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Deprecate unnecessary escape characters
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See twigphp#4123 twigphp#2712

This allows to change the implementation in v4 so that we no longer have to escape backslashes.
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@ruudk
ruudk committed Aug 11, 2024
1 parent 8a8f221 commit fc6704a
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Showing 3 changed files with 177 additions and 18 deletions.
23 changes: 19 additions & 4 deletions doc/templates.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -522,10 +522,25 @@ exist:
* ``"Hello World"``: Everything between two double or single quotes is a
string. They are useful whenever you need a string in the template (for
example as arguments to function calls, filters or just to extend or include
a template). A string can contain a delimiter if it is preceded by a
backslash (``\``) -- like in ``'It\'s good'``. If the string contains a
backslash (e.g. ``'c:\Program Files'``) escape it by doubling it
(e.g. ``'c:\\Program Files'``).
a template).

Note that certain characters require escaping:
* ``\f``: Form feed
* ``\n``: New line
* ``\r``: Carriage return
* ``\t``: Horizontal tab
* ``\v``: Vertical tab
* ``\x``: Hexadecimal escape sequence
* ``\0`` to ``\377``: Octal escape sequences representing characters
* ``\``: Backslash

When using single-quoted strings, the single quote character (``'``) needs to be escaped with a backslash (``\'``).
When using double-quoted strings, the double quote character (``"``) needs to be escaped with a backslash (``\"``).

For example, a single quoted string can contain a delimiter if it is preceded by a
backslash (``\``) -- like in ``'It\'s good'``. If the string contains a
backslash (e.g. ``'c:\Program Files'``) escape it by doubling it
(e.g. ``'c:\\Program Files'``).

* ``42`` / ``42.23``: Integers and floating point numbers are created by
writing the number down. If a dot is present the number is a float,
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79 changes: 77 additions & 2 deletions src/Lexer.php
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Original file line number Diff line number Diff line change
Expand Up @@ -367,7 +367,7 @@ private function lexExpression(): void
}
// strings
elseif (preg_match(self::REGEX_STRING, $this->code, $match, 0, $this->cursor)) {
$this->pushToken(/* Token::STRING_TYPE */ 7, stripcslashes(substr($match[0], 1, -1)));
$this->pushToken(/* Token::STRING_TYPE */ 7, $this->stripcslashes(substr($match[0], 1, -1), substr($match[0], 0, 1)));
$this->moveCursor($match[0]);
}
// opening double quoted string
Expand All @@ -382,6 +382,81 @@ private function lexExpression(): void
}
}

private function stripcslashes(string $str, string $quoteType): string
{
if (!str_contains($str, '\\')) {
return $str;
}

$result = '';
$length = strlen($str);
$specialChars = [
'f' => "\f",
'n' => "\n",
'r' => "\r",
't' => "\t",
'v' => "\v",
];

for ($i = 0; $i < $length; $i++) {
if ($str[$i] !== '\\' || $i + 1 >= $length) {
$result .= $str[$i];

continue;
}

$nextChar = $str[$i + 1];
if (isset($specialChars[$nextChar])) {
$result .= $specialChars[$nextChar];
$i++;
} elseif ($nextChar === '\\') {
$result .= '\\';
$i++;
} elseif ($nextChar === "'" || $nextChar === '"') {
if ($nextChar !== $quoteType) {
trigger_deprecation('twig/twig', '3.12', 'Character "%s" at position %d does not need to be escaped anymore.', $nextChar, $i + 2);
}
$result .= $nextChar;
$i++;
} elseif ($nextChar === '#' && $i + 2 < $length && $str[$i + 2] === '{') {
$result .= '#{';
$i += 2;
} elseif ($nextChar === 'x' && $i + 2 < $length && ctype_xdigit($str[$i + 2])) {
$hex = $str[$i + 2];
if ($i + 3 < $length && ctype_xdigit($str[$i + 3])) {
$hex .= $str[$i + 3];
$i++;
}
$result .= chr(hexdec($hex));
$i += 2;
} elseif (ctype_digit($nextChar) && $nextChar < '8') {
$octal = $nextChar;
for ($j = $i + 1; $j <= 3; $j++) {
$o = $j + 1;
if ($o >= $length) {
break;
}
if (!ctype_digit($str[$o])) {
break;
}
if ($str[$o] >= '8') {
break;
}
$octal .= $str[$o];
$i++;
}
$result .= chr(octdec($octal));
$i++;
} else {
trigger_deprecation('twig/twig', '3.12', 'Character "%s" at position %d does not need to be escaped anymore.', $nextChar, $i + 2);
$result .= $nextChar;
$i++;
}
}

