Assertions added

git-svn-id: https://forth-ev.de/repos/bigforth@1667 3b8d8251-53f3-0310-8f3b-fd1cb8370982

assert.fs

+\ assertions
+
+\ Copyright (C) 1995,1996,1997,1999,2002,2003,2007 Free Software Foundation, Inc.
+
+\ This file is part of Gforth.
+
+\ Gforth is free software; you can redistribute it and/or
+\ modify it under the terms of the GNU General Public License
+\ as published by the Free Software Foundation, either version 3
+\ of the License, or (at your option) any later version.
+
+\ This program is distributed in the hope that it will be useful,
+\ but WITHOUT ANY WARRANTY; without even the implied warranty of
+\ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+\ GNU General Public License for more details.
+
+\ You should have received a copy of the GNU General Public License
+\ along with this program. If not, see http://www.gnu.org/licenses/.
+
+variable assert-level ( -- a-addr ) \ gforth
+\ All assertions above this level are turned off.
+1 assert-level !
+
+: assertn ( n -- ) \ gforth assert-n
+    \ this is internal (it is not immediate)
+    assert-level @ >
+    if
+	POSTPONE (
+    then ;
+
+: assert0( ( -- ) \ gforth assert-zero
+    \ Important assertions that should always be turned on.
+    0 assertn ; immediate restrict
+: assert1( ( -- ) \ gforth assert-one
+    \ Normal assertions; turned on by default.
+    1 assertn ; immediate restrict
+: assert2( ( -- ) \ gforth assert-two
+    \ Debugging assertions.
+    2 assertn ; immediate restrict
+: assert3( ( -- ) \ gforth assert-three
+    \ Slow assertions that you may not want to turn on in normal debugging;
+    \ you would turn them on mainly for thorough checking.
+    3 assertn ; immediate restrict
+: assert( ( -- ) \ gforth
+    \ Equivalent to @code{assert1(}
+    POSTPONE assert1( ; immediate restrict
+
+: assert-throw  true abort" assertion failed" ;
+
+: ) ( -- ) \ gforth	close-paren
+    \ End an assertion.
+    postpone 0= postpone IF postpone ~~ postpone assert-throw
+    postpone THEN ; immediate