SMPLang

SMPLang is a simple expression language for PHP. It's currently in a pre-release state and any contributions and tests are welcome.

The language is partly inspired by Symfony Expression Language but there are some major differences. For more details and a performance benchmark, see test.php.

Install:

composer require leongrdic/smplang:dev-master

To use SMPLang, create a new instance of the SMPLang class and pass in an array of variables. These variables will be available to use in your expressions.

$smpl = new Le\SMPLang\SMPLang([
    'variableName' => 'value',
];

You can then call the evaluate() method on your SMPLang instance, passing in an expression string. This will return the result of the expression.

$smpl->evaluate($expression);

In case of an exception, Le\SMPLang\Exception will be thrown with short description of the error.

Syntax

Variables are accessed only by their name. If a variable is not defined, an exception will be thrown.

Array elements are accessed with the following syntax: array.key.0 (even numeric keys).

Object properties and methods are accessed with the following syntax: object.property or object.method(parameters).

Closures/functions are called with the following syntax: closure(parameter1, parameter2, ...)

Arrays are defined with the following syntax: [element1, element2, ...]

Array unpacking (...array) is supported in array definitions and closure calls.

Supported literals

• null
• booleans (true and false)
• strings ("string" or 'string')
• numbers (1, 1.2, -1, -1.2)
• arrays ([23, 'string'])
• hashes aren't supported currently

Arithmetic operators

• +: addition
• -: subtraction
• *: multiplication
• /: division
• %: modulo
• **: exponentiation

Comparison operators

• ===: strict equality
• !==: strict inequality
• ==: equality
• !=: inequality
• >: greater than
• <: less than
• >=: greater than or equal to
• <=: less than or equal to

Logical operators

• &&: logical and
• ||: logical or
• !: logical not

String concatenation

• ~: string concatenation

Ternary expressions

• a ? b : c
• a ?: b (is equivalent to a ? a : b)
• a ? b (is equivalent to a ? b : null)

Examples

$smpl = new Le\SMPLang\SMPLang();
$result = $smpl->evaluate('(1 + 2 * 3) / 7');
// $result will be 1

$smpl = new Le\SMPLang\SMPLang([
    'foo' => 'bar',
    'arr' => [1, 2, 3],
    'hash' => ['a' => 'b'],
]);

$result = $smpl->evaluate('foo ~ " " ~ arr.1 ~ " " ~ hash.a');
// $result will be "bar 2 b"

$smpl = new Le\SMPLang\SMPLang([
    'prepend' => fn(string $a): string => "hello $a",
    'reverse' => strrev(...),
]);

$result = $smpl->evaluate('prepend("simple " ~ reverse("world"))');
// $result will be "hello simple dlrow"

$smpl = new Le\SMPLang\SMPLang([
    'foo' => 'bar',
]);

$result = $smpl->evaluate('foo !== "bar" ? "yes" : "no"');
// $result will be "no"