Emit forward declarations for free functions

trans/tests/a.py

+# coding: utf-8
+
+# https://lab.nexedi.com/xavier_thompson/typon-snippets/blob/master/module/mymodule.cpp
+def f():
+    return 1 + g()
+
+def g():
+    return f()
+
+class T:
+    def f(self):
+        return 1 + self.g()
+
+    def g(self):
+        return self.f()
+
+if __name__ == "__main__":
+    pass
\ No newline at end of file

trans/transpiler/phases/emit_cpp/__init__.py

 # coding: utf-8
 import ast
+import enum
 from enum import Flag
 from itertools import chain
 from typing import Iterable
@@ -94,6 +95,11 @@ class CoroutineMode(Flag):
     TASK = 16 | ASYNC
     JOIN = 32 | ASYNC
 
+class FunctionEmissionKind(enum.Enum):
+    DECLARATION = enum.auto()
+    DEFINITION = enum.auto()
+    METHOD = enum.auto()
+
 def join(sep: str, items: Iterable[Iterable[str]]) -> Iterable[str]:
     items = iter(items)
     try:

trans/transpiler/phases/emit_cpp/block.py

@@ -6,7 +6,7 @@ from typing import Iterable, Optional
 from transpiler.phases.typing.scope import Scope
 from transpiler.phases.typing.types import BaseType, TY_INT, TY_BOOL, TypeVariable, Promise
 from transpiler.utils import compare_ast
-from transpiler.phases.emit_cpp import NodeVisitor, CoroutineMode, flatmap
+from transpiler.phases.emit_cpp import NodeVisitor, CoroutineMode, flatmap, FunctionEmissionKind
 from transpiler.phases.emit_cpp.expr import ExpressionVisitor
 from transpiler.phases.emit_cpp.search import SearchVisitor
 
@@ -26,7 +26,12 @@ class BlockVisitor(NodeVisitor):
         yield ";"
 
     def visit_FunctionDef(self, node: ast.FunctionDef) -> Iterable[str]:
+        yield from self.visit_free_func(node)
+
+    def visit_free_func(self, node: ast.FunctionDef, emission: FunctionEmissionKind) -> Iterable[str]:
         if getattr(node, "is_main", False):
+            if emission == FunctionEmissionKind.DECLARATION:
+                return
             # Special case handling for Python's interesting way of defining an entry point.
             # I mean, it's not *that* bad, it's just an attempt at retrofitting an "entry point" logic in a scripting
             # language that, by essence, uses "the start of the file" as the implicit entry point, since files are
@@ -44,49 +49,16 @@ class BlockVisitor(NodeVisitor):
             yield from FunctionVisitor(self.scope, CoroutineMode.TASK).emit_block(node.scope, block())
             return
 
-        yield "struct {"
-        yield from self.visit_func_new(node)
-        yield f"}} {node.name};"
-        return
-
-        yield "struct {"
-        yield from self.visit_func(node, CoroutineMode.FAKE)
-
-        class YieldVisitor(SearchVisitor):
-            def visit_Yield(self, node: ast.Yield) -> bool:
-                yield CoroutineMode.GENERATOR
-
-            def visit_FunctionDef(self, node: ast.FunctionDef):
-                yield from ()
-
-            def visit_ClassDef(self, node: ast.ClassDef):
-                yield from ()
-
-            def visit_Call(self, node: ast.Call):
-                func = node.func
-                if compare_ast(func, ast.parse("fork", mode="eval").body):
-                    yield CoroutineMode.JOIN
-                yield from ()
-
-        func_type = YieldVisitor().match(node.body)
-        if func_type is False:
-            func_type = CoroutineMode.TASK
-        yield from self.visit_func(node, func_type)
-        if func_type == CoroutineMode.GENERATOR:
-            templ, args, names = self.process_args(node.args)
-            if templ:
-                yield "template"
-                yield templ
-            yield f"auto operator()"
-            yield args
-            yield f"-> typon::Task<decltype(gen({', '.join(names)}))>"
-            yield "{"
-            yield f"co_return std::move(gen({', '.join(names)}));"
-            yield "}"
-        yield f"}} {node.name};"
+        if emission == FunctionEmissionKind.DECLARATION:
+            yield f"struct {node.name}_inner {{"
+        yield from self.visit_func_new(node, emission)
+        if emission == FunctionEmissionKind.DECLARATION:
+            yield f"}} {node.name};"
 
