Implement loop statement

git-svn-id: file:///svnroot/mailfromd/trunk@1337 7a8a7f39-df28-0410-adc6-e0d955640f24

1 files changed, 50 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index c6205d06..abebdfc8 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,56 @@ Please send mailfromd bug reports to <bug-mailfromd@gnu.org.ua>
 
 Version 3.1.91, SVN
 
+* next and pass
+
+Use `pass' instead of `next'.
+
+The `next' keyword has changed its semantics: it is now used to
+resume the next iteration of the enclosing loop statement (see
+below).
+
+For compatibility with the previous versions, its use outside of a
+loop statement is still allowed, but a warning is issued.  You are
+enouraged to replace all occurrances of `next' in your confifuration
+scripts with `pass'.
+
+* Loop
+
+The loop statement is implemented.  Its syntax is:
+
+loop [name]
+     [for <stmt>,] [while <stmt>,] [<stmt>]
+do
+     ...
+done [while <stmt>]
+
+* break and next
+
+The `break' statement exits from the enclosing loop.
+
+The `next' statement resumes the next iteration of the enclosing loop
+statement.
+
+Both statements take an optional argument specifying the identifier
+(name) of the loop to break from (or continue), this allows to build
+complex iterations consisting of nested loops.  For example, in this
+code (line numbers added for clarity):
+
+ 1   loop outer for set i 1, while %i < %N
+ 2   do
+ 3      ...
+ 4      loop for set j 1, while %j < %i
+ 5      do
+ 6         if foo(%j)
+ 7           break outer
+ 8         fi
+ 9      done
+10  done                                   
+11 accept
+
+if the call to `foo' in line 6 returns true, the control is immediately passed
+to `accept' in line 11.
+
 * Resizable stack
 
 The runtime stack of the MFL grows automatically as the need arises.