From b3f7431be4a7e380695b1e060f061d8ca63d5b8e Mon Sep 17 00:00:00 2001
From: kageru <kageru@encode.moe>
Date: Fri, 13 Dec 2019 10:44:13 +0100
Subject: [PATCH] Intcode: add method for single step execution

---
 2019/intcode/src/intcomputer.rs | 26 +++++++++++++++++++-------
 2019/intcode/src/lib.rs         |  1 +
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/2019/intcode/src/intcomputer.rs b/2019/intcode/src/intcomputer.rs
index 3493c91..809f25f 100644
--- a/2019/intcode/src/intcomputer.rs
+++ b/2019/intcode/src/intcomputer.rs
@@ -9,6 +9,7 @@ pub struct IntComputer {
 pub enum IntComputerResult {
     Halt,
     Output(i64),
+    Continue,
 }
 
 impl IntComputerResult {
@@ -16,6 +17,7 @@ impl IntComputerResult {
         match self {
             IntComputerResult::Halt => panic!("Attempted to get value of halt operation"),
             IntComputerResult::Output(o) => o,
+            IntComputerResult::Continue => panic!("Attempted to get value of non-output operation"),
         }
     }
 }
@@ -31,15 +33,25 @@ impl IntComputer {
         }
     }
 
+    pub fn step(&mut self) -> IntComputerResult {
+        match self.cmd_buffer.pop().unwrap_or_else(|| self.decode_next()) {
+            Operation::Halt {} => return IntComputerResult::Halt,
+            op => {
+                if let Some(o) = self.execute(op.to_owned()) {
+                    return IntComputerResult::Output(o);
+                } else {
+                    return IntComputerResult::Continue;
+                }
+            }
+        }
+    }
+
     pub fn run(&mut self) -> IntComputerResult {
         loop {
-            match self.cmd_buffer.pop().unwrap_or_else(|| self.decode_next()) {
-                Operation::Halt {} => return IntComputerResult::Halt,
-                op => {
-                    if let Some(o) = self.execute(op.to_owned()) {
-                        return IntComputerResult::Output(o);
-                    }
-                }
+            match self.step() {
+                IntComputerResult::Halt => return IntComputerResult::Halt,
+                IntComputerResult::Output(o) => return IntComputerResult::Output(o),
+                IntComputerResult::Continue => (),
             }
         }
     }
diff --git a/2019/intcode/src/lib.rs b/2019/intcode/src/lib.rs
index 4e08dea..23aad06 100644
--- a/2019/intcode/src/lib.rs
+++ b/2019/intcode/src/lib.rs
@@ -22,6 +22,7 @@ pub fn run_for_input(input: &Vec<i64>, acc: &mut i64, amp_phases: Vec<i64>) -> i
         match amplifier.run() {
             IntComputerResult::Output(output) => *acc = output,
             IntComputerResult::Halt => break,
+            IntComputerResult::Continue => unreachable!()
         }
     }
     *acc