index.js
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"use strict";
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.default = simplifyAccess;
var t = _interopRequireWildcard(require("@babel/types"));
function _getRequireWildcardCache() { if (typeof WeakMap !== "function") return null; var cache = new WeakMap(); _getRequireWildcardCache = function () { return cache; }; return cache; }
function _interopRequireWildcard(obj) { if (obj && obj.__esModule) { return obj; } if (obj === null || typeof obj !== "object" && typeof obj !== "function") { return { default: obj }; } var cache = _getRequireWildcardCache(); if (cache && cache.has(obj)) { return cache.get(obj); } var newObj = {}; var hasPropertyDescriptor = Object.defineProperty && Object.getOwnPropertyDescriptor; for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) { var desc = hasPropertyDescriptor ? Object.getOwnPropertyDescriptor(obj, key) : null; if (desc && (desc.get || desc.set)) { Object.defineProperty(newObj, key, desc); } else { newObj[key] = obj[key]; } } } newObj.default = obj; if (cache) { cache.set(obj, newObj); } return newObj; }
function simplifyAccess(path, bindingNames) {
path.traverse(simpleAssignmentVisitor, {
scope: path.scope,
bindingNames,
seen: new WeakSet()
});
}
const simpleAssignmentVisitor = {
UpdateExpression: {
exit(path) {
const {
scope,
bindingNames
} = this;
const arg = path.get("argument");
if (!arg.isIdentifier()) return;
const localName = arg.node.name;
if (!bindingNames.has(localName)) return;
if (scope.getBinding(localName) !== path.scope.getBinding(localName)) {
return;
}
if (path.parentPath.isExpressionStatement() && !path.isCompletionRecord()) {
const operator = path.node.operator == "++" ? "+=" : "-=";
path.replaceWith(t.assignmentExpression(operator, arg.node, t.numericLiteral(1)));
} else if (path.node.prefix) {
path.replaceWith(t.assignmentExpression("=", t.identifier(localName), t.binaryExpression(path.node.operator[0], t.unaryExpression("+", arg.node), t.numericLiteral(1))));
} else {
const old = path.scope.generateUidIdentifierBasedOnNode(arg.node, "old");
const varName = old.name;
path.scope.push({
id: old
});
const binary = t.binaryExpression(path.node.operator[0], t.identifier(varName), t.numericLiteral(1));
path.replaceWith(t.sequenceExpression([t.assignmentExpression("=", t.identifier(varName), t.unaryExpression("+", arg.node)), t.assignmentExpression("=", t.cloneNode(arg.node), binary), t.identifier(varName)]));
}
}
},
AssignmentExpression: {
exit(path) {
const {
scope,
seen,
bindingNames
} = this;
if (path.node.operator === "=") return;
if (seen.has(path.node)) return;
seen.add(path.node);
const left = path.get("left");
if (!left.isIdentifier()) return;
const localName = left.node.name;
if (!bindingNames.has(localName)) return;
if (scope.getBinding(localName) !== path.scope.getBinding(localName)) {
return;
}
path.node.right = t.binaryExpression(path.node.operator.slice(0, -1), t.cloneNode(path.node.left), path.node.right);
path.node.operator = "=";
}
}
};