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

@@ -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.
  ******************************************************************************/
@@ -47,33 +47,49 @@ export function getHiddenRules(grammar: ast.Grammar) {
  *      this function returns all rules of the specified grammar.
  */
 export function getAllReachableRules(grammar: ast.Grammar, allTerminals: boolean): Set<ast.AbstractRule> {
-    const ruleNames = new Set<string>();
     const entryRule = getEntryRule(grammar);
     if (!entryRule) {
         return new Set(grammar.rules);
     }
 
     const topMostRules = [entryRule as ast.AbstractRule].concat(getHiddenRules(grammar));
+    const collectedRules = new Set<ast.AbstractRule>();
     for (const rule of topMostRules) {
-        ruleDfs(rule, ruleNames, allTerminals);
+        ruleDfs(rule, collectedRules, allTerminals);
     }
 
     const rules = new Set<ast.AbstractRule>();
     for (const rule of grammar.rules) {
-        if (ruleNames.has(rule.name) || (ast.isTerminalRule(rule) && rule.hidden)) {
+        if (collectedRules.has(rule) || ((ast.isTerminalRule(rule) && rule.hidden))) {
             rules.add(rule);
         }
     }
+    for (const rule of collectedRules) {
+        if (!rules.has(rule)) {
+            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, visitedRules: Set<ast.AbstractRule> , allTerminals: boolean): void {
+    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 && !visitedRules.has(refRule)) {
+                ruleDfs(refRule, 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 && !visitedRules.has(refRule)) {
+                        ruleDfs(refRule,  visitedRules, allTerminals);
+                    }
+                }
             }
         }
     });

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 +37,53 @@ describe('Grammar Utils', () => {
         expect(reachableRules).toContain('Ws');
     });
 
+    test('getAllReachableRules should return rules referenced in cross references', 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;
+        Uncalled: name=IDX;
+        Called: name=INT;
+        terminal INT returns number: /[0-9]+/;    
+        terminal ID: /[A-Z][\\w_]*/;
+        terminal IDX: /[a-z][\\w_]*/;
+        `);
+        const grammar2 = await parse(`
+        grammar G2
+        import './${Utils.basename(grammar1.uri)}'
+        entry B: ref=[A] s=STRING c=Called;
+        terminal STRING: /"(\\.|[^"\\])*"|'(\\.|[^'\\])*'/;
+        `);
+        await services.shared.workspace.DocumentBuilder.build([grammar2, grammar1]);
+        // act
+        const reachableRules = [...getAllReachableRules(grammar2.parseResult.value, true)].map(r => r.name);
+        // assert
+        expect(reachableRules).toEqual(['B', 'STRING', 'ID', 'Called', 'INT' ])
+    });
+
+    test('getAllReachableRules should not return unused rules', async () => {
+        // no implicit ID rule call in cross ref
+        // [A] is short for [A:ID] thus the ID rule is needed by the parser and getAllReachableRules should return ID
+        const grammar1 = await parse(`
+        grammar G1
+        entry A:
+        'A' name=ID;
+        Other: name=STRING;
+        terminal STRING: /"(\\.|[^"\\])*"|'(\\.|[^'\\])*'/;
+        terminal ID: /[_a-zA-Z][\\w_]*/;
+        `);
+        const grammar2 = await parse(`
+        grammar G2
+        import './${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');
+    });
+
 });