Expose parser AST statements and expression/codegen types in published TypeScript declarations

[Copilot]

AlaSQL’s published types only exposed AlaSQLAST.compile(...), leaving parser/codegen consumers to cast around undocumented internals (statements, where, toJS). This PR surfaces the existing parser API in types/alasql.d.ts and documents stable expression node shapes already used in practice.

• Type surface: expose parsed statements

  • Adds statements: Statement[] to AlaSQLAST.
  • Introduces a typed Statement shape with where?: ExpressionWrapper to model common parser access patterns.

• Type surface: document expression codegen contract

  • Adds base AlaSQLExpression with:
    • toJS(context: string, tableid: string | number, defcols: AlaSQLDefaultColumns | null): string
  • Captures default-column map as AlaSQLDefaultColumns.

• Type surface: publish stable node shapes

  • Adds explicit node interfaces for:
    • Op (left, op, right/right1/right2)
    • Column (columnid, optional tableid, databaseid)
    • ParamValue (param)
    • NumValue (value)
    • StringValue (value)
    • LogicValue (value)
    • UniOp (op, right)
  • Adds ExpressionNode union over concrete node types.

• Regression coverage for parser consumers

  • Adds test/test2498.js to lock in:
    • parse(...).statements[0].where
    • where.toJS(...) producing executable JS expression
    • expected node-field access for the documented shapes

const ast = alasql.parse('SELECT 1 FROM ? WHERE x < $y');
const where = ast.statements[0].where;
const js = where.toJS('p', '', null);
const fn = new Function('alasql', 'p', 'params', `return Boolean(${js});`);

• Fixes Expose and document the parser AST + toJS() in the published types #2498

[mathiasrw]

Please be more specific by asserting towards the final complete object expected to be outputted.

[mathiasrw]

@copilot

[Copilot]

Updated in 381ad22. Test B now uses a single assert.deepStrictEqual against a complete expected object for the documented AST-node shapes, instead of scattered field-by-field assertions.

[mathiasrw]

Can you tell me a bit about why this is the right fix? It seems like a lot of code for this kind of fix.

[mathiasrw]

@copilot

[Copilot]

This is type-surface only (no runtime behavior changes), and most of the added lines are explicit interface declarations documenting parser shapes that already exist and are already used (statements, where, toJS, node fields like left/op/right, columnid, value, param). The reason for being explicit is to avoid unsafe casts for parser/codegen consumers and make those stable entry points discoverable in published typings. The added regression test is there to ensure we only expose shapes that actually parse today and to prevent accidental drift in future releases.