Class: Cabriolet::System::MemoryHandle

Inherits:
Object
  • Object
show all
Defined in:
lib/cabriolet/system/memory_handle.rb

Overview

MemoryHandle provides in-memory I/O operations using a StringIO-like interface

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data = "", mode = Constants::MODE_READ) ⇒ MemoryHandle

Initialize a new memory handle

Parameters:

  • data (String) (defaults to: "") —

    Initial data (for reading) or empty string (for writing)

  • mode (Integer) (defaults to: Constants::MODE_READ) —

    One of MODE_READ, MODE_WRITE, MODE_UPDATE, MODE_APPEND



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# File 'lib/cabriolet/system/memory_handle.rb', line 13

def initialize(data = "", mode = Constants::MODE_READ)
  @data = data.dup.force_encoding(Encoding::BINARY)
  @mode = mode
  @pos = mode == Constants::MODE_APPEND ? @data.bytesize : 0
  @closed = false
end

Instance Attribute Details

#data ⇒ Object (readonly)

Returns the value of attribute data.



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# File 'lib/cabriolet/system/memory_handle.rb', line 7

def data
  @data
end

#mode ⇒ Object (readonly)

Returns the value of attribute mode.



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# File 'lib/cabriolet/system/memory_handle.rb', line 7

def mode
  @mode
end

Instance Method Details

#close ⇒ void

This method returns an undefined value.

Close the handle



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# File 'lib/cabriolet/system/memory_handle.rb', line 83

def close
  @closed = true
end

#closed? ⇒ Boolean

Check if the handle is closed

Returns:

  • (Boolean) 


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# File 'lib/cabriolet/system/memory_handle.rb', line 90

def closed?
  @closed
end

#read(bytes) ⇒ String

Read bytes from memory

Parameters:

  • bytes (Integer) —

    Number of bytes to read

Returns:

  • (String) —

    Bytes read (binary encoding)



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# File 'lib/cabriolet/system/memory_handle.rb', line 24

def read(bytes)
  return "" if @pos >= @data.bytesize

  result = @data.byteslice(@pos, bytes) || ""
  @pos += result.bytesize
  result
end

#seek(offset, whence) ⇒ Integer

Seek to a position in memory

Parameters:

  • offset (Integer) —

    Offset to seek to

  • whence (Integer) —

    One of SEEK_START, SEEK_CUR, SEEK_END

Returns:

  • (Integer) —

    New position



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# File 'lib/cabriolet/system/memory_handle.rb', line 61

def seek(offset, whence)
  new_pos = case whence
            when Constants::SEEK_START then offset
            when Constants::SEEK_CUR then @pos + offset
            when Constants::SEEK_END then @data.bytesize + offset
            else
              raise ArgumentError, "Invalid whence value: #{whence}"
            end

  @pos = [[new_pos, 0].max, @data.bytesize].min
end

#tell ⇒ Integer

Get current position in memory

Returns:

  • (Integer) —

    Current position



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# File 'lib/cabriolet/system/memory_handle.rb', line 76

def tell
  @pos
end

#to_s ⇒ String Also known as: buffer

Get the complete data buffer

Returns:

  • (String) —

    All data in the buffer



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# File 'lib/cabriolet/system/memory_handle.rb', line 97

def to_s
  @data
end

#write(content) ⇒ Integer

Write bytes to memory

Parameters:

  • content (String) —

    Data to write

Returns:

  • (Integer) —

    Number of bytes written

Raises:



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# File 'lib/cabriolet/system/memory_handle.rb', line 36

def write(content)
  raise IOError, "Handle is closed" if @closed
  raise IOError, "Handle not opened for writing" if @mode == Constants::MODE_READ

  content = content.dup.force_encoding(Encoding::BINARY)

  if @pos >= @data.bytesize
    # Append to end
    @data << content
  else
    # Overwrite existing data
    before = @data.byteslice(0, @pos) || ""
    after = @data.byteslice((@pos + content.bytesize)..-1) || ""
    @data = before + content + after
  end

  @pos += content.bytesize
  content.bytesize
end