Merge pull request #46 from DouglasNeuroInformatics/parser

add ast parser

Author: joshunrau

package.json

@@ -111,6 +111,7 @@
     "passport-jwt": "^4.0.1",
     "serialize-error": "^12.0.0",
     "supertest": "^7.0.0",
+    "ts-morph": "^25.0.1",
     "type-fest": "^4.37.0",
     "unplugin-swc": "^1.5.1"
   },

pnpm-lock.yaml

@@ -0,0 +1,63 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+import { Parser } from '../parser.js';
+
+const fs = vi.hoisted(() => ({
+  existsSync: vi.fn(),
+  readFileSync: vi.fn()
+}));
+
+vi.mock('node:fs', () => fs);
+
+describe('Parser', () => {
+  let parser: Parser;
+
+  beforeEach(() => {
+    parser = new Parser();
+    fs.existsSync.mockReturnValue(true);
+  });
+
+  describe('parseUserConfig', () => {
+    it('should return an error if the provided file does not exist', () => {
+      fs.existsSync.mockReturnValueOnce(false);
+      expect(parser.parseUserConfig('config.ts')).toMatchObject({
+        error: {
+          message: `Config file does not exist: config.ts`
+        }
+      });
+    });
+    it('should return an error if the source code does not contain a default export', () => {
+      const sourceCode = "const config = { value: 'foo' };";
+      fs.readFileSync.mockReturnValueOnce(sourceCode);
+      expect(parser.parseUserConfig('config.ts')).toMatchObject({
+        error: {
+          message: "Source file 'config.ts' does not include a default export symbol"
+        }
+      });
+    });
+    it('should return an error if the default export does not reference anything', () => {
+      const sourceCode = 'export default config;';
+      fs.readFileSync.mockReturnValueOnce(sourceCode);
+      expect(parser.parseUserConfig('config.ts')).toMatchObject({
+        error: {
+          message: "Default export symbol in 'config.ts' has no declarations"
+        }
+      });
+    });
+    it('should return an error if the default export has multiple references', () => {
+      const sourceCode = 'var config = {}; var config = {}; export default config;';
+      fs.readFileSync.mockReturnValueOnce(sourceCode);
+      expect(parser.parseUserConfig('config.ts')).toMatchObject({
+        error: {
+          message: "Default export symbol in 'config.ts' has multiple declarations (2)"
+        }
+      });
+    });
+    it('should return ok if the config can be parsed', () => {
+      const sourceCode = 'const config = {}; export default config;';
+      fs.readFileSync.mockReturnValueOnce(sourceCode);
+      const result = parser.parseUserConfig('config.ts');
+      expect(result.isOk()).toBe(true);
+    });
+  });
+});

src/meta/__tests__/parser.test.ts

@@ -0,0 +1,51 @@
+import * as fs from 'node:fs';
+
+import { ExceptionBuilder, RuntimeException } from '@douglasneuroinformatics/libjs';
+import { ok, Result } from 'neverthrow';
+import { Node, Project, SourceFile, Symbol } from 'ts-morph';
+
+const { SyntaxParsingException } = new ExceptionBuilder().setParams({ name: 'SyntaxParsingException' }).build();
+
+export class Parser {
+  private readonly project: Project;
+
+  constructor() {
+    this.project = new Project();
+  }
+
+  parseUserConfig(configFile: string): Result<Node, Error> {
+    if (!fs.existsSync(configFile)) {
+      return RuntimeException.asErr(`Config file does not exist: ${configFile}`);
+    }
+    const sourceCode = fs.readFileSync(configFile, 'utf-8');
+    const sourceFile = this.project.createSourceFile(configFile, sourceCode);
+    return this.parseDefaultExportNode(sourceFile);
+  }
+
+  private parseDefaultExportNode(sourceFile: SourceFile): Result<Node, typeof SyntaxParsingException.Instance> {
+    const filename = sourceFile.getBaseName();
+    const defaultExportSymbol = sourceFile.getDefaultExportSymbol();
+    if (!defaultExportSymbol) {
+      return SyntaxParsingException.asErr(`Source file '${filename}' does not include a default export symbol`);
+    }
+    const resolvedSymbol = this.resolveAliasedSymbol(defaultExportSymbol);
+    const declarations = resolvedSymbol.getDeclarations();
+    if (declarations.length === 0) {
+      return SyntaxParsingException.asErr(`Default export symbol in '${filename}' has no declarations`);
+    }
+    if (declarations.length > 1) {
+      return SyntaxParsingException.asErr(
+        `Default export symbol in '${filename}' has multiple declarations (${declarations.length})`
+      );
+    }
+    return ok(declarations[0]!);
+  }
+
+  private resolveAliasedSymbol(symbol: Symbol): Symbol {
+    let current = symbol;
+    while (current.getAliasedSymbol()) {
+      current = current.getAliasedSymbol()!;
+    }
+    return current;
+  }
+}