Fix circuit rendering for long gate names

compiler/qsc_circuit/src/circuit.rs

@@ -228,12 +228,14 @@ fn fmt_qubit_label(id: usize) -> String {
 
 /// "── A ──"
 fn fmt_on_qubit_wire(obj: &str) -> String {
-    format!("{:─^COLUMN_WIDTH$}", format!(" {obj} "))
+    let width = obj.len() + 4;
+    format!("{:─^width$}", format!(" {obj} "))
 }
 
 /// "══ A ══"
 fn fmt_on_classical_wire(obj: &str) -> String {
-    format!("{:═^COLUMN_WIDTH$}", format!(" {obj} "))
+    let width = obj.len() + 4;
+    format!("{:═^width$}", format!(" {obj} "))
 }
 
 impl Display for Circuit {

compiler/qsc_circuit/src/circuit/tests.rs

@@ -267,3 +267,62 @@ fn two_targets() {
     "]]
     .assert_eq(&c.to_string());
 }
+
+#[test]
+fn long_gate_names() {
+    let c = Circuit {
+        operations: vec![
+            Operation {
+                gate: "rx".to_string(),
+                display_args: Some("3.1416".to_string()),
+                is_controlled: false,
+                is_adjoint: false,
+                is_measurement: false,
+                controls: vec![],
+                targets: vec![Register::quantum(0)],
+                children: vec![],
+            },
+            Operation {
+                gate: "H".to_string(),
+                display_args: None,
+                is_controlled: false,
+                is_adjoint: false,
+                is_measurement: false,
+                controls: vec![],
+                targets: vec![Register::quantum(1)],
+                children: vec![],
+            },
+            Operation {
+                gate: "rx".to_string(),
+                display_args: Some("3.1416".to_string()),
+                is_controlled: false,
+                is_adjoint: false,
+                is_measurement: false,
+                controls: vec![],
+                targets: vec![Register::quantum(2)],
+                children: vec![],
+            },
+        ],
+        qubits: vec![
+            Qubit {
+                id: 0,
+                num_children: 0,
+            },
+            Qubit {
+                id: 1,
+                num_children: 0,
+            },
+            Qubit {
+                id: 2,
+                num_children: 0,
+            },
+        ],
+    };
+
+    expect![[r"
+        q_0     rx(3.1416)
+        q_1    ─── H ───
+        q_2     rx(3.1416)
+    "]]
+    .assert_eq(&c.to_string());
+}

samples/notebooks/circuits.ipynb

@@ -336,6 +336,70 @@
    "source": [
     "Circuit(qsharp.dump_circuit())"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Let's test the rendering of long gate names in the circuit."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "print(\"gates that fit the column width\")\n",
+    "print(\"circuit looks okay\")\n",
+    "\n",
+    "qsharp.eval(\"\"\"\n",
+    "\n",
+    "use q0 = Qubit();\n",
+    "use q1 = Qubit();\n",
+    "\n",
+    "H(q0);\n",
+    "H(q1);\n",
+    "X(q1);\n",
+    "CNOT(q0, q1);\n",
+    "M(q0)\n",
+    "\n",
+    "\"\"\")\n",
+    "\n",
+    "print(qsharp.dump_circuit())\n",
+    "\n",
+    "print(\"q_2 has gates that are too wide for the column width\")\n",
+    "print(\"circuit wires disappear, and the vertical columns don't align anymore\")\n",
+    "\n",
+    "qsharp.eval(\"\"\"\n",
+    "\n",
+    "use q2 = Qubit();\n",
+    "\n",
+    "Rx(1.0, q2);\n",
+    "Rx(1.0, q2);\n",
+    "\n",
+    "\"\"\")\n",
+    "\n",
+    "print(qsharp.dump_circuit())\n",
+    "\n",
+    "print(\"q_3 has gates with both short and long gate labels\")\n",
+    "print(\"here, the column widths should be variable so that the H doesn't take up too much width, but rx(1.000) still fits within a column\")\n",
+    "\n",
+    "qsharp.eval(\"\"\"\n",
+    "\n",
+    "use q3 = Qubit();\n",
+    "\n",
+    "H(q3);\n",
+    "Rx(1.0, q3);\n",
+    "H(q3);\n",
+    "Rx(1.0, q3);\n",
+    "H(q3);\n",
+    "Rx(1.0, q3);\n",
+    "\n",
+    "\"\"\")\n",
+    "\n",
+    "print(qsharp.dump_circuit())"
+   ]
   }
  ],
  "metadata": {