From 854edb86c975530391b197084d5ba03d86ad3718 Mon Sep 17 00:00:00 2001
From: Justin Worthe <justin.worthe@entelect.co.za>
Date: Mon, 12 Dec 2016 12:20:19 +0200
Subject: Perf AOC12

---
 aoc12/src/main.rs | 95 +++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 67 insertions(+), 28 deletions(-)

diff --git a/aoc12/src/main.rs b/aoc12/src/main.rs
index bcd591c..e3b6038 100644
--- a/aoc12/src/main.rs
+++ b/aoc12/src/main.rs
@@ -5,63 +5,101 @@ use std::io::BufReader;
 use std::io::prelude::*;
 use std::fs::File;
 
+enum Instruction {
+    CpyLit(i32, usize),
+    CpyReg(usize, usize),
+    Inc(usize),
+    Dec(usize),  
+    Jnz(usize, i32),
+    Jmp(i32),
+    Noop
+}
 
-fn main() {
-    let program = read_file();
-
-    let mut registers: [i32; 4] = [0;4];
-    registers[2] = 1; //init c to 1
-    let mut pc: usize = 0;
-
-    let cpy_lit = Regex::new(r"cpy ([-\d]+) (a|b|c|d)").unwrap();
-    let cpy_reg = Regex::new(r"cpy (a|b|c|d) (a|b|c|d)").unwrap();
-    let inc = Regex::new(r"inc (a|b|c|d)").unwrap();
-    let dec = Regex::new(r"dec (a|b|c|d)").unwrap();
-    let jnz_lit = Regex::new(r"jnz ([-\d]+) ([-\d]+)").unwrap();
-    let jnz_reg = Regex::new(r"jnz (a|b|c|d) ([-\d]+)").unwrap();
+impl Instruction {
+    fn parse(line: &str) -> Instruction {
+        let cpy_lit: Regex = Regex::new(r"cpy ([-\d]+) (a|b|c|d)").unwrap();
+        let cpy_reg = Regex::new(r"cpy (a|b|c|d) (a|b|c|d)").unwrap();
+        let inc = Regex::new(r"inc (a|b|c|d)").unwrap();
+        let dec = Regex::new(r"dec (a|b|c|d)").unwrap();
+        let jnz_lit = Regex::new(r"jnz ([-\d]+) ([-\d]+)").unwrap();
+        let jnz_reg = Regex::new(r"jnz (a|b|c|d) ([-\d]+)").unwrap();
 
-    
-    while pc < program.len() {
-        let line = program[pc].as_ref();
-        let mut pc_next: usize = pc+1;
-        
         if cpy_lit.is_match(line) {
             let cap = cpy_lit.captures(line).unwrap();
             let src: i32 = cap.at(1).unwrap().parse().unwrap();
             let dest = to_register_index(cap.at(2).unwrap());
-            registers[dest] = src;
+            Instruction::CpyLit(src, dest)
         }
         else if cpy_reg.is_match(line) {
             let cap = cpy_reg.captures(line).unwrap();
             let src = to_register_index(cap.at(1).unwrap());
             let dest = to_register_index(cap.at(2).unwrap());
-            registers[dest] = registers[src];
+            Instruction::CpyReg(src, dest)
         }
         else if inc.is_match(line) {
             let cap = inc.captures(line).unwrap();
             let dest = to_register_index(cap.at(1).unwrap());
-            registers[dest] = registers[dest] + 1;
+            Instruction::Inc(dest)
         }
         else if dec.is_match(line) {
             let cap = dec.captures(line).unwrap();
             let dest = to_register_index(cap.at(1).unwrap());
-            registers[dest] = registers[dest] - 1;
+            Instruction::Dec(dest)
         }
         else if jnz_lit.is_match(line) {
             let cap = jnz_lit.captures(line).unwrap();
             let condition: i32 = cap.at(1).unwrap().parse().unwrap();
             let offset: i32 = cap.at(2).unwrap().parse().unwrap();
             if condition != 0 {
-                pc_next = (pc as i32 + offset) as usize;
+                Instruction::Jmp(offset)
+            }
+            else {
+                Instruction::Noop
             }
         }
         else if jnz_reg.is_match(line) {
             let cap = jnz_reg.captures(line).unwrap();
             let condition = to_register_index(cap.at(1).unwrap());
             let offset: i32 = cap.at(2).unwrap().parse().unwrap();
-            if registers[condition] != 0 {
-                pc_next = (pc as i32 + offset) as usize;
-            }
+            Instruction::Jnz(condition, offset)
+        }
+        else {
+            panic!("Invalid instruction line")
+        }
+    }
+}
+
+fn main() {
+    let program = read_file();
+
+    let mut registers: [i32; 4] = [0, 0, 1, 0];
+    let mut pc: usize = 0;
+    
+    while pc < program.len() {
+        let mut pc_next: usize = pc+1;
+
+        match program[pc] {
+            Instruction::CpyLit(src, dest) => {
+                registers[dest] = src;
+            },
+            Instruction::CpyReg(src, dest) => {
+                registers[dest] = registers[src];
+            },
+            Instruction::Inc(dest) => {
+                registers[dest] += 1;
+            },
+            Instruction::Dec(dest) => {
+                registers[dest] -= 1;
+            },
+            Instruction::Jnz(condition, offset) => {
+                if registers[condition] != 0 {
+                    pc_next = (pc as i32 + offset) as usize;
+                }
+            },
+            Instruction::Jmp(offset) => {
+                pc_next = (pc as i32 + offset) as usize
+            },
+            Instruction::Noop => {}
         }
 
         pc = pc_next;
@@ -81,10 +119,11 @@ fn to_register_index(name: &str) -> usize {
     }
 }
 
-fn read_file() -> Vec<String> {
+fn read_file() -> Vec<Instruction> {
     let file = BufReader::new(File::open("input.txt").unwrap());
     file.lines()
-        .map(|line| line.unwrap().trim().to_string())
+        .map(|line| line.unwrap())
         .filter(|line| line.len() > 0)
+        .map(|line| Instruction::parse(line.trim()))
         .collect()
 }
-- 
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