Add parser error message provider service

packages/langium/src/default-module.ts

@@ -46,6 +46,7 @@ import { DefaultIndexManager } from './workspace/index-manager';
 import { DefaultWorkspaceManager } from './workspace/workspace-manager';
 import { DefaultLexer } from './parser/lexer';
 import { JSDocDocumentationProvider } from './documentation';
+import { LangiumParserErrorMessageProvider } from './parser/langium-parser';
 
 /**
  * Context required for creating the default language-specific dependency injection module.
@@ -69,7 +70,8 @@ export function createDefaultModule(context: DefaultModuleContext): Module<Langi
             CompletionParser: (services) => createCompletionParser(services),
             ValueConverter: () => new DefaultValueConverter(),
             TokenBuilder: () => new DefaultTokenBuilder(),
-            Lexer: (services) => new DefaultLexer(services)
+            Lexer: (services) => new DefaultLexer(services),
+            ParserErrorMessageProvider: () => new LangiumParserErrorMessageProvider()
         },
         lsp: {
             CompletionProvider: (services) => new DefaultCompletionProvider(services),

packages/langium/src/parser/langium-parser.ts

@@ -78,7 +78,10 @@ export abstract class AbstractLangiumParser implements BaseParser {
     constructor(services: LangiumServices) {
         this.lexer = services.parser.Lexer;
         const tokens = this.lexer.definition;
-        this.wrapper = new ChevrotainWrapper(tokens, services.parser.ParserConfig);
+        this.wrapper = new ChevrotainWrapper(tokens, {
+            ...services.parser.ParserConfig,
+            errorMessageProvider: services.parser.ParserErrorMessageProvider
+        });
     }
 
     alternatives(idx: number, choices: Array<IOrAlt<any>>): void {
@@ -350,27 +353,22 @@ export interface IParserDefinitionError {
     ruleName?: string
 }
 
-export class LangiumParserErrorMessageProvider implements IParserErrorMessageProvider {
+export class AbstractParserErrorMessageProvider implements IParserErrorMessageProvider {
 
-    buildMismatchTokenMessage({ expected, actual }: {
+    buildMismatchTokenMessage(options: {
         expected: TokenType
         actual: IToken
         previous: IToken
         ruleName: string
     }): string {
-        const expectedMsg = expected.LABEL
-            ? '`' + expected.LABEL + '`'
-            : expected.name.endsWith(':KW')
-                ? `keyword '${expected.name.substring(0, expected.name.length - 3)}'`
-                : `token of type '${expected.name}'`;
-        return `Expecting ${expectedMsg} but found \`${actual.image}\`.`;
+        return defaultParserErrorProvider.buildMismatchTokenMessage(options);
     }
 
-    buildNotAllInputParsedMessage({ firstRedundant }: {
+    buildNotAllInputParsedMessage(options: {
         firstRedundant: IToken
         ruleName: string
     }): string {
-        return `Expecting end of file but found \`${firstRedundant.image}\`.`;
+        return defaultParserErrorProvider.buildNotAllInputParsedMessage(options);
     }
 
     buildNoViableAltMessage(options: {
@@ -395,6 +393,30 @@ export class LangiumParserErrorMessageProvider implements IParserErrorMessagePro
 
 }
 
+export class LangiumParserErrorMessageProvider extends AbstractParserErrorMessageProvider {
+
+    override buildMismatchTokenMessage({ expected, actual }: {
+        expected: TokenType
+        actual: IToken
+        previous: IToken
+        ruleName: string
+    }): string {
+        const expectedMsg = expected.LABEL
+            ? '`' + expected.LABEL + '`'
+            : expected.name.endsWith(':KW')
+                ? `keyword '${expected.name.substring(0, expected.name.length - 3)}'`
+                : `token of type '${expected.name}'`;
+        return `Expecting ${expectedMsg} but found \`${actual.image}\`.`;
+    }
+
+    override buildNotAllInputParsedMessage({ firstRedundant }: {
+        firstRedundant: IToken
+        ruleName: string
+    }): string {
+        return `Expecting end of file but found \`${firstRedundant.image}\`.`;
+    }
+}
+
 export interface CompletionParserResult {
     tokens: IToken[]
     elementStack: AbstractElement[]

packages/langium/src/services.ts

@@ -59,6 +59,7 @@ import type { InlayHintProvider } from './lsp/inlay-hint-provider';
 import type { WorkspaceSymbolProvider } from './lsp/workspace-symbol-provider';
 import type { NodeKindProvider } from './lsp/node-kind-provider';
 import type { FuzzyMatcher } from './lsp/fuzzy-matcher';
+import type { IParserErrorMessageProvider } from 'chevrotain';
 
 /**
  * The services generated by `langium-cli` for a single language. These are derived from the
@@ -103,6 +104,7 @@ export type LangiumDefaultServices = {
         GrammarConfig: GrammarConfig
         ValueConverter: ValueConverter
         LangiumParser: LangiumParser
+        ParserErrorMessageProvider: IParserErrorMessageProvider
         CompletionParser: LangiumCompletionParser
         TokenBuilder: TokenBuilder
         Lexer: Lexer