[FEATURE] Refactor `maps.py`

[TheGupta2012]

Feature Description

The current maps.py file is ~1400 LOC. To improve maintainability, it will be good to separate it out into distinct modules.

Implementation (Optional)

Logically distinct modules like - maps/gates.py, maps/constants.py and maps/expressions.py

[ashmitjsg]

Hi @TheGupta2012, Can I work on this issue?

[TheGupta2012]

Sure, go ahead!

[ashmitjsg]

Hi @TheGupta2012, I did the setup and explored the codebase. Before making the changes I wanted to confirm which functions have to be moved to which file. Here is what I have figured out yet:

/src/pyqasm/map/gates.py:

• u3_gate
• u3_inv_gate
• u2_gate
• u2_inv_gate
• global_phase_gate
• sxdg_gate_op
• cy_gate
• ch_gate
• xy_gate
• xx_plus_yy_gate
• ryy_gate
• zz_gate
• phaseshift_gate
• cswap_gate
• pswap_gate
• iswap_gate
• crx_gate
• cry_gate
• crz_gate
• cu_gate
• cu3_gate
• cu1_gate
• csx_gate
• rxx_gate
• rccx_gate
• rzz_gate
• cphaseshift_gate
• cphaseshift00_gate
• cphaseshift01_gate
• cphaseshift10_gate
• gpi_gate
• gpi2_gate
• ms_gate
• ccx_gate_op
• ecr_gate
• c3sx_gate
• c4x_gate
• prx_gate
• one_qubit_gate_op
• one_qubit_rotation_op
• two_qubit_gate_op

/src/pyqasm/map/constants.py:

• OPERATOR_MAP
• ONE_QUBIT_OP_MAP
• ONE_QUBIT_ROTATION_MAP
• TWO_QUBIT_OP_MAP
• THREE_QUBIT_OP_MAP
• FOUR_QUBIT_OP_MAP
• FIVE_QUBIT_OP_MAP
• SELF_INVERTING_ONE_QUBIT_OP_SET
• ST_GATE_INV_MAP
• ROTATION_INVERSION_ONE_QUBIT_OP_MAP
• U_INV_ROTATION_MAP
• LIMITS_MAP
• CONSTANTS_MAP
• VARIABLE_TYPE_MAP
• VARIABLE_TYPE_CAST_MAP
• ARRAY_TYPE_MAP
• MAX_ARRAY_DIMENSIONS
• SWITCH_BLACKLIST_STMTS
• SUPPORTED_QASM_VERSIONS
• QUANTUM_STATEMENTS

/src/pyqasm/map/expressions.py:

• qasm3_expression_op_map
• map_qasm_op_to_callable
• map_qasm_inv_op_to_callable
• qasm_variable_type_cast

Let me know if the segregation I have done is correct so that I can move forward with the task.

[TheGupta2012]

Hi @devilkiller-ag, thank you for working on this. Adding some comments below -

1. Naming the folder as maps would be better
2. The segregation for gates.py should also include -

• OPERATOR_MAP
• ONE_QUBIT_OP_MAP
• ONE_QUBIT_ROTATION_MAP
• TWO_QUBIT_OP_MAP
• THREE_QUBIT_OP_MAP
• FOUR_QUBIT_OP_MAP
• FIVE_QUBIT_OP_MAP
• SELF_INVERTING_ONE_QUBIT_OP_SET
• ST_GATE_INV_MAP
• ROTATION_INVERSION_ONE_QUBIT_OP_MAP
• U_INV_ROTATION_MAP

This is because if you add these in the constants.py file, it would greatly increase the size of the imports due to the fact that you will have to import every gate implementation from gates.py. Moreover, keeping the map_qasm_op_to_callable and map_qasm_inv_op_to_callable inside gates.py would make more sense as they are logically related to the gates.

3. In similar fashion, every element related to expressions should be placed inside the expressions. Thus -

• LIMITS_MAP
• CONSTANTS_MAP
• VARIABLE_TYPE_MAP
• VARIABLE_TYPE_CAST_MAP
• ARRAY_TYPE_MAP
• MAX_ARRAY_DIMENSIONS

should be moved to expressions.py

Now that I think of it using a constants.py file might group unrelated constants together which we do not want. Better to just use expressions.py and gates.py for the segregration. For the -

• SWITCH_BLACKLIST_STMTS
• SUPPORTED_QASM_VERSIONS
• QUANTUM_STATEMENTS

we can move them to the __init__.py file for the maps directory. This will allow us to do something like from pyqasm.maps import QUANTUM_STATEMENTS directly, without having a separate file for these constants.