libxslt-wasm/dist/utils/DataSegment.js

JavaScript bindings for libxslt compiled to WebAssembly

import { NULL_POINTER } from "../constants.js";
class DataSegment {
    dataOffset;
    constructor(ptr) {
        /**
         * `ptr` must ALWAYS exist (e.g. be non-null) when creating a new instance.
         * - Checking if `this.dataOffset` is `null` will always be a valid check to
         *   see if the instance has been deleted or not.
         * - Many C functions return `null` as a failure state, which should not
         *   fail silently
         * - Checking if `.dataOffset === null` AND `.dataOffset === 0` is unclear
         * - If the output is the null pointer, instead of returning the wrapper
         *   class, it should return null (e.g. `DataSegment | null` and not
         *   `DataSegment`)
         */
        if (ptr === NULL_POINTER) {
            throw new RangeError("Constructor called with null pointer");
        }
        this.dataOffset = ptr;
    }
    /* While it would be tempting to throw an error in this function if
     * `this.dataOffset` is `null`, it would prevent some valid use cases such as
     * checking if a pointer exists.
     */
    getValue() {
        return this.dataOffset ?? NULL_POINTER;
    }
    /**
     * `.delete()` is the convention Emscripten uses for freeing memory. For this
     * base class, it does not free the pointer and only sets it to `null` since
     * some convenience functions exist that free more than one pointer
     */
    delete() {
        this.dataOffset = null;
    }
    /**
     * Implements the `Disposable` interface as part of the ECMAScript Explicit
     * Ressource Management proposal. This way, users can either dispose resources
     * imperatively (`.delete()`) or declaratively (`using`)
     *
     * @see {@link https://github.com/tc39/proposal-explicit-resource-management}
     * @see {@link https://www.typescriptlang.org/docs/handbook/release-notes/typescript-5-2.html#using-declarations-and-explicit-resource-management}
     */
    [Symbol.dispose]() {
        this.delete();
    }
}
export { DataSegment };