From 3f9e231ebf99277d19267c4a299b5a3a855f406d Mon Sep 17 00:00:00 2001
From: Volodymyr Patuta <6977238-fiplox@users.noreply.gitlab.com>
Date: Thu, 5 Nov 2020 00:06:48 +0100
Subject: [PATCH] new paser + generate random instructions

---
 Cargo.toml    |   2 +
 src/conf.pest |   3 ++
 src/main.rs   | 138 ++++++++++++++++++++++++--------------------------
 3 files changed, 71 insertions(+), 72 deletions(-)
 create mode 100644 src/conf.pest

diff --git a/Cargo.toml b/Cargo.toml
index a264f32..858be56 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,3 +9,5 @@ edition = "2018"
 [dependencies]
 clap = "2.33.3"
 rand = "0.7.3"
+pest = "2.0"
+pest_derive = "2.0"
diff --git a/src/conf.pest b/src/conf.pest
new file mode 100644
index 0000000..67df1e6
--- /dev/null
+++ b/src/conf.pest
@@ -0,0 +1,3 @@
+world = { ASCII_DIGIT* ~ " " ~ ASCII_DIGIT* }
+robot_init = { ASCII_DIGIT* ~ " " ~ ASCII_DIGIT* ~ " " ~ ("S" | "N" | "W" | "E") }
+robot_instructions = { ASCII_ALPHA_UPPER+ }
diff --git a/src/main.rs b/src/main.rs
index 22feaca..1568944 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -13,7 +13,13 @@
 // You should have received a copy of the GNU General Public License
 // along with this program. If not, see <http://www.gnu.org/licenses/>.
 
+extern crate pest;
+#[macro_use]
+extern crate pest_derive;
+
 use clap::{App, Arg};
+use pest::Parser;
+use rand::Rng;
 use std::collections::HashMap;
 use std::fs;
 use std::io;
@@ -21,6 +27,10 @@ use std::io;
 mod robot;
 mod world;
 
+#[derive(Parser)]
+#[grammar = "conf.pest"]
+pub struct ConfParser;
+
 /// Check if the robot is in the map.
 fn check_map(r: &robot::Robot, w: &world::World) -> Result<(), String> {
     if r.p.x < 0 || r.p.y < 0 || r.p.x > w.x || r.p.y > w.y {
@@ -48,119 +58,96 @@ fn create_hash_map(pool: &Vec<robot::Robot>, hash: &mut HashMap<robot::Position,
     }
 }
 
