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add an option to generate a partial ast definition #1854

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4b33986
add an option to generate optional properties in ast
ydaveluy Mar 18, 2025
5e942c8
add test case
ydaveluy Mar 19, 2025
76b576e
generate a partial ast
ydaveluy Mar 27, 2025
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4 changes: 4 additions & 0 deletions packages/langium-cli/langium-config-schema.json
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Original file line number Diff line number Diff line change
Expand Up @@ -171,6 +171,10 @@
"langiumInternal": {
"description": "A flag to determine whether langium uses itself to bootstrap",
"type": "boolean"
},
"generatePartialAst": {
"description": "Generate a partial AST with optional properties (usefull to access the parsed AST with an incomplete document)",
"type": "boolean"
}
},
"required": [
Expand Down
9 changes: 6 additions & 3 deletions packages/langium-cli/src/generate.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ import { loadConfig } from './package.js';
import { AstUtils, GrammarAST } from 'langium';
import { createLangiumGrammarServices, resolveImport, resolveImportUri, resolveTransitiveImports } from 'langium/grammar';
import { NodeFileSystem } from 'langium/node';
import { generateAst } from './generator/ast-generator.js';
import { generateAst, generateAstPartial } from './generator/ast-generator.js';
import { serializeGrammar } from './generator/grammar-serializer.js';
import { generateModule } from './generator/module-generator.js';
import { generateBnf } from './generator/bnf-generator.js';
Expand Down Expand Up @@ -327,7 +327,7 @@ export async function runGenerator(config: LangiumConfig, options: GenerateOptio
const output = path.resolve(relPath, config.out ?? 'src/generated');
log('log', options, `Writing generated files to ${chalk.white.bold(output)}`);

if (await rmdirWithFail(output, ['ast.ts', 'grammar.ts', 'module.ts'], options)) {
if (await rmdirWithFail(output, ['ast.ts', 'ast-partial.ts', 'grammar.ts', 'module.ts'], options)) {
return buildResult(false);
}
if (await mkdirWithFail(output, options)) {
Expand All @@ -336,7 +336,10 @@ export async function runGenerator(config: LangiumConfig, options: GenerateOptio

const genAst = generateAst(grammarServices, embeddedGrammars, config);
await writeWithFail(path.resolve(updateLangiumInternalAstPath(output, config), 'ast.ts'), genAst, options);

if(config.generatePartialAst) {
const genAstPartial = generateAstPartial(grammarServices, embeddedGrammars, config);
await writeWithFail(path.resolve(updateLangiumInternalAstPath(output, config), 'ast-partial.ts'), genAstPartial, options);
}
const serializedGrammar = serializeGrammar(grammarServices, embeddedGrammars, config);
await writeWithFail(path.resolve(output, 'grammar.ts'), serializedGrammar, options);

Expand Down
43 changes: 41 additions & 2 deletions packages/langium-cli/src/generator/ast-generator.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -12,9 +12,10 @@ import { collectAst, collectTypeHierarchy, findReferenceTypes, isAstType, mergeT
import { generatedHeader } from './node-util.js';
import { collectKeywords, collectTerminalRegexps } from './langium-util.js';

export function generateAst(services: LangiumCoreServices, grammars: Grammar[], config: LangiumConfig): string {
export function generateAst(services: LangiumCoreServices, grammars: Grammar[], config: LangiumConfig,): string {
const astTypes = collectAst(grammars, services.shared.workspace.LangiumDocuments);
const importFrom = config.langiumInternal ? `../../syntax-tree${config.importExtension}` : 'langium';

/* eslint-disable @typescript-eslint/indent */
const fileNode = expandToNode`
${generatedHeader}
Expand All @@ -25,7 +26,7 @@ export function generateAst(services: LangiumCoreServices, grammars: Grammar[],
${generateTerminalConstants(grammars, config)}

${joinToNode(astTypes.unions, union => union.toAstTypesString(isAstType(union.type)), { appendNewLineIfNotEmpty: true })}
${joinToNode(astTypes.interfaces, iFace => iFace.toAstTypesString(true), { appendNewLineIfNotEmpty: true })}
${joinToNode(astTypes.interfaces, iFace => iFace.toAstTypesString(true, false), { appendNewLineIfNotEmpty: true })}
${
astTypes.unions = astTypes.unions.filter(e => isAstType(e.type)),
generateAstReflection(config, astTypes)
Expand All @@ -34,6 +35,30 @@ export function generateAst(services: LangiumCoreServices, grammars: Grammar[],
return toString(fileNode);
/* eslint-enable @typescript-eslint/indent */
}
export function generateAstPartial(services: LangiumCoreServices, grammars: Grammar[], config: LangiumConfig,): string {
const astTypes = collectAst(grammars, services.shared.workspace.LangiumDocuments);
const importFrom = config.langiumInternal ? `../../syntax-tree${config.importExtension}` : 'langium';

/* eslint-disable @typescript-eslint/indent */
const fileNode = expandToNode`
${generatedHeader}

/* eslint-disable */
import * as langium from '${importFrom}';
import * as ast from './ast.js';

