Promela |
Predefined |
nempty |
NAME
nempty -
predefined, boolean function to test emptiness of a channel.
SYNTAX
nempty( varref )
DESCRIPTION
The expression
nempty(q) , with
q a channel name, is equivalent to the expression
(len(q) != 0)where q is a channel name. The Promela grammar prohibits this from being written as !empty(q) .
Using nempty instead of its equivalents can preserve the validity of reductions that are applied during verifications, especially in combination with the use of xr and xs channel assertions.
NOTES
Note that if predefined functions such as
empty , nempty , full , and
nfull are used in macro definitions used for propositional
symbols in LTL formulae, they may well unintentionally
appear under a negation sign, which will trigger syntax
errors from Spin.
SEE ALSO
condition
empty
full
len
ltl
nfull
xr
xs
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(Page updated: 28 November 2004) |