Justin Ridgewell 2afe9404fe
Use Object Spread Syntax (#7777)
* Use Object Spread Syntax

* Nits
2018-04-23 21:44:27 -04:00

90 lines
2.6 KiB
JavaScript

import * as t from "@babel/types";
const handle = {
handle(member) {
const { node, parent, parentPath } = member;
// MEMBER++ -> _set(MEMBER, (_ref = (+_get(MEMBER))) + 1), _ref
// ++MEMBER -> _set(MEMBER, (+_get(MEMBER)) + 1)
if (parentPath.isUpdateExpression({ argument: node })) {
const { operator, prefix } = parent;
// Give the state handler a chance to memoize the member,
// since we'll reference it twice.
if (this.memoize) {
this.memoize(member);
}
const value = t.binaryExpression(
operator[0],
t.unaryExpression("+", this.get(member)),
t.numericLiteral(1),
);
if (prefix) {
parentPath.replaceWith(this.set(member, value));
} else {
const { scope } = member;
const ref = scope.generateUidIdentifierBasedOnNode(node);
scope.push({ id: ref });
value.left = t.assignmentExpression("=", t.cloneNode(ref), value.left);
parentPath.replaceWith(
t.sequenceExpression([this.set(member, value), t.cloneNode(ref)]),
);
}
return;
}
// MEMBER = VALUE -> _set(MEMBER, VALUE)
// MEMBER += VALUE -> _set(MEMBER, _get(MEMBER) + VALUE)
if (parentPath.isAssignmentExpression({ left: node })) {
const { operator, right } = parent;
let value = right;
if (operator !== "=") {
// Give the state handler a chance to memoize the member,
// since we'll reference it twice.
if (this.memoize) {
this.memoize(member);
}
value = t.binaryExpression(
operator.slice(0, -1),
this.get(member),
value,
);
}
parentPath.replaceWith(this.set(member, value));
return;
}
// MEMBER(ARGS) -> _call(MEMBER, ARGS)
if (parentPath.isCallExpression({ callee: node })) {
const { arguments: args } = parent;
parentPath.replaceWith(this.call(member, args));
return;
}
// MEMBER -> _get(MEMBER)
member.replaceWith(this.get(member));
},
};
// We do not provide a default traversal visitor
// Instead, caller passes one, and must call `state.handle` on the members
// it wishes to be transformed.
// Additionally, the caller must pass in a state object with at least
// get, set, and call methods.
// Optionally, a memoize method may be defined on the state, which will be
// called when the member is a self-referential update.
export default function memberExpressionToFunctions(path, visitor, state) {
path.traverse(visitor, {
...state,
...handle,
});
}