Handle undefined values correctly in ordered-else. Previously an undefined value
in one of the blocks could cause the entire rule to evaluate to undefined.
Handle undefined values correctly in generic rule refs to prevent them from
propagating to output.
Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>
Previously we used to rely on whether there was a value in the
data document for a given rule path. This approach cannot handle
the case of evaluating a.b when a.b.c has been evaluated but
a.b.d has not been evaluated. Upon evaluating a.b.c, the data document
will already have a value of a.b even though a.b.d has not yet
been evaluated.
Hence we need to keep track of evaluated rules separately.
Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>
