How to implement syntax highlighting?

[Charliego3]

like markdown, go ...

[vgorloff]

Ideally, if language developers will provide implementation of the Language Server Protocol (https://microsoft.github.io/language-server-protocol/). Then you can hook up data which comes from LSP into TextView and apply appropriate rendering attributes.

[krzyzanowskim]

With a help of https://github.com/ChimeHQ/Neon with tree-sitter parser and grammars is one way. I plan to add tree-sitter support to the STTextView at one point.

[iliasaz]

Would love to see tree-sitter or Neon integration with STTextView, especially for large docs / low latency use case.

[krzyzanowskim]

me too. I don't think @mattmassicotte himself has time to contribute here. I didn't find time myself to sit on it yet, but that's something I would like to add as a plugin for the text view.

[mattmassicotte]

First, just a quick clarification. The semantic tokens feature of Language Server Protocol can be used to augment existing highlighting, but it is not a great system on its own. Very high latency, often does not support incremental edits, and typically has a relatively small file size limitation. Think of it as a nice secondary system.

Now, I made Neon because I've come to believe that it doesn't make sense for syntax highlighting to be within a view. It is much more flexible to keep the view and the data the view renders (the highlighted text) separate. Neon can probably just plug right into STTextView. And if not, I would be very happy to help make that work.

At a higher level, I'd love to see STTextView be a very good text view, and to focus on that. I think that highlighting can be external, and both it and the view will end up better for it.

[krzyzanowskim]

Use the dedicated plugin STTextView-Plugin-Neon it works great!

[Cubik65536]

there's ni iOS plugin as of yet, you're the first. Steps:

1. Chekout that macOS template krzyzanowskim/STTextView-Plugin-Template
2. Change platform to iOS in package krzyzanowskim/STTextView-Plugin-Template@main/Package.swift
3. Try to build DummyPlugin by commenting out what doesn't work krzyzanowskim/STTextView-Plugin-Template@main/Sources/DummyPlugin/DummyPlugin.swift

Now you have a buildable foundation

4. Checkout Neon plugin krzyzanowskim/STTextView-Plugin-Neon
5. Look at it and port/copy code to iOS

Ideally both platforms can be supported from the same package using build dependencies

for reference you can use the way I choosed when build multiplatform STTextView package main/Package.swift

I'm trying to learn how this works, now I got the dummy plugin compiled and even running with the SwiftUI demo in this repo with

TextView(
	text: $text,
	selection: $selection,
	options: [.wrapLines, .highlightSelectedLine, .showLineNumbers],
	plugins: [DummyPlugin()]
)

However, as I uncommented some of the print statement (e.g. the one in didChangeText), I still can't see if it is in effect because there are nothing printed out. Is that normal? The dummy plugin now is basically just:

import Foundation
import UIKit

import STTextView

public struct DummyPlugin: STPlugin {

    public init() { }

    public func setUp(context: any Context) {
        context.events.onWillChangeText(willChangeText)
        context.events.onDidChangeText(didChangeText)
        context.events.shouldChangeText(shouldChangeText)
        context.events.onContextMenu(contextMenu)
    }

    private func willChangeText(in affectedRange: NSTextRange) {
         print("will change handler!")
    }

    private func didChangeText(in affectedRange: NSTextRange, replacementString: String?) {
         print("did change handler from plugin!")
    }

    private func shouldChangeText(in textRange: NSTextRange, replacementString: String?) -> Bool {
        // if replacementString == "a" {
        //    return false
        // } 
        return true
    }

    private func contextMenu(_ location: NSTextLocation, _ contentManager: NSTextContentManager) -> UIMenu {
        let menu = UIMenu(title: "Dummy Plugin", children: [])
//        menu.autoenablesItems = false
//        menu.addItem(withTitle: "Dummy Action", action: nil, keyEquivalent: "")
//        menu.addItem(withTitle: "Smart Action", action: nil, keyEquivalent: "")
        return menu
    }
}

[krzyzanowskim]

Is that normal?

that's not normal. maybe plugins support is broken on iOS. I'll take a look at it tomorrow, unless you find the cause earlier

[Cubik65536]

Is that normal?

that's not normal. maybe plugins support is broken on iOS. I'll take a look at it tomorrow, unless you find the cause earlier

Ok, thanks! I'll also try to take a look at it.

[Cubik65536]

Is that normal?

that's not normal. maybe plugins support is broken on iOS. I'll take a look at it tomorrow, unless you find the cause earlier

Is there any updates? I couldn't figure out what's wrong :(

[Cubik65536]

I tried to dig a little bit dipper, and it seems that setUp(context: any Context) of the plugin has never been executed. And it seems that the UIKit SwiftUI version of TextView had the plugin loading disabled?

STTextView/Sources/STTextViewSwiftUIUIKit/TextView.swift

Lines 93 to 95 in 8d5d376

	//for plugin in plugins {
	// textView.addPlugin(plugin)
	//}

/cc @krzyzanowskim