Adding initial pass at pyzx ir transformation

Signed-off-by: Alex McCaskey <mccaskeyaj@ornl.gov>

python/CMakeLists.txt

@@ -47,5 +47,6 @@ file(GLOB PYDECORATORS benchmark/chemistry/*.py benchmark/qpt/*.py
                        plugins/cirq/*.py
                        plugins/qiskit/*.py
                        plugins/observables/*.py
+                       plugins/pyzx/*.py
                        plugins/optimizers/*.py)
 install(FILES ${PYDECORATORS} DESTINATION ${CMAKE_INSTALL_PREFIX}/py-plugins)

python/examples/pyzx_example.py

+import xacc
+
+qpu = xacc.getAccelerator('aer', {'sim-type':'statevector'})
+q = xacc.qalloc(2)
+
+# Create a bell state program with too many cnots
+xacc.qasm('''
+.compiler xasm
+.circuit foo
+.parameters x,y,z
+.qbit q
+H(q[0]);
+CX(q[0], q[1]);
+CX(q[0], q[1]);
+CX(q[0], q[1]);
+Measure(q[0]);
+Measure(q[1]);
+''')
+f = xacc.getCompiled('foo')
+
+# Run the python contributed IRTransformation that uses qiskit
+optimizer = xacc.getIRTransformation('pyzx')
+optimizer.apply(f, None, {})
+
+# should have 4 instructions, not 6
+assert(4 == f.nInstructions())
+print(f.toString())
+
+qbits = xacc.qalloc(2)
+qpu.execute(qbits, f)
+
+print(qbits)

python/plugins/pyzx/README.md

+To use this plugin, you need pyzx greater than 0.5.1. As of this 
+writing you have to install from source
+
+```bash
+$ git clone https://github.com/Quantomatic/pyzx && cd pyzx
+$ python3 -m pip install . --user
+```
\ No newline at end of file

python/plugins/pyzx/pyzx_pass.py

+import xacc
+from pelix.ipopo.decorators import ComponentFactory, Property, Requires, Provides, \
+    Validate, Invalidate, Instantiate
+
+@ComponentFactory("pyzx_pass_factory")
+@Provides("irtransformation")
+@Property("_irtransformation", "irtransformation", "pyzx")
+@Property("_name", "name", "pyzx")
+@Instantiate("pyzx_pass_instance")
+class PyzxIRTransformation(xacc.IRTransformation):
+    def __init__(self):
+        xacc.IRTransformation.__init__(self)
+
+    def type(self):
+        return xacc.IRTransformationType.Optimization
+
+    def name(self):
+        return 'pyzx'
+
+    def apply(self, program, accelerator, options):
+        # Import qiskit modules here so that users
+        # who don't have qiskit can still use rest of xacc
+        from pyzx.circuit import Circuit
+        from pyzx import simplify, extract, optimize
+
+        # Map CompositeInstruction program to OpenQasm string
+        openqasm_compiler = xacc.getCompiler('staq')
+        src = openqasm_compiler.translate(program).replace('\\','')
+      
+        measures = []
+        lines = src.split('\n')
+        for l in lines:
+            if 'measure' in l or 'creg' in l:
+                measures.append(l)
+        
+        c = Circuit.from_qasm(src)
+        g = c.to_graph()
+        
+        simplify.full_reduce(g,quiet=True)
+        c2 = extract.extract_circuit(g)
+        c3 = optimize.basic_optimization(c2.to_basic_gates())
+        c3 = c3.to_basic_gates()
+        c3 = c3.split_phase_gates()
+        output = c3.to_qasm()
+        for measure in measures:
+            output += '\n' + measure
+
+        # Map the output to OpenQasm and map to XACC IR
+        out_prog = openqasm_compiler.compile(output, accelerator).getComposites()[0]
+
+        # update the given program CompositeInstruction reference
+        program.clear()
+        for inst in out_prog.getInstructions():
+            program.addInstruction(inst)
+
+        return
+
+
+
+
+
+
+
+