text Metaobject范围

Posted 2021-05-02

package metaobjectTest


@doc{*
    Ranges are attached to types. A variable of type Int@range(first, last)
    can only contain values between first and last (inclusive). This is 
    checked at compile-time when a literal is assigned to the variable 
    and at run-time if an expression is assigned to the variable.
*}
object Range

    func run {
        
        var Int@range(1, 12) hour;
        hour = 7; // ok
        // hour = 20; // compile-time error
        let outOfLimitsHour = 30;
        {
              // runtime error
            hour = outOfLimitsHour; 
        } catch: { (: ExceptionStr e :)  
           // do nothing
        };
        var Int@range(1, 24) hour24;
        hour24 = hour; // ok
        // hour = hour24; // compile-time error


        // other examples

        var Char@range('a', 'c') ch_a_c;

        var Char ch;
        ch = 'a';
        ch_a_c = 'a';
        ok = true;
        {
            ch_a_c = ch;
        } catch: { (: ExceptionStr e :) ok = false };
        assert ok;

        ch = 'e';
        ok = false;
        {
            ch_a_c = ch;
        } catch: { (: ExceptionStr e :) ok = true };
        assert ok;

        var Int@range(1, 12) month;
        var Int@range(5, 10) n57;
        n57 = 6;
        month = n57;


        p = 13;
        month = 4;
        ok = false;
        {
            var v66 = [ month, p, 7 ];
        } catch: { (: ExceptionStr e :) ok = true };
        assert !ok;

        ok = false;
        {
            var m787 = [ month -> month, p -> 5, 4 -> 1 ];
        } catch: { (: ExceptionStr e :) ok = true };
        assert !ok;

        ok = false;
        {
            var m676 = [ month -> month, 5 -> p, 5 -> 9 ]
        } catch: { (: ExceptionStr e :) ok = true };
        assert !ok;

        ok = false;
        {
            var k67 = month;
            k67 = p;
        } catch: { (: ExceptionStr e :) ok = true };
        assert ok;

        ok = false;
        {
            let Int@range(0, 1) k69 = p;
        } catch: { (: ExceptionStr e :) ok = true };
        assert ok;


        ok = false;
        {
            var Int@range(0, 1) n5656 = 0;
            n5656 = n5656 + 1;
            n5656 = n5656 + 1

        } catch: { (: ExceptionStr e :) ok = true };
        assert ok;


        ok = false;
        {
            var Int@range(0, 1) n5656 = 0;
            n5656 = n5656 - 1;
        } catch: { (: ExceptionStr e :) ok = true };
        assert ok;

    }

end