Makefile

@@ -8,7 +8,7 @@ server:
 	python3.8 -m http.server
 
 test: venv/.done
-	venv/bin/pytest tests
+	venv/bin/pytest tests $(TEST_FLAGS)
 
 lint: venv/.done
 	venv/bin/pylint py2wasm

README.md

@@ -2,3 +2,9 @@ webasm (python)
 ===============
 
 You will need wat2wasm from github.com/WebAssembly/wabt in your path.
+
+Ideas
+=====
+- https://github.com/wasmerio/wasmer-python
+- https://github.com/diekmann/wasm-fizzbuzz
+- https://blog.scottlogic.com/2018/04/26/webassembly-by-hand.html

py2wasm/python.py

@@ -127,6 +127,9 @@ class Visitor:
 
             return self.visit_Call(module, wlocals, "None", stmt.value)
 
+        if isinstance(stmt, ast.If):
+            return self.visit_If(module, func, wlocals, stmt)
+
         raise NotImplementedError(stmt)
 
     def visit_Return(
@@ -137,14 +140,44 @@ class Visitor:
             stmt: ast.Return,
         ) -> StatementGenerator:
         """
-        Visits a statement node
+        Visits a Return node
         """
 
         assert stmt.value is not None
 
         return_type = _parse_annotation(func.returns)
 
-        return self.visit_expr(module, wlocals, return_type, stmt.value)
+        yield from self.visit_expr(module, wlocals, return_type, stmt.value)
+        yield wasm.Statement('return')
+
+    def visit_If(
+            self,
+            module: wasm.Module,
+            func: ast.FunctionDef,
+            wlocals: WLocals,
+            stmt: ast.If,
+        ) -> StatementGenerator:
+        """
+        Visits an If node
+        """
+        yield from self.visit_expr(
+            module,
+            wlocals,
+            'bool',
+            stmt.test,
+        )
+
+        yield wasm.Statement('if')
+
+        for py_stmt in stmt.body:
+            yield from self.visit_stmt(module, func, wlocals, py_stmt)
+
+        yield wasm.Statement('else')
+
+        for py_stmt in stmt.orelse:
+            yield from self.visit_stmt(module, func, wlocals, py_stmt)
+
+        yield wasm.Statement('end')
 
     def visit_expr(
             self,
@@ -159,6 +192,12 @@ class Visitor:
         if isinstance(node, ast.BinOp):
             return self.visit_BinOp(module, wlocals, exp_type, node)
 
+        if isinstance(node, ast.UnaryOp):
+            return self.visit_UnaryOp(module, wlocals, exp_type, node)
+
+        if isinstance(node, ast.Compare):
+            return self.visit_Compare(module, wlocals, exp_type, node)
+
         if isinstance(node, ast.Call):
             return self.visit_Call(module, wlocals, exp_type, node)
 
@@ -170,6 +209,24 @@ class Visitor:
 
         raise NotImplementedError(node)
 
+    def visit_UnaryOp(
+            self,
+            module: wasm.Module,
+            wlocals: WLocals,
+            exp_type: str,
+            node: ast.UnaryOp,
+        ) -> StatementGenerator:
+        """
+        Visits a UnaryOp node as (part of) an expression
+        """
+        del module
+        del wlocals
+
+        if not isinstance(node.operand, ast.Constant):
+            raise NotImplementedError
+
+        return self.visit_Constant(exp_type, node.operand)
+
     def visit_BinOp(
             self,
             module: wasm.Module,
@@ -189,6 +246,34 @@ class Visitor:
 
         raise NotImplementedError(node.op)
 
