Perform parser optimizations in production mode

examples/arithmetics/src/language-server/generated/module.ts

@@ -10,7 +10,8 @@ import { ArithmeticsGrammar } from './grammar.js';
 export const ArithmeticsLanguageMetaData = {
     languageId: 'arithmetics',
     fileExtensions: ['.calc'],
-    caseInsensitive: true
+    caseInsensitive: true,
+    mode: 'development'
 } as const satisfies LanguageMetaData;
 
 export const ArithmeticsGeneratedSharedModule: Module<LangiumSharedCoreServices, LangiumGeneratedSharedCoreServices> = {

examples/domainmodel/src/language-server/generated/module.ts

@@ -10,7 +10,8 @@ import { DomainModelGrammar } from './grammar.js';
 export const DomainModelLanguageMetaData = {
     languageId: 'domain-model',
     fileExtensions: ['.dmodel'],
-    caseInsensitive: false
+    caseInsensitive: false,
+    mode: 'development'
 } as const satisfies LanguageMetaData;
 
 export const parserConfig: IParserConfig = {

examples/requirements/src/language-server/generated/module.ts

@@ -10,13 +10,15 @@ import { RequirementsGrammar, TestsGrammar } from './grammar.js';
 export const RequirementsLanguageMetaData = {
     languageId: 'requirements-lang',
     fileExtensions: ['.req'],
-    caseInsensitive: false
+    caseInsensitive: false,
+    mode: 'development'
 } as const satisfies LanguageMetaData;
 
 export const TestsLanguageMetaData = {
     languageId: 'tests-lang',
     fileExtensions: ['.tst'],
-    caseInsensitive: false
+    caseInsensitive: false,
+    mode: 'development'
 } as const satisfies LanguageMetaData;
 
 export const RequirementsAndTestsGeneratedSharedModule: Module<LangiumSharedCoreServices, LangiumGeneratedSharedCoreServices> = {

examples/statemachine/src/language-server/generated/module.ts

@@ -10,7 +10,8 @@ import { StatemachineGrammar } from './grammar.js';
 export const StatemachineLanguageMetaData = {
     languageId: 'statemachine',
     fileExtensions: ['.statemachine'],
-    caseInsensitive: false
+    caseInsensitive: false,
+    mode: 'development'
 } as const satisfies LanguageMetaData;
 
 export const StatemachineGeneratedSharedModule: Module<LangiumSharedCoreServices, LangiumGeneratedSharedCoreServices> = {

packages/generator-langium/templates/core/.package.json

@@ -12,6 +12,7 @@
         "watch": "tsc -b <%= tsconfig %> --watch",
         "lint": "eslint src --ext ts",
         "langium:generate": "langium generate",
+        "langium:generate:production": "langium generate --mode=production",
         "langium:watch": "langium generate --watch"
     },
     "dependencies": {

packages/langium-cli/src/generator/module-generator.ts

@@ -12,6 +12,7 @@ import { generatedHeader } from './node-util.js';
 export function generateModule(grammars: Grammar[], config: LangiumConfig, grammarConfigMap: Map<Grammar, LangiumLanguageConfig>): string {
     const grammarsWithName = grammars.filter(grammar => !!grammar.name);
     const parserConfig = config.chevrotainParserConfig;
+    const mode = config.mode;
     const hasIParserConfigImport = Boolean(parserConfig) || grammars.some(grammar => grammarConfigMap.get(grammar)?.chevrotainParserConfig !== undefined);
     let needsGeneralParserConfig = undefined;
 
@@ -41,12 +42,14 @@ export function generateModule(grammars: Grammar[], config: LangiumConfig, gramm
             grammarsWithName,
             grammar => {
                 const config = grammarConfigMap.get(grammar)!;
+                const modeValue = mode === 'production' ? mode : 'development';
                 return expandToNode`
 
                     export const ${ grammar.name }LanguageMetaData = {
                         languageId: '${config.id}',
                         fileExtensions: [${config.fileExtensions && joinToNode(config.fileExtensions, e => appendQuotesAndDot(e), { separator: ', ' })}],
-                        caseInsensitive: ${Boolean(config.caseInsensitive)}
+                        caseInsensitive: ${Boolean(config.caseInsensitive)},
+                        mode: '${modeValue}'
                     } as const satisfies LanguageMetaData;
                 `;
             },

