src/core/common/StringUtils.ts
/*
* Copyright (C) 2010 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.
*/
/*namespace com.google.zxing.common {*/
/*import java.nio.charset.Charset;*/
/*import java.util.Map;*/
import DecodeHintType from '../DecodeHintType';
import CharacterSetECI from './CharacterSetECI';
import StringEncoding from '../util/StringEncoding';
import { int } from '../../customTypings';
import Charset from '../util/Charset';
/**
* Common string-related functions.
*
* @author Sean Owen
* @author Alex Dupre
*/
export default class StringUtils {
public static SHIFT_JIS = CharacterSetECI.SJIS.getName(); // "SJIS"
public static GB2312 = 'GB2312';
public static ISO88591 = CharacterSetECI.ISO8859_1.getName(); // "ISO8859_1"
private static EUC_JP = 'EUC_JP';
private static UTF8 = CharacterSetECI.UTF8.getName(); // "UTF8"
private static PLATFORM_DEFAULT_ENCODING = StringUtils.UTF8; // "UTF8"//Charset.defaultCharset().name()
private static ASSUME_SHIFT_JIS = false;
// SHIFT_JIS.equalsIgnoreCase(PLATFORM_DEFAULT_ENCODING) ||
// EUC_JP.equalsIgnoreCase(PLATFORM_DEFAULT_ENCODING);
static castAsNonUtf8Char(code: number, encoding: Charset = null) {
// ISO 8859-1 is the Java default as UTF-8 is JavaScripts
// you can see this method as a Java version of String.fromCharCode
const e = encoding ? encoding.getName() : this.ISO88591;
// use passed format (fromCharCode will return UTF8 encoding)
return StringEncoding.decode(new Uint8Array([code]), e);
}
/**
* @param bytes bytes encoding a string, whose encoding should be guessed
* @param hints decode hints if applicable
* @return name of guessed encoding; at the moment will only guess one of:
* {@link #SHIFT_JIS}, {@link #UTF8}, {@link #ISO88591}, or the platform
* default encoding if none of these can possibly be correct
*/
public static guessEncoding(bytes: Uint8Array, hints: Map<DecodeHintType, any>): string {
if (hints !== null && hints !== undefined && undefined !== hints.get(DecodeHintType.CHARACTER_SET)) {
return hints.get(DecodeHintType.CHARACTER_SET).toString();
}
// For now, merely tries to distinguish ISO-8859-1, UTF-8 and Shift_JIS,
// which should be by far the most common encodings.
const length = bytes.length;
let canBeISO88591 = true;
let canBeShiftJIS = true;
let canBeUTF8 = true;
let utf8BytesLeft = 0;
// int utf8LowChars = 0
let utf2BytesChars = 0;
let utf3BytesChars = 0;
let utf4BytesChars = 0;
let sjisBytesLeft = 0;
// int sjisLowChars = 0
let sjisKatakanaChars = 0;
// int sjisDoubleBytesChars = 0
let sjisCurKatakanaWordLength = 0;
let sjisCurDoubleBytesWordLength = 0;
let sjisMaxKatakanaWordLength = 0;
let sjisMaxDoubleBytesWordLength = 0;
// int isoLowChars = 0
// int isoHighChars = 0
let isoHighOther = 0;
const utf8bom = bytes.length > 3 &&
bytes[0] === /*(byte) */0xEF &&
bytes[1] === /*(byte) */0xBB &&
bytes[2] === /*(byte) */0xBF;
for (let i = 0;
i < length && (canBeISO88591 || canBeShiftJIS || canBeUTF8);
i++) {
const value = bytes[i] & 0xFF;
// UTF-8 stuff
if (canBeUTF8) {
if (utf8BytesLeft > 0) {
if ((value & 0x80) === 0) {
canBeUTF8 = false;
} else {
utf8BytesLeft--;
}
} else if ((value & 0x80) !== 0) {
if ((value & 0x40) === 0) {
canBeUTF8 = false;
} else {
utf8BytesLeft++;
if ((value & 0x20) === 0) {
utf2BytesChars++;
} else {
utf8BytesLeft++;
if ((value & 0x10) === 0) {
utf3BytesChars++;
} else {
utf8BytesLeft++;
if ((value & 0x08) === 0) {
utf4BytesChars++;
} else {
canBeUTF8 = false;
}
}
}
}
} // else {
// utf8LowChars++
// }
}
// ISO-8859-1 stuff
if (canBeISO88591) {
if (value > 0x7F && value < 0xA0) {
canBeISO88591 = false;
} else if (value > 0x9F) {
if (value < 0xC0 || value === 0xD7 || value === 0xF7) {
isoHighOther++;
} // else {
// isoHighChars++
// }
} // else {
// isoLowChars++
// }
}
// Shift_JIS stuff
if (canBeShiftJIS) {
if (sjisBytesLeft > 0) {
if (value < 0x40 || value === 0x7F || value > 0xFC) {
canBeShiftJIS = false;
} else {
sjisBytesLeft--;
}
