Support detailed ligatures and variants

Fixes #5284

addons/addon-ligatures/src/LigaturesAddon.ts

@@ -15,19 +15,22 @@ export interface ITerminalAddon {
 
 export class LigaturesAddon implements ITerminalAddon , ILigaturesApi {
   private readonly _fallbackLigatures: string[];
+  private readonly _fontFeatureSettings?: string;
 
   private _terminal: Terminal | undefined;
   private _characterJoinerId: number | undefined;
 
   constructor(options?: Partial<ILigatureOptions>) {
+    // Source: calt set from https://github.com/be5invis/Iosevka?tab=readme-ov-file#ligations
     this._fallbackLigatures = (options?.fallbackLigatures || [
       '<--', '<---', '<<-', '<-', '->', '->>', '-->', '--->',
       '<==', '<===', '<<=', '<=', '=>', '=>>', '==>', '===>', '>=', '>>=',
-      '<->', '<-->', '<--->', '<---->', '<=>', '<==>', '<===>', '<====>', '-------->',
-      '<~~', '<~', '~>', '~~>', '::', ':::', '==', '!=', '===', '!==',
-      ':=', ':-', ':+', '<*', '<*>', '*>', '<|', '<|>', '|>', '+:', '-:', '=:', ':>',
-      '++', '+++', '<!--', '<!---', '<***>'
+      '<->', '<-->', '<--->', '<---->', '<=>', '<==>', '<===>', '<====>', '::', ':::',
+      '<~~', '</', '</>', '/>', '~~>', '==', '!=', '/=', '~=', '<>', '===', '!==', '!===',
+      '<:', ':=', '*=', '*+', '<*', '<*>', '*>', '<|', '<|>', '|>', '+*', '=*', '=:', ':>',
+      '/*', '*/', '+++', '<!--', '<!---'
     ]).sort((a, b) => b.length - a.length);
+    this._fontFeatureSettings = options?.fontFeatureSettings;
   }
 
   public activate(terminal: Terminal): void {
@@ -36,7 +39,7 @@ export class LigaturesAddon implements ITerminalAddon , ILigaturesApi {
     }
     this._terminal = terminal;
     this._characterJoinerId = enableLigatures(terminal, this._fallbackLigatures);
-    terminal.element.style.fontFeatureSettings = '"liga" on, "calt" on';
+    terminal.element.style.fontFeatureSettings = this._fontFeatureSettings ?? '"calt" on';
   }
 
   public dispose(): void {

addons/addon-ligatures/src/Types.ts

@@ -5,4 +5,5 @@
 
 export interface ILigatureOptions {
   fallbackLigatures: string[];
+  fontFeatureSettings: string;
 }