Making getParameter const on Instruction

quantum/aqc/ir/DWKernel.hpp

@@ -160,7 +160,7 @@ public:
 		return weights;
 	}
 
-	virtual InstructionParameter getParameter(const int idx) {
+	virtual InstructionParameter getParameter(const int idx) const {
 		XACCError("DWKernel does not contain runtime parameters.");
 	}
 

quantum/aqc/ir/DWQMI.hpp

@@ -142,7 +142,7 @@ public:
 	 * @param idx The index of the parameter.
 	 * @return param The InstructionParameter at the given index.
 	 */
-	virtual InstructionParameter getParameter(const int idx) {
+	virtual InstructionParameter getParameter(const int idx) const {
 		return parameter;
 	}
 

quantum/gate/ir/GateFunction.hpp

@@ -154,7 +154,7 @@ public:
 		return retStr;
 	}
 
-	virtual InstructionParameter getParameter(const int idx) {
+	virtual InstructionParameter getParameter(const int idx) const {
 		if (idx + 1 > parameters.size()) {
 			XACCError("Invalid Parameter requested.");
 		}

quantum/gate/ir/GateInstruction.hpp

@@ -141,7 +141,7 @@ public:
 		enabled = true;
 	}
 
-	virtual InstructionParameter getParameter(const int idx) {
+	virtual InstructionParameter getParameter(const int idx) const {
 		if (idx + 1 > parameters.size()) {
 			XACCError("Invalid Parameter requested from Parameterized Gate Instruction.");
 		}

xacc/ir/Instruction.hpp

@@ -95,7 +95,7 @@ public:
 	 * @param idx The index of the parameter.
 	 * @return param The InstructionParameter at the given index.
 	 */
-	virtual InstructionParameter getParameter(const int idx) = 0;
+	virtual InstructionParameter getParameter(const int idx) const = 0;
 
 	/**
 	 * Return all of this Instruction's parameters.