-    def visit_func_new(self, node: ast.FunctionDef, skip_first_arg: bool = False) -> Iterable[str]:
+    def visit_func_new(self, node: ast.FunctionDef, emission: FunctionEmissionKind, skip_first_arg: bool = False) -> Iterable[str]:
         yield from self.visit(node.type.return_type)
+        if emission == FunctionEmissionKind.DEFINITION:
+            yield f"{node.name}_inner::"
         yield "operator()"
         yield "("
         args_iter = zip(node.args.args, node.type.parameters)
@@ -101,6 +73,10 @@ class BlockVisitor(NodeVisitor):
 
         inner_scope = node.inner_scope
 
+        if emission == FunctionEmissionKind.DECLARATION:
+            yield ";"
+            return
+
         yield "{"
 
         class ReturnVisitor(SearchVisitor):
@@ -133,123 +109,6 @@ class BlockVisitor(NodeVisitor):
 
         yield "}"
 
-
-    def visit_func(self, node: ast.FunctionDef, generator: CoroutineMode) -> Iterable[str]:
-        templ, args, names = self.process_args(node.args)
-        if templ:
-            yield "template"
-            yield templ
-
-        class ReturnVisitor(SearchVisitor):
-            def visit_Return(self, node: ast.Return) -> bool:
-                yield True
-
-            def visit_Yield(self, node: ast.Yield) -> bool:
-                yield True
-
-            def visit_FunctionDef(self, node: ast.FunctionDef):
-                yield from ()
-
-            def visit_ClassDef(self, node: ast.ClassDef):
-                yield from ()
-
-        has_return = ReturnVisitor().match(node.body)
-
-        if CoroutineMode.SYNC in generator:
-            if has_return:
-                yield "auto"
-            else:
-                yield "void"
-            yield "sync"
-        elif CoroutineMode.GENERATOR in generator:
-            yield "auto gen"
-        else:
-            yield "auto operator()"
-        yield args
-        if CoroutineMode.ASYNC in generator:
-            yield "-> typon::"
-            if CoroutineMode.TASK in generator:
-                yield "Task"
-            elif CoroutineMode.GENERATOR in generator:
-                yield "Generator"
-            elif CoroutineMode.JOIN in generator:
-                yield "Join"
-            yield f"<decltype(sync({', '.join(names)}))>"
-        yield "{"
-        inner_scope = node.inner_scope
-
-        for child in node.body:
-            # Python uses module- and function- level scoping. Blocks, like conditionals and loops, do not form scopes
-            # on their own. Variables are still accessible in the remainder of the parent function or in the global
-            # scope if outside a function.
-            # This is different from C++, where scope is tied to any code block. To emulate this behavior, we need to
-            # declare all variables in the first inner scope of a function.
-            # For example,
-            # ```py
-            # def f():
-            #     if True:
-            #         x = 1
-            #     print(x)
-            # ```
-            # is translated to
-            # ```cpp
-            # auto f() {
-            #     decltype(1) x;
-            #     if (true) {
-            #         x = 1;
-            #     }
-            #     print(x);
-            # }
-            # ```
-            # `decltype` allows for proper typing (`auto` can't be used for variables with values later assigned, since
-            # this would require real type inference, akin to what Rust does).
-            # This is only done, though, for *nested* blocks of a function. Root-level variables are declared with
-            # `auto`:
-            # ```py
-            # x = 1
-            # def f():
-            #     y = 2
-            # ```
-            # is translated to
-            # ```cpp
-            # auto x = 1;
-            # auto f() {
-            #     auto y = 2;
-            # }
-            # ```
-            from transpiler.phases.emit_cpp.function import FunctionVisitor
-            child_visitor = FunctionVisitor(inner_scope, generator)
-
-            if True:
-                for name, decl in getattr(child, "decls", {}).items():
-                    #yield f"decltype({' '.join(self.expr().visit(decl.type))}) {name};"
-                    yield from self.visit(decl.type)
-                    yield f" {name};"
-                yield from child_visitor.visit(child)
-            else:
-                # We need to do this in two-passes. This unfortunately breaks our nice generator state-machine architecture.
-                # Fair enough.
-                # TODO(zdimension): break this in two visitors
-                [*child_code] = child_visitor.visit(child)
-
-                # Hoist inner variables to the root scope.
-                for var, decl in child_visitor.scope.vars.items():
-                    if decl.kind == VarKind.LOCAL:  # Nested declarations become `decltype` declarations.
-                        if getattr(decl.val[1], "in_await", False):
-                            # TODO(zdimension): really?
-                            yield f"decltype({decl.val[0][9:]}.operator co_await().await_resume()) {var};"
-                        else:
-                            yield f"decltype({decl.val[0]}) {var};"
-                    elif decl.kind in (VarKind.GLOBAL, VarKind.NONLOCAL):  # `global` and `nonlocal` just get hoisted as-is.
-                        inner_scope.vars[var] = decl
-                yield from child_code  # Yeet back the child node code.
-        if CoroutineMode.FAKE in generator:
-            yield "TYPON_UNREACHABLE();"  # So the compiler doesn't complain about missing return statements.
-        elif CoroutineMode.ASYNC in generator and CoroutineMode.GENERATOR not in generator:
-            if not has_return:
-                yield "co_return;"
-        yield "}"
-
     def visit_lvalue(self, lvalue: ast.expr, declare: bool = False) -> Iterable[str]:
         if isinstance(lvalue, ast.Tuple):
             yield f"std::tie({', '.join(flatmap(self.visit_lvalue, lvalue.elts))})"

