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113 lines
3.6 KiB
113 lines
3.6 KiB
<?php
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/** @license MIT
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* Copyright 2018 J. King et al.
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* See LICENSE and AUTHORS files for details */
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declare(strict_types=1);
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namespace MensBeam\Intl\Encoding;
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class XUserDefined extends AbstractEncoding implements Coder, Decoder {
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public const NAME = "x-user-defined";
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public const LABELS = ["x-user-defined"];
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/** Retrieve the next character in the string, in UTF-8 encoding
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*
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* The returned character may be a replacement character, or the empty string if the end of the string has been reached
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*/
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public function nextChar(): string {
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// get the byte at the current position
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$b = $this->string[$this->posChar] ?? "";
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if ($b === "") {
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return "";
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}
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$this->posChar++;
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$this->posByte++;
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$p = ord($b);
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if ($p < 0x80) {
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// if the byte is an ASCII character or end of input, simply return it
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return $b;
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} else {
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return UTF8::encode(0xF700 + $p);
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}
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}
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/** Decodes the next character from the string and returns its code point number
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*
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* If the end of the string has been reached, false is returned
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*
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* @return int|bool
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*/
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public function nextCode() {
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// get the byte at the current position
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$b = $this->string[$this->posChar] ?? "";
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if ($b === "") {
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return false;
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}
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$this->posChar++;
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$this->posByte++;
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$p = ord($b);
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if ($p < 0x80) {
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// if the byte is an ASCII character or end of input, simply return it
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return $p;
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} else {
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return 0xF700 + $p;
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}
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}
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/** Advance $distance characters through the string
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*
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* If $distance is negative, the operation will be performed in reverse
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*
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* If the end (or beginning) of the string was reached before the end of the operation, the remaining number of requested characters is returned
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*/
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public function seek(int $distance): int {
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if ($distance > 0) {
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while ($this->posChar < $this->lenByte && $distance > 0) {
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$this->nextCode();
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$distance--;
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}
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return $distance;
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} elseif ($distance < 0) {
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$distance = abs($distance);
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while ($this->posChar > 0 && $distance > 0) {
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$this->posChar--;
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$this->posByte--;
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$distance--;
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}
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return $distance;
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} else {
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return 0;
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}
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}
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public static function encode(int $codePoint, bool $fatal = true): string {
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if ($codePoint < 0 || $codePoint > 0x10FFFF) {
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throw new EncoderException("Encountered code point outside Unicode range ($codePoint)", self::E_INVALID_CODE_POINT);
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} elseif ($codePoint < 0x80) {
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return chr($codePoint);
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} elseif ($codePoint >= 0xF780 && $codePoint <= 0xF7FF) {
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return chr($codePoint - 0xF780 + 0x80);
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} else {
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return self::errEnc(!$fatal, $codePoint);
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}
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}
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/** @codeCoverageIgnore */
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protected function seekBack(int $distance): int {
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// stub: not used
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return 0;
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}
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/** Calculates the length of the string in code points
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*
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* Note that this may involve processing to the end of the string
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*/
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public function lenChar(): int {
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return $this->lenByte;
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}
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/** Returns whether the character pointer is at the end of the string */
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public function eof(): bool {
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return $this->posChar >= $this->lenByte;
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}
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}
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