State Class — react Architecture

Source Code

compiler/packages/babel-plugin-react-compiler/src/Optimization/DeadCodeElimination.ts lines 72–112

class State {
  env: Environment;
  named: Set<string> = new Set();
  identifiers: Set<IdentifierId> = new Set();

  constructor(env: Environment) {
    this.env = env;
  }

  // Mark the identifier as being referenced (not dead code)
  reference(identifier: Identifier): void {
    this.identifiers.add(identifier.id);
    if (identifier.name !== null) {
      this.named.add(identifier.name.value);
    }
  }

  /*
   * Check if any version of the given identifier is used somewhere.
   * This checks both for usage of this specific identifer id (ssa id)
   * and (for named identifiers) for any usages of that identifier name.
   */
  isIdOrNameUsed(identifier: Identifier): boolean {
    return (
      this.identifiers.has(identifier.id) ||
      (identifier.name !== null && this.named.has(identifier.name.value))
    );
  }

  /*
   * Like `used()`, but only checks for usages of this specific identifier id
   * (ssa id).
   */
  isIdUsed(identifier: Identifier): boolean {
    return this.identifiers.has(identifier.id);
  }

  get count(): number {
    return this.identifiers.size;
  }
}