Initial commit

src/Program/ProgramParser.php

@@ -0,0 +1,77 @@
+<?php
+
+namespace Program;
+
+use RuntimeException;
+
+class ProgramParser
+{
+	public function parseFile(string $filename): Program
+	{
+		$lines = explode(PHP_EOL, file_get_contents($filename));
+		$lines = array_filter($lines);
+
+		return $this->parse($lines);
+	}
+
+
+	public function parse(array $lines): Program
+	{
+		// In the first parsing stage, all words are parsed from the file.
+		/** @var Word[] $words */
+		$words = [];
+		foreach ($lines as $line) {
+			$characters = str_split(trim($line) . ' ');
+			$state = 'NONE';
+			$wordBuffer = [];
+			foreach ($characters as $character) {
+				if ('READING' === $state) {
+					if ('-' === $character || is_numeric($character)) {
+						$wordBuffer['value'] .= $character;
+						continue;
+					}
+					// Word is finished
+					$words[] = new Word($wordBuffer['register'], $wordBuffer['value']);
+					$wordBuffer = [];
+					$state = 'NONE';
+					continue;
+				}
+
+				if ('NONE' === $state && ctype_alpha($character)) {
+					$state = 'READING';
+					$wordBuffer = ['register' => $character, 'value' => ''];
+					continue;
+				}
+
+				if (stripos($line, 'EOF') !== false) {
+					break 2; // End of program reached
+				}
+
+				if (';' === $character) {
+					break; // Rest of line is a comment
+				}
+			}
+		}
+
+		// In the second stage, the words are ordered by N numbers
+		// and shaped into a program
+		$firstWord = array_shift($words);
+		if (!preg_match('/^N9\d\d\d$/i', $firstWord)) {
+			throw new RuntimeException('Expected program number, got ' . $firstWord);
+		}
+		$program = new Program($firstWord->value);
+		$lineBuffer = null;
+		foreach ($words as $word) {
+			if ($word->register === 'N') {
+				if (!is_null($lineBuffer)) {
+					$program->addBlock($lineBuffer);
+				}
+				$lineBuffer = new Block($word->value);
+				continue;
+			}
+			$lineBuffer->addWord($word);
+		}
+
+		return $program;
+	}
+}