a cursor of the given pool, initialising it to point at its given offset. If offset is not given, defaults to zero, that is to say, the byte pool’s beginning.



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# File 'lib/baikal/cursor.rb', line 19

def initialize pool, offset = 0
  raise 'Type mismatch' unless pool.is_a? Baikal::Pool
  raise 'Type mismatch' unless offset.is_a? Integer
  super()
  @pool = pool
  @offset = offset
  return
end

Instance Attribute Details

#offset ⇒ Object

The cursor’s current offset into the underlying byte pool.



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# File 'lib/baikal/cursor.rb', line 12

def offset
  @offset
end

Instance Method Details

#eof? ⇒ Boolean

Returns true if the cursor has passed the last byte currently in the underlying pool or false otherwise.

Returns:

  • (Boolean) 


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# File 'lib/baikal/cursor.rb', line 291

def eof?
  return @offset >= @pool.size
end

#parse_blob(size) ⇒ Object

Retrieves a specified number of bytes from the underlying pool’s current position and advances the cursor by the same number.

Error if the blob referred to by this cursor and this byte count lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 254

def parse_blob size
  raise 'Type mismatch' unless size.is_a? Integer
  raise 'Invalid blob size' unless size >= 0
  blob = @pool.get_blob(@offset, size)
  @offset += size
  return blob
end

#parse_signed_byte ⇒ Object

Retrieves a signed byte from the underlying pool’s current position and advances the cursor by one byte.

Error if the byte referred to by this cursor lies outside the boundaries of the underlying pool.



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# File 'lib/baikal/cursor.rb', line 90

def parse_signed_byte
  value = @pool.get_signed_byte(@offset)
  @offset += 1
  return value
end

#parse_signed_octa ⇒ Object

Retrieves a signed octabyte from the underlying pool’s current position using the pool’s currently selected byte order and advances the cursor by eight bytes.

Error if the octa referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 132

def parse_signed_octa
  value = @pool.get_signed_octa(@offset)
  @offset += 8
  return value
end

#parse_signed_tetra ⇒ Object

Retrieves a signed tetrabyte from the underlying pool’s current position using the pool’s currently selected byte order and advances the cursor by four bytes.

Error if the tetra referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 118

def parse_signed_tetra
  value = @pool.get_signed_tetra(@offset)
  @offset += 4
  return value
end

#parse_signed_wyde ⇒ Object

Retrieves a signed wyde from the underlying pool’s current position using the pool’s currently selected byte order and advances the cursor by two bytes.

Error if the wyde referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 104

def parse_signed_wyde
  value = @pool.get_signed_wyde(@offset)
  @offset += 2
  return value
end

#parse_unsigned_byte ⇒ Object

Retrieves an unsigned byte from the underlying pool’s current position and advances the cursor by one byte.

Error if the byte referred to by this cursor lies outside the boundaries of the underlying pool.



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# File 'lib/baikal/cursor.rb', line 35

def parse_unsigned_byte
  value = @pool.get_unsigned_byte(@offset)
  @offset += 1
  return value
end

#parse_unsigned_integer(size) ⇒ Object

Retrieves an unsigned integer of the given size (which must be 1, 2, 4 or 8) from the underlying pool’s current position using the pool’s currently selected byte order and advances the cursor by the integer’s size.

Error if the integer of this size referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 241

def parse_unsigned_integer size
  value = @pool.get_unsigned_integer(size, @offset)
  @offset += size
  return value
end

#parse_unsigned_octa ⇒ Object

Retrieves an unsigned octabyte from the underlying pool’s current position using the pool’s currently selected byte order and advances the cursor by eight bytes.

Error if the octa referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 77

def parse_unsigned_octa
  value = @pool.get_unsigned_octa(@offset)
  @offset += 8
  return value
end

#parse_unsigned_tetra ⇒ Object

Retrieves an unsigned tetrabyte from the underlying pool’s current position using the pool’s currently selected byte order and advances the cursor by four bytes.

Error if the tetra referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 63

def parse_unsigned_tetra
  value = @pool.get_unsigned_tetra(@offset)
  @offset += 4
  return value
end

#parse_unsigned_wyde ⇒ Object

Retrieves an unsigned wyde from the underlying pool’s current position using the pool’s currently selected byte order and advances the cursor by two bytes.

Error if the wyde referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 49

def parse_unsigned_wyde
  value = @pool.get_unsigned_wyde(@offset)
  @offset += 2
  return value
end

#peek_signed_byte ⇒ Object

Retrieves a signed byte from the underlying pool’s current position. Does not affect the position.

Error if the byte referred to by this cursor lies outside the boundaries of the underlying pool.



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# File 'lib/baikal/cursor.rb', line 192

def peek_signed_byte
  return @pool.get_signed_byte(@offset)
end

#peek_signed_octa ⇒ Object

Retrieves a signed octabyte from the underlying pool’s current position using the pool’s currently selected byte order. Does not affect the position.

Error if the octa referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 228

def peek_signed_octa
  return @pool.get_signed_octa(@offset)
end

#peek_signed_tetra ⇒ Object

Retrieves a signed tetrabyte from the underlying pool’s current position using the pool’s currently selected byte order. Does not affect the position.

Error if the tetra referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 216

def peek_signed_tetra
  return @pool.get_signed_tetra(@offset)
end

#peek_signed_wyde ⇒ Object

Retrieves a signed wyde from the underlying pool’s current position using the pool’s currently selected byte order. Does not affect the position.

Error if the wyde referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 204

def peek_signed_wyde
  return @pool.get_signed_wyde(@offset)
end

#peek_unsigned_byte ⇒ Object

Retrieves an unsigned byte from the underlying pool’s current position. Does not affect the position.

Error if the byte referred to by this cursor lies outside the boundaries of the underlying pool.



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# File 'lib/baikal/cursor.rb', line 145

def peek_unsigned_byte
  return @pool.get_unsigned_byte(@offset)
end

#peek_unsigned_octa ⇒ Object

Retrieves an unsigned octabyte from the underlying pool’s current position using the pool’s currently selected byte order. Does not affect the position.

Error if the octa referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 181

def peek_unsigned_octa
  return @pool.get_unsigned_octa(@offset)
end

#peek_unsigned_tetra ⇒ Object

Retrieves an unsigned tetrabyte from the underlying pool’s current position using the pool’s currently selected byte order. Does not affect the position.

Error if the tetra referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 169

def peek_unsigned_tetra
  return @pool.get_unsigned_tetra(@offset)
end

#peek_unsigned_wyde ⇒ Object

Retrieves an unsigned wyde from the underlying pool’s current position using the pool’s currently selected byte order. Does not affect the position.

Error if the wyde referred to by this cursor lies outside the boundaries of the underlying pool, even partially.



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# File 'lib/baikal/cursor.rb', line 157

def peek_unsigned_wyde
  return @pool.get_unsigned_wyde(@offset)
end

#skip(delta) ⇒ Object

Moves the cursor forwards by delta bytes, passing a part of the byte sequence without parsing.

Error if delta is negative.



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# File 'lib/baikal/cursor.rb', line 268

def skip delta
  raise 'Type mismatch' unless delta.is_a? Integer
  raise 'Invalid byte count' if delta < 0
  @offset += delta
  return
end

#unskip(delta) ⇒ Object

Moves the cursor backwards by delta bytes.

Error if delta is negative.



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# File 'lib/baikal/cursor.rb', line 280

def unskip delta
  raise 'Type mismatch' unless delta.is_a? Integer
  raise 'Invalid byte count' if delta < 0
  @offset -= delta
  return
end