+    def visit_Compare(
+            self,
+            module: wasm.Module,
+            wlocals: WLocals,
+            exp_type: str,
+            node: ast.Compare,
+        ) -> StatementGenerator:
+        """
+        Visits a Compare node as (part of) an expression
+        """
+        assert 'bool' == exp_type
+
+        if 1 != len(node.ops) or 1 != len(node.comparators):
+            raise NotImplementedError
+
+        yield from self.visit_expr(module, wlocals, 'i32', node.left)
+        yield from self.visit_expr(module, wlocals, 'i32', node.comparators[0])
+
+        if isinstance(node.ops[0], ast.Lt):
+            yield wasm.Statement('i32.lt_s')
+            return
+
+        if isinstance(node.ops[0], ast.Gt):
+            yield wasm.Statement('i32.gt_s')
+            return
+
+        raise NotImplementedError(node.ops)
+
     def visit_Call(
             self,
             module: wasm.Module,

requirements.txt

@@ -1,4 +1,5 @@
 mypy==0.812
 pylint==2.7.4
 pytest==6.2.2
+pytest-integration==0.2.2
 pywasm==1.0.7

tests/integration/test_fib.py

@@ -1,5 +1,8 @@
+import pytest
+
 from .helpers import Suite
 
+@pytest.mark.slow_integration_test
 def test_fib():
     code_py = """
 def helper(n: i32, a: i32, b: i32) -> i32:

tests/integration/test_simple.py

@@ -1,5 +1,8 @@
+import pytest
+
 from .helpers import Suite
 
+@pytest.mark.integration_test
 def test_return():
     code_py = """
 @exported
@@ -7,11 +10,25 @@ def testEntry() -> i32:
     return 13
 """
 
-    result = Suite(code_py, 'test_fib').run_code()
+    result = Suite(code_py, 'test_return').run_code()
 
     assert 13 == result.returned_value
     assert [] == result.log_int32_list
 
+@pytest.mark.integration_test
+def test_arg():
+    code_py = """
+@exported
+def testEntry(a: i32) -> i32:
+    return a
+"""
+
+    result = Suite(code_py, 'test_return').run_code(125)
+
+    assert 125 == result.returned_value
+    assert [] == result.log_int32_list
+
+@pytest.mark.integration_test
 def test_addition():
     code_py = """
 @exported
@@ -19,11 +36,57 @@ def testEntry() -> i32:
     return 10 + 3
 """
 
-    result = Suite(code_py, 'test_fib').run_code()
+    result = Suite(code_py, 'test_addition').run_code()
 
     assert 13 == result.returned_value
     assert [] == result.log_int32_list
 
+@pytest.mark.integration_test
+def test_if_simple():
+    code_py = """
+@exported
+def testEntry(a: i32) -> i32:
+    if a > 10:
+        return 1
+
+    return 0
+"""
+
+    suite = Suite(code_py, 'test_return')
+
+    result = suite.run_code(10)
+    assert 0 == result.returned_value
+    assert [] == result.log_int32_list
+
+    result = suite.run_code(11)
+    assert 1 == result.returned_value
+
+@pytest.mark.integration_test
+def test_if_complex():
+    code_py = """
+@exported
+def testEntry(a: i32) -> i32:
+    if a > 10:
+        return 10
+    elif a > 0:
+        return a
+    else:
+        return 0
+
+    return -1 # Required due to function type
+"""
+
+    suite = Suite(code_py, 'test_return')
+
+    assert 10 == suite.run_code(20).returned_value
+    assert 10 == suite.run_code(10).returned_value
+
+    assert 8 == suite.run_code(8).returned_value
+
+    assert 0 == suite.run_code(0).returned_value
+    assert 0 == suite.run_code(-1).returned_value
+
+@pytest.mark.integration_test
 def test_call():
     code_py = """
 def helper(left: i32, right: i32) -> i32:
@@ -34,7 +97,7 @@ def testEntry() -> i32:
     return helper(10, 3)
 """
 
-    result = Suite(code_py, 'test_fib').run_code()
+    result = Suite(code_py, 'test_call').run_code()
 
     assert 13 == result.returned_value
     assert [] == result.log_int32_list