Constraint Solver

ConstraintSolver is the final project of the course of Advanced Programming, whose goal was to develop a constraint solver and the corresponding recursive descent parser for domain-specific-language from scratch.

The constraint solver deploys a backtracking algorithm with constraint propagation in order to generate the solutions one at time.

Grammar

The constraints recognized by the parser have to be expressed by using the following grammar:

Dsl      ::= stats sat notSat
Stats    ::= var "= {" vals "}" stats | ε
Vals     ::= val seqVals | ε
SeqVals  ::= "," val seqVals | ε
Sat      ::= "{" cons "}" | ε
NotSat   ::= "!{" cons "}" | ε
Cons     ::=  pair seqCons | ε
SeqCons  ::= "," pair seqCons | ε
Pair     ::= "(" val "," val ")"
Var      ::= identifier
Val      ::= string

For example, the possible values for the variables a, b and c can be expressed as:

a = {a1, a2, a3}
b = {b1, b2, b3}
c = {c1, c2, c3}

while the constraints that variables should (resp. should not) satisfy are expressed as:

{(a1, c2), (b3, c3), (a3, b1)}
!{(a1, b1), (a1, c1), (a2, c2)}