dotty.tools.repl

An ambiguous prefix that matches multiple commands

A phase that collects user defined top level imports.

These imports must be collected as typed trees and therefore after Typer.

A command is on the format:

:commandName <optional arguments...>

The Command trait denotes these commands

A command that is used to display the documentation associated with the given expression.

:help shows the different commands implemented by the Dotty repl

:imports lists the imports that have been explicitly imported during the session

:load <path> interprets a scala file as if entered line-by-line into the REPL

Main entry point to the REPL

Parsed result is simply a newline

A parsing result from string input

An error free parsing resulting in a list of untyped trees

A placeholder phase that receives parse trees..

It is called "parser" for the convenience of collective muscle memory.

This enables -Vprint:parser.

:quit exits the repl

This subclass of Compiler is adapted for use in the REPL.

• compiles parsed expression in the current REPL state:
  • adds the appropriate imports in scope
  • wraps expressions into a dummy object
• provides utility to query the type of an expression
• provides utility to query the documentation of an expression

Main REPL instance, orchestrating input, compilation and presentation

A phase that assembles wrapped parse trees from user input.

Ths ReplState attachment indicates Repl wrapping is required.

This enables -Vprint:repl so that users can see how their code snippet was wrapped.

Reset the session to the initial state from when the repl program was started

A JSR 223 (Scripting API) compatible wrapper around the REPL for improved interoperability with software that supports it.

It works by instantiating a new script engine through the script engine manager. The script engine provides a eval method to evaluate scripts in string form. Example use:

val m = new javax.script.ScriptEngineManager() val e = m.getEngineByName("scala") println(e.eval("42"))

ctrl-c obtained from input string

The state of the REPL contains necessary bindings instead of having to have mutation

The compiler in the REPL needs to do some wrapping in order to compile valid code. This wrapping occurs when a single MemberDef that cannot be top-level needs to be compiled. In order to do this, we need some unique identifier for each of these wrappers. That identifier is objectIndex.

Free expressions such as 1 + 1 needs to have an assignment in order to be of use. These expressions are therefore given a identifier on the format resX where X starts at 0 and each new expression that needs an identifier is given the increment of the old identifier. This identifier is valIndex.

A parsing result containing syntax errors

To find out the type of an expression you may simply do:

scala> :type (1 * 54).toString
String

An unknown command that will not be handled by the REPL

Contains the different data and type structures used to model results in the REPL