#282 Add strict po loader

src/Generator/PoGenerator.php

@@ -65,6 +65,18 @@ public function generateString(Translations $translations): string
 
             $prefix = $translation->isDisabled() ? '#~ ' : '';
 
+            if ($context = $translation->getPreviousContext()) {
+                $lines[] = sprintf('%s#| msgctxt %s', $prefix, self::encode($context));
+            }
+
+            if ($original = $translation->getPreviousOriginal()) {
+                $lines[] = sprintf('%s#| msgid %s', $prefix, self::encode($original));
+            }
+
+            if ($plural = $translation->getPreviousPlural()) {
+                $lines[] = sprintf('%s#| msgid_plural %s', $prefix, self::encode($plural));
+            }
+
             if ($context = $translation->getContext()) {
                 $lines[] = sprintf('%smsgctxt %s', $prefix, self::encode($context));
             }

src/Loader/StrictPoLoader.php

@@ -0,0 +1,349 @@
+<?php
+declare(strict_types = 1);
+
+namespace Gettext\Loader;
+
+use Exception;
+use Gettext\Translation;
+use Gettext\Translations;
+
+/**
+ * Class to load a PO file.
+ */
+final class StrictPoLoader extends Loader
+{
+    /** @var Translations */
+    private $translations;
+    /** @var Translation */
+    private $translation;
+    private $data;
+    private $position;
+    private $inPreviousComment;
+
+    public function loadString(string $string, Translations $translations = null): Translations
+    {
+        $this->data = $string;
+        $this->position = 0;
+        $this->translations = parent::loadString($string, $translations);
+        for ($this->newEntry(); $this->getChar() !== null; $this->newEntry()) {
+            while ($this->readComment());
+            $this->readContext();
+            $this->readId();
+            if ($this->readPlural()) {
+                for ($isRequired = true; $this->readPluralTranslation($isRequired); $isRequired = false);
+            } else {
+                $this->readTranslation();
+            }
+            $this->saveEntry();
+        }
+        $this->processHeader();
+        return $this->translations;
+    }
+
+    private function newEntry(): void
+    {
+        $this->inPreviousComment = false;
+        $this->translation = $this->createTranslation(null, '');
+    }
+
+    private function saveEntry(): void
+    {
+        $this->translations->add($this->translation);
+    }
+
+    private function readDisabledComment(): bool
+    {
+        return $this->translation->isDisabled() && $this->readString('#~');
+    }
+
+    private function readPreviousTranslationComment(): bool
+    {
+        return $this->inPreviousComment && $this->readString('#|');
+    }
+
+    private function readWhiteSpace(): bool
+    {
+        $position = $this->position;
+        while ((ctype_space($this->getChar() ?? '') && $this->nextChar())
+            || $this->readDisabledComment()
+            || $this->readPreviousTranslationComment());
+        return $position !== $this->position;
+    }
+
+    private function readString(string $word): bool
+    {
+        return substr($this->data, $this->position, strlen($word)) === $word
+            ? !!($this->position += strlen($word))
+            : false;
+    }
+
+    private function readChar(string $char): bool
+    {
+        return $this->getChar() === $char
+            ? !!++$this->position
+            : false;
+    }
+
+    private function nextChar(): ?string
+    {
+        $char = $this->getChar();
+        if ($char !== null) {
+            ++$this->position;
+        }
+        return $char;
+    }
+
+    private function getChar(): ?string
+    {
+        return $this->data[$this->position] ?? null;
+    }
+
+    private function readNumber(): string
+    {
+        for ($data = ''; ctype_digit($this->getChar() ?? ''); $data .= $this->nextChar());
+        return $data;
+    }
+
+    private function readCommentString(): string
+    {
+        for ($data = ''; ($this->getChar() ?? "\n") !== "\n"; $data .= $this->nextChar());
+        return $data;
+    }
+
+    private function readQuotedString(): string
+    {
+        static $aliases = [
+            '\\' => '\\',
+            'a' => "\x07",
+            'b' => "\x08",
+            'e' => "\x1b",
+            'f' => "\x0c",
+            'n' => "\n",
+            'r' => "\r",
+            't' => "\t",
+            'v' => "\x0b",
+            '"' => '"',
+        ];
+        $hasData = false;
+        for ($data = '';;) {
+            if (!$this->readChar('"')) {
+                if ($hasData) {
+                    break;
+                }
+                throw new Exception("Expected an opening quote at byte {$this->position}");
+            }
+            for (; ($char = $this->getChar() ?? '"') !== '"'; $data .= $char) {
+                $this->nextChar();
+                if ($char === '\\') {
+                    if (($alias = $aliases[$this->nextChar()] ?? null) === null) {
+                        throw new Exception("Invalid quoted character at byte {$this->position}");
+                    }
+                    $char = $alias;
+                    continue;
+                }
+                if ($char === "\n") {
+                    throw new Exception("New line character must be encoded at byte {$this->position}");
+                }
+            }
+            if (!$this->readChar('"')) {
+                throw new Exception("Expected an ending quote at byte {$this->position}");
+            }
+            $this->readWhiteSpace();
+            $hasData = true;
+        }
+        return $data;
+    }
+
+    private function readComment(): bool
+    {
+        $this->readWhiteSpace();
+        if (!$this->readChar('#')) {
+            return false;
+        }
+        $type = '';
+        if (is_int(strpos('~|,:.', $char = $this->getChar() ?? ''))) {
+            $type = $char;
+            ++$this->position;
+        }
+        // Only a single space might be optionally added
+        $this->readChar(' ');
+        switch ($type) {
+            case '':
+                $data = $this->readCommentString();
+                $this->translation->getComments()->add($data);
+                break;
+            case '~':
+                if ($this->inPreviousComment) {
