From 4bc04bd7e346bedb798ed8f9c8b801df21155036 Mon Sep 17 00:00:00 2001
From: artus40 <artus@landoftheunicorn.ovh>
Date: Fri, 15 Feb 2019 13:46:39 +0100
Subject: [PATCH] refactors Problem, adds Solution

---
 planner/src/bin/weekly.rs |  5 +--
 planner/src/solver.rs     | 84 +++++++++++++++++----------------------
 2 files changed, 38 insertions(+), 51 deletions(-)

diff --git a/planner/src/bin/weekly.rs b/planner/src/bin/weekly.rs
index ba046b2..fc5d23f 100644
--- a/planner/src/bin/weekly.rs
+++ b/planner/src/bin/weekly.rs
@@ -5,20 +5,19 @@ extern crate cookbook;
 
 use std::time;
 use std::fmt::Debug;
-use std::fmt::Display;
 use std::hash::Hash;
 use cookbook::*;
 use planner::{
     *, Value,
     solver::{
-        Variables,
+        Solution,
         Domain,
         Problem
     }
 };
 
 
-fn pretty_output<K: Eq + Hash + Debug>(res: &Variables<Value, K>) -> String {
+fn pretty_output<K: Eq + Hash + Debug>(res: &Solution<Value, K>) -> String {
     let mut repr = String::new();
     for (var,value) in res {
         let value = match value {
diff --git a/planner/src/solver.rs b/planner/src/solver.rs
index c04f48a..ebc3ca9 100644
--- a/planner/src/solver.rs
+++ b/planner/src/solver.rs
@@ -7,7 +7,9 @@ use std::clone::Clone;
 use std::collections::HashMap;
 
 /// An assignments map of variables
-pub type Variables<'a, V> = Vec<Option<&'a V>>;
+type Variables<'a, V> = Vec<Option<&'a V>>;
+/// A solution returned by [`Solver`]
+pub type Solution<'a, V, K> = HashMap<K, Option<&'a V>>;
 
 enum Assignment<'a, V> {
     Update(usize, &'a V),
@@ -124,7 +126,7 @@ impl<'a, V, K: Eq + Hash + Clone> Problem<'a, V, K> {
     }
 
     pub fn from_template() -> Problem<'a, V, K> {
-        let mut builder = Self::build();
+        let builder = Self::build();
 
         builder.finish()
     }
@@ -169,12 +171,8 @@ impl<'a, V, K: Eq + Hash + Clone> Problem<'a, V, K> {
         return true;
     }
 
-    /// Returns all complete solutions, after visiting all possible outcomes using a stack (DFS).
-    pub fn solve_all(&mut self) -> Vec<Variables<'a,V>>
-        where V: Clone + fmt::Debug,
-              K: Clone + fmt::Debug,
-    {
-        let mut solutions: Vec<Variables<V>> = vec![];
+    fn _solve(&mut self, limit: Option<usize>) -> Vec<Solution<'a, V, K>> {
+        let mut solutions: Vec<Solution<V, K>> = vec![];
         let mut stack: Vec<Assignment<'a, V>> = vec![];
         if let Some(mut init_updates) = self._push_updates() {
             stack.append(&mut init_updates);
@@ -185,7 +183,15 @@ impl<'a, V, K: Eq + Hash + Clone> Problem<'a, V, K> {
 
         loop {
             let node = stack.pop();
+            // There is no more combination to try out
             if node.is_none() { break; };
+            // Exit early if we have enough solutions
+            if limit.is_some()
+               && solutions.len() == limit.unwrap()
+            {
+                break;
+            };
+
             match node.unwrap() {
                 Assignment::Update(idx, val) => {
                     // Assign the variable and open new branches, if any.
@@ -196,7 +202,12 @@ impl<'a, V, K: Eq + Hash + Clone> Problem<'a, V, K> {
                     } else {
                         // Assignements are completed
                         if self._is_valid() {
-                            solutions.push(self.variables.clone());
+                            solutions.push(
+                                // Builds Solution
+                                self.keys.iter().cloned()
+                                    .zip(self.variables.iter().cloned())
+                                    .collect()
+                            );
                         };
                     };
                 },
@@ -207,44 +218,21 @@ impl<'a, V, K: Eq + Hash + Clone> Problem<'a, V, K> {
             };
         };
         solutions
-    }
 
-    pub fn solve_one(&mut self) -> Option<Variables<'a,V>>
+    }
+    /// Returns all complete solutions, after visiting all possible outcomes using a stack (DFS).
+    pub fn solve_all(&mut self) -> Vec<Solution<'a,V,K>>
         where V: Clone + fmt::Debug,
               K: Clone + fmt::Debug,
     {
-        let mut stack: Vec<Assignment<'a, V>> = vec![];
-        if let Some(mut init_updates) = self._push_updates() {
-            stack.append(&mut init_updates);
-        } else {
-            panic!("Could not initialize !");
-        }
+        self._solve(None) // No limit
+    }
 
-        loop {
-            let node = stack.pop();
-            if node.is_none() {
-                return None;
-            };
-            match node.unwrap() {
-                Assignment::Update(idx, val) => {
-                    // Assign the variable and open new branches, if any.
-                    self.variables[idx] = 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(idx) => {
-                    // We are closing this branch, unset the variable
-                    self.variables[idx] = None;
-                },
-            };
-        }
+    pub fn solve_one(&mut self) -> Option<Solution<'a,V,K>>
+        where V: Clone + fmt::Debug,
+              K: Clone + fmt::Debug,
+    {
+        self._solve(Some(1)).pop()
     }
 }
 
@@ -294,10 +282,10 @@ mod tests {
             })
             .finish();
 
-        let solutions: Vec<Variables<i32>> = vec![
-            [Some(&3), Some(&3)].iter().cloned().collect(),
-            [Some(&2), Some(&2)].iter().cloned().collect(),
-            [Some(&1), Some(&1)].iter().cloned().collect(),
+        let solutions: Vec<Solution<i32, _>> = vec![
+            [(String::from("Left"), Some(&3)), (String::from("Right"), Some(&3))].iter().cloned().collect(),
+            [(String::from("Left"), Some(&2)), (String::from("Right"), Some(&2))].iter().cloned().collect(),
+            [(String::from("Left"), Some(&1)), (String::from("Right"), Some(&1))].iter().cloned().collect(),
         ];
 
         assert_eq!(problem.solve_all(), solutions);
@@ -315,8 +303,8 @@ mod tests {
             })
             .finish();
 
-        let solutions: Vec<Variables<i32>> = vec![
-            [Some(&2), Some(&2)].iter().cloned().collect(),
+        let solutions: Vec<Solution<i32, String>> = vec![
+            [(String::from("Left"), Some(&2)), (String::from("Right"), Some(&2))].iter().cloned().collect(),
         ];
 
         assert_eq!(problem.solve_all(), solutions);