From bdb6cfe9274523ea28ff0df28a8de5808f795005 Mon Sep 17 00:00:00 2001
From: Nicholas Ward <npward@berkeley.edu>
Date: Thu, 1 Jul 2021 13:11:34 -0700
Subject: [PATCH] skeleton

---
 src/gates/insertion.rs | 99 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 src/gates/insertion.rs

diff --git a/src/gates/insertion.rs b/src/gates/insertion.rs
new file mode 100644
index 00000000..9977c6ac
--- /dev/null
+++ b/src/gates/insertion.rs
@@ -0,0 +1,99 @@
+use crate::circuit_builder::CircuitBuilder;
+use crate::field::extension_field::target::ExtensionTarget;
+use crate::field::extension_field::Extendable;
+use crate::field::field::Field;
+use crate::gates::gate::{Gate, GateRef};
+use crate::generator::{SimpleGenerator, WitnessGenerator};
+use crate::target::Target;
+use crate::vars::{EvaluationTargets, EvaluationVars};
+use crate::wire::Wire;
+use crate::witness::PartialWitness;
+
+/// A gate for inserting a value into a list at a non-deterministic location.
+pub struct InsertionGate;
+
+impl InsertionGate {
+    pub fn get<F: Extendable<D>, const D: usize>() -> GateRef<F, D> {
+
+        GateRef::new(InsertionGate)
+    }
+
+    pub const CONST_INPUT: usize = 0;
+
+    pub const WIRE_OUTPUT: usize = 0;
+}
+
+impl<F: Extendable<D>, const D: usize> Gate<F, D> for InsertionGate {
+    fn id(&self) -> String {
+        format!("{:?}<D={}>", self, D)
+    }
+
+    fn eval_unfiltered(&self, vars: EvaluationVars<F, D>) -> Vec<F::Extension> {
+        let input = vars.local_constants[Self::CONST_INPUT];
+        let output = vars.local_wires[Self::WIRE_OUTPUT];
+        vec![output - input]
+    }
+
+    fn eval_unfiltered_recursively(
+        &self,
+        builder: &mut CircuitBuilder<F, D>,
+        vars: EvaluationTargets<D>,
+    ) -> Vec<ExtensionTarget<D>> {
+        let input = vars.local_constants[Self::CONST_INPUT];
+        let output = vars.local_wires[Self::WIRE_OUTPUT];
+        vec![builder.sub_extension(output, input)]
+    }
+
+    fn generators(
+        &self,
+        gate_index: usize,
+        local_constants: &[F],
+    ) -> Vec<Box<dyn WitnessGenerator<F>>> {
+        let gen = ConstantGenerator {
+            gate_index,
+            constant: local_constants[0],
+        };
+        vec![Box::new(gen)]
+    }
+
+    fn num_wires(&self) -> usize {
+        1
+    }
+
+    fn num_constants(&self) -> usize {
+        1
+    }
+
+    fn degree(&self) -> usize {
+        1
+    }
+
+    fn num_constraints(&self) -> usize {
+        1
+    }
+}
+
+#[derive(Debug)]
+struct InsertionGenerator<F: Field> {
+    gate_index: usize,
+    
+}
+
+impl<F: Field> SimpleGenerator<F> for InsertionGenerator<F> {
+    fn dependencies(&self) -> Vec<Target> {
+        Vec::new()
+    }
+
+    fn run_once(&self, _witness: &PartialWitness<F>) -> PartialWitness<F> {
+        let wire = Wire {
+            gate: self.gate_index,
+            input: ConstantGate::WIRE_OUTPUT,
+        };
+        PartialWitness::singleton_target(Target::Wire(wire), self.constant)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    
+}