Implement Map tick method

src/maputil.rs

@@ -1,7 +1,7 @@
 use structs::{ Map, SnakeInfo };
 use util;
 use serde::ser::{ Serialize, Serializer };
-use util::{ translate_position };
+use util::{ translate_position, step_in_direction };
 
 #[derive(PartialEq, Debug)]
 pub enum Tile<'a> {
@@ -126,6 +126,47 @@ impl Map {
 		let (x,y) = coordinate;
 		x < 0 || x >= self.width || y < 0 || y >= self.height
 	}
+
+	pub fn tick(&self, decisions: Vec<Direction>) -> Map {
+		if decisions.len() < self.snakeInfos.len() {
+			panic!("All snakes have to make a decision");
+		}
+
+		let worldTick = self.worldTick + 1;
+		let mut newSnakeInfos: Vec<SnakeInfo> = vec![];
+		
+		let grow_snakes: bool = worldTick % 3 == 1;
+
+		if !grow_snakes {
+			for i in 0..newSnakeInfos.len() {
+				newSnakeInfos[i].positions.pop();
+			}
+		}
+
+		for i in 0..self.snakeInfos.len() {
+			let snake: &mut SnakeInfo = &mut newSnakeInfos[i];
+			
+			if(self.can_snake_move_in_direction(snake, decisions[i])) {
+				let head_position = snake.positions[0].clone();
+				snake.positions.insert(0,
+					step_in_direction(
+						head_position,
+						decisions[i],
+						self.width
+					),
+				);
+			}
+		}
+
+		Map {
+			width: self.width.clone(),
+			height: self.height.clone(),
+			worldTick: worldTick,
+			snakeInfos: newSnakeInfos,
+			foodPositions: self.foodPositions.clone(),
+			obstaclePositions: self.obstaclePositions.clone(),
+		}
+	}
 }
 
 #[cfg(test)]

src/util.rs

@@ -1,3 +1,5 @@
+use maputil::{ Direction };
+
 #[allow(dead_code)]
 pub fn vector_diff(a: (i32, i32), b: (i32, i32)) -> (i32,i32) {(
 		a.0 - b.0,
@@ -15,6 +17,19 @@ pub fn translate_position(position: i32, map_width: i32) -> (i32,i32) {
 	(x as i32, y as i32)
 }
 
+#[allow(dead_code)]
+pub fn step_in_direction(position: i32, direction: Direction, map_width: i32) -> i32 {
+	let xy = translate_position(position, map_width);
+	let dxy = match direction {
+		Direction::Down  => (xy.0, xy.1 + 1),
+		Direction::Up    => (xy.0, xy.1 - 1),
+		Direction::Left  => (xy.0 - 1, xy.1),
+		Direction::Right => (xy.0 + 1, xy.1),
+	};
+
+	translate_coordinate(dxy, map_width)
+}
+
 #[allow(dead_code)]
 pub fn translate_positions(positions: &Vec<i32>, map_width: i32) -> Vec<(i32,i32)> {
 	positions.into_iter().map(|pos| translate_position(*pos, map_width)).collect()