} else if (value === 0x80 || value === 0xA0 || value > 0xEF) {
canBeShiftJIS = false;
} else if (value > 0xA0 && value < 0xE0) {
sjisKatakanaChars++;
sjisCurDoubleBytesWordLength = 0;
sjisCurKatakanaWordLength++;
if (sjisCurKatakanaWordLength > sjisMaxKatakanaWordLength) {
sjisMaxKatakanaWordLength = sjisCurKatakanaWordLength;
}
} else if (value > 0x7F) {
sjisBytesLeft++;
// sjisDoubleBytesChars++
sjisCurKatakanaWordLength = 0;
sjisCurDoubleBytesWordLength++;
if (sjisCurDoubleBytesWordLength > sjisMaxDoubleBytesWordLength) {
sjisMaxDoubleBytesWordLength = sjisCurDoubleBytesWordLength;
}
} else {
// sjisLowChars++
sjisCurKatakanaWordLength = 0;
sjisCurDoubleBytesWordLength = 0;
}
}
}
if (canBeUTF8 && utf8BytesLeft > 0) {
canBeUTF8 = false;
}
if (canBeShiftJIS && sjisBytesLeft > 0) {
canBeShiftJIS = false;
}
// Easy -- if there is BOM or at least 1 valid not-single byte character (and no evidence it can't be UTF-8), done
if (canBeUTF8 && (utf8bom || utf2BytesChars + utf3BytesChars + utf4BytesChars > 0)) {
return StringUtils.UTF8;
}
// Easy -- if assuming Shift_JIS or at least 3 valid consecutive not-ascii characters (and no evidence it can't be), done
if (canBeShiftJIS && (StringUtils.ASSUME_SHIFT_JIS || sjisMaxKatakanaWordLength >= 3 || sjisMaxDoubleBytesWordLength >= 3)) {
return StringUtils.SHIFT_JIS;
}
// Distinguishing Shift_JIS and ISO-8859-1 can be a little tough for short words. The crude heuristic is:
// - If we saw
// - only two consecutive katakana chars in the whole text, or
// - at least 10% of bytes that could be "upper" not-alphanumeric Latin1,
// - then we conclude Shift_JIS, else ISO-8859-1
if (canBeISO88591 && canBeShiftJIS) {
return (sjisMaxKatakanaWordLength === 2 && sjisKatakanaChars === 2) || isoHighOther * 10 >= length
? StringUtils.SHIFT_JIS : StringUtils.ISO88591;
}
// Otherwise, try in order ISO-8859-1, Shift JIS, UTF-8 and fall back to default platform encoding
if (canBeISO88591) {
return StringUtils.ISO88591;
}
if (canBeShiftJIS) {
return StringUtils.SHIFT_JIS;
}
if (canBeUTF8) {
return StringUtils.UTF8;
}
// Otherwise, we take a wild guess with platform encoding
return StringUtils.PLATFORM_DEFAULT_ENCODING;
}
/**
*
* @see https://stackoverflow.com/a/13439711/4367683
*
* @param append The new string to append.
* @param args Argumets values to be formated.
*/
public static format(append: string, ...args: any[]) {
let i = -1;
function callback(exp: string | number, p0: any, p1: any, p2: any, p3: any, p4: any) {
if (exp === '%%') return '%';
if (args[++i] === undefined) return undefined;
exp = p2 ? parseInt(p2.substr(1)) : undefined;
let base = p3 ? parseInt(p3.substr(1)) : undefined;
let val: string;
switch (p4) {
case 's': val = args[i]; break;
case 'c': val = args[i][0]; break;
case 'f': val = parseFloat(args[i]).toFixed(exp); break;
case 'p': val = parseFloat(args[i]).toPrecision(exp); break;
case 'e': val = parseFloat(args[i]).toExponential(exp); break;
case 'x': val = parseInt(args[i]).toString(base ? base : 16); break;
case 'd': val = parseFloat(parseInt(args[i], base ? base : 10).toPrecision(exp)).toFixed(0); break;
}
val = typeof val === 'object' ? JSON.stringify(val) : (+val).toString(base);
let size = parseInt(p1); /* padding size */
let ch = p1 && (p1[0] + '') === '0' ? '0' : ' '; /* isnull? */
while (val.length < size) val = p0 !== undefined ? val + ch : ch + val; /* isminus? */
return val;
}
let regex = /%(-)?(0?[0-9]+)?([.][0-9]+)?([#][0-9]+)?([scfpexd%])/g;
return append.replace(regex, callback);
}
/**
*
*/
public static getBytes(str: string, encoding: CharacterSetECI): Uint8Array {
return StringEncoding.encode(str, encoding);
}
/**
* Returns the charcode at the specified index or at index zero.
*/
public static getCharCode(str: string, index = 0): int {
return str.charCodeAt(index);
}
/**
* Returns char for given charcode
*/
public static getCharAt(charCode: number): string {
return String.fromCharCode(charCode);
}
}