Add support for nested functions

trans/transpiler/phases/emit_cpp/__init__.py

@@ -111,6 +111,7 @@ class FunctionEmissionKind(enum.Enum):
     DECLARATION = enum.auto()
     DEFINITION = enum.auto()
     METHOD = enum.auto()
+    LAMBDA = enum.auto()
 
 def join(sep: str, items: Iterable[Iterable[str]]) -> Iterable[str]:
     items = iter(items)

trans/transpiler/phases/emit_cpp/block.py

@@ -56,6 +56,9 @@ class BlockVisitor(NodeVisitor):
             yield f"}} {node.name};"
 
     def visit_func_new(self, node: ast.FunctionDef, emission: FunctionEmissionKind, skip_first_arg: bool = False) -> Iterable[str]:
+        if emission == FunctionEmissionKind.LAMBDA:
+            yield "[&]"
+        else:
             if emission == FunctionEmissionKind.METHOD:
                 yield "template <typename Self>"
             yield from self.visit(node.type.return_type)
@@ -89,6 +92,10 @@ class BlockVisitor(NodeVisitor):
             yield ";"
             return
 
+        if emission == FunctionEmissionKind.LAMBDA:
+            yield "->"
+            yield from self.visit(node.type.return_type)
+
         yield "{"
 
         class ReturnVisitor(SearchVisitor):

trans/transpiler/phases/emit_cpp/function.py

@@ -113,3 +113,9 @@ class FunctionVisitor(BlockVisitor):
             #yield from self.visit(handler)
             pass
             # todo
+    def visit_FunctionDef(self, node: ast.FunctionDef) -> Iterable[str]:
+        yield "auto"
+        yield self.fix_name(node.name)
+        yield "="
+        yield from self.visit_func_new(node, FunctionEmissionKind.LAMBDA)
+        yield ";"

trans/transpiler/phases/typing/common.py

@@ -5,7 +5,7 @@ from typing import Dict, Optional
 from transpiler.utils import highlight
 from transpiler.phases.typing.annotations import TypeAnnotationVisitor
 from transpiler.phases.typing.scope import Scope, ScopeKind, VarDecl
-from transpiler.phases.typing.types import BaseType, TypeVariable, TY_NONE, TypeType
+from transpiler.phases.typing.types import BaseType, TypeVariable, TY_NONE, TypeType, BuiltinFeature
 from transpiler.phases.utils import NodeVisitorSeq
 
 PRELUDE = Scope.make_global()
@@ -16,6 +16,10 @@ class ScoperVisitor(NodeVisitorSeq):
     root_decls: Dict[str, VarDecl] = field(default_factory=dict)
     cur_class: Optional[TypeType] = None
 
+    def expr(self) -> "ScoperExprVisitor":
+        from transpiler.phases.typing.expr import ScoperExprVisitor
+        return ScoperExprVisitor(self.scope, self.root_decls)
+
     def anno(self) -> "TypeAnnotationVisitor":
         return TypeAnnotationVisitor(self.scope, self.cur_class)
 
@@ -58,7 +62,15 @@ class ScoperVisitor(NodeVisitorSeq):
         for b in node.body:
             decls = {}
             visitor = ScoperBlockVisitor(node.inner_scope, decls)
+            visitor.fdecls = []
             visitor.visit(b)
+            if len(visitor.fdecls) > 1:
+                raise NotImplementedError("?")
+            elif len(visitor.fdecls) == 1:
+                fnode, frtype = visitor.fdecls[0]
+                self.visit_function_definition(fnode, frtype)
+                del node.inner_scope.vars[fnode.name]
+                visitor.visit_assign_target(ast.Name(fnode.name), fnode.type)
             b.decls = decls
         if not node.inner_scope.has_return:
             rtype.unify(TY_NONE)  # todo: properly indicate missing return
@@ -78,3 +90,6 @@ def get_next(iter_type):
         from transpiler.phases.typing.exceptions import NotIteratorError
         raise NotIteratorError(iter_type)
     return next_type
+
+def is_builtin(x, feature):
+    return isinstance(x, BuiltinFeature) and x.val == feature
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