+fn gen_random_instructions() -> String {
+    let mut rng = rand::thread_rng();
+    let n = rng.gen_range(5, 10);
+    let mut instructions = String::with_capacity(n);
+    const CHARSET: &[u8] = b"LRF";
+    for _ in 0..n {
+        let l = rng.gen_range(0, CHARSET.len());
+        instructions.push(CHARSET[l] as char);
+    }
+
+    instructions
+}
+
 /// Parse the config file, generate the world and robot pool.
 fn parse_config(conf: String, pool: &mut Vec<robot::Robot>) -> Result<world::World, String> {
-    let mut lines = conf.lines();
-    // The first line of the config file should be the World.
-    let raw_line: &str = match lines.next() {
-        Some(raw) => raw,
-        None => {
-            return Err(String::from(
-                "Could not read the first line of the config file !",
-            ))
-        }
+    let mut lines: Vec<&str> = conf.split('\n').collect();
+    let raw_world = match ConfParser::parse(Rule::world, lines.remove(0)) {
+        Ok(s) => s.as_str(),
+        Err(e) => return Err(format!("{}", e)),
     };
-    let mut tokens = raw_line.split_whitespace();
-    let token1 = match tokens.next() {
-        Some(raw) => raw,
-        None => {
-            return Err(String::from(
-                "Could not read the first token of the first line !",
-            ))
-        }
-    };
-    let token2 = match tokens.next() {
-        Some(raw) => raw,
-        None => {
-            return Err(String::from(
-                "Could not read the second token of the first line !",
-            ))
-        }
-    };
-    let x: i32 = match token1.parse::<i32>() {
-        Ok(x) => x,
-        Err(_) => {
-            return Err(String::from(
-                "Could not convert token one from the first string to i32",
-            ))
-        }
-    };
-    let y: i32 = match token2.parse::<i32>() {
-        Ok(x) => x,
-        Err(_) => {
-            return Err(String::from(
-                "Could not convert token two from the first string to i32",
-            ))
-        }
-    };
-    let w = world::World { x, y };
+    let mut w: Vec<i32> = Vec::with_capacity(2);
+    for n in raw_world.split_whitespace() {
+        let v: i32 = match n.parse::<i32>() {
+            Ok(x) => x,
+            Err(_) => return Err(String::from("World config is broken.")),
+        };
+        w.push(v);
+    }
+    let world = world::World { x: w[0], y: w[1] };
+    lines.remove(0);
     let mut r_id: u32 = 0;
     loop {
         r_id += 1;
-        // This line should be empty.
-        let empty_line = match lines.next() {
-            None => break,
-            Some(x) => x,
-        };
-        if !empty_line.is_empty() {
-            return Err(String::from("This line should be empty !"));
+        if lines.len() == 0 {
+            break;
         }
-        let raw_setup = match lines.next() {
-            None => return Err(String::from("This line should be the config !")),
-            Some(raw) => raw,
+        let raw_setup = match ConfParser::parse(Rule::robot_init, lines.remove(0)) {
+            Ok(s) => s.as_str(),
+            Err(e) => return Err(format!("{}", e)),
         };
-        if raw_setup.is_empty() {
-            return Err(String::from("This line should not be empty !"));
-        }
-        let raw_inst = match lines.next() {
-            None => return Err(String::from("This line should be the instruction !")),
-            Some(raw) => raw,
+
+        let rand_instructions = gen_random_instructions();
+        let l = lines.remove(0);
+
+        let instructions = match ConfParser::parse(Rule::robot_instructions, l) {
+            Ok(s) => s.as_str(),
+            Err(_) => rand_instructions.as_str(),
         };
-        if raw_inst.is_empty() {
-            return Err(String::from("This line should not be empty !"));
-        }
-        // Parse the setup line of the robot.
+
         let mut setup = raw_setup.split_whitespace();
         let pos_x = match setup.next() {
+            Some(raw) => raw,
             None => {
                 return Err(String::from(
                     "Could not read the first token of the setup line !",
                 ))
             }
-            Some(raw) => raw,
         };
         let pos_y = match setup.next() {
+            Some(raw) => raw,
             None => {
                 return Err(String::from(
                     "Could not read the second token of the setup line !",
                 ))
             }
-            Some(raw) => raw,
         };
         let orientation = match setup.next() {
+            Some(raw) => raw,
             None => {
                 return Err(String::from(
                     "Could not read the third token of the setup line !",
                 ))
             }
-            Some(raw) => raw,
         };
         // Convert values of the setup line
         let r_x = match pos_x.parse::<i32>() {
+            Ok(raw) => raw,
             Err(_) => {
                 return Err(String::from(
                     "Could not convert the first token of the setup ligne to i32 !",
                 ))
             }
-            Ok(raw) => raw,
         };
         let r_y = match pos_y.parse::<i32>() {
+            Ok(raw) => raw,
             Err(_) => {
                 return Err(String::from(
                     "Could not convert the second token of the setup ligne to i32 !",
                 ))
             }
-            Ok(raw) => raw,
         };
         let r_o = match orientation {
             "N" => robot::Orientation::N,
@@ -173,9 +160,8 @@ fn parse_config(conf: String, pool: &mut Vec<robot::Robot>) -> Result<world::Wor
                 ))
             }
         };
-
         // Convert instructions line.
-        let inst: Vec<char> = raw_inst.chars().rev().collect();
+        let inst: Vec<char> = instructions.chars().rev().collect();
         if !robot::is_instructions(&inst) {
             return Err(String::from("Invalid instructions !"));
         }
@@ -183,13 +169,21 @@ fn parse_config(conf: String, pool: &mut Vec<robot::Robot>) -> Result<world::Wor
         let r = robot::Robot::new(r_id, r_o, robot::Position { x: r_x, y: r_y }, inst);
 
         // Load robot inside the pool.
-        match check_map(&r, &w) {
+        match check_map(&r, &world) {
             Ok(()) => pool.push(r),
             Err(err) => return Err(err),
         }
+
+        if lines.len() == 0 {
+            break;
+        }
+        if l.len() == 0 {
+            continue;
+        }
+        lines.remove(0);
     }
 
-    Ok(w)
+    Ok(world)
 }
 
 /// Retrieve the content of a file and return it as a string.