PrismJS/prism

[Brain storming] New language dependency system

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#2880 opened on Apr 30, 2021

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 (40 comments) (0 reactions) (0 assignees)JavaScript (11,488 stars) (1,296 forks)batch import
corehelp wantedlanguage-definitions

Description

Motivation

Our current language dependency system has a few problems:

  • It is incompatible with ESM.

    The current system relies on load order to manage both require dependencies and optional dependencies. Optional dependencies simply cannot be expressed using ESM's static import syntax.

  • It has to be enforced by the user.

    Nothing stops our users from loading languages in the wrong order. We regularly get issues where people have this problem.

  • It does not support third-party language definitions.

    Right now, all dependencies have to be declared in components.json. This makes it very hard for authors of third-party languages to integrate their languages. They are essentially forced to write languages with zero dependencies.

The first problem is huge because ESM is a goal for v2.0.

Goals

Primary goals:

  • ESM-compatible.

    We have to be able to either write or create ESM source files. Source files have to be able to import each other to fulfill their require dependencies. (E.g. the JS language has to be able to import C-like.)

  • Optional dependencies.

    The dependency system has to support optional dependencies. They are the reason this issue exists and they are necessary for Prism.

Secondary goals:

  • Third-party authors should be able to "hook" into our dependency system.
  • Making the Node hack unnecessary.

Non-goals

  • Backwards-compatibility.

  • Modify dependencies.

    Modify dependencies are not strictly necessary. Right now, Prism has 13 modify dependencies. 12 of those can be easily converted into optional dependencies. Only 1 modify dependency will be difficult to convert into an optional dependency but I'm sure that we can find a solution for that.

@LeaVerou @Golmote @mAAdhaTTah

Contributor guide

Tech stack
javascriptnodejs
Domain
build systemdeveloper experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Understanding of Prism's dependency systemKnowledge of ESM modulesFamiliarity with JavaScript developmentFamiliarity with Node.js module system
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Study the current dependency implementation in components.json and the Node hack in prism core.js (line 1167). Analyze existing 13 modify dependencies to determine how they can be converted to optional dependencies. Explore ESM import patterns to support both required and optional dependencies. Consider how third party authors can hook into the system without modifying components.json.