trans/transpiler/phases/emit_cpp/class_.py

@@ -4,7 +4,7 @@ from typing import Iterable
 
 from dataclasses import dataclass
 from transpiler.phases.typing.scope import Scope
-from transpiler.phases.emit_cpp import NodeVisitor
+from transpiler.phases.emit_cpp import NodeVisitor, FunctionEmissionKind
 
 
 class ClassVisitor(NodeVisitor):
@@ -47,7 +47,7 @@ class ClassInnerVisitor(NodeVisitor):
         yield "struct {"
         yield "type* self;"
         from transpiler.phases.emit_cpp.block import BlockVisitor
-        yield from BlockVisitor(self.scope).visit_func_new(node, True)
+        yield from BlockVisitor(self.scope).visit_func_new(node, FunctionEmissionKind.METHOD, True)
         yield f"}} {node.name} {{ this }};"
 
 @dataclass

trans/transpiler/phases/emit_cpp/file.py

@@ -3,7 +3,7 @@ import ast
 from typing import Iterable
 
 from transpiler.phases.emit_cpp.block import BlockVisitor
-from transpiler.phases.emit_cpp.module import ModuleVisitor
+from transpiler.phases.emit_cpp.module import ModuleVisitor, ModuleVisitor2
 
 
 # noinspection PyPep8Naming
@@ -17,6 +17,9 @@ class FileVisitor(BlockVisitor):
         yield from visitor.includes
         yield "namespace PROGRAMNS {"
         yield from code
+        visitor = ModuleVisitor2(self.scope)
+        code = [line for stmt in node.body for line in visitor.visit(stmt)]
+        yield from code
         yield "}"
         yield "int main(int argc, char* argv[]) {"
         yield "py_sys::all.argv = PyList<PyStr>(std::vector<PyStr>(argv, argv + argc));"

trans/transpiler/phases/emit_cpp/module.py

@@ -3,8 +3,8 @@ import ast
 from typing import Iterable
 
 from dataclasses import dataclass, field
-
-from transpiler.phases.emit_cpp import CoroutineMode
+from transpiler.phases.typing.scope import Scope
+from transpiler.phases.emit_cpp import CoroutineMode, FunctionEmissionKind, NodeVisitor
 from transpiler.phases.emit_cpp.block import BlockVisitor
 from transpiler.phases.emit_cpp.class_ import ClassVisitor
 from transpiler.phases.emit_cpp.function import FunctionVisitor
@@ -46,3 +46,17 @@ class ModuleVisitor(BlockVisitor):
 
     def visit_ClassDef(self, node: ast.ClassDef) -> Iterable[str]:
         yield from ClassVisitor().visit(node)
+
+    def visit_FunctionDef(self, node: ast.FunctionDef) -> Iterable[str]:
+        yield from super().visit_free_func(node, FunctionEmissionKind.DECLARATION)
+
+
+@dataclass
+class ModuleVisitor2(NodeVisitor):
+    scope: Scope
+    def visit_FunctionDef(self, node: ast.FunctionDef) -> Iterable[str]:
+        yield from BlockVisitor(self.scope).visit_free_func(node, FunctionEmissionKind.DEFINITION)
+
+    def visit_AST(self, node: ast.AST) -> Iterable[str]:
+        yield ""
+        pass