Move stuff around

src-web/components/core/Editor/widgets.ts

@@ -0,0 +1,76 @@
+import type { DecorationSet, ViewUpdate } from '@codemirror/view';
+import { Decoration, EditorView, MatchDecorator, ViewPlugin, WidgetType } from '@codemirror/view';
+
+class PlaceholderWidget extends WidgetType {
+  constructor(readonly name: string) {
+    super();
+  }
+  eq(other: PlaceholderWidget) {
+    return this.name == other.name;
+  }
+  toDOM() {
+    const elt = document.createElement('span');
+    elt.className = 'placeholder-widget';
+    elt.textContent = this.name;
+    return elt;
+  }
+  ignoreEvent() {
+    return false;
+  }
+}
+
+/**
+ * This is a custom MatchDecorator that will not decorate a match if the selection is inside it
+ */
+class BetterMatchDecorator extends MatchDecorator {
+  updateDeco(update: ViewUpdate, deco: DecorationSet): DecorationSet {
+    if (!update.startState.selection.eq(update.state.selection)) {
+      return super.createDeco(update.view);
+    } else {
+      return super.updateDeco(update, deco);
+    }
+  }
+}
+
+const placeholderMatcher = new BetterMatchDecorator({
+  regexp: /\$\{\[\s*([^\]\s]+)\s*]}/g,
+  decoration(match, view, matchStartPos) {
+    const matchEndPos = matchStartPos + match[0].length - 1;
+
+    // Don't decorate if the cursor is inside the match
+    for (const r of view.state.selection.ranges) {
+      if (r.from > matchStartPos && r.to <= matchEndPos) return null;
+    }
+
+    const groupMatch = match[1];
+    if (groupMatch == null) {
+      // Should never happen, but make TS happy
+      console.warn('Group match was empty', match);
+      return null;
+    }
+
+    return Decoration.replace({
+      inclusive: true,
+      widget: new PlaceholderWidget(groupMatch),
+    });
+  },
+});
+
+export const placeholders = ViewPlugin.fromClass(
+  class {
+    placeholders: DecorationSet;
+    constructor(view: EditorView) {
+      this.placeholders = placeholderMatcher.createDeco(view);
+    }
+    update(update: ViewUpdate) {
+      this.placeholders = placeholderMatcher.updateDeco(update, this.placeholders);
+    }
+  },
+  {
+    decorations: (instance) => instance.placeholders,
+    provide: (plugin) =>
+      EditorView.atomicRanges.of((view) => {
+        return view.plugin(plugin)?.placeholders || Decoration.none;
+      }),
+  },
+);