adds solve_one

planner/src/solver.rs

@@ -144,6 +144,39 @@ impl<'a,V, K: Eq + Hash + Clone> Problem<'a, V, K> {
         };
         solutions
     }
+
+    pub fn solve_one(&mut self) -> Option<Variables<'a,V,K>>
+        where V: Clone + fmt::Debug,
+              K: Clone + fmt::Debug,
+    {
+        let mut stack: Vec<Assignment<'a, V, K>> = vec![];
+        stack.append(&mut self._push_updates().unwrap());
+        loop {
+            let node = stack.pop();
+            if node.is_none() {
+                return None;
+            };
+            match node.unwrap() {
+                Assignment::Update(key, val) => {
+                    // Assign the variable and open new branches, if any.
+                    *self.variables.get_mut(&key).unwrap() = Some(val);
+                    // TODO: handle case of empty domain.values
+                    if let Some(mut nodes) = self._push_updates() {
+                        stack.append(&mut nodes);
+                    } else {
+                        // Assignements are completed
+                        if self._is_valid() {
+                            return Some(self.variables.clone());
+                        };
+                    };
+                },
+                Assignment::Clear(key) => {
+                    // We are closing this branch, unset the variable
+                    *self.variables.get_mut(&key).unwrap() = None;
+                },
+            };
+        }
+    }
 }
 
 pub struct ProblemBuilder<'a, V, K>(Problem<'a, V, K>);

web/src/main.rs

@@ -103,19 +103,20 @@ mod api {
         let mut problem = problem
             .add_constraint(|_| true)
             .finish();
-        let results = problem.solve_all();
-        let one_result = results.first().unwrap();
-
-        Json(TemplateObject {
-            items: one_result
-                    .into_iter()
-                    .map(|(k,v)| {
-                        TemplateItems {
-                            key: (format!("{}", k.0), format!("{:?}", k.1)),
-                            value: v.map(|r| RecipeObject::from(&conn, r.clone())),
-                    }})
-                    .collect(),
-        })
+        if let Some(one_result) = problem.solve_one() {
+            Json(TemplateObject {
+                items: one_result
+                        .into_iter()
+                        .map(|(k,v)| {
+                            TemplateItems {
+                                key: (format!("{}", k.0), format!("{:?}", k.1)),
+                                value: v.map(|r| RecipeObject::from(&conn, r.clone())),
+                        }})
+                        .collect(),
+            })
+        } else {
+            panic!("No solution at all !");
+        }
     }
 }