# -*- coding: utf-8 -*-
# This code is part of Qiskit.
#
# (C) Copyright IBM 2017, 2018.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
"""
AST (abstract syntax tree) to DAG (directed acyclic graph) converter.
Acts as an OpenQASM interpreter.
"""
from collections import OrderedDict
from qiskit.dagcircuit import DAGCircuit
from qiskit.exceptions import QiskitError
from qiskit.circuit import QuantumRegister, ClassicalRegister, Gate
from qiskit.qasm.node.real import Real
from qiskit.circuit.instruction import Instruction
from qiskit.circuit.measure import Measure
from qiskit.circuit.reset import Reset
from qiskit.circuit.barrier import Barrier
from qiskit.circuit.library.standard_gates.x import CCXGate
from qiskit.circuit.library.standard_gates.swap import CSwapGate
from qiskit.circuit.library.standard_gates.x import CXGate
from qiskit.circuit.library.standard_gates.y import CYGate
from qiskit.circuit.library.standard_gates.z import CZGate
from qiskit.circuit.library.standard_gates.swap import SwapGate
from qiskit.circuit.library.standard_gates.h import HGate
from qiskit.circuit.library.standard_gates.i import IGate
from qiskit.circuit.library.standard_gates.s import SGate
from qiskit.circuit.library.standard_gates.s import SdgGate
from qiskit.circuit.library.standard_gates.t import TGate
from qiskit.circuit.library.standard_gates.t import TdgGate
from qiskit.circuit.library.standard_gates.u1 import U1Gate
from qiskit.circuit.library.standard_gates.u2 import U2Gate
from qiskit.circuit.library.standard_gates.u3 import U3Gate
from qiskit.circuit.library.standard_gates.x import XGate
from qiskit.circuit.library.standard_gates.y import YGate
from qiskit.circuit.library.standard_gates.z import ZGate
from qiskit.circuit.library.standard_gates.rx import RXGate
from qiskit.circuit.library.standard_gates.ry import RYGate
from qiskit.circuit.library.standard_gates.rz import RZGate
from qiskit.circuit.library.standard_gates.rxx import RXXGate
from qiskit.circuit.library.standard_gates.rzz import RZZGate
from qiskit.circuit.library.standard_gates.u1 import CU1Gate
from qiskit.circuit.library.standard_gates.u3 import CU3Gate
from qiskit.circuit.library.standard_gates.h import CHGate
from qiskit.circuit.library.standard_gates.rx import CRXGate
from qiskit.circuit.library.standard_gates.ry import CRYGate
from qiskit.circuit.library.standard_gates.rz import CRZGate
[docs]def ast_to_dag(ast):
"""Build a ``DAGCircuit`` object from an AST ``Node`` object.
Args:
ast (Program): a Program Node of an AST (parser's output)
Return:
DAGCircuit: the DAG representing an OpenQASM's AST
Raises:
QiskitError: if the AST is malformed.
Example:
.. jupyter-execute::
from qiskit.converters import ast_to_dag
from qiskit import qasm, QuantumCircuit, ClassicalRegister, QuantumRegister
from qiskit.visualization import dag_drawer
%matplotlib inline
q = QuantumRegister(3, 'q')
c = ClassicalRegister(3, 'c')
circ = QuantumCircuit(q, c)
circ.h(q[0])
circ.cx(q[0], q[1])
circ.measure(q[0], c[0])
circ.rz(0.5, q[1]).c_if(c, 2)
qasm_str = circ.qasm()
ast = qasm.Qasm(data=qasm_str).parse()
dag = ast_to_dag(ast)
dag_drawer(dag)
"""
dag = DAGCircuit()
AstInterpreter(dag)._process_node(ast)
return dag
class AstInterpreter:
"""Interprets an OpenQASM by expanding subroutines and unrolling loops."""
standard_extension = {"u1": U1Gate,
"u2": U2Gate,
"u3": U3Gate,
"x": XGate,
"y": YGate,
"z": ZGate,
"t": TGate,
"tdg": TdgGate,
"s": SGate,
"sdg": SdgGate,
"swap": SwapGate,
"rx": RXGate,
"rxx": RXXGate,
"ry": RYGate,
"rz": RZGate,
"rzz": RZZGate,
"id": IGate,
"h": HGate,
"cx": CXGate,
"cy": CYGate,
"cz": CZGate,
"ch": CHGate,
"crx": CRXGate,
"cry": CRYGate,
"crz": CRZGate,
"cu1": CU1Gate,
"cu3": CU3Gate,
"ccx": CCXGate,
"cswap": CSwapGate}
def __init__(self, dag):
"""Initialize interpreter's data."""
