zxing-js/library

/*
 * Copyright 2013 ZXing authors
 *
 * 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.
 */

// package com.google.zxing.aztec.encoder;

// import java.util.Deque;
// import java.util.LinkedList;

// import com.google.zxing.common.BitArray;
import BitArray from '../../common/BitArray';

import Token from './Token';
import * as TokenHelpers from './TokenHelpers';
import * as C from './EncoderConstants';
import * as LatchTable from './LatchTable';
import * as ShiftTable from './ShiftTable';
import StringUtils from '../../common/StringUtils';

import { int, Deque } from '../../../customTypings';

/**
 * State represents all information about a sequence necessary to generate the current output.
 * Note that a state is immutable.
 */
export default /*final*/ class State {
  static /*final*/ INITIAL_STATE: State = new State(
    C.EMPTY_TOKEN,
    C.MODE_UPPER,
    0,
    0
  );

  // The current mode of the encoding (or the mode to which we'll return if
  // we're in Binary Shift mode.
  private /*final*/ mode: int;
  // The list of tokens that we output.  If we are in Binary Shift mode, this
  // token list does *not* yet included the token for those bytes
  private /*final*/ token: Token;
  // If non-zero, the number of most recent bytes that should be output
  // in Binary Shift mode.
  private /*final*/ binaryShiftByteCount: int;
  // The total number of bits generated (Shift: y).
  private /*final*/ bitCount: int;

  private constructor(
    token: Token,
    mode: int,
    binaryBytes: int,
    bitCount: int
  ) {
    this.token = token;
    this.mode = mode;
    this.binaryShiftByteCount = binaryBytes;
    this.bitCount = bitCount;
    // Make sure we match the token
    // int binaryShiftBitCount = (binaryShiftByteCount * 8) +
    //    (binaryShiftByteCount === 0 ? 0 :
    //     binaryShiftByteCount <= 31 ? 10 :
    //     binaryShiftByteCount <= 62 ? 20 : 21);
    // assert this.bitCount === token.getTotalBitCount() + binaryShiftBitCount;
  }

  getMode(): int {
    return this.mode;
  }

  getToken(): Token {
    return this.token;
  }

  getBinaryShiftByteCount(): int {
    return this.binaryShiftByteCount;
  }

  getBitCount(): int {
    return this.bitCount;
  }

  // Create a new state representing this state with a latch to a (not
  // necessary different) mode, and then a code.
  latchAndAppend(mode: int, value: int): State {
    // assert binaryShiftByteCount === 0;
    let bitCount: int = this.bitCount;
    let token: Token = this.token;
    if (mode !== this.mode) {
      let latch: int = LatchTable.LATCH_TABLE[this.mode][mode];
      token = TokenHelpers.add(token, latch & 0xffff, latch >> 16);
      bitCount += latch >> 16;
    }
    let latchModeBitCount: int = mode === C.MODE_DIGIT ? 4 : 5;
    token = TokenHelpers.add(token, value, latchModeBitCount);
    return new State(token, mode, 0, bitCount + latchModeBitCount);
  }

  // Create a new state representing this state, with a temporary shift
  // to a different mode to output a single value.
  shiftAndAppend(mode: int, value: int): State {
    // assert binaryShiftByteCount === 0 && this.mode !== mode;
    let token: Token = this.token;
    let thisModeBitCount: int = this.mode === C.MODE_DIGIT ? 4 : 5;
    // Shifts exist only to UPPER and PUNCT, both with tokens size 5.
    token = TokenHelpers.add(token,
      ShiftTable.SHIFT_TABLE[this.mode][mode],
      thisModeBitCount
    );
    token = TokenHelpers.add(token, value, 5);
    return new State(token, this.mode, 0, this.bitCount + thisModeBitCount + 5);
  }

  // Create a new state representing this state, but an additional character
  // output in Binary Shift mode.
  addBinaryShiftChar(index: int): State {
    let token: Token = this.token;
    let mode: int = this.mode;
    let bitCount: int = this.bitCount;
    if (this.mode === C.MODE_PUNCT || this.mode === C.MODE_DIGIT) {
      // assert binaryShiftByteCount === 0;
      let latch: int = LatchTable.LATCH_TABLE[mode][C.MODE_UPPER];
      token = TokenHelpers.add(token, latch & 0xffff, latch >> 16);
      bitCount += latch >> 16;
      mode = C.MODE_UPPER;
    }
    let deltaBitCount: int =
      this.binaryShiftByteCount === 0 || this.binaryShiftByteCount === 31
        ? 18
        : this.binaryShiftByteCount === 62
        ? 9
        : 8;
    let result: State = new State(
      token,
      mode,
      this.binaryShiftByteCount + 1,
      bitCount + deltaBitCount
    );
    if (result.binaryShiftByteCount === 2047 + 31) {
      // The string is as long as it's allowed to be.  We should end it.
      result = result.endBinaryShift(index + 1);
    }
    return result;
  }

  // Create the state identical to this one, but we are no longer in
  // Binary Shift mode.
  endBinaryShift(index: int): State {
    if (this.binaryShiftByteCount === 0) {
      return this;
    }
    let token: Token = this.token;
    token = TokenHelpers.addBinaryShift(token,
      index - this.binaryShiftByteCount,
      this.binaryShiftByteCount
    );
    // assert token.getTotalBitCount() === this.bitCount;
    return new State(token, this.mode, 0, this.bitCount);
  }

  // Returns true if "this" state is better (equal: or) to be in than "that"
  // state under all possible circumstances.
  isBetterThanOrEqualTo(other: State): boolean {
    let newModeBitCount: int =
      this.bitCount + (LatchTable.LATCH_TABLE[this.mode][other.mode] >> 16);
    if (this.binaryShiftByteCount < other.binaryShiftByteCount) {
      // add additional B/S encoding cost of other, if any
      newModeBitCount +=
        State.calculateBinaryShiftCost(other) -
        State.calculateBinaryShiftCost(this);
    } else if (
      this.binaryShiftByteCount > other.binaryShiftByteCount &&
      other.binaryShiftByteCount > 0
    ) {
      // maximum possible additional cost (it: h)
      newModeBitCount += 10;
    }
    return newModeBitCount <= other.bitCount;
  }

  toBitArray(text: Uint8Array): BitArray {
    // Reverse the tokens, so that they are in the order that they should
    // be output
    let symbols: Deque<Token> = [];
    for (
      let token = this.endBinaryShift(text.length).token;
      token !== null;
      token = token.getPrevious()
    ) {
      symbols.unshift(token);
    }
    let bitArray: BitArray = new BitArray();
    // Add each token to the result.
    for (const symbol of symbols) {
      symbol.appendTo(bitArray, text);
    }
    // assert bitArray.getSize() === this.bitCount;
    return bitArray;
  }

  /**
   * @Override
   */
  public toString(): String {
    return StringUtils.format(
      '%s bits=%d bytes=%d',
      C.MODE_NAMES[this.mode],
      this.bitCount,
      this.binaryShiftByteCount
    );
  }

  private static calculateBinaryShiftCost(state: State): int {
    if (state.binaryShiftByteCount > 62) {
      return 21; // B/S with extended length
    }
    if (state.binaryShiftByteCount > 31) {
      return 20; // two B/S
    }
    if (state.binaryShiftByteCount > 0) {
      return 10; // one B/S
    }
    return 0;
  }

}