The following is a valid line of sdf:
(COND B==1'b0&&C==1'b0&&D==1'b0 (IOPATH A Z (61.500:100.000:150.900) (26.900:40.000:61.400)))
However, the literal "1'b0" is not being matched, as it does not match to the regex for a float. I am unsure if the sdf standard allows for floating points to be used at this point.
I will open a pull request with a very simple fix to this issue. With my simple test .sdf unfortunately the test fails, as the white spacing is different. Though that should be a simple case to add to the test suite.