README

exprml-php is a PHP library implementing an ExprML interpreter. The ExprML is a programming language that can evaluate expressions represented in JSON (and JSON-compatible YAML).

The ExprML language specification is available at https://github.com/exprml/exprml-language .

Installation

composer require exprml/exprml-php
composer dump-autoload

Example

Evaluate an expression

<?php

use Exprml\Decoder;
use Exprml\Encoder;
use Exprml\Evaluator;
use Exprml\Evaluator\Config;
use Exprml\Parser;
use Exprml\PB\Exprml\V1\DecodeInput;
use Exprml\PB\Exprml\V1\EncodeInput;
use Exprml\PB\Exprml\V1\EvaluateInput;
use Exprml\PB\Exprml\V1\ParseInput;

require 'vendor/autoload.php';

// Decode the input source code.
$decodeResult = (new Decoder())
    ->decode((new DecodeInput())->setText("cat: ['`Hello`', '`, `', '`ExprML`', '`!`']"));

// Parse AST from the decoded value.
$parseResult = (new Parser())
    ->parse((new ParseInput())->setValue($decodeResult->getValue()));

// Evaluate the parsed AST to get the result value.
$evaluator = new Evaluator(new Config());
$evaluateResult = $evaluator
    ->evaluate((new EvaluateInput())->setExpr($parseResult->getExpr()));

// Encode the evaluated result to get the final output.
$encodeResult = (new Encoder())
    ->encode((new EncodeInput())->setValue($evaluateResult->getValue()));

printf($encodeResult->getText() . "\n");
// => Hello, ExprML!

Call PHP functions from ExprML

<?php

use Exprml\Decoder;
use Exprml\Encoder;
use Exprml\Evaluator;
use Exprml\Evaluator\Config;
use Exprml\Parser;
use Exprml\PB\Exprml\V1\DecodeInput;
use Exprml\PB\Exprml\V1\EncodeInput;
use Exprml\PB\Exprml\V1\EvaluateInput;
use Exprml\PB\Exprml\V1\EvaluateOutput;
use Exprml\PB\Exprml\V1\Expr\Path;
use Exprml\PB\Exprml\V1\ParseInput;
use Exprml\PB\Exprml\V1\Value;

require 'vendor/autoload.php';

$decodeResult = (new Decoder())
    ->decode((new DecodeInput())->setText('$hello: { $name: "`ExprML Extension`" }'));
$parseResult = (new Parser())
    ->parse((new ParseInput())->setValue($decodeResult->getValue()));

$config = (new Config())->setExtension([
    // Define an extension function named $hello, which takes an argument $name and returns a greeting string.
    '$hello' => function (Path $path, array $args) {
        /** @var Value $name */
        $name = $args['$name'];
        $ret = (new Value())
            ->setType(Value\Type::STR)
            ->setStr('Hello, ' . $name->getStr() . '!');
        return (new EvaluateOutput())->setValue($name);
    },
]);

$evaluateResult = (new Evaluator($config))
    ->evaluate((new EvaluateInput())->setExpr($parseResult->getExpr()));
$encodeResult = (new Encoder())
    ->encode((new EncodeInput())->setValue($evaluateResult->getValue()));
printf($encodeResult->getText() . "\n");
// => 'Hello, ExprML Extension!'

Hook PHP functions before and after each evaluation of nested expressions

<?php

use Exprml\Decoder;
use Exprml\Evaluator;
use Exprml\Evaluator\Config;
use Exprml\Parser;
use Exprml\Path;
use Exprml\PB\Exprml\V1\DecodeInput;
use Exprml\PB\Exprml\V1\EvaluateInput;
use Exprml\PB\Exprml\V1\EvaluateOutput;
use Exprml\PB\Exprml\V1\ParseInput;
use Exprml\PB\Exprml\V1\Value;

require 'vendor/autoload.php';

$decodeResult = (new Decoder())
    ->decode((new DecodeInput())->setText("cat: ['`Hello`', '`, `', '`ExprML`', '`!`']"));
$parseResult = (new Parser())
    ->parse((new ParseInput())->setValue($decodeResult->getValue()));

$config = (new Config())
    ->setBeforeEvaluate(
        /* Hook a function before the evaluation of each expression. */
        function (EvaluateInput $input) {
            printf("before:\t%s\n", Path::format($input->getExpr()->getPath()));
        })
    ->setAfterEvaluate(
        /* Hook a function after the evaluation of each expression. */
        function (EvaluateInput $input, EvaluateOutput $output) {
            printf("after:\t%s --> %s\n",
                Path::format($input->getExpr()->getPath()),
                Value\Type::name($output->getValue()->getType()));
        });

(new Evaluator($config))
    ->evaluate((new EvaluateInput())->setExpr($parseResult->getExpr()));
# =>
# before: /
# before: /cat/0
# after:  /cat/0 --> STR
# before: /cat/1
# after:  /cat/1 --> STR
# before: /cat/2
# after:  /cat/2 --> STR
# before: /cat/3
# after:  /cat/3 --> STR
# after:  / --> STR

API documentation

https://exprml.github.io/exprml-php/docs/api/

Packagist

https://packagist.org/packages/exprml/exprml-php