1 files changed, 210 insertions, 10 deletions
diff --git a/libpsi-core/src/core/circuit.rs b/libpsi-core/src/core/circuit.rs
index 27c106d..293d509 100644
--- a/libpsi-core/src/core/circuit.rs
+++ b/libpsi-core/src/core/circuit.rs
@@ -1,19 +1,219 @@
-use super::{ClassicalRegister, QuantumRegister};
+use super::{QuantumGate, QuantumRegister, QuantumState};
+use crate::Vector;
+use core::fmt;
+
+#[derive(Clone)]
+pub struct CircuitOperation<'a> {
+    pub gate: &'a QuantumGate<'a>,
+    pub targets: Vec<usize>,
+}
+
+impl<'a> CircuitOperation<'a> {
+    pub fn new(gate: &'a QuantumGate<'a>, targets: Vec<usize>) -> Self {
+        CircuitOperation { gate, targets }
+    }
+}
 
-#[allow(unused)]
 pub struct QuantumCircuit<'a> {
-    quantum_registers: &'a [QuantumRegister<'a>],
-    classical_registers: &'a [ClassicalRegister<'a>],
+    register: QuantumRegister<'a>,
+    operations: Vec<CircuitOperation<'a>>,
 }
 
 impl<'a> QuantumCircuit<'a> {
-    pub fn new(
-        quantum_registers: &'a [QuantumRegister<'a>],
-        classical_registers: &'a [ClassicalRegister<'a>],
-    ) -> QuantumCircuit<'a> {
+    pub fn new(num_qubits: usize) -> QuantumCircuit<'a> {
+        let names: Vec<String> = (0..num_qubits).map(|i| format!("q{}", i)).collect();
+        let leaked_names: &'a [String] = Box::leak(names.into_boxed_slice());
+        let name_refs: Vec<&'a str> = leaked_names.iter().map(|s| s.as_str()).collect();
+
         QuantumCircuit {
-            quantum_registers,
-            classical_registers,
+            register: QuantumRegister::new(
+                Box::leak(Box::new("circuit".to_string())).as_str(),
+                &name_refs,
+            ),
+            operations: Vec::new(),
+        }
+    }
+
+    pub fn from_register(register: QuantumRegister<'a>) -> QuantumCircuit<'a> {
+        QuantumCircuit {
+            register,
+            operations: Vec::new(),
+        }
+    }
+
+    pub fn num_qubits(&self) -> usize {
+        self.register.num_qubits()
+    }
+
+    pub fn state(&self) -> QuantumState {
+        self.register.get_state()
+    }
+
+    pub fn register(&self) -> &QuantumRegister<'a> {
+        &self.register
+    }
+
+    pub fn operations(&self) -> &[CircuitOperation<'a>] {
+        &self.operations
+    }
+
+    pub fn apply(&mut self, gate: &'a QuantumGate<'a>, targets: &[usize]) -> &mut Self {
+        self.register.apply_gate(gate, targets);
+        self.operations
+            .push(CircuitOperation::new(gate, targets.to_vec()));
+        self
+    }
+
+    pub fn h(&mut self, target: usize) -> &mut Self {
+        use crate::gates::HADAMARD;
+        self.register.apply_gate(&HADAMARD, &[target]);
+        self.operations
+            .push(CircuitOperation::new(&HADAMARD, vec![target]));
+        self
+    }
+
+    pub fn x(&mut self, target: usize) -> &mut Self {
+        use crate::gates::PAULI_X;
+        self.register.apply_gate(&PAULI_X, &[target]);
+        self.operations
+            .push(CircuitOperation::new(&PAULI_X, vec![target]));
+        self
+    }
+
+    pub fn y(&mut self, target: usize) -> &mut Self {
+        use crate::gates::PAULI_Y;
+        self.register.apply_gate(&PAULI_Y, &[target]);
+        self.operations
+            .push(CircuitOperation::new(&PAULI_Y, vec![target]));
+        self
+    }
+
+    pub fn z(&mut self, target: usize) -> &mut Self {
+        use crate::gates::PAULI_Z;
+        self.register.apply_gate(&PAULI_Z, &[target]);
+        self.operations
+            .push(CircuitOperation::new(&PAULI_Z, vec![target]));
+        self
+    }
+
+    pub fn s(&mut self, target: usize) -> &mut Self {
+        use crate::gates::S_GATE;
+        self.register.apply_gate(&S_GATE, &[target]);
+        self.operations
+            .push(CircuitOperation::new(&S_GATE, vec![target]));
+        self
+    }
+
+    pub fn t(&mut self, target: usize) -> &mut Self {
