From f5115464ec29b5558473a14ad214dec8897dafb2 Mon Sep 17 00:00:00 2001
From: Erez Sh <erezshin@gmail.com>
Date: Mon, 30 Aug 2021 13:56:27 +0100
Subject: [PATCH 1/5] ast_utils: Added support for WithMeta (Initial)

---
 lark/ast_utils.py | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/lark/ast_utils.py b/lark/ast_utils.py
index b5463a2..f1ab317 100644
--- a/lark/ast_utils.py
+++ b/lark/ast_utils.py
@@ -19,13 +19,22 @@ class AsList(object):
     Subclasses will be instanciated with the parse results as a single list, instead of as arguments.
     """
 
+class WithMeta(object):
+    pass
+
 def camel_to_snake(name):
     return re.sub(r'(?<!^)(?=[A-Z])', '_', name).lower()
 
 def _call(func, _data, children, _meta):
     return func(*children)
+def _call_with_meta(func, _data, children, meta):
+    return func(meta, children)
+def _call_with_meta_inline(func, _data, children, meta):
+    return func(meta, *children)
 
 inline = v_args(wrapper=_call)
+with_meta = v_args(wrapper=_call_with_meta)
+with_meta_inline = v_args(wrapper=_call_with_meta_inline)
 
 def create_transformer(ast_module, transformer=None):
     """Collects `Ast` subclasses from the given module, and creates a Lark transformer that builds the AST.
@@ -45,7 +54,11 @@ def create_transformer(ast_module, transformer=None):
         if not name.startswith('_') and inspect.isclass(obj):
             if issubclass(obj, Ast):
                 if not issubclass(obj, AsList):
-                    obj = inline(obj).__get__(t)
+                        obj = with_meta_inline(obj).__get__(t)
+                    else:
+                        obj = inline(obj).__get__(t)
+                elif issubclass(obj, WithMeta):
+                    obj = with_meta(obj).__get__(t)
 
                 setattr(t, camel_to_snake(name), obj)
 

From a85f7d96675019efe2f35954dd4e71765fb99ee5 Mon Sep 17 00:00:00 2001
From: Erez Sh <erezshin@gmail.com>
Date: Mon, 30 Aug 2021 13:59:05 +0100
Subject: [PATCH 2/5] Oops

---
 lark/ast_utils.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lark/ast_utils.py b/lark/ast_utils.py
index f1ab317..a92dcbe 100644
--- a/lark/ast_utils.py
+++ b/lark/ast_utils.py
@@ -54,6 +54,7 @@ def create_transformer(ast_module, transformer=None):
         if not name.startswith('_') and inspect.isclass(obj):
             if issubclass(obj, Ast):
                 if not issubclass(obj, AsList):
+                    if issubclass(obj, WithMeta):
                         obj = with_meta_inline(obj).__get__(t)
                     else:
                         obj = inline(obj).__get__(t)

From 9638ad8edb62b6fa932b6020a934440d2a1c02b0 Mon Sep 17 00:00:00 2001
From: Erez Sh <erezshin@gmail.com>
Date: Tue, 31 Aug 2021 11:37:09 +0100
Subject: [PATCH 3/5] ast_utils: Refactor and improve interface

---
 examples/advanced/create_ast.py |  3 ++-
 lark/ast_utils.py               | 29 +++++++++--------------------
 2 files changed, 11 insertions(+), 21 deletions(-)

diff --git a/examples/advanced/create_ast.py b/examples/advanced/create_ast.py
index 537e8a8..c855d84 100644
--- a/examples/advanced/create_ast.py
+++ b/examples/advanced/create_ast.py
@@ -31,7 +31,8 @@ class _Statement(_Ast):
     pass
 
 @dataclass
-class Value(_Ast):
+class Value(_Ast, ast_utils.WithMeta):
+    meta: object
     value: object
 
 @dataclass
diff --git a/lark/ast_utils.py b/lark/ast_utils.py
index a92dcbe..3b8a12a 100644
--- a/lark/ast_utils.py
+++ b/lark/ast_utils.py
@@ -20,23 +20,16 @@ class AsList(object):
     """
 
 class WithMeta(object):
+    """Abstract class
+
+    Subclasses will be instanciated the Meta instance of the tree. (see ``v_args`` for more detail)
+    """
     pass
 
 def camel_to_snake(name):
     return re.sub(r'(?<!^)(?=[A-Z])', '_', name).lower()
 
