6 Glossary

6.1.2430 WHILE CORE

Interpretation:

Interpretation semantics for this word are undefined.

Compilation:

( C: dest -- orig dest )

Put the location of a new unresolved forward reference orig onto the control flow stack, under the existing dest. Append the run-time semantics given below to the current definition. The semantics are incomplete until orig and dest are resolved (e.g., by REPEAT).

Run-time:

( x -- )

If all bits of x are zero, continue execution at the location specified by the resolution of orig.

See:

A.6.1.2430 WHILE.

Rationale:

Typical use: : X ... BEGIN ... test WHILE ... REPEAT ... ;

Testing:

T{ : GI3 BEGIN DUP 5 < WHILE DUP 1+ REPEAT ; -> }T
T{ 0 GI3 -> 0 1 2 3 4 5 }T
T{ 4 GI3 -> 4 5 }T
T{ 5 GI3 -> 5 }T
T{ 6 GI3 -> 6 }T

T{ : GI5 BEGIN DUP 2 > WHILE
DUP 5 < WHILE DUP 1+ REPEAT
123 ELSE 345 THEN ; -> }T
T{ 1 GI5 -> 1 345 }T
T{ 2 GI5 -> 2 345 }T
T{ 3 GI5 -> 3 4 5 123 }T
T{ 4 GI5 -> 4 5 123 }T
T{ 5 GI5 -> 5 123 }T

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MatteoVitturi [208] There is an error in testingComment2021-08-20 20:54:31

GI5 don't compile correctly. To cope with subsequent test it should be as follow.

T{ : GI5 DUP 2 > IF BEGIN 
         DUP 5 < WHILE DUP 1+ REPEAT 
         123 ELSE 345 THEN ; -> }T

MatteoVitturiNew Version: There is an error in testing [r715] 2021-08-20 21:56:52

Hide differences~~GI5 don't compile correctly. To cope with subsequent test it should be as follow.~~

GI5 don't compile correctly. To cope with subsequent tests it should be as follow.

T{ : GI5 DUP 2 > IF BEGIN 
         DUP 5 < WHILE DUP 1+ REPEAT 
         123 ELSE 345 THEN ; -> }T

BerndPaysan [r716] 2021-08-21 09:48:45

GI5 tests multiple WHILEs, and compiles correctly on systems that implement WHILE and REPEAT correctly. You are supposed to resolve one WHILE (the latest) at REPEAT, and leave the others to a matching ELSE or THEN.

Closed

flaagel [r797] 2022-02-22 12:28:19

This is a tricky implementation point. Z79Forth also choked on this particular piece of the test suite. Not that it is really a problem since my primary allegiance is 79-STANDARD but I still believe that ANS compliance, whenever achievable, is desirable. This is now fixed and I will release the updated code on GitHub soon.

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