The Expression Syntax
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The Expression Syntax
The ExpressionLanguage component uses a specific syntax which is based on the expression syntax of Twig. In this document, you can find all supported syntaxes.
Supported Literals
The component supports:
- strings - single and double quotes (e.g.
'hello') - numbers - e.g.
103 - arrays - using JSON-like notation (e.g.
[1, 2]) - hashes - using JSON-like notation (e.g.
{ foo: 'bar' }) - booleans -
trueandfalse - null -
null
Caution
A backslash (\) must be escaped by 4 backslashes (
1 2
echo $expressionLanguage->evaluate('"\\\\"'); // prints \
$expressionLanguage->evaluate('"a\\\\b" matches "/^a\\\\\\\\b$/"'); // returns trueControl characters (e.g. \n) in expressions are replaced with
whitespace. To avoid this, escape the sequence with a single backslash
(e.g. \\n).
Working with Objects
When passing objects into an expression, you can use different syntaxes to access properties and call methods on the object.
Accessing Public Properties
Public properties on objects can be accessed by using the . syntax, similar
to JavaScript:
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class Apple
{
public $variety;
}
$apple = new Apple();
$apple->variety = 'Honeycrisp';
var_dump($expressionLanguage->evaluate(
'fruit.variety',
array(
'fruit' => $apple,
)
));This will print out Honeycrisp.
Calling Methods
The . syntax can also be used to call methods on an object, similar to
JavaScript:
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class Robot
{
public function sayHi($times)
{
$greetings = array();
for ($i = 0; $i < $times; $i++) {
$greetings[] = 'Hi';
}
return implode(' ', $greetings).'!';
}
}
$robot = new Robot();
var_dump($expressionLanguage->evaluate(
'robot.sayHi(3)',
array(
'robot' => $robot,
)
));This will print out Hi Hi Hi!.
Working with Functions
You can also use registered functions in the expression by using the same
syntax as PHP and JavaScript. The ExpressionLanguage component comes with one
function by default: constant(), which will return the value of the PHP
constant:
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define('DB_USER', 'root');
var_dump($expressionLanguage->evaluate(
'constant("DB_USER")'
));This will print out root.
Tip
To read how to register your own functions to use in an expression, see "Extending the ExpressionLanguage".
Working with Arrays
If you pass an array into an expression, use the [] syntax to access
array keys, similar to JavaScript:
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$data = array('life' => 10, 'universe' => 10, 'everything' => 22);
var_dump($expressionLanguage->evaluate(
'data["life"] + data["universe"] + data["everything"]',
array(
'data' => $data,
)
));This will print out 42.
Supported Operators
The component comes with a lot of operators:
Arithmetic Operators
+(addition)-(subtraction)*(multiplication)/(division)%(modulus)**(pow)
For example:
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var_dump($expressionLanguage->evaluate(
'life + universe + everything',
array(
'life' => 10,
'universe' => 10,
'everything' => 22,
)
));This will print out 42.
Bitwise Operators
&(and)|(or)^(xor)
Comparison Operators
==(equal)===(identical)!=(not equal)!==(not identical)<(less than)>(greater than)<=(less than or equal to)>=(greater than or equal to)matches(regex match)
Tip
To test if a string does not match a regex, use the logical not
operator in combination with the matches operator:
1
$expressionLanguage->evaluate('not ("foo" matches "/bar/")'); // returns trueYou must use parenthesis because the unary operator not has precedence
over the binary operator matches.
Examples:
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$ret1 = $expressionLanguage->evaluate(
'life == everything',
array(
'life' => 10,
'universe' => 10,
'everything' => 22,
)
);
$ret2 = $expressionLanguage->evaluate(
'life > everything',
array(
'life' => 10,
'universe' => 10,
'everything' => 22,
)
);Both variables would be set to false.
Logical Operators
notor!andor&&oror||
For example:
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$ret = $expressionLanguage->evaluate(
'life < universe or life < everything',
array(
'life' => 10,
'universe' => 10,
'everything' => 22,
)
);This $ret variable will be set to true.
String Operators
~(concatenation)
For example:
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var_dump($expressionLanguage->evaluate(
'firstName~" "~lastName',
array(
'firstName' => 'Arthur',
'lastName' => 'Dent',
)
));This would print out Arthur Dent.
Array Operators
in(contain)not in(does not contain)
For example:
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class User
{
public $group;
}
$user = new User();
$user->group = 'human_resources';
$inGroup = $expressionLanguage->evaluate(
'user.group in ["human_resources", "marketing"]',
array(
'user' => $user,
)
);The $inGroup would evaluate to true.
Numeric Operators
..(range)
For example:
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class User
{
public $age;
}
$user = new User();
$user->age = 34;
$expressionLanguage->evaluate(
'user.age in 18..45',
array(
'user' => $user,
)
);This will evaluate to true, because user.age is in the range from
18 to 45.
Ternary Operators
foo ? 'yes' : 'no'foo ?: 'no'(equal tofoo ? foo : 'no')foo ? 'yes'(equal tofoo ? 'yes' : '')
