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Flatten inShadow logic for readability.

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This commit is contained in:
Logan Smyth 2016-03-06 18:14:25 -08:00
parent 60d773f370
commit 8b8e3ddbec
1 changed files with 42 additions and 20 deletions
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62
packages/babel-traverse/src/path/ancestry.js
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@ -188,30 +188,52 @@ export function inType() {
}
/**
* Check if we're inside a shadowed function.
* Checks whether the binding for 'key' is a local binding in its current function context.
*
* Checks if the current path either is, or has a direct parent function that is, inside
* of a function that is marked for shadowing of a binding matching 'key'. Also returns
* the parent path if the parent path is an arrow, since arrow functions pass through
* binding values to their parent, meaning they have no local bindings.
*
* Shadowing means that when the given binding is transformed, it will read the binding
* value from the container containing the shadow function, rather than from inside the
* shadow function.
*
* Function shadowing is acheieved by adding a "shadow" property on "FunctionExpression"
* and "FunctionDeclaration" node types.
*
* Node's "shadow" props have the following behavior:
*
* - Boolean true will cause the function to shadow both "this" and "arguments".
* - {this: false} Shadows "arguments" but not "this".
* - {arguments: false} Shadows "this" but not "arguments".
*
* Separately, individual identifiers can be flagged with two flags:
*
* - _forceShadow - If truthy, this specific identifier will be bound in the closest
* Function that is not flagged "shadow", or the Program.
* - _shadowedFunctionLiteral - When set to a NodePath, this specific identifier will be bound
* to this NodePath/Node or the Program.
*/
export function inShadow(key?) {
let path = this;
do {
if (path.isFunction()) {
let shadow = path.node.shadow;
if (shadow) {
// this is because sometimes we may have a `shadow` value of:
//
// { this: false }
//
// we need to catch this case if `inShadow` has been passed a `key`
if (!key || shadow[key] !== false) {
return path;
}
} else if (path.isArrowFunctionExpression()) {
return path;
}
let parentFn = this.isFunction() ? this : this.findParent((p) => p.isFunction());
if (!parentFn) return;
// normal function, we've found our function context
return null;
let shadow = parentFn.node.shadow;
if (shadow) {
// this is because sometimes we may have a `shadow` value of:
//
// { this: false }
//
// we need to catch this case if `inShadow` has been passed a `key`
if (!key || shadow[key] !== false) {
return parentFn;
}
} while (path = path.parentPath);
} else if (parentFn.isArrowFunctionExpression()) {
return parentFn;
}
// normal function, we've found our function context
return null;
}