WebAssembly build

[easbar]

Can you give some advice how to compile libvim to WebAssembly? its mentioned in the README.md but I could not find any instructions how this is done.

I do not know the esy tool very well, but I think I was able to build the library under linux using this script in src/build (running it from src):

# build in this folder
cur__install=my_build_wasm
# the lib folder is not created by the makefile for some reason -> created it manually
mkdir -p $cur__install/lib
emconfigure ./configure --disable-selinux CFLAGS=-fPIC
emmake make installlibvim DESTDIR=$cur__install

There were some failing checks though (not sure if this is the problem):

checking --with-tlib argument... empty: automatic terminal library selection
checking for tgetent in -ltinfo... no
checking for tgetent in -lncurses... no
checking for tgetent in -ltermlib... no
checking for tgetent in -ltermcap... no
checking for tgetent in -lcurses... no
no terminal library found
checking for tgetent()... configure: error: NOT FOUND!
      You need to install a terminal library; for example ncurses.
      Or specify the name of the library with --with-tlib.

Anyway I got a libvim.a file and tried compiling this code:

#include <stdio.h>
#include "libvim.h"

void sayHello() {
        printf("hello\n");
}

int main(int argc, char** argv) {
        vimInit(argc, argv);
        sayHello();
}

using this command:

emcc -Iinclude -Iinclude/proto -DHAVE_CONFIG_H -fPIC main.c lib/libvim.a -o index.html

But then I got this error:

wasm-ld: error: unknown file type: libvim.o

This works fine using gcc:

# after running the same build script but with configure/make instead of emconfigure/emmake
gcc -Iinclude -Iinclude/proto -DHAVE_CONFIG_H main.c lib/libvim.a -lSM -lICE -lXt -lX11 -lXdmcp -lm -ltinfo -lnsl -ldl

Any idea what could be wrong? Did you have success using this library with WebAssembly yet? If so it would be great if you could add some directions how.

[elebeaup]

Emscripten does not seem to support ncurses. But, libvim is not responsible for rendering the user interface. So, I think we can skip this check.

After some tweaks, I succeeded in compiling libvim to WebAssembly. I tested part of the API (motion, update buffer callback, get vim mode, input and key press,...) and it works.

I have a question about the cursor position. @bryphe In oni2, how is the cursor position handled after a vim motion? Do you check after each keyboard event if the cursor position has changed? In the API, I cannot find any callback about the cursor position that would be triggered after a vim motion (w, h, j, gg,...)

[bryphe]

After some tweaks, I succeeded in compiling libvim to WebAssembly. I tested part of the API (motion, update buffer callback, get vim mode, input and key press,...) and it works.

@elebeaup - very exciting! Thanks for exploring this and sharing what you've done so far. Would be interested to see it in action

In oni2, how is the cursor position handled after a vim motion? Do you check after each keyboard event if the cursor position has changed? In the API, I cannot find any callback about the cursor position that would be triggered after a vim motion (w, h, j, gg,...)

Good question - you're exactly right in terms of the strategy Onivim 2 uses: we get the cursor position with vimCursorGetLine/vimCursorGetColumn after running libvim's vimKey/vimExecute/vimCommand.

[titanous]

I played around with this a bit in December. I ended up ripping out some terminal-related stuff in order to get it to build. This is what I ended up with: https://github.com/titanous/libvim/commit/ffdb7d9ad6e22f0152b39aacffc23e261456c874

I haven't had time to fully test/integrate and clean this up, but I wanted to checkpoint here in case someone else got to it first.

[elebeaup]

You can find my work in progress here : elebeaup@9aff8976cd0b338945feeaefce0526d33c9243e0.

Compiling

$ emconfigure ./configure
$ emmake make libvim.js

Testing

$ cd wasm
$ npm install
$ npm test