From 55f68cccc168a1d5d88101540fb5f51bb45a5583 Mon Sep 17 00:00:00 2001
From: Christian Dietrich <christian.dietrich.opensource@gmail.com>
Date: Tue, 15 Aug 2023 17:11:49 +0200
Subject: [PATCH] add implicit ID rule call for cross refs to
 getAllReachableRules

Fixes #1151

Signed-off-by: Christian Dietrich <christian.dietrich.opensource@gmail.com>
---
 packages/langium/src/utils/grammar-util.ts    | 28 +++++++----
 .../langium/test/utils/grammar-util.test.ts   | 46 ++++++++++++++++++-
 2 files changed, 65 insertions(+), 9 deletions(-)

diff --git a/packages/langium/src/utils/grammar-util.ts b/packages/langium/src/utils/grammar-util.ts
index ef018bfc0..3a1831583 100644
--- a/packages/langium/src/utils/grammar-util.ts
+++ b/packages/langium/src/utils/grammar-util.ts
@@ -1,5 +1,5 @@
 /******************************************************************************
- * Copyright 2021-2022 TypeFox GmbH
+ * Copyright 2021-2023 TypeFox GmbH
  * This program and the accompanying materials are made available under the
  * terms of the MIT License, which is available in the project root.
  ******************************************************************************/
@@ -54,26 +54,38 @@ export function getAllReachableRules(grammar: ast.Grammar, allTerminals: boolean
     }
 
     const topMostRules = [entryRule as ast.AbstractRule].concat(getHiddenRules(grammar));
+    const rules = new Set<ast.AbstractRule>();
     for (const rule of topMostRules) {
-        ruleDfs(rule, ruleNames, allTerminals);
+        ruleDfs(rule, ruleNames, rules, allTerminals);
     }
 
-    const rules = new Set<ast.AbstractRule>();
+    
     for (const rule of grammar.rules) {
-        if (ruleNames.has(rule.name) || (ast.isTerminalRule(rule) && rule.hidden)) {
+        if ((ast.isTerminalRule(rule) && rule.hidden)) {
             rules.add(rule);
         }
     }
     return rules;
 }
 
-function ruleDfs(rule: ast.AbstractRule, visitedSet: Set<string>, allTerminals: boolean): void {
-    visitedSet.add(rule.name);
+function ruleDfs(rule: ast.AbstractRule, visitedRuleNames: Set<string>, visitedRules: Set<ast.AbstractRule> , allTerminals: boolean): void {
+    visitedRuleNames.add(rule.name);
+    visitedRules.add(rule)
     streamAllContents(rule).forEach(node => {
         if (ast.isRuleCall(node) || (allTerminals && ast.isTerminalRuleCall(node))) {
             const refRule = node.rule.ref;
-            if (refRule && !visitedSet.has(refRule.name)) {
-                ruleDfs(refRule, visitedSet, allTerminals);
+            if (refRule && !visitedRuleNames.has(refRule.name)) {
+                ruleDfs(refRule, visitedRuleNames, visitedRules, allTerminals);
+            }
+        } else if (ast.isCrossReference(node)) {
+            const term = getCrossReferenceTerminal(node)
+            if (term !== undefined) {
+                if (ast.isRuleCall(term) || (allTerminals && ast.isTerminalRuleCall(term))) {
+                    const refRule = term.rule.ref;
+                    if (refRule && !visitedRuleNames.has(refRule.name)) {
+                        ruleDfs(refRule, visitedRuleNames, visitedRules, allTerminals);
+                    }
+                }
             }
         }
     });
diff --git a/packages/langium/test/utils/grammar-util.test.ts b/packages/langium/test/utils/grammar-util.test.ts
index 5a4b7b46c..9e01ee402 100644
--- a/packages/langium/test/utils/grammar-util.test.ts
+++ b/packages/langium/test/utils/grammar-util.test.ts
@@ -1,5 +1,5 @@
 /******************************************************************************
- * Copyright 2022 TypeFox GmbH
+ * Copyright 2022-2023 TypeFox GmbH
  * This program and the accompanying materials are made available under the
  * terms of the MIT License, which is available in the project root.
  ******************************************************************************/
@@ -8,6 +8,7 @@ import type { Grammar } from '../../src';
 import { describe, expect, test } from 'vitest';
 import { createLangiumGrammarServices, EmptyFileSystem, getAllReachableRules } from '../../src';
 import { parseHelper } from '../../src/test';
+import { Utils } from 'vscode-uri';
 
 const services = createLangiumGrammarServices(EmptyFileSystem);
 const parse = parseHelper<Grammar>(services.grammar);
@@ -36,4 +37,47 @@ describe('Grammar Utils', () => {
         expect(reachableRules).toContain('Ws');
     });
 
+    test('ID implicit called should be returned by getAllReachableRules', async () => {
+        // [A] is short for [A:ID] thus the ID rule is needed by the parser and getAllReachableRules should return ID
+        const grammar1 = await parse(`
+        grammar G1
+        entry A:
+            'A' name=ID;
+        terminal ID: /[_a-zA-Z][\\w_]*/;
+        `);
+        const grammar2 = await parse(`
+        grammar G2
+        import './${Utils.basename(grammar1.uri)}'
+        entry B: ref=[A];
+        `);
+        await services.shared.workspace.DocumentBuilder.build([grammar2, grammar1]);
+        // act
+        const reachableRules = [...getAllReachableRules(grammar2.parseResult.value, true)].map(r => r.name);
+        // assert
+        expect(reachableRules).toContain('ID');
+    });
+
+    test('ID not implicit called should not be returned by getAllReachableRules', async () => {
+        // no implicit ID rule call in cross ref
+       // [A] is short for [A:ID] thus the ID rule is needed by the parser and getAllReachableRules should return ID
+       const grammar1 = await parse(`
+       grammar G1
+       entry A:
+           'A' name=ID;
+       Other: name=STRING; 
+       terminal ID: /[_a-zA-Z][\\w_]*/;
+       `);
+       const grammar2 = await parse(`
+       grammar G2
+       import './${Utils.basename(grammar1.uri)}'
+       entry B: ref=[A];
+       `);
+       await services.shared.workspace.DocumentBuilder.build([grammar2, grammar1]);
+       // act
+       const reachableRules = [...getAllReachableRules(grammar2.parseResult.value, true)].map(r => r.name);
+       
+       // assert
+       expect(reachableRules).not.toContain('STRING');
+    });
+
 });