/*
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* Copyright 2013 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// import java.util.Collection;
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// import java.util.Collections;
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import Collections from '../../util/Collections';
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// import java.util.Comparator;
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// import java.util.Iterator;
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// import java.util.LinkedList;
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import State from './State';
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import * as C from './EncoderConstants';
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import * as CharMap from './CharMap';
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import * as ShiftTable from './ShiftTable';
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import StringUtils from '../../common/StringUtils';
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/**
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* This produces nearly optimal encodings of text into the first-level of
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* encoding used by Aztec code.
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*
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* It uses a dynamic algorithm. For each prefix of the string, it determines
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* a set of encodings that could lead to this prefix. We repeatedly add a
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* character and generate a new set of optimal encodings until we have read
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* through the entire input.
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*
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* @author Frank Yellin
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* @author Rustam Abdullaev
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*/
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export default /*public final*/ class HighLevelEncoder {
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constructor(text) {
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this.text = text;
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}
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/**
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* @return text represented by this encoder encoded as a {@link BitArray}
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*/
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encode() {
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const spaceCharCode = StringUtils.getCharCode(' ');
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const lineBreakCharCode = StringUtils.getCharCode('\n');
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let states = Collections.singletonList(State.INITIAL_STATE);
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for (let index = 0; index < this.text.length; index++) {
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let pairCode;
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let nextChar = index + 1 < this.text.length ? this.text[index + 1] : 0;
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switch (this.text[index]) {
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case StringUtils.getCharCode('\r'):
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pairCode = nextChar === lineBreakCharCode ? 2 : 0;
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break;
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case StringUtils.getCharCode('.'):
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pairCode = nextChar === spaceCharCode ? 3 : 0;
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break;
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case StringUtils.getCharCode(','):
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pairCode = nextChar === spaceCharCode ? 4 : 0;
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break;
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case StringUtils.getCharCode(':'):
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pairCode = nextChar === spaceCharCode ? 5 : 0;
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break;
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default:
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pairCode = 0;
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}
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if (pairCode > 0) {
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// We have one of the four special PUNCT pairs. Treat them specially.
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// Get a new set of states for the two new characters.
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states = HighLevelEncoder.updateStateListForPair(states, index, pairCode);
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index++;
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}
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else {
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// Get a new set of states for the new character.
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states = this.updateStateListForChar(states, index);
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}
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}
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// We are left with a set of states. Find the shortest one.
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const minState = Collections.min(states, (a, b) => {
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return a.getBitCount() - b.getBitCount();
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});
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// Convert it to a bit array, and return.
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return minState.toBitArray(this.text);
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}
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// We update a set of states for a new character by updating each state
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// for the new character, merging the results, and then removing the
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// non-optimal states.
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updateStateListForChar(states, index) {
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const result = [];
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for (let state /*State*/ of states) {
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this.updateStateForChar(state, index, result);
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}
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return HighLevelEncoder.simplifyStates(result);
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}
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// Return a set of states that represent the possible ways of updating this
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// state for the next character. The resulting set of states are added to
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// the "result" list.
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updateStateForChar(state, index, result) {
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let ch = (this.text[index] & 0xff);
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let charInCurrentTable = CharMap.CHAR_MAP[state.getMode()][ch] > 0;
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let stateNoBinary = null;
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for (let mode /*int*/ = 0; mode <= C.MODE_PUNCT; mode++) {
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let charInMode = CharMap.CHAR_MAP[mode][ch];
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if (charInMode > 0) {
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if (stateNoBinary == null) {
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// Only create stateNoBinary the first time it's required.
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stateNoBinary = state.endBinaryShift(index);
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}
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// Try generating the character by latching to its mode
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if (!charInCurrentTable ||
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mode === state.getMode() ||
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mode === C.MODE_DIGIT) {
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// If the character is in the current table, we don't want to latch to
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// any other mode except possibly digit (which uses only 4 bits). Any
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// other latch would be equally successful *after* this character, and
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// so wouldn't save any bits.
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const latchState = stateNoBinary.latchAndAppend(mode, charInMode);
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result.push(latchState);
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}
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// Try generating the character by switching to its mode.
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if (!charInCurrentTable &&
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ShiftTable.SHIFT_TABLE[state.getMode()][mode] >= 0) {
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// It never makes sense to temporarily shift to another mode if the
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// character exists in the current mode. That can never save bits.
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const shiftState = stateNoBinary.shiftAndAppend(mode, charInMode);
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result.push(shiftState);
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}
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}
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}
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if (state.getBinaryShiftByteCount() > 0 ||
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CharMap.CHAR_MAP[state.getMode()][ch] === 0) {
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// It's never worthwhile to go into binary shift mode if you're not already
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// in binary shift mode, and the character exists in your current mode.
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// That can never save bits over just outputting the char in the current mode.
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let binaryState = state.addBinaryShiftChar(index);
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result.push(binaryState);
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}
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}
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static updateStateListForPair(states, index, pairCode) {
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const result = [];
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for (let state /*State*/ of states) {
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this.updateStateForPair(state, index, pairCode, result);
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}
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return this.simplifyStates(result);
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}
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static updateStateForPair(state, index, pairCode, result) {
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let stateNoBinary = state.endBinaryShift(index);
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// Possibility 1. Latch to C.MODE_PUNCT, and then append this code
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result.push(stateNoBinary.latchAndAppend(C.MODE_PUNCT, pairCode));
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if (state.getMode() !== C.MODE_PUNCT) {
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// Possibility 2. Shift to C.MODE_PUNCT, and then append this code.
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// Every state except C.MODE_PUNCT (handled above) can shift
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result.push(stateNoBinary.shiftAndAppend(C.MODE_PUNCT, pairCode));
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}
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if (pairCode === 3 || pairCode === 4) {
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// both characters are in DIGITS. Sometimes better to just add two digits
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let digitState = stateNoBinary
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.latchAndAppend(C.MODE_DIGIT, 16 - pairCode) // period or comma in DIGIT
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.latchAndAppend(C.MODE_DIGIT, 1); // space in DIGIT
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result.push(digitState);
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}
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if (state.getBinaryShiftByteCount() > 0) {
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// It only makes sense to do the characters as binary if we're already
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// in binary mode.
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let binaryState = state
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.addBinaryShiftChar(index)
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.addBinaryShiftChar(index + 1);
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result.push(binaryState);
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}
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}
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static simplifyStates(states) {
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let result = [];
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for (const newState of states) {
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let add = true;
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for (const oldState of result) {
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if (oldState.isBetterThanOrEqualTo(newState)) {
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add = false;
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break;
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}
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if (newState.isBetterThanOrEqualTo(oldState)) {
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// iterator.remove();
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result = result.filter(x => x !== oldState); // remove old state
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}
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}
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if (add) {
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result.push(newState);
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}
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}
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return result;
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}
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}
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