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

@@ -59,7 +59,8 @@ function languageConfigToMetaData(config: LangiumLanguageConfig): LanguageMetaDa
     return {
         languageId: config.id,
         fileExtensions: config.fileExtensions ?? [],
-        caseInsensitive: Boolean(config.caseInsensitive)
+        caseInsensitive: Boolean(config.caseInsensitive),
+        mode: 'development'
     };
 }
 

packages/langium/src/grammar/generated/module.ts

@@ -13,7 +13,8 @@ import { LangiumGrammarGrammar } from './grammar.js';
 export const LangiumGrammarLanguageMetaData = {
     languageId: 'langium',
     fileExtensions: ['.langium'],
-    caseInsensitive: false
+    caseInsensitive: false,
+    mode: 'development'
 } as const satisfies LanguageMetaData;
 
 export const LangiumGrammarParserConfig: IParserConfig = {

packages/langium/src/grammar/internal-grammar-util.ts

@@ -182,7 +182,8 @@ export async function createServicesForGrammar<L extends LangiumServices = Langi
     const languageMetaData = config.languageMetaData ?? {
         caseInsensitive: false,
         fileExtensions: [`.${grammarNode.name?.toLowerCase() ?? 'unknown'}`],
-        languageId: grammarNode.name ?? 'UNKNOWN'
+        languageId: grammarNode.name ?? 'UNKNOWN',
+        mode: 'development'
     };
     const generatedSharedModule: Module<LangiumGeneratedSharedCoreServices> = {
         AstReflection: () => interpretAstReflection(grammarNode),

packages/langium/src/languages/language-meta-data.ts

@@ -4,8 +4,17 @@
  * terms of the MIT License, which is available in the project root.
  ******************************************************************************/
 
+/**
+ * Metadata of a language.
+ */
 export interface LanguageMetaData {
     languageId: string;
     fileExtensions: readonly string[];
     caseInsensitive: boolean;
+    /**
+     * Mode used to optimize code for development or production environments.
+     *
+     * In production mode, all Chevrotain lexer/parser validations are disabled.
+     */
+    mode: 'development' | 'production';
 }

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

@@ -135,8 +135,10 @@ export abstract class AbstractLangiumParser implements BaseParser {
     constructor(services: LangiumCoreServices) {
         this.lexer = services.parser.Lexer;
         const tokens = this.lexer.definition;
+        const production = services.LanguageMetaData.mode === 'production';
         this.wrapper = new ChevrotainWrapper(tokens, {
             ...services.parser.ParserConfig,
+            skipValidations: production,
             errorMessageProvider: services.parser.ParserErrorMessageProvider
         });
     }
@@ -631,13 +633,16 @@ class ChevrotainWrapper extends EmbeddedActionsParser {
     // This array is set in the base implementation of Chevrotain.
     definitionErrors: IParserDefinitionError[];
 
-    constructor(tokens: TokenVocabulary, config?: IParserConfig) {
+    constructor(tokens: TokenVocabulary, config: IParserConfig) {
         const useDefaultLookahead = config && 'maxLookahead' in config;
         super(tokens, {
             ...defaultConfig,
             lookaheadStrategy: useDefaultLookahead
                 ? new LLkLookaheadStrategy({ maxLookahead: config.maxLookahead })
-                : new LLStarLookaheadStrategy(),
+                : new LLStarLookaheadStrategy({
+                    // If validations are skipped, don't log the lookahead warnings
+                    logging: config.skipValidations ? () => { } : undefined
+                }),
             ...config,
         });
     }

packages/langium/src/parser/lexer.ts

@@ -51,8 +51,10 @@ export class DefaultLexer implements Lexer {
         });
         this.tokenTypes = this.toTokenTypeDictionary(tokens);
         const lexerTokens = isTokenTypeDictionary(tokens) ? Object.values(tokens) : tokens;
+        const production = services.LanguageMetaData.mode === 'production';
         this.chevrotainLexer = new ChevrotainLexer(lexerTokens, {
-            positionTracking: 'full'
+            positionTracking: 'full',
+            skipValidations: production
         });
     }