Add wrappers for basic chuffed functions in lib.rs. Recreate example/…

…template.cpp in main.rs using wrapper functions. Update wrapper.h with ffi hacks and add wrapper.cpp. Update build.rs, build.sh and clean.sh accordingly

solvers/chuffed/build.rs

@@ -16,6 +16,8 @@ fn main() {
  println!("cargo:rustc-link-search=all=./solvers/chuffed/vendor/build/");
  println!("cargo:rustc-link-lib=static=chuffed");
  println!("cargo:rustc-link-lib=static=chuffed_fzn");
+ println!("cargo:rustc-link-search=all=./solvers/chuffed/");
+ println!("cargo:rustc-link-lib=static=wrapper");
 
  // also need to (dynamically) link to c++ stdlib
  // https://flames-of-code.netlify.app/blog/rust-and-cmake-cplusplus/
@@ -64,6 +66,15 @@ fn bind() {
  // in C++ stdlib that will make it crash.
  .allowlist_function("createVars")
  .allowlist_function("createVar")
+ .allowlist_function("all_different")
+ .allowlist_function("branch")
+ .allowlist_function("output_vars")
+ .allowlist_function("var_sym_break")
+ .allowlist_function("new_dummy_problem")
+ .allowlist_function("get_idx")
+ .allowlist_function("p_addVars")
+ .allowlist_function("p_setcallback")
+ .allowlist_function("branch_IntVar")
  .clang_arg("-Ivendor/build") // generated from configure.py
  .clang_arg("-Ivendor")
  .clang_arg(r"--std=gnu++11")

solvers/chuffed/build.sh

@@ -4,9 +4,14 @@ SCRIPT_DIR=$(dirname "$0")
 
 git submodule init
 git submodule update
-cd "$SCRIPT_DIR"
+cd "$SCRIPT_DIR" || exit
 
 echo "------ BUILDING ------"
 cd vendor || exit
 cmake -B build -S .
 cmake --build build
+cd ..
+
+# Build wrapper.cpp as static library
+g++ -c wrapper.cpp -Ivendor
+ar rvs libwrapper.a wrapper.o

solvers/chuffed/clean.sh

@@ -2,3 +2,5 @@
 
 cargo clean
 rm -rf vendor/build
+rm libwrapper.a
+rm wrapper.o

solvers/chuffed/compile_flags.txt

@@ -0,0 +1,3 @@
+-I./vendor
+-xc++
+--std=c++11

solvers/chuffed/src/lib.rs

@@ -4,3 +4,45 @@ pub mod bindings {
  #![allow(non_snake_case)]
  include!(concat!(env!("OUT_DIR"), "/chuffed_bindings.rs"));
 }
+
+pub mod wrappers{
+ use crate::bindings::{IntVar, createVar, createVars, vec, all_different, ConLevel, VarBranch, branch_IntVar, ValBranch};
+ use core::ptr;
+
+ // The signature of createVar is below for reference.
+ // createVar(x: *mut *mut IntVar, min: ::std::os::raw::c_int, max: ::std::os::raw::c_int, el: bool)
+ pub fn create_var(min: i32, max: i32, el: bool) -> *mut IntVar {
+ let mut ptr: *mut IntVar = ptr::null_mut();
+
+ unsafe {
+ createVar(&mut ptr, min, max, el);
+ ptr 
+ }
+ }
+
+ // createVars void createVars(vec<IntVar*>& x, int n, int min, int max, bool el)
+ pub fn create_vars(n: i32, min:i32, max:i32, el:bool) -> *mut vec<*mut IntVar> {
+
+ let ptr: *mut vec<*mut IntVar> = ptr::null_mut();
+
+ unsafe {
+ createVars(ptr, n, min, max, el);
+ ptr 
+ }
+ }
+
+ // void all_different(vec<IntVar*>& x, ConLevel cl)
+ pub unsafe fn all_different_wrapper(x: *mut vec<*mut IntVar>, cl: ConLevel) {
+ unsafe {
+ all_different(x, cl);
+ }
+ }
+
+ // void branch(vec<Branching*> x, VarBranch var_branch, ValBranch val_branch);
+ pub unsafe fn branch_wrapper(x: *mut vec<*mut IntVar>, var_branch: VarBranch, val_branch: ValBranch) {
+ unsafe {
+ branch_IntVar(x, var_branch, val_branch);
+ }
+ }
+}
+

