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- /*************************************************************
- *
- * Copyright (c) 2018-2022 The MathJax Consortium
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- /**
- * @fileoverview Implements bit-fields with extendable field names
- *
- * @author dpvc@mathjax.org (Davide Cervone)
- */
- export class BitField {
- /**
- * The largest bit available
- */
- protected static MAXBIT = 1 << 31;
- /**
- * The next bit to be allocated
- */
- protected static next: number = 1;
- /**
- * The map of names to bit positions
- */
- protected static names: Map<string, number> = new Map();
- /**
- * The bits that are set
- */
- protected bits: number = 0;
- /**
- * @param {string} names The names of the bit positions to reserve
- */
- public static allocate(...names: string[]) {
- for (const name of names) {
- if (this.has(name)) {
- throw new Error('Bit already allocated for ' + name);
- }
- if (this.next === BitField.MAXBIT) {
- throw new Error('Maximum number of bits already allocated');
- }
- this.names.set(name, this.next);
- this.next <<= 1;
- }
- }
- /**
- * @param {string} name The name of the bit to check for being defined
- * @return {boolean} True if the named bit is already allocated
- */
- public static has(name: string): boolean {
- return this.names.has(name);
- }
- /**
- * @param {string} name The name of the bit position to set
- */
- public set(name: string) {
- this.bits |= this.getBit(name);
- }
- /**
- * @param {string} name The name of the bit position to clear
- */
- public clear(name: string) {
- this.bits &= ~this.getBit(name);
- }
- /**
- * @param {string} name The name of the bit to check if set
- * @return {boolean} True if the named bit is set
- */
- public isSet(name: string): boolean {
- return !!(this.bits & this.getBit(name));
- }
- /**
- * Clear all bits
- */
- public reset() {
- this.bits = 0;
- }
- /**
- * @param {string} name The name whose bit position is needed (error if not defined)
- * @return {number} The position of the named bit
- */
- protected getBit(name: string): number {
- const bit = (this.constructor as typeof BitField).names.get(name);
- if (!bit) {
- throw new Error('Unknown bit-field name: ' + name);
- }
- return bit;
- }
- }
- /**
- * @param {string[]} names The name of the positions to allocate initially
- * @return {typeof AbstractBitField} The bit-field class with names allocated
- */
- export function BitFieldClass(...names: string[]): typeof BitField {
- const Bits = class extends BitField {};
- Bits.allocate(...names);
- return Bits;
- }
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