55 lines
1.6 KiB
JavaScript
55 lines
1.6 KiB
JavaScript
import { types as t } from "@babel/core";
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export default function() {
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/**
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* Helper function to run a statement before an expression by replacing it with a comma expression
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* and wrapping the statement in an IIFE as the first operand.
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*/
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function statementBeforeExpression(statement, expression) {
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return t.sequenceExpression([
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t.callExpression(
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t.functionExpression(null, [], t.blockStatement([statement])),
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[],
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),
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expression,
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]);
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}
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return {
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visitor: {
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Scope({ scope }) {
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for (const name in scope.bindings) {
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const binding = scope.bindings[name];
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if (binding.kind !== "const") continue;
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for (const violation of (binding.constantViolations: Array)) {
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const throwNode = t.throwStatement(
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t.newExpression(t.identifier("Error"), [
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t.stringLiteral(`"${name}" is read-only`),
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]),
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);
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if (violation.isAssignmentExpression()) {
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violation
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.get("right")
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.replaceWith(
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statementBeforeExpression(
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throwNode,
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violation.get("right").node,
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),
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);
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} else if (violation.isUpdateExpression()) {
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violation.replaceWith(
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statementBeforeExpression(throwNode, violation.node),
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);
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} else if (violation.isForXStatement()) {
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violation.ensureBlock();
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violation.node.body.body.unshift(throwNode);
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}
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}
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}
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},
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},
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};
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}
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