${generateTerminalConstantsPartial(grammars, config)}

${joinToNode(astTypes.unions, union => union.toAstTypesString(isAstType(union.type), true), { appendNewLineIfNotEmpty: true })}
${joinToNode(astTypes.interfaces, iFace => iFace.toAstTypesString(true, true), { appendNewLineIfNotEmpty: true })}
${
astTypes.unions = astTypes.unions.filter(e => isAstType(e.type)),
generateAstReflectionPartial(config, astTypes)
}
`;
return toString(fileNode);
/* eslint-enable @typescript-eslint/indent */
}

function generateAstReflection(config: LangiumConfig, astTypes: AstTypes): Generated {
const typeNames: string[] = astTypes.interfaces.map(t => t.name)
Expand Down Expand Up @@ -68,6 +93,14 @@ function generateAstReflection(config: LangiumConfig, astTypes: AstTypes): Gener
`.appendNewLine();
}

function generateAstReflectionPartial(config: LangiumConfig, _astTypes: AstTypes): Generated {

return expandToNode`

export type { ${config.projectName}AstType, ${config.projectName}AstReflection } from './ast.js';
export const reflection = ast.reflection;
`.appendNewLine();
}
function buildTypeMetaDataMethod(astTypes: AstTypes): Generated {
/* eslint-disable @typescript-eslint/indent */
return expandToNode`
Expand Down Expand Up @@ -252,3 +285,9 @@ function generateTerminalConstants(grammars: Grammar[], config: LangiumConfig):
export type ${config.projectName}TokenNames = ${config.projectName}TerminalNames | ${config.projectName}KeywordNames;
`.appendNewLine();
}

function generateTerminalConstantsPartial(grammars: Grammar[], config: LangiumConfig): Generated {
return expandToNode`
export { ${config.projectName}Terminals, type ${config.projectName}TerminalNames, type ${config.projectName}KeywordNames, type ${config.projectName}TokenNames } from './ast.js';
`.appendNewLine();
}
2 changes: 2 additions & 0 deletions packages/langium-cli/src/package-types.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,8 @@ export interface LangiumConfig {
chevrotainParserConfig?: IParserConfig,
/** The following option is meant to be used only by Langium itself */
langiumInternal?: boolean
/** Generate a partial AST with optional properties (usefull to access the parsed AST with an incomplete document) */
generatePartialAst?: boolean
}

export interface LangiumLanguageConfig {
Expand Down
28 changes: 18 additions & 10 deletions packages/langium/src/grammar/type-system/type-collector/types.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -121,14 +121,14 @@ export class UnionType {
this.dataType = options?.dataType;
}

toAstTypesString(reflectionInfo: boolean): string {
toAstTypesString(reflectionInfo: boolean, isPartial?: boolean): string {
const unionNode = expandToNode`
export type ${this.name} = ${propertyTypeToString(this.type, 'AstType')};
`.appendNewLine();

if (reflectionInfo) {
unionNode.appendNewLine()
.append(addReflectionInfo(this.name));
.append(addReflectionInfo(this.name, isPartial));
}

if (this.dataType) {
Expand Down Expand Up @@ -218,7 +218,7 @@ export class InterfaceType {
this.abstract = abstract;
}

toAstTypesString(reflectionInfo: boolean): string {
toAstTypesString(reflectionInfo: boolean, isPartial?: boolean): string {
const interfaceSuperTypes = this.interfaceSuperTypes.map(e => e.name);
const superTypes = interfaceSuperTypes.length > 0 ? distinctAndSorted([...interfaceSuperTypes]) : ['langium.AstNode'];
const interfaceNode = expandToNode`
Expand All @@ -233,15 +233,15 @@ export class InterfaceType {
body.append(`readonly $type: ${distinctAndSorted([...this.typeNames]).map(e => `'${e}'`).join(' | ')};`).appendNewLine();
}
body.append(
pushProperties(this.properties, 'AstType')
pushProperties(this.properties, 'AstType', isPartial)
);
});
interfaceNode.append('}').appendNewLine();

if (reflectionInfo) {
interfaceNode
.appendNewLine()
.append(addReflectionInfo(this.name));
.append(addReflectionInfo(this.name, isPartial));
}

return toString(interfaceNode);
Expand All @@ -253,7 +253,7 @@ export class InterfaceType {
return toString(
expandToNode`
interface ${name}${superTypes.length > 0 ? ` extends ${superTypes}` : ''} {
${pushProperties(this.properties, 'DeclaredType', reservedWords)}
${pushProperties(this.properties, 'DeclaredType', false, reservedWords)}
}
`.appendNewLine()
);
Expand Down Expand Up @@ -408,12 +408,13 @@ function typeParenthesis(type: PropertyType, name: string): string {
function pushProperties(
properties: Property[],
mode: 'AstType' | 'DeclaredType',
isPartial?: boolean,
reserved = new Set<string>()
): Generated {

function propertyToString(property: Property): string {
const name = mode === 'AstType' ? property.name : escapeReservedWords(property.name, reserved);
const optional = property.optional && !isMandatoryPropertyType(property.type);
const optional = !isMandatoryPropertyType(property.type) && property.defaultValue === undefined && (property.optional || isPartial);
const propType = propertyTypeToString(property.type, mode);
return `${name}${optional ? '?' : ''}: ${propType};`;
}
Expand All @@ -440,14 +441,21 @@ export function isMandatoryPropertyType(propertyType: PropertyType): boolean {
}
}

function addReflectionInfo(name: string): Generated {
return expandToNode`
function addReflectionInfo(name: string, isPartial?: boolean): Generated {
return (isPartial ?
expandToNode`
export const ${name} = ast.${name};

export function is${name}(item: unknown): item is ${name} {
return reflection.isInstance(item, ${name});
}
`: expandToNode`
export const ${name} = '${name}';

export function is${name}(item: unknown): item is ${name} {
return reflection.isInstance(item, ${name});
}
`.appendNewLine();
`).appendNewLine();
}

function addDataTypeReflectionInfo(union: UnionType): Generated {
Expand Down