#2716 add InterfaceDeclGen to f2pygen

src/psyclone/f2pygen.py

@@ -1275,6 +1275,58 @@ def _check_initial_values(self, _type, _values):
             "for derived-type declarations are not supported.")
 
 
+class InterfaceDeclGen(BaseDeclGen):
+    '''
+    Generates the declaration for a Fortran interface block of the form:
+
+        interface my_wrapper
+          module procedure :: name1, name1, ...
+        end interface my_wrapper
+
+    The declaration is added to the supplied parent node.
+
+    :param parent: f2pygen node to which to add this declaration as a child.
+    :type parent: :py:class:`psyclone.f2pygen.ModuleGen`
+    :param str name: the name of the interface block.
+    :param entity_decls: names of procedures to declare within the block.
+    :type entity_decls: list[str]
+
+    :raises TypeError: if the supplied parent is not a ModuleGen (since
+                       interfaces must be declared within modules).
+    :raises ValueError: if a list of procedure names is not supplied.
+
+    '''
+    def __init__(self, parent, name, entity_decls):
+        if not isinstance(parent, ModuleGen):
+            raise TypeError(f"An InterfaceDeclGen must have a ModuleGen as "
+                            f"parent but got '{type(parent).__name__}'")
+        if not isinstance(entity_decls, list) or not entity_decls:
+            raise ValueError(
+                f"The routine names to use within Interface '{name}' must be "
+                f"supplied as a list of str to 'entity_decls' but got "
+                f"{entity_decls}")
+        name_list = ", ".join(entity_decls)
+        reader = FortranStringReader(f"interface {name}\n"
+                                     f"  module procedure :: {name_list}\n"
+                                     f"end interface {name}\n")
+        reader.set_format(FortranFormat(True, True))  # free form, strict
+        line1 = reader.next()
+        interf = fparser1.block_statements.Interface(parent.root, line1)
+        line2 = reader.next()
+        procedures = fparser1.block_statements.ModuleProcedure(parent.root,
+                                                               line2)
+        interf.content.append(procedures)
+        line3 = reader.next()
+        end_interf = fparser1.block_statements.EndInterface(interf, line3)
+        self._decl = interf
+        interf.content.append(end_interf)
+
+    def _check_initial_values(self):
+        '''
+        Empty routine required to override that from abstract base class.
+        '''
+
+
 class TypeCase(Case):
     ''' Generate a Fortran SELECT CASE statement '''
     # TODO can this whole class be deleted?

src/psyclone/tests/f2pygen_test.py

@@ -40,7 +40,8 @@
 from psyclone.f2pygen import (
     adduse, AssignGen, AllocateGen, BaseGen, CallGen, CharDeclGen, CommentGen,
     DeallocateGen, DeclGen, DirectiveGen, DoGen, IfThenGen, ImplicitNoneGen,
-    ModuleGen, PSyIRGen, SelectionGen, SubroutineGen, TypeDeclGen, UseGen)
+    InterfaceDeclGen, ModuleGen, PSyIRGen, SelectionGen, SubroutineGen,
+    TypeDeclGen, UseGen)
 from psyclone.errors import GenerationError, InternalError
 from psyclone.psyir.nodes import Node, Return
 from psyclone.tests.utilities import Compile, count_lines, line_number
@@ -1342,7 +1343,6 @@ def test_declgen_multiple_use2():
     sub.add(DeclGen(sub, datatype="integer",
                     entity_decls=datanames))
     gen = str(sub.root)
-    print(gen)
     expected = (
         "      INTEGER data1, data2\n"
         "      REAL data1")
@@ -1351,6 +1351,36 @@ def test_declgen_multiple_use2():
     assert datanames == ["data1", "data2"]
 
 
+def test_interfacedeclgen():
+    '''Tests for InterfaceDeclGen.'''
+    module = ModuleGen(name="testmodule")
+    sub1 = SubroutineGen(module, name="sub32")
+    module.add(sub1)
+    sub2 = SubroutineGen(module, name="sub64")
+    module.add(sub2)
+    with pytest.raises(TypeError) as err:
+        InterfaceDeclGen(sub1, name="my_interface", entity_decls=[])
+    assert ("An InterfaceDeclGen must have a ModuleGen as parent"
+            in str(err.value))
+    with pytest.raises(ValueError) as err:
+        InterfaceDeclGen(module, name="my_interface", entity_decls=[])
+    assert ("The routine names to use within Interface 'my_interface' must be"
+            in str(err.value))
+    module.add(InterfaceDeclGen(module, name="my_interface",
+                                entity_decls=["sub32", "sub64"]))
+    gen = str(module.root).lower()
+    expected = """\
+  module testmodule
+    implicit none
+    interface my_interface
+    module procedure sub32, sub64
+    end interface my_interface
+    contains"""
+    assert expected in gen
+    # Can't compile this without properly creating subroutines with arguments
+    # of different precisions.
+
+
 @pytest.mark.xfail(reason="No way to add body of DEFAULT clause")
 def test_selectiongen():
     ''' Check that SelectionGen works as expected '''
@@ -1364,7 +1394,6 @@ def test_selectiongen():
     # TODO how do we specify what happens in the default case?
     sgen.adddefault()
     gen = str(sub.root)
-    print(gen)
     expected = ("SELECT CASE ( my_var )\n"
                 "CASE ( 1 )\n"
                 "        happy = .TRUE.\n"