78 lines
1.8 KiB
PHP
78 lines
1.8 KiB
PHP
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<?php
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namespace Program;
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use RuntimeException;
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class ProgramParser
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{
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public function parseFile(string $filename): Program
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{
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$lines = explode(PHP_EOL, file_get_contents($filename));
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$lines = array_filter($lines);
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return $this->parse($lines);
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}
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public function parse(array $lines): Program
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{
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// In the first parsing stage, all words are parsed from the file.
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/** @var Word[] $words */
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$words = [];
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foreach ($lines as $line) {
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$characters = str_split(trim($line) . ' ');
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$state = 'NONE';
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$wordBuffer = [];
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foreach ($characters as $character) {
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if ('READING' === $state) {
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if ('-' === $character || is_numeric($character)) {
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$wordBuffer['value'] .= $character;
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continue;
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}
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// Word is finished
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$words[] = new Word($wordBuffer['register'], $wordBuffer['value']);
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$wordBuffer = [];
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$state = 'NONE';
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continue;
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}
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if ('NONE' === $state && ctype_alpha($character)) {
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$state = 'READING';
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$wordBuffer = ['register' => $character, 'value' => ''];
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continue;
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}
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if (stripos($line, 'EOF') !== false) {
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break 2; // End of program reached
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}
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if (';' === $character) {
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break; // Rest of line is a comment
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}
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}
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}
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// In the second stage, the words are ordered by N numbers
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// and shaped into a program
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$firstWord = array_shift($words);
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if (!preg_match('/^N9\d\d\d$/i', $firstWord)) {
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throw new RuntimeException('Expected program number, got ' . $firstWord);
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}
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$program = new Program($firstWord->value);
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$lineBuffer = null;
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foreach ($words as $word) {
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if ($word->register === 'N') {
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if (!is_null($lineBuffer)) {
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$program->addBlock($lineBuffer);
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}
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$lineBuffer = new Block($word->value);
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continue;
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}
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$lineBuffer->addWord($word);
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}
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return $program;
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}
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}
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