2 files changed, 166 insertions, 0 deletions
diff --git a/entries/lilylin/fractran/src/engines/mod.rs b/entries/lilylin/fractran/src/engines/mod.rs
new file mode 100644
index 0000000..6870b7c
--- /dev/null
+++ b/entries/lilylin/fractran/src/engines/mod.rs
@@ -0,0 +1,2 @@
+
+pub mod register;
diff --git a/entries/lilylin/fractran/src/engines/register.rs b/entries/lilylin/fractran/src/engines/register.rs
new file mode 100644
index 0000000..c7c847b
--- /dev/null
+++ b/entries/lilylin/fractran/src/engines/register.rs
@@ -0,0 +1,164 @@
+use std::collections::HashMap;
+
+use crate::core::Program;
+
+#[derive(Debug)]
+pub struct Register {
+    pub program: Program,
+    pub output_base: u64, // which prime factor registers should be used to determine output
+}
+
+#[derive(Debug)]
+struct Instruction {
+    conditions: Vec<(usize, u64)>, // index, amt pairs
+    increment: Vec<(usize, u64)>,
+}
+
+impl Register {
+    fn prime_factorize(x: u64) -> Vec<(u64, u64)> {
+        let primes = primes::factors_uniq(x);
+        let mut prime_factorized = Vec::new();
+        // println!("val: {:?}", x);
+        for prime in primes {
+            let mut amount = 1;
+            loop {
+                if x % prime.pow(amount + 1) != 0 {
+                    break;
+                }
+                amount += 1;
+            }
+            // println!("{:?}, {:?}", prime, amount);
+            prime_factorized.push((prime, amount as u64));
+        }
+        return prime_factorized;
+    }
+    fn convert(&self) -> (Vec<u64>, Vec<Instruction>, HashMap<usize, u64>) {
+        let mut primes = Vec::new();
+
+        let mut prime_to_index = |prime: u64| {
+            let index: usize;
+            if primes.contains(&prime) {
+                index = primes.iter().position(|&x| x == prime).unwrap();
+            } else {
+                index = primes.len();
+                primes.push(prime);
+            }
+            return index;
+        };
+
+        let mut instrs = Vec::new();
+        for fraction in &self.program.fractions {
+            let denom_pfs = Register::prime_factorize(fraction.1 as u64);
+            let num_pfs = Register::prime_factorize(fraction.0 as u64);
+            instrs.push(Instruction {
+                conditions: denom_pfs
+                    .iter()
+                    .map(|x| (prime_to_index(x.0), x.1))
+                    .collect(),
+                increment: num_pfs.iter().map(|x| (prime_to_index(x.0), x.1)).collect(),
+            })
+        }
+
+        let mut initial_registers = Vec::new();
+        initial_registers.resize(primes.len(), 0);
+        for (prime, amt) in Register::prime_factorize(self.program.initial) {
+            let idx = primes.iter().position(|&x| x == prime).unwrap();
+            initial_registers[idx] = amt;
+        }
+
+        let output_condition: HashMap<usize, u64> = Register::prime_factorize(self.output_base)
+            .iter()
+            .map(|(prime, amt)| (primes.iter().position(|&x| x == *prime).unwrap(), *amt))
+            .collect();
+
+        // println!("Prime layout: {:?}", primes);
+        // println!("Output condition: {:?}", output_condition);
+        return (initial_registers, instrs, output_condition);
+    }
+}
+
+impl IntoIterator for Register {
+    type Item = u64;
+    type IntoIter = RegisterIter;
+
+    fn into_iter(self) -> Self::IntoIter {
+        let (registers, instructions, output_condition) = self.convert();
+        RegisterIter {
+            instructions,
+            registers,
+            output_condition,
+        }
+    }
+}
+
+pub struct RegisterIter {
+    instructions: Vec<Instruction>,
+    registers: Vec<u64>,
+    output_condition: HashMap<usize, u64>,
+}
+
+// impl RegisterIter {
+//     fn registers_to_val(&self) -> BigUint {
+//         let mut val = BigUint::zero();
+//         for (amt, prime) in self.registers.iter().zip(&self.prime_mapping) {
+//             val += prime.to_biguint().unwrap().pow(*amt);
+//         }
+//         return val;
+//     }
+// }
+
+impl Iterator for RegisterIter {
+    type Item = u64;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            for instr in &self.instructions {
+                if instr
+                    .conditions
+                    .iter()
+                    .all(|(idx, amt)| self.registers[*idx] >= *amt)
+                {
+                    instr
+                        .conditions
+                        .iter()
+                        .for_each(|(idx, amt)| self.registers[*idx] -= *amt);
+                    instr
+                        .increment
+                        .iter()
+                        .for_each(|(idx, amt)| self.registers[*idx] += *amt);
+                    break;
+                }
+            }
+
+            // Output condition checking
+            // Check that all other registers are 0
+            if !self
+                .registers
+                .iter()
+                .enumerate()
+                .all(|(idx, val)| self.output_condition.contains_key(&idx) || *val == 0)
+            {
+                continue;
+            }
+
+            // Check that the condition registers are multiples of the condition amounts
+            if !self
+                .output_condition
+                .iter()
+                .all(|(idx, cond)| self.registers[*idx] % cond == 0)
+            {
+                continue;
+            }
+
+            // Check that condition registers are the _same_ multipel of the condition amounts
+            let mut xs = self
+                .output_condition
+                .iter()
+                .map(|(idx, cond)| self.registers[*idx] / cond);
+            let first = xs.next().unwrap();
+            if xs.all(|y| y == first) {
+                return Some(first);
+            }
+        }
+    }
+}