+                    throw new Exception("Inconsistent use of #~ at byte {$this->position}");
+                }
+                $this->translation->disable();
+                break;
+            case '|':
+                $this->inPreviousComment = true;
+                $this->translation->setPreviousContext($this->readIdentifier('msgctxt'));
+                $this->translation->setPreviousOriginal($this->readIdentifier('msgid', true));
+                $this->translation->setPreviousPlural($this->readIdentifier('msgid_plural'));
+                $this->inPreviousComment = false;
+                break;
+            case ',':
+                $data = $this->readCommentString();
+                foreach (array_map('trim', explode(',', trim($data))) as $value) {
+                    $this->translation->getFlags()->add($value);
+                }
+                break;
+            case ':':
+                $data = $this->readCommentString();
+                foreach (preg_split('/\s+/', trim($data)) as $value) {
+                    if (preg_match('/^(.+)(:(\d*))?$/U', $value, $matches)) {
+                        $line = isset($matches[3]) ? intval($matches[3]) : null;
+                        $this->translation->getReferences()->add($matches[1], $line);
+                    }
+                }
+                break;
+            case '.':
+                $data = $this->readCommentString();
+                $this->translation->getExtractedComments()->add($data);
+                break;
+        }
+        return true;
+    }
+
+    private function readIdentifier(string $identifier, bool $isRequired = false): ?string
+    {
+        $this->readWhiteSpace();
+        if (!$this->readString($identifier)) {
+            if ($isRequired) {
+                throw new Exception("Expected identifier $identifier at byte {$this->position}");
+            }
+            return null;
+        }
+        $this->readWhiteSpace();
+        return $this->readQuotedString();
+    }
+
+    private function readContext(): bool
+    {
+        if (($data = $this->readIdentifier('msgctxt')) === null) {
+            return false;
+        }
+        $this->translation = $this->translation->withContext($data);
+        return true;
+    }
+
+    private function readId(): void
+    {
+        $data = $this->readIdentifier('msgid', true);
+        $this->translation = $this->translation->withOriginal($data);
+    }
+
+    private function readPlural(): bool
+    {
+        if (($data = $this->readIdentifier('msgid_plural')) === null) {
+            return false;
+        }
+        $this->translation->setPlural($data);
+        return true;
+    }
+
+    private function readTranslation(): void
+    {
+        $this->readWhiteSpace();
+        if (!$this->readString('msgstr')) {
+            throw new Exception("Expected msgstr at byte {$this->position}");
+        }
+        $this->readWhiteSpace();
+        $data = $this->readQuotedString();
+        $this->translation->translate($data);
+    }
+
+    private function readPluralTranslation(bool $isRequired = false): bool
+    {
+        $this->readWhiteSpace();
+        if (!$this->readString('msgstr')) {
+            if ($isRequired) {
+                throw new Exception("Expected indexed msgstr at byte {$this->position}");
+            }
+            return false;
+        }
+        $this->readWhiteSpace();
+        if (!$this->readChar('[')) {
+            throw new Exception("Expected [ character at byte {$this->position}");
+        }
+        if (!strlen($index = $this->readNumber())) {
+            throw new Exception("Expected msgstr index at byte {$this->position}");
+        }
+        $this->readWhiteSpace();
+        if (!$this->readChar(']')) {
+            throw new Exception("Expected ] character at byte {$this->position}");
+        }
+        $translations = $this->translation->getPluralTranslations();
+        if (($translation = $this->translation->getTranslation()) !== null) {
+            array_unshift($translations, $translation);
+        }
+        if (count($translations) !== (int) $index) {
+            throw new Exception("The msgstr has an invalid index at byte {$this->position}");
+        }
+        $this->readWhiteSpace();
+        $data = $this->readQuotedString();
+        $translations[] = $data;
+        $this->translation->translate(array_shift($translations));
+        $this->translation->translatePlural(...$translations);
+        return true;
+    }
+
+    private function processHeader(): void
+    {
+        $translations = $this->translations;
+        if (!($header = $translations->find(null, ''))) {
+            return;
+        }
+
+        $translations->remove($header);
+        $description = $header->getComments()->toArray();
+
+        if (!empty($description)) {
+            $translations->setDescription(implode("\n", $description));
+        }
+
+        $flags = $header->getFlags()->toArray();
+
+        if (!empty($flags)) {
+            $translations->getFlags()->add(...$flags);
+        }
+
+        $headers = $translations->getHeaders();
+
+        foreach (self::readHeaders($header->getTranslation()) as $name => $value) {
+            $headers->set($name, $value);
+        }
+    }
+
+    private function readHeaders(?string $string): array
+    {
+        if (empty($string)) {
+            return [];
+        }
+        $headers = [];
+        $lines = explode("\n", $string);
+        $name = null;
+        foreach ($lines as $line) {
+            if ($line === '') {
+                continue;
+            }
+            // Checks if it is a header definition line.
+            // Useful for distinguishing between header definitions and possible continuations of a header entry.
+            if (preg_match('/^[\w-]+:/', $line)) {
+                [$name, $value] = array_map('trim', explode(':', $line, 2));
+                $headers[$name] = $value;
+                continue;
+            }
+            // Data without a definition
+            if ($name === null) {
+                throw new Exception("The header data is missing a definition at byte {$this->position}");
+            }
+            $value = $headers[$name] ?? '';
+            $headers[$name] = $value . $line;
+        }
+        return $headers;
+    }
+}