# DAG object to populate
self.dag = dag
# OPENQASM version number (ignored for now)
self.version = 0.0
# Dict of gates names and properties
self.gates = OrderedDict()
# Keeping track of conditional gates
self.condition = None
# List of dictionaries mapping local parameter ids to expression Nodes
self.arg_stack = [{}]
# List of dictionaries mapping local bit ids to global ids (name, idx)
self.bit_stack = [{}]
def _process_bit_id(self, node):
"""Process an Id or IndexedId node as a bit or register type.
Return a list of tuples (Register,index).
"""
reg = None
if node.name in self.dag.qregs:
reg = self.dag.qregs[node.name]
elif node.name in self.dag.cregs:
reg = self.dag.cregs[node.name]
else:
raise QiskitError("expected qreg or creg name:",
"line=%s" % node.line,
"file=%s" % node.file)
if node.type == "indexed_id":
# An indexed bit or qubit
return [reg[node.index]]
elif node.type == "id":
# A qubit or qreg or creg
if not self.bit_stack[-1]:
# Global scope
return list(reg)
else:
# local scope
if node.name in self.bit_stack[-1]:
return [self.bit_stack[-1][node.name]]
raise QiskitError("expected local bit name:",
"line=%s" % node.line,
"file=%s" % node.file)
return None
def _process_custom_unitary(self, node):
"""Process a custom unitary node."""
name = node.name
if node.arguments is not None:
args = self._process_node(node.arguments)
else:
args = []
bits = [self._process_bit_id(node_element)
for node_element in node.bitlist.children]
if name in self.gates:
gargs = self.gates[name]["args"]
gbits = self.gates[name]["bits"]
# Loop over register arguments, if any.
maxidx = max(map(len, bits))
for idx in range(maxidx):
self.arg_stack.append({gargs[j]: args[j]
for j in range(len(gargs))})
# Only index into register arguments.
element = [idx * x for x in
[len(bits[j]) > 1 for j in range(len(bits))]]
self.bit_stack.append({gbits[j]: bits[j][element[j]]
for j in range(len(gbits))})
self._create_dag_op(name,
[self.arg_stack[-1][s].sym() for s in gargs],
[self.bit_stack[-1][s] for s in gbits])
self.arg_stack.pop()
self.bit_stack.pop()
else:
raise QiskitError("internal error undefined gate:",
"line=%s" % node.line, "file=%s" % node.file)
def _process_gate(self, node, opaque=False):
"""Process a gate node.
If opaque is True, process the node as an opaque gate node.
"""
self.gates[node.name] = {}
de_gate = self.gates[node.name]
de_gate["print"] = True # default
de_gate["opaque"] = opaque
de_gate["n_args"] = node.n_args()
de_gate["n_bits"] = node.n_bits()
if node.n_args() > 0:
de_gate["args"] = [element.name for element in node.arguments.children]
else:
de_gate["args"] = []
de_gate["bits"] = [c.name for c in node.bitlist.children]
if node.name in self.standard_extension:
return
if opaque:
de_gate["body"] = None
else:
de_gate["body"] = node.body
def _process_cnot(self, node):
"""Process a CNOT gate node."""
id0 = self._process_bit_id(node.children[0])
id1 = self._process_bit_id(node.children[1])
if not (len(id0) == len(id1) or len(id0) == 1 or len(id1) == 1):
raise QiskitError("internal error: qreg size mismatch",
"line=%s" % node.line, "file=%s" % node.file)
maxidx = max([len(id0), len(id1)])
for idx in range(maxidx):
if len(id0) > 1 and len(id1) > 1:
self.dag.apply_operation_back(CXGate(), [id0[idx], id1[idx]], [], self.condition)
elif len(id0) > 1:
self.dag.apply_operation_back(CXGate(), [id0[idx], id1[0]], [], self.condition)
else:
self.dag.apply_operation_back(CXGate(), [id0[0], id1[idx]], [], self.condition)
def _process_measure(self, node):
"""Process a measurement node."""
id0 = self._process_bit_id(node.children[0])
id1 = self._process_bit_id(node.children[1])
if len(id0) != len(id1):
raise QiskitError("internal error: reg size mismatch",
"line=%s" % node.line, "file=%s" % node.file)
for idx, idy in zip(id0, id1):
self.dag.apply_operation_back(Measure(), [idx], [idy], self.condition)
def _process_if(self, node):
"""Process an if node."""
