34d73ebef0
* Correct update expression Number coercion You have to `ToNumber` whatever the `UpdateExpression` argument is. * Fix systemjs update expression
111 lines
2.8 KiB
JavaScript
111 lines
2.8 KiB
JavaScript
import * as t from "@babel/types";
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export default function simplifyAccess(path: NodePath, bindingNames) {
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path.traverse(simpleAssignmentVisitor, {
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scope: path.scope,
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bindingNames,
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seen: new WeakSet(),
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});
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}
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const simpleAssignmentVisitor = {
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UpdateExpression: {
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exit(path) {
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const { scope, bindingNames } = this;
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const arg = path.get("argument");
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if (!arg.isIdentifier()) return;
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const localName = arg.node.name;
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if (!bindingNames.has(localName)) return;
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// redeclared in this scope
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if (scope.getBinding(localName) !== path.scope.getBinding(localName)) {
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return;
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}
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if (
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path.parentPath.isExpressionStatement() &&
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!path.isCompletionRecord()
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) {
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// ++i => (i += 1);
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const operator = path.node.operator == "++" ? "+=" : "-=";
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path.replaceWith(
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t.assignmentExpression(operator, arg.node, t.numericLiteral(1)),
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);
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} else if (path.node.prefix) {
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// ++i => (i = (+i) + 1);
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path.replaceWith(
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t.assignmentExpression(
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"=",
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t.identifier(localName),
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t.binaryExpression(
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path.node.operator[0],
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t.unaryExpression("+", arg.node),
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t.numericLiteral(1),
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),
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),
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);
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} else {
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const old = path.scope.generateUidIdentifierBasedOnNode(
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arg.node,
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"old",
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);
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const varName = old.name;
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path.scope.push({ id: old });
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const binary = t.binaryExpression(
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path.node.operator[0],
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t.identifier(varName),
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t.numericLiteral(1),
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);
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// i++ => (_old = (+i), i = _old + 1, _old)
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path.replaceWith(
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t.sequenceExpression([
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t.assignmentExpression(
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"=",
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t.identifier(varName),
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t.unaryExpression("+", arg.node),
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),
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t.assignmentExpression("=", t.cloneNode(arg.node), binary),
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t.identifier(varName),
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]),
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);
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}
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},
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},
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AssignmentExpression: {
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exit(path) {
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const { scope, seen, bindingNames } = this;
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if (path.node.operator === "=") return;
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if (seen.has(path.node)) return;
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seen.add(path.node);
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const left = path.get("left");
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if (!left.isIdentifier()) return;
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// Simple update-assign foo += 1;
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// => exports.foo = (foo += 1);
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const localName = left.node.name;
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if (!bindingNames.has(localName)) return;
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// redeclared in this scope
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if (scope.getBinding(localName) !== path.scope.getBinding(localName)) {
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return;
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}
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path.node.right = t.binaryExpression(
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path.node.operator.slice(0, -1),
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t.cloneNode(path.node.left),
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path.node.right,
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);
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path.node.operator = "=";
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},
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},
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};
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