return $result;
}

private function lexRawData(): void
{
if (!preg_match($this->regexes['lex_raw_data'], $this->code, $match, \PREG_OFFSET_CAPTURE, $this->cursor)) {
Expand Down Expand Up @@ -423,7 +498,7 @@ private function lexString(): void
$this->moveCursor($match[0]);
$this->pushState(self::STATE_INTERPOLATION);
} elseif (preg_match(self::REGEX_DQ_STRING_PART, $this->code, $match, 0, $this->cursor) && '' !== $match[0]) {
$this->pushToken(/* Token::STRING_TYPE */ 7, stripcslashes($match[0]));
$this->pushToken(/* Token::STRING_TYPE */ 7, $this->stripcslashes($match[0], '"'));
$this->moveCursor($match[0]);
} elseif (preg_match(self::REGEX_DQ_STRING_DELIM, $this->code, $match, 0, $this->cursor)) {
[$expect, $lineno] = array_pop($this->brackets);
Expand Down
93 changes: 81 additions & 12 deletions tests/LexerTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
*/

use PHPUnit\Framework\TestCase;
use Symfony\Bridge\PhpUnit\ExpectDeprecationTrait;
use Twig\Environment;
use Twig\Error\SyntaxError;
use Twig\Lexer;
Expand All @@ -21,6 +22,8 @@

class LexerTest extends TestCase
{
use ExpectDeprecationTrait;

public function testNameLabelForTag()
{
$template = '{% § %}';
Expand Down Expand Up @@ -178,23 +181,89 @@ public function testBigNumbers()
$this->assertEquals('922337203685477580700', $node->getValue());
}

public function testStringWithEscapedDelimiter()
/**
* @dataProvider getStringWithEscapedDelimiter
*/
public function testStringWithEscapedDelimiter(string $template, string $expected)
{
$lexer = new Lexer(new Environment(new ArrayLoader()));
$stream = $lexer->tokenize(new Source($template, 'index'));
$stream->expect(Token::VAR_START_TYPE);
$token = $stream->expect(Token::STRING_TYPE);
$this->assertSame($expected, $token->getValue());
}

public function getStringWithEscapedDelimiter()
{
$tests = [
"{{ 'foo \' bar' }}" => 'foo \' bar',
'{{ "foo \" bar" }}' => 'foo " bar',
yield '{{ \'\x6\' }} => \x6' => [
'{{ \'\x6\' }}',
"\x6",
];
yield '{{ \'\065\x64\' }} => \065\x64' => [
'{{ \'\065\x64\' }}',
"\065\x64",
];
yield '{{ \'App\\\\Test\' }} => App\Test' => [
'{{ \'App\\\\Test\' }}',
'App\\Test',
];
yield '{{ "App\#{var}" }} => App#{var}' => [
'{{ "App\#{var}" }}',
'App#{var}',
];
yield '{{ \'foo \\\' bar\' }} => foo \' bar' => [
'{{ \'foo \\\' bar\' }}',
'foo \' bar',
];
yield '{{ "foo \" bar" }} => foo " bar' => [
'{{ "foo \\" bar" }}',
'foo " bar',
];
yield '{{ \'\f\n\r\t\v\' }} => \f\n\r\t\v' => [
'{{ \'\\f\\n\\r\\t\\v\' }}',
"\f\n\r\t\v",
];
yield '{{ \'\\\\f\\\\n\\\\r\\\\t\\\\v\' }} => \\f\\n\\r\\t\\v' => [
'{{ \'\\\\f\\\\n\\\\r\\\\t\\\\v\' }}',
'\\f\\n\\r\\t\\v',
];
}

/**
* @group legacy
* @dataProvider getStringWithEscapedDelimiterProducingDeprecation
*/
public function testStringWithEscapedDelimiterProducingDeprecation(string $template, string $expected, string $expectedDeprecation)
{
$this->expectDeprecation($expectedDeprecation);

$lexer = new Lexer(new Environment(new ArrayLoader()));
foreach ($tests as $template => $expected) {
$stream = $lexer->tokenize(new Source($template, 'index'));
$stream->expect(Token::VAR_START_TYPE);
$stream->expect(Token::STRING_TYPE, $expected);
$stream = $lexer->tokenize(new Source($template, 'index'));
$stream->expect(Token::VAR_START_TYPE);
$stream->expect(Token::STRING_TYPE, $expected);

// add a dummy assertion here to satisfy PHPUnit, the only thing we want to test is that the code above
// can be executed without throwing any exceptions
$this->addToAssertionCount(1);
}
// add a dummy assertion here to satisfy PHPUnit, the only thing we want to test is that the code above
// can be executed without throwing any exceptions
$this->addToAssertionCount(1);
}

public function getStringWithEscapedDelimiterProducingDeprecation()
{
yield '{{ \'App\Test\' }} => AppTest' => [
'{{ \'App\\Test\' }}',
'AppTest',
"Since twig/twig 3.11: Character \"T\" at position 5 does not need to be escaped anymore.",
];
yield '{{ "foo \\\' bar" }} => foo \' bar' => [
'{{ "foo \\\' bar" }}',
'foo \' bar',
"Since twig/twig 3.11: Character \"'\" at position 6 does not need to be escaped anymore.",
];
yield '{{ \'foo \" bar\' }} => foo " bar' => [
'{{ \'foo \\" bar\' }}',
'foo " bar',
'Since twig/twig 3.11: Character """ at position 6 does not need to be escaped anymore.',
];
}

public function testStringWithInterpolation()
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