creg_name = node.children[0].name
creg = self.dag.cregs[creg_name]
cval = node.children[1].value
self.condition = (creg, cval)
self._process_node(node.children[2])
self.condition = None
def _process_children(self, node):
"""Call process_node for all children of node."""
for kid in node.children:
self._process_node(kid)
def _process_node(self, node):
"""Carry out the action associated with a node."""
if node.type == "program":
self._process_children(node)
elif node.type == "qreg":
qreg = QuantumRegister(node.index, node.name)
self.dag.add_qreg(qreg)
elif node.type == "creg":
creg = ClassicalRegister(node.index, node.name)
self.dag.add_creg(creg)
elif node.type == "id":
raise QiskitError("internal error: _process_node on id")
elif node.type == "int":
raise QiskitError("internal error: _process_node on int")
elif node.type == "real":
raise QiskitError("internal error: _process_node on real")
elif node.type == "indexed_id":
raise QiskitError("internal error: _process_node on indexed_id")
elif node.type == "id_list":
# We process id_list nodes when they are leaves of barriers.
return [self._process_bit_id(node_children)
for node_children in node.children]
elif node.type == "primary_list":
# We should only be called for a barrier.
return [self._process_bit_id(m) for m in node.children]
elif node.type == "gate":
self._process_gate(node)
elif node.type == "custom_unitary":
self._process_custom_unitary(node)
elif node.type == "universal_unitary":
args = self._process_node(node.children[0])
qid = self._process_bit_id(node.children[1])
for element in qid:
self.dag.apply_operation_back(U3Gate(*args, element), self.condition)
elif node.type == "cnot":
self._process_cnot(node)
elif node.type == "expression_list":
return node.children
elif node.type == "binop":
raise QiskitError("internal error: _process_node on binop")
elif node.type == "prefix":
raise QiskitError("internal error: _process_node on prefix")
elif node.type == "measure":
self._process_measure(node)
elif node.type == "format":
self.version = node.version()
elif node.type == "barrier":
ids = self._process_node(node.children[0])
qubits = []
for qubit in ids:
for j, _ in enumerate(qubit):
qubits.append(qubit[j])
self.dag.apply_operation_back(Barrier(len(qubits)), qubits, [])
elif node.type == "reset":
id0 = self._process_bit_id(node.children[0])
for i, _ in enumerate(id0):
self.dag.apply_operation_back(Reset(), [id0[i]], [], self.condition)
elif node.type == "if":
self._process_if(node)
elif node.type == "opaque":
self._process_gate(node, opaque=True)
elif node.type == "external":
raise QiskitError("internal error: _process_node on external")
else:
raise QiskitError("internal error: undefined node type",
node.type, "line=%s" % node.line,
"file=%s" % node.file)
return None
def _gate_definition_to_qiskit_definition(self, node, params):
"""From a gate definition in qasm, to a gate.definition format."""
definition = []
qreg = QuantumRegister(node['n_bits'])
bit_args = {node['bits'][i]: q for i, q in enumerate(qreg)}
exp_args = {node['args'][i]: Real(q) for i, q in enumerate(params)}
for child_op in node['body'].children:
qparams = []
eparams = []
for param_list in child_op.children[1:]:
if param_list.type == 'id_list':
qparams = [bit_args[param.name] for param in param_list.children]
elif param_list.type == 'expression_list':
for param in param_list.children:
eparams.append(param.sym(nested_scope=[exp_args]))
op = self._create_op(child_op.name, params=eparams)
definition.append((op, qparams, []))
return definition
def _create_dag_op(self, name, params, qargs):
"""
Create a DAG node out of a parsed AST op node.
Args:
name (str): operation name to apply to the DAG
params (list): op parameters
qargs (list(Qubit)): qubits to attach to
Raises:
QiskitError: if encountering a non-basis opaque gate
"""
op = self._create_op(name, params)
self.dag.apply_operation_back(op, qargs, [], condition=self.condition)
def _create_op(self, name, params):
if name in self.standard_extension:
op = self.standard_extension[name](*params)
elif name in self.gates:
if self.gates[name]['opaque']:
# call an opaque gate
op = Gate(name=name, num_qubits=self.gates[name]['n_bits'], params=params)
else:
# call a custom gate
op = Instruction(name=name,
num_qubits=self.gates[name]['n_bits'],
num_clbits=0,
params=params)
op.definition = self._gate_definition_to_qiskit_definition(self.gates[name],
params=params)
else:
raise QiskitError("unknown operation for ast node name %s" % name)
return op