sourav-das/stem-separator

1import type { StringReader, StringWriter } from './strings';2 3export const comma = ','.charCodeAt(0);4export const semicolon = ';'.charCodeAt(0);5 6const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';7const intToChar = new Uint8Array(64); // 64 possible chars.8const charToInt = new Uint8Array(128); // z is 122 in ASCII9 10for (let i = 0; i < chars.length; i++) {11  const c = chars.charCodeAt(i);12  intToChar[i] = c;13  charToInt[c] = i;14}15 16export function decodeInteger(reader: StringReader, relative: number): number {17  let value = 0;18  let shift = 0;19  let integer = 0;20 21  do {22    const c = reader.next();23    integer = charToInt[c];24    value |= (integer & 31) << shift;25    shift += 5;26  } while (integer & 32);27 28  const shouldNegate = value & 1;29  value >>>= 1;30 31  if (shouldNegate) {32    value = -0x80000000 | -value;33  }34 35  return relative + value;36}37 38export function encodeInteger(builder: StringWriter, num: number, relative: number): number {39  let delta = num - relative;40 41  delta = delta < 0 ? (-delta << 1) | 1 : delta << 1;42  do {43    let clamped = delta & 0b011111;44    delta >>>= 5;45    if (delta > 0) clamped |= 0b100000;46    builder.write(intToChar[clamped]);47  } while (delta > 0);48 49  return num;50}51 52export function hasMoreVlq(reader: StringReader, max: number) {53  if (reader.pos >= max) return false;54  return reader.peek() !== comma;55}56