* Check that Z3_get_numeral_small is given non-null out params
Analogous to other Z3_get_numeral_* functions with out params.
* Note that Z3_get_numeral_small is essentially redundant
The error behavior of Z3_get_numeral_small does not follow the pattern of
the other functions. The functions that have out params and return a bool
indicating success (such as Z3_get_numeral_rational_int64) return false
rather than signaling an error when given an unsupported expression
argument (such as a rounding mode value). The functions that do not have out
params signal an error in such cases. Z3_get_numeral_small is the odd one
out in that it signals errors and returns a status bool.
This error handling is the only difference between Z3_get_numeral_small and
Z3_get_numeral_rational_int64, so this patch adds a comment to the
documentation.
Add API solve_for(vars).
It takes a list of variables and returns a triangular solved form for the variables.
Currently for arithmetic. The solved form is a list with elements of the form (var, term, guard).
Variables solved in the tail of the list do not occur before in the list.
For example it can return a solution [(x, z, True), (y, x + z, True)] because first x was solved to be z,
then y was solved to be x + z which is the same as 2z.
Add congruent_explain that retuns an explanation for congruent terms.
Terms congruent in the final state after calling SimpleSolver().check() can be queried for
an explanation, i.e., a list of literals that collectively entail the equality under congruence closure.
The literals are asserted in the final state of search.
Adjust smt_context cancellation for the smt.qi.max_instantiations parameter.
It gets checked when qi-queue elements are consumed.
Prior it was checked on insertion time, which didn't allow for processing as many
instantations as there were in the queue. Moreover, it would not cancel the solver.
So it would keep adding instantations to the queue when it was full / depleted the
configuration limit.
The bulk of the functionality using these was removed between
Z3 4.4.1 and 4.5.0, back in 2015.
Co-authored-by: Bruce Mitchener <bruce.mitchener@configura.com>
An initial update to support polymorphism from SMTLIB3 and the API (so far C, Python).
The WIP SMTLIB3 format is assumed to be supporting the following declaration
```
(declare-type-var A)
```
Whenever A is used in a type signature of a function/constant or bound quantified variable, it is taken to mean that all instantiations of A are included in the signature and assertions.
For example, if the function f is declared with signature A -> A, then there is a version of f for all instances of A.
The semantics of polymorphism appears to follow previous proposals: the instances are effectively different functions.
This may clash with some other notions, such as the type signature forall 'a . 'a -> 'a would be inhabited by a unique function (the identity), while this is not enforced in this version (and hopefully never because it is more busy work).
The C API has the function 'Z3_mk_type_variable' to create a type variable and applying functions modulo polymorphic type signatures is possible.
The kind Z3_TYPE_VAR is added to sort discriminators.
This version is considered as early alpha. It passes a first rudimentary unit test involving quantified axioms, declare-fun, define-fun, and define-fun-rec.
This update includes an experimental feature to access a congruence closure data-structure after search.
It comes with several caveats as pre-processing is free to eliminate terms. It is therefore necessary to use a solver that does not eliminate the terms you want to track for congruence of. This is partially addressed by using SimpleSolver or incremental mode solving.
```python
from z3 import *
s = SimpleSolver()
x, y, z = Ints('x y z')
s.add(x == y)
s.add(y == z)
s.check()
print(s.root(x), s.root(y), s.root(z))
print(s.next(x), s.next(y), s.next(z))
```
Add Z3_enable_concurrent_dec_ref to the API.
It is enables behavior of dec_ref functions that are exposed over the API to work with concurrent GC. The API calls to dec_ref are queued and processed in the main thread where context operations take place (in a way that is assumed thread safe as context operations are only allowed to be serialized on one thread at a time).
Adding new API object to maintain state between calls to parser.
The state is incremental: all declarations of sorts and functions are valid in the next parse. The parser produces an ast-vector of assertions that are parsed in the current calls.
The following is a unit test:
```
from z3 import *
pc = ParserContext()
A = DeclareSort('A')
pc.add_sort(A)
print(pc.from_string("(declare-const x A) (declare-const y A) (assert (= x y))"))
print(pc.from_string("(declare-const z A) (assert (= x z))"))
print(parse_smt2_string("(declare-const x Int) (declare-const y Int) (assert (= x y))"))
s = Solver()
s.from_string("(declare-sort A)")
s.from_string("(declare-const x A)")
s.from_string("(declare-const y A)")
s.from_string("(assert (= x y))")
print(s.assertions())
s.from_string("(declare-const z A)")
print(s.assertions())
s.from_string("(assert (= x z))")
print(s.assertions())
```
It produces results of the form
```
[x == y]
[x == z]
[x == y]
[x == y]
[x == y]
[x == y, x == z]
```
Thus, the set of assertions returned by a parse call is just the set of assertions added.
The solver maintains state between parser calls so that declarations made in a previous call are still available when declaring the constant 'z'.
The same holds for the parser_context_from_string function: function and sort declarations either added externally or declared using SMTLIB2 command line format as strings are valid for later calls.
add API to define forward reference to recursively defined datatype.
The forward reference should be used only when passed to constructor declarations that are used in a datatype definition (Z3_mk_datatypes). The call to Z3_mk_datatypes ensures that the forward reference can be resolved with respect to constructors.
