109d99bb5e
When, for example, a function is moved between from one place to another we recrawl and end up double counting any references it holds to the upper scope. This protects against that. (The same thing is done for constant violations in the `reassign` method)
102 lines
2.0 KiB
JavaScript
102 lines
2.0 KiB
JavaScript
import type NodePath from "../path";
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/**
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* This class is responsible for a binding inside of a scope.
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*
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* It tracks the following:
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*
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* * Node path.
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* * Amount of times referenced by other nodes.
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* * Paths to nodes that reassign or modify this binding.
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* * The kind of binding. (Is it a parameter, declaration etc)
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*/
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export default class Binding {
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constructor({ existing, identifier, scope, path, kind }) {
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this.identifier = identifier;
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this.scope = scope;
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this.path = path;
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this.kind = kind;
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this.constantViolations = [];
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this.constant = true;
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this.referencePaths = [];
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this.referenced = false;
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this.references = 0;
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this.clearValue();
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if (existing) {
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this.constantViolations = [].concat(
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existing.path,
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existing.constantViolations,
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this.constantViolations
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);
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}
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}
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constantViolations: Array<NodePath>;
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constant: boolean;
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referencePaths: Array<NodePath>;
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referenced: boolean;
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references: number;
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hasDeoptedValue: boolean;
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hasValue: boolean;
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value: any;
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deoptValue() {
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this.clearValue();
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this.hasDeoptedValue = true;
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}
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setValue(value: any) {
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if (this.hasDeoptedValue) return;
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this.hasValue = true;
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this.value = value;
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}
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clearValue() {
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this.hasDeoptedValue = false;
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this.hasValue = false;
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this.value = null;
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}
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/**
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* Register a constant violation with the provided `path`.
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*/
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reassign(path: Object) {
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this.constant = false;
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if (this.constantViolations.indexOf(path) !== -1) {
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return;
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}
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this.constantViolations.push(path);
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}
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/**
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* Increment the amount of references to this binding.
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*/
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reference(path: NodePath) {
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if (this.referencePaths.indexOf(path) !== -1) {
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return;
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}
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this.referenced = true;
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this.references++;
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this.referencePaths.push(path);
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}
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/**
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* Decrement the amount of references to this binding.
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*/
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dereference() {
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this.references--;
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this.referenced = !!this.references;
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}
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}
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