Edit in JSFiddle

var app = angular.module('customValidation', []);

var INTEGER_REGEXP = /^\-?\d+$/;
app.directive('integer', function () {
    return {
        require: 'ngModel',
        link: function (scope, elm, attrs, ctrl) {
            ctrl.$parsers.unshift(function (viewValue) {
                if (INTEGER_REGEXP.test(viewValue)) {
                    // it is valid
                    ctrl.$setValidity('integer', true);
                    return viewValue;
                } else {
                    // it is invalid, return undefined (no model update)
                    ctrl.$setValidity('integer', false);
                    return undefined;
                }
            });
        }
    };
});

var FLOAT_REGEXP = /^\-?\d+((\.|\,)\d+)?$/;
app.directive('smartFloat', function () {
    return {
        require: 'ngModel',
        link: function (scope, elm, attrs, ctrl) {
            ctrl.$parsers.unshift(function (viewValue) {
                if (FLOAT_REGEXP.test(viewValue)) {
                    ctrl.$setValidity('float', true);
                    return parseFloat(viewValue.replace(',', '.'));
                } else {
                    ctrl.$setValidity('float', false);
                    return undefined;
                }
            });
        }
    };
});

<div ng-app='customValidation'>
    <form name="form" class="css-form" novalidate>
        <div>Size (integer 0 - 10):
            <input type="number" ng-model="size" name="size" min="0" max="10" integer />{{size}}
            <br /> <span ng-show="form.size.$error.integer">This is not valid integer!</span>
 <span ng-show="form.size.$error.min || form.size.$error.max">
      The value must be in range 0 to 10!</span>

        </div>
        <div>Length (float):
            <input type="text" ng-model="length" name="length" smart-float />{{length}}
            <br /> <span ng-show="form.length.$error.float">
      This is not a valid float number!</span>

        </div>
    </form>
</div>