Components

这个 issue 是对可能的 shell 组件进行头脑风暴，包括 translator、dispatcher、buffer、compiler、executor 和 renderer，但没有指定任何文件、测试或入口点。首先将提案缩小到一个具体组件，并定义其接口和验收标准；当该范围明确的组件及其预期行为都得到清晰说明时，工作就完成了。

I can think of a lot of potentially useful, pluggable components. The following is a brain dump of the types of components I can imagine. Some of them may not need their own types, but can share types with other components.

• Translator from raw input bytes to high level events. If we integrate with a specific terminal, we can receive high level events directly, allowing us to handle, for example, touchpad gestures.
• Dispatcher: Translate events into directives, I.E. what to do. This component can handle key bindings.
• Buffer: Translates directives that operate on text into new text.
• Compiler: Translates a text buffer into Ok(AST) or Err(Error).
• Stage: A -> Result<B, Error> (could implement lexing, parsing, or rest of the compiler)
• Executor: Executes an AST.
• Completor: Returns completions for a partial buffer
• Historian: Given an executed command, and a result, adds a history entry.
• Suggestor: Given a partial buffer, gives suggestions. (Like flags, as opposed to full completions of the buffer)
• Prompter: Draws the prompt.
• Optimizer: Given a program, produces a modified or better program.
• Analyzer: Given a program, catches errors with that program statically. Might also produce an output program which is better typed.
• Helper: Given a buffer, produce help about that buffer. (About command, args, probably)
• Multiplexer: Handle multiplexing input between multiple shells. (Like tmux.)
• Searcher: Handles finding binaries in your path.
• Renderer: Turns markup into styled text.