py2wasm/python.py

@@ -72,7 +72,37 @@ class Visitor:
 
                 return wasm.Import(module, name, intname, _parse_import_args(node.args))
 
-        return wasm.Function(node.name, exported)
+        result = _parse_annotation(node.returns)
+
+        statements = [
+            self.visit_stmt(node, stmt)
+            for stmt in node.body
+        ]
+
+        return wasm.Function(node.name, exported, result, statements)
+
+    def visit_stmt(self, func: ast.FunctionDef, stmt: ast.stmt) -> wasm.Statement:
+        """
+        Visits a statement node
+        """
+        if isinstance(stmt, ast.Return):
+            return self.visit_Return(func, stmt)
+
+        raise NotImplementedError
+
+    def visit_Return(self, func: ast.FunctionDef, stmt: ast.Return) -> wasm.Statement:
+        """
+        Visits a statement node
+        """
+        assert isinstance(stmt.value, ast.Constant)
+        assert isinstance(stmt.value.value, int)
+
+        return_type = _parse_annotation(func.returns)
+
+        return wasm.Statement(
+            '{}.const'.format(return_type),
+            str(stmt.value.value)
+        )
 
 def _parse_import_decorator(func_name: str, args: List[ast.expr]) -> Tuple[str, str, str]:
     """

py2wasm/wasm.py

@@ -2,7 +2,7 @@
 Python classes for storing the representation of Web Assembly code
 """
 
-from typing import Iterable, List, Tuple
+from typing import Iterable, List, Optional, Tuple
 
 class Import:
     """
@@ -49,12 +49,18 @@ class Function:
     """
     Represents a Web Assembly function
     """
-    def __init__(self, name: str, exported: bool = True) -> None:
+    def __init__(
+            self,
+            name: str,
+            exported: bool,
+            result: Optional[str],
+            statements: Iterable[Statement],
+        ) -> None:
         self.name = name
         self.exported = exported
         self.params: List[Tuple[str, str]] = []
-        self.returns = None
+        self.result = result
-        self.statements: List[Statement] = []
+        self.statements = [*statements]
 
     def generate(self) -> str:
         """
@@ -65,6 +71,9 @@ class Function:
         for nam, typ in self.params:
             header += ' (param ${} {})'.format(nam, typ)
 
+        if self.result:
+            header += ' (result {})'.format(self.result)
+
         return '(func {}\n    {})'.format(
             header,
             '\n    '.join(x.generate() for x in self.statements),

tests/integration/test_simple.py

@@ -0,0 +1,13 @@
+from .helpers import Suite
+
+def test_return():
+    code_py = """
+@exported
+def testEntry() -> i32:
+    return 13
+"""
+
+    result = Suite(code_py, 'test_fib').run_code()
+
+    assert 13 is result.returned_value
+    assert [] == result.log_int32_list