-def _call(func, _data, children, _meta):
-    return func(*children)
-def _call_with_meta(func, _data, children, meta):
-    return func(meta, children)
-def _call_with_meta_inline(func, _data, children, meta):
-    return func(meta, *children)
-
-inline = v_args(wrapper=_call)
-with_meta = v_args(wrapper=_call_with_meta)
-with_meta_inline = v_args(wrapper=_call_with_meta_inline)
-
-def create_transformer(ast_module, transformer=None):
+def create_transformer(ast_module, transformer=None, decorator_factory=v_args):
     """Collects `Ast` subclasses from the given module, and creates a Lark transformer that builds the AST.
 
     For each class, we create a corresponding rule in the transformer, with a matching name.
@@ -47,20 +40,16 @@ def create_transformer(ast_module, transformer=None):
     Parameters:
         ast_module: A Python module containing all the subclasses of ``ast_utils.Ast``
         transformer (Optional[Transformer]): An initial transformer. Its attributes may be overwritten.
+        decorator_factory (Callable): An optional callable accepting two booleans, inline, and meta, 
+            and returning a decorator for the methods of ``transformer``. (default: ``v_args``).
     """
     t = transformer or Transformer()
 
     for name, obj in inspect.getmembers(ast_module):
         if not name.startswith('_') and inspect.isclass(obj):
             if issubclass(obj, Ast):
-                if not issubclass(obj, AsList):
-                    if issubclass(obj, WithMeta):
-                        obj = with_meta_inline(obj).__get__(t)
-                    else:
-                        obj = inline(obj).__get__(t)
-                elif issubclass(obj, WithMeta):
-                    obj = with_meta(obj).__get__(t)
-
+                wrapper = decorator_factory(inline=not issubclass(obj, AsList), meta=issubclass(obj, WithMeta))
+                obj = wrapper(obj).__get__(t)
                 setattr(t, camel_to_snake(name), obj)
 
     return t
\ No newline at end of file

From 53b58e713793d8cfd7ffeebd04d527791519a342 Mon Sep 17 00:00:00 2001
From: Erez Sh <erezshin@gmail.com>
Date: Tue, 31 Aug 2021 11:42:27 +0100
Subject: [PATCH 4/5] Examples: Added correct type-info to the create_ast
 example

---
 examples/advanced/create_ast.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/examples/advanced/create_ast.py b/examples/advanced/create_ast.py
index c855d84..95ce520 100644
--- a/examples/advanced/create_ast.py
+++ b/examples/advanced/create_ast.py
@@ -15,6 +15,7 @@ from typing import List
 from dataclasses import dataclass
 
 from lark import Lark, ast_utils, Transformer, v_args
+from lark.tree import Meta
 
 this_module = sys.modules[__name__]
 
@@ -32,7 +33,8 @@ class _Statement(_Ast):
 
 @dataclass
 class Value(_Ast, ast_utils.WithMeta):
-    meta: object
+    "Uses WithMeta to include line-number metadata in the meta attribute"
+    meta: Meta
     value: object
 
 @dataclass

From 2b5f98478578a65fe0be4c4de8b72f90178133db Mon Sep 17 00:00:00 2001
From: Erez Sh <erezshin@gmail.com>
Date: Tue, 31 Aug 2021 12:16:39 +0100
Subject: [PATCH 5/5] ast_utils: Fix docstring

---
 lark/ast_utils.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lark/ast_utils.py b/lark/ast_utils.py
index 3b8a12a..0c03d45 100644
--- a/lark/ast_utils.py
+++ b/lark/ast_utils.py
@@ -22,7 +22,7 @@ class AsList(object):
 class WithMeta(object):
     """Abstract class
 
-    Subclasses will be instanciated the Meta instance of the tree. (see ``v_args`` for more detail)
+    Subclasses will be instanciated with the Meta instance of the tree. (see ``v_args`` for more detail)
     """
     pass