Symfony\Component\PropertyAccess\PropertyAccessor::setValue PHP Method

    public function setValue(&$objectOrArray, $propertyPath, $value)
    {
        $propertyPath = $this->getPropertyPath($propertyPath);

        $zval = array(
            self::VALUE => $objectOrArray,
            self::REF => &$objectOrArray,
        );
        $propertyValues = $this->readPropertiesUntil($zval, $propertyPath, $propertyPath->getLength() - 1);
        $overwrite = true;

        try {
            if (PHP_VERSION_ID < 70000 && false === self::$previousErrorHandler) {
                self::$previousErrorHandler = set_error_handler(self::$errorHandler);
            }

            for ($i = count($propertyValues) - 1; 0 <= $i; --$i) {
                $zval = $propertyValues[$i];
                unset($propertyValues[$i]);

                // You only need set value for current element if:
                // 1. it's the parent of the last index element
                // OR
                // 2. its child is not passed by reference
                //
                // This may avoid uncessary value setting process for array elements.
                // For example:
                // '[a][b][c]' => 'old-value'
                // If you want to change its value to 'new-value',
                // you only need set value for '[a][b][c]' and it's safe to ignore '[a][b]' and '[a]'
                //
                if ($overwrite) {
                    $property = $propertyPath->getElement($i);

                    if ($propertyPath->isIndex($i)) {
                        if ($overwrite = !isset($zval[self::REF])) {
                            $ref = &$zval[self::REF];
                            $ref = $zval[self::VALUE];
                        }
                        $this->writeIndex($zval, $property, $value);
                        if ($overwrite) {
                            $zval[self::VALUE] = $zval[self::REF];
                        }
                    } else {
                        $this->writeProperty($zval, $property, $value);
                    }

                    // if current element is an object
                    // OR
                    // if current element's reference chain is not broken - current element
                    // as well as all its ancients in the property path are all passed by reference,
                    // then there is no need to continue the value setting process
                    if (is_object($zval[self::VALUE]) || isset($zval[self::IS_REF_CHAINED])) {
                        break;
                    }
                }

                $value = $zval[self::VALUE];
            }
        } catch (\TypeError $e) {
            self::throwInvalidArgumentException($e->getMessage(), $e->getTrace(), 0);
        } finally {
            if (PHP_VERSION_ID < 70000 && false !== self::$previousErrorHandler) {
                restore_error_handler();
                self::$previousErrorHandler = false;
            }
        }
    }

 protected function getConstraintViolation(ConstraintViolation $constraintViolation, array &$messages)
 {
     $path = new PropertyPath($constraintViolation->getPropertyPath());
     $elements = $path->getElements();
     $elements[] = $constraintViolation->getConstraint()->validatedBy();
     $this->propertyAccessor->setValue($messages, $this->buildPath($elements), $constraintViolation->getMessage());
 }