@formscript/analyzer

Static analysis of a FormScript document — the commitment of §2.3 of the specification.

The analyzer answers one question: can this document ever be compiled? It runs before any evaluation and reports every error the specification requires a conforming runtime to catch at compile time.

What it detects

Usage

import { analyze } from '@formscript/analyzer';

const result = analyze(document, { file: 'application.forms' });

if (!result.ok) {
  for (const error of result.errors) {
    console.error(`${error.code} ${error.location?.line}:${error.location?.column} ${error.message}`);
  }
}

analyze returns every diagnostic it produced in diagnostics, and the reported set in reported: the errors of the earliest non-empty stage, plus every warning. The stage of a diagnostic is the class of its code in the catalogue of §14, and the stage order is the order of that catalogue's sections. See applyDiagnosticOrder, which applies the same rule to the lexer's and the parser's diagnostics.

Notes

• The analyzer never evaluates an expression. Tier A1 satisfiability (§10.6.1) works on the AST and the type lattice alone.
• A value of type any suppresses every type error, because the type system cannot prove anything about it. The runtime checks it instead.
• The two-planes rule (§12.6) is checked over the operands a computation consumes, so a ternary branch or a coalesce operand — which is an alternative, not an operand — may carry a display value: it is the expression's own result, and a custom constraint may use it as its message (Spec-12.9).
• A choice declares an enum type and nothing else (Spec-7.13): options and optionsFrom on a choice are E-PROP-02, and a choice whose type is not an enum is E-TYPE-02.

Public API

32 exported symbols.