1 files changed, 34 insertions, 0 deletions

diff --git a/language-web/src/main/js/editor/semanticHighlighting.ts b/language-web/src/main/js/editor/semanticHighlighting.ts
new file mode 100644
index 00000000..2d6804f8
--- /dev/null
+++ b/language-web/src/main/js/editor/semanticHighlighting.ts
@@ -0,0 +1,34 @@
+import { StateEffect, StateField, TransactionSpec } from '@codemirror/state';
+import { EditorView, Decoration, DecorationSet } from '@codemirror/view';
+
+const setSemanticHighlightingEffect = StateEffect.define<DecorationSet>();
+
+export function setSemanticHighlighting(decorations: DecorationSet): TransactionSpec {
+  return {
+    effects: [
+      setSemanticHighlightingEffect.of(decorations),
+    ],
+  };
+}
+
+export const semanticHighlighting = StateField.define<DecorationSet>({
+  create() {
+    return Decoration.none;
+  },
+  update(currentDecorations, transaction) {
+    let newDecorations: DecorationSet | null = null;
+    transaction.effects.forEach((effect) => {
+      if (effect.is(setSemanticHighlightingEffect)) {
+        newDecorations = effect.value;
+      }
+    });
+    if (newDecorations === null) {
+      if (transaction.docChanged) {
+        return currentDecorations.map(transaction.changes);
+      }
+      return currentDecorations;
+    }
+    return newDecorations;
+  },
+  provide: (f) => EditorView.decorations.from(f),
+});