Merge pull request #37 from hodgestar/feature/add-extern-port-statement

Add parser support for "extern port" and "extern frame" statements

Author: levbishop

source/grammar/openpulseParser.g4

@@ -30,6 +30,8 @@ openpulseStatement:
         | endStatement
         | expressionStatement
         | externStatement
+        | externFrameStatement
+        | externPortStatement
         | forStatement
         | gateCallStatement
         | ifStatement
@@ -59,3 +61,7 @@ scalarType:
     | PORT
     | FRAME
     ;
+
+
+externFrameStatement: EXTERN FRAME Identifier SEMICOLON;
+externPortStatement: EXTERN PORT Identifier SEMICOLON;

source/openpulse/openpulse/ast.py

@@ -131,6 +131,24 @@ class CalibrationBlock(QASMNode):
     body: List[Statement]
 
 
+@dataclass
+class ExternFrameStatement(QASMNode):
+    """
+    Node representing an extern frame statement.
+    """
+
+    name: Identifier
+
+
+@dataclass
+class ExternPortStatement(QASMNode):
+    """
+    Node representing an extern port statement.
+    """
+
+    name: Identifier
+
+
 # Override the class from openqasm3
 @dataclass
 class CalibrationStatement(Statement):

source/openpulse/openpulse/parser.py

@@ -43,6 +43,7 @@
     span,
     QASMNodeVisitor,
     _raise_from_context,
+    _visit_identifier,
     parse as parse_qasm3,
 )
 from openqasm3.visitor import QASMVisitor
@@ -194,6 +195,12 @@ def visitCalibrationBlock(self, ctx: openpulseParser.CalibrationBlockContext):
                 body=[self.visit(statement) for statement in ctx.openpulseStatement()]
             )
 
+    def visitExternFrameStatement(self, ctx: openpulseParser.OpenpulseStatementContext):
+        return openpulse_ast.ExternFrameStatement(name=_visit_identifier(ctx.Identifier()))
+
+    def visitExternPortStatement(self, ctx: openpulseParser.OpenpulseStatementContext):
+        return openpulse_ast.ExternPortStatement(name=_visit_identifier(ctx.Identifier()))
+
     def visitScalarType(self, ctx: openpulseParser.ScalarTypeContext):
         if ctx.WAVEFORM() or ctx.PORT() or ctx.FRAME():
             return self._visitPulseType(ctx)

source/openpulse/tests/test_openpulse_parser.py

@@ -399,9 +399,11 @@ def test_permissive_parsing(capsys):
             port xy_port;
             port tx_port;
             port rx_port;
+            extern port cx_port;
             frame xy_frame = newframe(xy_port, 3714500000.0, 0);
             frame tx_frame = newframe(tx_port, 7883050000.0, 0);
             frame rx_frame = newframe(rx_port, 7883050000.0, 0);
+            extern frame cx_frame;
             waveform rabi_pulse_wf = gaussian(1e-07, 2.5e-08, 1.0, 0.0);
             waveform readout_waveform_wf = constant(5e-06, 0.03);
             waveform readout_kernel_wf = constant(5e-06, 1.0);