A simple parser for the GCL language used in the course Program Verification. The parser is written using Happy and Haskell. A Cabal build file is included to build the library.
This parser admits a richer language than the base GCL to also accommodate optional assignments. You can ignore the parts of the parser/syntax that you don't need in your parts of assignments.
To compile the tool, the following package are required:
- array
- containers
- optparse-applicative
- pretty.
To compile the library, run the command cabal build
.
After building (see above), you can run ghci from ./src, passing the path to where Cabal puts the generated files, and passing relevant language options:
ghci -i../dist/build -XNamedFieldPuns
From there you can load packages e.g. :l GCLParser.Parser
and try out functions defined there in the interpreter.
The module GCLParser.Parser
exports two functions:
parseGCLstring :: String -> ParseResult Program
parseGCLfile :: FilePath -> IO (ParseResult Program)
The first is to parse a GCL program from a string, and the second is to parse from a text file. The parser returns a value of type ParseResult Program
, which is a synonym for Either String Program
. Such value takes the form of either Left e
where e
is an error message if the parsing fails, or Right p
if the parsing is successful. In the later case, p
is a value of type Program
which is a datatype used to structurally repfresent a GCL program. See the module GCLParser.GCLDatatype
for its definition.
Note that the module GCLParser.Parser
is generated by Happy. The source code is src/GCLParser/Parser.y
, which is a Happy parser definition. So, if you need to change the parser, you should not edit Parser.hs
manually, but instead edit Parser.y
.
The module GCLParser.PrettyPrint
provides a function to pretty print a value of type Program
:
ppProgram2String :: Program -> String
The module GCLInterpreter
provides a function to execute a GCL program, given a starting state.
execProgram :: Program -> State -> Either (String,State) State
Be mindful that this tool is experimental, and is not made for performance. There is also some incompleteness when interpreting the ∀ and ∃ quantifiers. Obviously, we can't actually check such a quantifier over the whole space of integers, so some practical choice was made. See the module in-code documentation.
The module MuGCL
provides a function that generate mutants of a GCP Program.
Given a program P, the function below generates a bunch of so-called
mutants. Each is a program P', which is a copy of P, but where it is changed
in one place (e.g. some expression "i<n" is mutated to "i<=n").
mutateProgram :: Program -> [(MutationType,Program)]
You can use this mutants to test the completeness of your verification
tool (it should be able to kill all the mutants, but see also my note in
the documentation of MuGCL
).
See in /docs
.
Unfortunately almost none. But if some of you know how to make Happy produces a more friendly error message, do let me know.
See in /examples
Many thanks to Stefan Koppier for providing the initial implementation of the parser.
Contributors: Stefan Koppier, Wishnu Prasetya