packages/babel-traverse/src/scope/binding.js
import type NodePath from "../path";
/**
* This class is responsible for a binding inside of a scope.
*
* It tracks the following:
*
* * Node path.
* * Amount of times referenced by other nodes.
* * Paths to nodes that reassign or modify this binding.
* * The kind of binding. (Is it a parameter, declaration etc)
*/
export default class Binding {
constructor({ identifier, scope, path, kind }) {
this.identifier = identifier;
this.scope = scope;
this.path = path;
this.kind = kind;
this.constantViolations = [];
this.constant = true;
this.referencePaths = [];
this.referenced = false;
this.references = 0;
this.clearValue();
}
constantViolations: Array<NodePath>;
constant: boolean;
referencePaths: Array<NodePath>;
referenced: boolean;
references: number;
hasDeoptedValue: boolean;
hasValue: boolean;
value: any;
deoptValue() {
this.clearValue();
this.hasDeoptedValue = true;
}
setValue(value: any) {
if (this.hasDeoptedValue) return;
this.hasValue = true;
this.value = value;
}
clearValue() {
this.hasDeoptedValue = false;
this.hasValue = false;
this.value = null;
}
/**
* Register a constant violation with the provided `path`.
*/
reassign(path: Object) {
this.constant = false;
if (this.constantViolations.indexOf(path) !== -1) {
return;
}
this.constantViolations.push(path);
}
/**
* Increment the amount of references to this binding.
*/
reference(path: NodePath) {
if (this.referencePaths.indexOf(path) !== -1) {
return;
}
this.referenced = true;
this.references++;
this.referencePaths.push(path);
}
/**
* Decrement the amount of references to this binding.
*/
dereference() {
this.references--;
this.referenced = !!this.references;
}
}