smuuf/primi

<?php

declare(strict_types=1);

namespace Smuuf\Primi\Structures;

use \Smuuf\StrictObject;
use \Smuuf\Primi\Context;
use \Smuuf\Primi\Ex\EngineError;
use \Smuuf\Primi\Ex\RuntimeError;
use \Smuuf\Primi\Values\AbstractValue;

/**
 * @internal
 */
class AssignmentTargets {

    use StrictObject;

    /** @var string[] List of target variable names. */
    private array $targets;

    /**
     * If true, there is only a single target and assigned value does not need
     * unpacking.
     */
    private ?string $singleTarget;

    /** Total number of targets. */
    private int $targetsCount;

    /**
     * @param array<int, string> $targets
     */
    public function __construct(array $targets = []) {

        if (!\array_is_list($targets)) {
            throw new EngineError(
                "Assignment targets must be specified as a list array");
        }

        $this->targets = $targets;
        $this->targetsCount = \count($targets);
        $this->singleTarget = $this->targetsCount === 1
            ? $targets[0]
            : \null;

    }

    /**
     * @param AbstractValue $value
     * @return void
     */
    public function assign(AbstractValue $value, Context $ctx) {

        if ($this->singleTarget !== \null) {
            $ctx->setVariable($this->singleTarget, $value);
            return;
        }

        $iter = $value->getIterator();
        if ($iter === \null) {
            throw new RuntimeError("Cannot unpack non-iterable");
        }

        $buffer = [];
        $targetIndex = 0;
        foreach ($iter as $value) {

            if (\array_key_exists($targetIndex, $this->targets)) {
                $buffer[$this->targets[$targetIndex]] = $value;
            } else {
                throw new RuntimeError(
                    "Too many values to unpack (expected {$this->targetsCount})");
            }

            $targetIndex++;

        }

        if ($targetIndex < $this->targetsCount) {
            throw new RuntimeError("Not enough values to unpack (expected {$this->targetsCount} but got {$targetIndex})");
        }

        $ctx->setVariables($buffer);

    }

}