Add RecAddDefinition and AddDefinition

This commit adds support for defining functions (recursive or not)
through defineFun and defineFunRec from the base API.

Author: caioraposo

cvc5_pythonic_api/cvc5_pythonic.py

@@ -64,7 +64,6 @@
   * FiniteDomainSort
   * Fixedpoint API
   * SMT2 file support
-  * recursive functions
 * Not missing, but different
   * Options
     * as expected
@@ -150,6 +149,8 @@ def __init__(self):
         self.vars = {}
         # An increasing identifier used to make fresh identifiers
         self.next_fresh_var = 0
+        # Function definitions to be added to a solver once it is created
+        self.defined_functions = []
 
     def __del__(self):
         self.tm = None
@@ -937,6 +938,48 @@ def FreshFunction(*sig):
     return Function(name, *sig)
 
 
+def RecFunction(name, *sig):
+    """Create a new SMT uninterpreted function with the given sorts."""
+    return Function(name, sig)
+
+
+def RecAddDefinition(func, args, body):
+    """Define a new SMT recursive function with the given function declaration.
+    Replaces constants in `args` with bound variables.
+
+    >>> fact = Function('fact', IntSort(), IntSort())
+    >>> n = Int('n')
+    >>> RecAddDefinition(fact, n, If(n == 0, 1, n * fact(n - 1)))
+    >>> solve(Not(fact(5) == 120))
+    unsat
+    """
+    if is_app(args):
+        args = [args]
+    ctx = func.ctx
+    consts = [a.ast for a in args]
+    vars_ = [ctx.tm.mkVar(a.sort().ast, str(a)) for a in args]
+    subbed_body = body.ast.substitute(consts, vars_)
+    ctx.defined_functions.append(((func.ast, vars_, subbed_body), True))
+
+
+def AddDefinition(name, args, body):
+    """Define a new SMT function with the given function declaration.
+    Replaces constants in `args` with bound variables.
+
+    >>> x, y = Ints('x y')
+    >>> minus = AddDefinition(minus, [x, y], x - y)
+    >>> solve(Not(minus(10, 5) == 5))
+    unsat
+    """
+    if is_app(args):
+        args = [args]
+    ctx = body.ctx
+    consts = [a.ast for a in args]
+    vars_ = [ctx.tm.mkVar(a.sort().ast, str(a)) for a in args]
+    subbed_body = body.ast.substitute(consts, vars_)
+    ctx.defined_functions.append(((name, vars_, subbed_body.getSort(), subbed_body), False))
+
+
 #########################################
 #
 # Expressions
@@ -6006,6 +6049,16 @@ def initFromLogic(self):
             self.solver.setLogic(self.logic)
         self.solver.setOption("produce-models", "true")
 
+    def add_func_definitions(self):
+        """Add function definitions present in the current context"""
+        # FIXME: This is a temporary fix and should be removed once the base
+        # API have the proper solution in place.
+        for func in self.ctx.defined_functions:
+            if func[1]:
+                self.solver.defineFunRec(*func[0])
+            else:
+                self.solver.defineFun(*func[0])
+        
     def __del__(self):
         if self.solver is not None:
             self.solver = None
@@ -6190,6 +6243,7 @@ def check(self, *assumptions):
         unsat
         >>> s.resetAssertions()
         """
+        self.add_func_definitions()
         assumptions = _get_args(assumptions)
         r = CheckSatResult(self.solver.checkSatAssuming(*[a.ast for a in assumptions]))
         self.last_result = r