Track scopes for definition field

Author: szuend

src/builder/builder.test.ts

@@ -4,7 +4,11 @@
 
 import { beforeEach, describe, it } from "jsr:@std/testing/bdd";
 import { ScopeInfoBuilder } from "./builder.ts";
-import { assertEquals, assertStrictEquals } from "jsr:@std/assert";
+import {
+  assertEquals,
+  assertNotStrictEquals,
+  assertStrictEquals,
+} from "jsr:@std/assert";
 
 describe("ScopeInfoBuilder", () => {
   let builder: ScopeInfoBuilder;
@@ -126,4 +130,49 @@ describe("ScopeInfoBuilder", () => {
       builder.endRange(0, 20);
     });
   });
+
+  describe("currentScope", () => {
+    it("returns 'null' when no scope is on the stack", () => {
+      assertStrictEquals(builder.currentScope(), null);
+    });
+
+    it("returns the currently open scope (top-level)", () => {
+      builder.startScope(0, 0);
+
+      assertNotStrictEquals(builder.currentScope(), null);
+    });
+
+    it("returns the currently open scope (nested)", () => {
+      builder.startScope(0, 0).startScope(10, 0);
+
+      assertEquals(builder.currentScope()?.start, { line: 10, column: 0 });
+    });
+  });
+
+  describe("lastScope", () => {
+    it("returns 'null' when no scope was closed yet", () => {
+      assertStrictEquals(builder.lastScope(), null);
+    });
+
+    it("returns the last closed scope (top-level)", () => {
+      builder.startScope(0, 0).endScope(10, 0);
+
+      assertNotStrictEquals(builder.lastScope(), null);
+    });
+
+    it("returns the last closed scope (nested)", () => {
+      builder.startScope(0, 0).startScope(10, 0).endScope(20, 0);
+
+      assertEquals(builder.lastScope()?.start, { line: 10, column: 0 });
+    });
+
+    it("returns the last closed scope after starting new ones", () => {
+      builder.startScope(0, 0).startScope(10, 0).endScope(20, 0).startScope(
+        30,
+        0,
+      );
+
+      assertEquals(builder.lastScope()?.start, { line: 10, column: 0 });
+    });
+  });
 });

src/builder/builder.ts

@@ -21,6 +21,10 @@ export class ScopeInfoBuilder {
   #scopeStack: OriginalScope[] = [];
   #rangeStack: GeneratedRange[] = [];
 
+  #scopeCounter = 0;
+  #scopeToCount = new Map<OriginalScope, number>();
+  #lastScope: OriginalScope | null = null;
+
   addNullScope(): this {
     this.#scopes.push(null);
     return this;
@@ -46,6 +50,7 @@ export class ScopeInfoBuilder {
       scope.parent = this.#scopeStack.at(-1);
     }
     this.#scopeStack.push(scope);
+    this.#scopeToCount.set(scope, this.#scopeCounter++);
 
     return this;
   }
@@ -79,10 +84,25 @@ export class ScopeInfoBuilder {
     } else {
       this.#scopeStack.at(-1)!.children.push(scope);
     }
+    this.#lastScope = scope;
 
     return this;
   }
 
+  /**
+   * @returns The OriginalScope opened with the most recent `startScope` call, but not yet closed.
+   */
+  currentScope(): OriginalScope | null {
+    return this.#scopeStack.at(-1) ?? null;
+  }
+
+  /**
+   * @returns The most recent OriginalScope closed with `endScope`.
+   */
+  lastScope(): OriginalScope | null {
+    return this.#lastScope;
+  }
+
   startRange(line: number, column: number): this {
     const range: GeneratedRange = {
       start: { line, column },
@@ -122,6 +142,7 @@ export class ScopeInfoBuilder {
 
     this.#scopes = [];
     this.#ranges = [];
+    this.#scopeToCount.clear();
 
     return info;
   }