Protocol for content types that can be stored in delta operations.

The Content protocol defines how different content types behave within the OT system. By default, strings are supported, but you can implement this protocol for custom embedded content types like images, videos, or nested documents.

Built-in Implementations

• BitString - Standard Elixir strings
• Otzel.Content.Iomemo - Efficient IO-list based strings (default)
• Otzel.Content.Ot - Nested OT documents

Implementing Custom Content

For simple atomic embeds (size 1, cannot be split), use the atomic: true option:

defmodule MyApp.ImageEmbed do
  use Otzel.Content, atomic: true

  defstruct [:url, :width, :height]

  def invert(_, _), do: raise "not implemented"
  def compose(_, _), do: raise "not implemented"
  def transform(_, _, _), do: raise "not implemented"
end

The atomic: true option automatically implements:

• size/1 - Returns 1
• take/2 - Returns the whole content
• merge_into/2 - Returns nil (cannot merge)
• as_binary/1 - Returns nil
• embed?/1 - Returns true (is embedded content)
• diff/2 - Returns empty list for equal content, or delete+insert for different content

Checking Content Type

Use embed?/1 to check if content is an embedded type (returns true) or string-like (returns false):

Otzel.Content.embed?(string_content)  # => false
Otzel.Content.embed?(embed_content)   # => true