From d5083f4cce47567644fd1b2c5923e5d0dcd98d44 Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Sun, 7 Mar 2021 10:17:40 -0700
Subject: don't round-trip everything through strings!!!

---
 src/basic_actors.rs |  3 ++-
 src/main.rs         |  3 ++-
 src/number.rs       | 54 +++++++++++++++++++++++++++++------------------------
 3 files changed, 34 insertions(+), 26 deletions(-)

diff --git a/src/basic_actors.rs b/src/basic_actors.rs
index da391cf..130c1e2 100644
--- a/src/basic_actors.rs
+++ b/src/basic_actors.rs
@@ -1,4 +1,5 @@
 use std::collections::HashMap;
+use std::convert::TryInto;
 use std::sync::mpsc::{SyncSender, Receiver};
 
 use crate::actor::{Value, Type, Actorful, Slot};
@@ -98,7 +99,7 @@ impl Actorful for RepeatValue {
                 if let Value::Number(count) = count {
                     // TODO figure out what a smart thing to do would be here instead
                     // this API design is deliberately suboptimal because i'd like to not do it
-                    let count: usize = format!("{}", count).parse().unwrap();
+                    let count: usize = count.try_into().unwrap();
                     let vec = vec![value; count];
                     output_channels["List"].send(Value::List(vec)).unwrap();
                 }
diff --git a/src/main.rs b/src/main.rs
index 6bf920b..8617d6a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,4 @@
+use std::convert::TryInto;
 use std::time::Duration;
 
 use minifb::{Key, Window, WindowOptions, MouseMode};
@@ -119,7 +120,7 @@ fn main() {
                 let u32_data: Vec<u32> = data.into_iter()
                     .map(|x| {
                         if let actor::Value::Number(x) = x {
-                            format!("{}", x).parse().unwrap()
+                            x.try_into().unwrap()
                         } else {
                             panic!("bruh")
                         }
diff --git a/src/number.rs b/src/number.rs
index 94a67f1..5ea7949 100644
--- a/src/number.rs
+++ b/src/number.rs
@@ -1,10 +1,12 @@
 use std::cmp::max;
-use std::fmt::{Display, Formatter, Result as FormatResult};
+use std::convert::TryFrom;
+use std::num::TryFromIntError;
 use std::ops::Add;
 
 #[derive(Clone)]
 pub struct Number {
-    pub integer_part: String,
+    // least significant first
+    pub integer_part: Vec<usize>,
 }
 
 macro_rules! int_conv {
@@ -12,7 +14,19 @@ macro_rules! int_conv {
         impl From<$t> for Number {
             fn from(x: $t) -> Number {
                 Number {
-                    integer_part: x.to_string(),
+                    integer_part: vec![x as usize],
+                }
+            }
+        }
+
+        impl TryFrom<Number> for $t {
+            type Error = TryFromIntError;
+
+            fn try_from(x: Number) -> Result<$t, TryFromIntError> {
+                if x.integer_part.len() > 1 {
+                    <u8>::try_from(-1).map(|_| 0)
+                } else {
+                    <$t>::try_from(x.integer_part[0]).map_err(|_| <u8>::try_from(-1).unwrap_err())
                 }
             }
         }
@@ -21,33 +35,25 @@ macro_rules! int_conv {
 
 int_conv!(u8, u16, u32, u64, usize, i8, i16, i32, i64, isize);
 
-impl Display for Number {
-    fn fmt(&self, f: &mut Formatter<'_>) -> FormatResult {
-        f.write_str(&self.integer_part)
-    }
-}
-
 impl Add for Number {
     type Output = Number;
 
     fn add(self, rhs: Self) -> Self::Output {
         let longest_ipart_len = max(self.integer_part.len(), rhs.integer_part.len());
-        let self_padded = format!("{:0>len$}", self.integer_part, len=longest_ipart_len);
-        let rhs_padded = format!("{:0>len$}", rhs.integer_part, len=longest_ipart_len);
-        let mut result_ipart_reverse = "".to_string();
-        let mut carry: u8 = 0;
-        for (self_char, rhs_char) in self_padded.chars().rev().zip(rhs_padded.chars().rev()) {
-            let self_char_val = self_char.to_digit(10).unwrap() as u8;
-            let rhs_char_val = rhs_char.to_digit(10).unwrap() as u8;
-            let sum = self_char_val + rhs_char_val + carry;
-            let sum_last_digit = (sum % 10).to_string().chars().next().unwrap();
-            carry = sum / 10;
-            result_ipart_reverse.push(sum_last_digit);
-        }
-        if carry > 0 {
-            result_ipart_reverse.push_str(&carry.to_string());
+        let mut result_ipart = vec![];
+        let mut carry: usize = 0;
+        for i in 0..longest_ipart_len {
+            let self_part = self.integer_part.get(i).copied().unwrap_or(0);
+            let rhs_part = rhs.integer_part.get(i).copied().unwrap_or(0);
+            let (half_sum, early_carry) = self_part.overflowing_add(rhs_part);
+            let (full_sum, late_carry) = half_sum.overflowing_add(carry);
+            carry = if early_carry || late_carry {
+                1
+            } else {
+                0
+            };
+            result_ipart.push(full_sum);
         }
-        let result_ipart = result_ipart_reverse.chars().rev().collect();
         Number {
             integer_part: result_ipart,
         }
-- 
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