+        use crate::gates::T_GATE;
+        self.register.apply_gate(&T_GATE, &[target]);
+        self.operations
+            .push(CircuitOperation::new(&T_GATE, vec![target]));
+        self
+    }
+
+    pub fn cnot(&mut self, control: usize, target: usize) -> &mut Self {
+        use crate::gates::CNOT;
+        self.register.apply_gate(&CNOT, &[control, target]);
+        self.operations
+            .push(CircuitOperation::new(&CNOT, vec![control, target]));
+        self
+    }
+
+    pub fn cx(&mut self, control: usize, target: usize) -> &mut Self {
+        self.cnot(control, target)
+    }
+
+    pub fn cz(&mut self, control: usize, target: usize) -> &mut Self {
+        use crate::gates::CZ;
+        self.register.apply_gate(&CZ, &[control, target]);
+        self.operations
+            .push(CircuitOperation::new(&CZ, vec![control, target]));
+        self
+    }
+
+    pub fn swap(&mut self, qubit1: usize, qubit2: usize) -> &mut Self {
+        use crate::gates::SWAP;
+        self.register.apply_gate(&SWAP, &[qubit1, qubit2]);
+        self.operations
+            .push(CircuitOperation::new(&SWAP, vec![qubit1, qubit2]));
+        self
+    }
+
+    pub fn ccnot(&mut self, control1: usize, control2: usize, target: usize) -> &mut Self {
+        use crate::gates::TOFFOLI;
+        self.register
+            .apply_gate(&TOFFOLI, &[control1, control2, target]);
+        self.operations.push(CircuitOperation::new(
+            &TOFFOLI,
+            vec![control1, control2, target],
+        ));
+        self
+    }
+
+    pub fn toffoli(&mut self, control1: usize, control2: usize, target: usize) -> &mut Self {
+        self.ccnot(control1, control2, target)
+    }
+
+    pub fn cswap(&mut self, control: usize, target1: usize, target2: usize) -> &mut Self {
+        use crate::gates::FREDKIN;
+        self.register
+            .apply_gate(&FREDKIN, &[control, target1, target2]);
+        self.operations.push(CircuitOperation::new(
+            &FREDKIN,
+            vec![control, target1, target2],
+        ));
+        self
+    }
+
+    pub fn fredkin(&mut self, control: usize, target1: usize, target2: usize) -> &mut Self {
+        self.cswap(control, target1, target2)
+    }
+
+    pub fn reset(&mut self) -> &mut Self {
+        let n = self.num_qubits();
+        let names: Vec<String> = (0..n).map(|i| format!("q{}", i)).collect();
+        let leaked_names: &'a [String] = Box::leak(names.into_boxed_slice());
+        let name_refs: Vec<&'a str> = leaked_names.iter().map(|s| s.as_str()).collect();
+
+        self.register = QuantumRegister::new(
+            Box::leak(Box::new("circuit".to_string())).as_str(),
+            &name_refs,
+        );
+        self.operations.clear();
+        self
+    }
+
+    pub fn probability(&self, state_index: usize) -> f64 {
+        let state = self.state();
+        let amp = state.get(state_index);
+        amp.norm2()
+    }
+
+    pub fn probabilities(&self) -> Vec<f64> {
+        let state = self.state();
+        let n = 1 << self.num_qubits();
+        (0..n).map(|i| state.get(i).norm2()).collect()
+    }
+}
+
+impl<'a> fmt::Display for QuantumCircuit<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        writeln!(f, "QuantumCircuit ({} qubits)", self.num_qubits())?;
+        writeln!(f, "Operations:")?;
+        for (i, op) in self.operations.iter().enumerate() {
+            writeln!(f, "  {}: {} on {:?}", i, op.gate.name, op.targets)?;
+        }
+        writeln!(f, "State:")?;
+        let state = self.state();
+        let n = 1 << self.num_qubits();
+        for i in 0..n {
+            let amp = state.get(i);
+            if amp.real.abs() > 1e-10 || amp.imaginary.abs() > 1e-10 {
+                let basis: String = format!("{:0width$b}", i, width = self.num_qubits());
+                writeln!(f, "  |{}⟩: {:.4}", basis, amp)?;
+            }
         }
+        Ok(())
     }
 }