solvers/chuffed/src/main.rs

@@ -1,8 +1,44 @@
-use chuffed_rs::bindings::createVar;
-use chuffed_rs::bindings::IntVar;
-pub fn main() {
- let mut var = std::mem::MaybeUninit::<IntVar>::uninit();
- unsafe {
- createVar(&mut var.as_mut_ptr(), 0, 5, false);
+use chuffed_rs::wrappers::{create_vars, all_different_wrapper, branch_wrapper};
+use chuffed_rs::bindings::{IntVar, ConLevel_CL_DEF, VarBranch_VAR_INORDER, VarBranch_VAR_MIN_MIN, vec, new_dummy_problem, get_idx, p_addVars, p_setcallback}; 
+
+unsafe fn post_constraints(_n: i32) -> *mut vec<*mut IntVar> {
+ // Create constant
+ let n: i32 = _n;
+ // Create some variables
+ let x: *mut vec<*mut IntVar> = create_vars(n, 0, n, false);
+
+ // Post some constraints
+ all_different_wrapper(x, ConLevel_CL_DEF);
+
+ // Post some branchings
+ branch_wrapper(x as _, VarBranch_VAR_INORDER, VarBranch_VAR_MIN_MIN); 
+
+ x
+}
+
+// Custom printing function for this problem
+#[no_mangle]
+pub unsafe extern "C" fn callback(x: *mut vec<*mut IntVar>) {
+ print!("First output is: {:?}", get_idx(x, 0));
+}
+
+fn main() {
+ let args: Vec<String> = std::env::args().collect();
+
+ if args.len() != 2 {
+ println!("Invalid number of arguments");
+ return;
+ }
+
+ let n: i32 = args[1].parse().expect("Invalid input");
+
+ unsafe{
+ let x = post_constraints(n);
+ // make new dummy problem
+ let p = new_dummy_problem();
+ // Call problem.addvars()
+ p_addVars(p, x);
+ // Call problem.setcallback()
+ p_setcallback(p, Some(callback));
  }
 }

solvers/chuffed/wrapper.cpp

@@ -0,0 +1,15 @@
+#include "./wrapper.h"
+
+DummyProblem *new_dummy_problem() { return new DummyProblem(); }
+void p_addVars(DummyProblem *p, vec<IntVar *> *_searchVars) {
+ p->addVars(_searchVars);
+}
+void p_setcallback(DummyProblem *p, void (*_callback)(vec<IntVar *> *)) {
+ p->setcallback(_callback);
+}
+IntVar get_idx(vec<IntVar *> *x, int i) { return **x[i]; }
+
+void branch_IntVar(vec<IntVar *> *x, VarBranch var_branch,
+ ValBranch val_branch) {
+ branch(*x, var_branch, val_branch);
+}

solvers/chuffed/wrapper.h

@@ -1 +1,23 @@
+#include "chuffed/branching/branching.h"
+#include "chuffed/core/engine.h"
+#include "chuffed/core/propagator.h"
 #include "chuffed/vars/modelling.h"
+
+class DummyProblem {
+public:
+ vec<IntVar *> *searchVars;
+ // callback
+ void (*callback)(vec<IntVar *> *);
+
+ void print() { callback(searchVars); }
+ void setcallback(void (*_callback)(vec<IntVar *> *)) { callback = _callback; }
+ void addVars(vec<IntVar *> *_searchVars) { searchVars = _searchVars; }
+};
+
+DummyProblem *new_dummy_problem();
+void p_addVars(DummyProblem *p, vec<IntVar *> *_searchVars);
+void p_setcallback(DummyProblem *p, void (*_callback)(vec<IntVar *> *));
+IntVar get_idx(vec<IntVar *> *x, int i);
+
+void branch_IntVar(vec<IntVar *> *x, VarBranch var_branch,
+ ValBranch val_branch);