allows QASM2 destructive measurements

CMakeLists.txt

@@ -26,6 +26,7 @@ option(WITH_EXAMPLES "Enable example compilation" OFF)
 option(WITH_UNIT_TESTS "Enable unit testing" OFF)
 option(SANITIZE "Enable code sanitizing (only for gcc/clang)" OFF)
 option(USE_OPENQASM2_SPECS "Use OpenQASM 2.0 standard instead of Qiskit gate specifications" OFF)
+option(USE_OPENQASM2_DESTRUCTIVE_MEASUREMENTS "Use destructive measurements when executing OpenQASM 2.0 circuits" OFF)
 
 #### Enable OpenQASM 2.0 specs, see DISCREPANCIES.md for a comparison with Qiskit
 if (${USE_OPENQASM2_SPECS})
@@ -34,6 +35,14 @@ else ()
     target_compile_definitions(libqpp INTERFACE -DUSE_OPENQASM2_SPECS=false)
 endif ()
 
+#### Use destructive measurements when executing OpenQASM 2.0 circuits
+if (${USE_OPENQASM2_DESTRUCTIVE_MEASUREMENTS})
+    target_compile_definitions(libqpp INTERFACE -DUSE_OPENQASM2_DESTRUCTIVE_MEASUREMENTS=true)
+else ()
+    target_compile_definitions(libqpp INTERFACE -DUSE_OPENQASM2_DESTRUCTIVE_MEASUREMENTS=false)
+endif ()
+
+
 #### Dependencies, do not modify unless you know what you're doing
 if (${WITH_EXAMPLES} OR ${WITH_UNIT_TESTS})
     include(cmake/qpp_dependencies.cmake)

include/qasm/qasm.hpp

@@ -514,9 +514,15 @@ class QCircuitBuilder final : public ast::Visitor {
         auto c_args = var_access_as_creg(stmt.c_arg());
         auto circuit = ctx.get_circuit();
 
-        // apply measurements non-desctructively
+        // apply measurements non-destructively (destructively if
+        // the CMake option USE_OPENQASM2_DESTRUCTIVE_MEASUREMENTS is ON
+        // (OFF by default))
+        bool is_destructive = false;
+#if USE_OPENQASM2_DESTRUCTIVE_MEASUREMENTS
+        is_destructive = true;
+#endif
         for (idx i = 0; i < q_args.size(); i++) {
-            circuit->measureZ(q_args[i], c_args[i], false);
+            circuit->measureZ(q_args[i], c_args[i], is_destructive);
         }
     }
 
@@ -805,7 +811,7 @@ class QCircuitBuilder final : public ast::Visitor {
 };
 
 /**
- * \brief Reads a OpenQASM circuit from stdin and returns its qpp::QCircuit
+ * \brief Reads an OpenQASM circuit from stdin and returns its qpp::QCircuit
  * representation
  *
  * \return qpp::QCircuit
@@ -821,7 +827,7 @@ inline QCircuit read(std::istream& stream) {
 }
 
 /**
- * \brief Reads a OpenQASM circuit from a file and returns its qpp::QCircuit
+ * \brief Reads an OpenQASM circuit from a file and returns its qpp::QCircuit
  * representation
  *
  * \return qpp::QCircuit