Add Documentation for Python 3.9 AST changes

.editorconfig

@@ -34,3 +34,10 @@ indent_size = 2
 indent_style = tab
 indent_size = unset
 tab_width = unset
+
+[*.bat]
+indent_style = tab
+end_of_line = crlf
+
+[LICENSE]
+insert_final_newline = false

.travis.yml

@@ -5,7 +5,6 @@ matrix:
         - name: "coding-conventions & docs"
           python: "3.6"
           env: TOXENV=docs,lint
-          before_install:
           after_success:
         - python: "2.7"
           env: TOXENV=py27,py27-datetime
@@ -19,13 +18,11 @@ matrix:
           env: TOXENV=py38,py38-datetime
         - python: "3.9-dev"
           env: TOXENV=py39,py39-datetime
-
-before_install:
-    -  travis_retry pip install -U -c constraints.txt coveralls coverage
+#        - python: "3.10-dev"
+#          env: TOXENV=py310,py310-datetime
 
 install:
-    - travis_retry pip install -U pip setuptools
-    - travis_retry pip install -U -c constraints.txt tox
+    - travis_retry pip install -U -c constraints.txt pip setuptools coveralls coverage tox
 
 script:
     - travis_retry tox

docs/contributing/ast/python3_9.ast

@@ -0,0 +1,165 @@
+-- Python 3.9 AST
+-- ASDL's 4 builtin types are:
+-- identifier, int, string, constant
+
+module Python version "3.9"
+{
+    mod = Module(stmt* body, type_ignore* type_ignores)
+        | Interactive(stmt* body)
+        | Expression(expr body)
+        | FunctionType(expr* argtypes, expr returns)
+
+    stmt = FunctionDef(identifier name,
+                     arguments args,
+                     stmt* body,
+                     expr* decorator_list,
+                     expr? returns,
+                     string? type_comment)
+         | AsyncFunctionDef(identifier name,
+                            arguments args,
+                            stmt* body,
+                            expr* decorator_list,
+                            expr? returns,
+                            string? type_comment)
+
+         | ClassDef(identifier name,
+                    expr* bases,
+                    keyword* keywords,
+                    stmt* body,
+                    expr* decorator_list)
+         | Return(expr? value)
+
+         | Delete(expr* targets)
+         | Assign(expr* targets, expr value, string? type_comment)
+         | AugAssign(expr target, operator op, expr value)
+         -- 'simple' indicates that we annotate simple name without parens
+         | AnnAssign(expr target, expr annotation, expr? value, int simple)
+
+         -- use 'orelse' because else is a keyword in target languages
+         | For(expr target, expr iter, stmt* body, stmt* orelse, string? type_comment)
+         | AsyncFor(expr target, expr iter, stmt* body, stmt* orelse, string? type_comment)
+         | While(expr test, stmt* body, stmt* orelse)
+         | If(expr test, stmt* body, stmt* orelse)
+         | With(withitem* items, stmt* body, string? type_comment)
+         | AsyncWith(withitem* items, stmt* body, string? type_comment)
+
+         | Raise(expr? exc, expr? cause)
+         | Try(stmt* body, excepthandler* handlers, stmt* orelse, stmt* finalbody)
+         | Assert(expr test, expr? msg)
+
+         | Import(alias* names)
+         | ImportFrom(identifier? module, alias* names, int? level)
+
+         | Global(identifier* names)
+         | Nonlocal(identifier* names)
+         | Expr(expr value)
+         | Pass
+         | Break
+         | Continue
+
+         -- col_offset is the byte offset in the utf8 string the parser uses
+         attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)
+
+         -- BoolOp() can use left & right?
+    expr = BoolOp(boolop op, expr* values)
+         | NamedExpr(expr target, expr value)
+         | BinOp(expr left, operator op, expr right)
+         | UnaryOp(unaryop op, expr operand)
+         | Lambda(arguments args, expr body)
+         | IfExp(expr test, expr body, expr orelse)
+         | Dict(expr* keys, expr* values)
+         | Set(expr* elts)
+         | ListComp(expr elt, comprehension* generators)
+         | SetComp(expr elt, comprehension* generators)
+         | DictComp(expr key, expr value, comprehension* generators)
+         | GeneratorExp(expr elt, comprehension* generators)
+         -- the grammar constrains where yield expressions can occur
+         | Await(expr value)
+         | Yield(expr? value)
+         | YieldFrom(expr value)
+         -- need sequences for compare to distinguish between
+         -- x < 4 < 3 and (x < 4) < 3
+         | Compare(expr left, cmpop* ops, expr* comparators)
+         | Call(expr func, expr* args, keyword* keywords)
+         | FormattedValue(expr value, int? conversion, expr? format_spec)
+         | JoinedStr(expr* values)
+         | Constant(constant value, string? kind)
+
+         -- the following expression can appear in assignment context
+         | Attribute(expr value, identifier attr, expr_context ctx)
+         | Subscript(expr value, expr slice, expr_context ctx)
+         | Starred(expr value, expr_context ctx)
+         | Name(identifier id, expr_context ctx)
+         | List(expr* elts, expr_context ctx)
+         | Tuple(expr* elts, expr_context ctx)
+
+         -- can appear only in Subscript
+         | Slice(expr? lower, expr? upper, expr? step)
+
+          -- col_offset is the byte offset in the utf8 string the parser uses
+          attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)
+
+    expr_context = Load
+                 | Store
+                 | Del
+
+    boolop = And
+           | Or
+
+    operator = Add
+             | Sub
+             | Mult
+             | MatMult
+             | Div
+             | Mod
+             | Pow
+             | LShift
+             | RShift
+             | BitOr
+             | BitXor
+             | BitAnd
+             | FloorDiv
+
+    unaryop = Invert
+            | Not
+            | UAdd
+            | USub
+
+    cmpop = Eq
+          | NotEq
+          | Lt
+          | LtE
+          | Gt
+          | GtE
+          | Is
+          | IsNot
+          | In
+          | NotIn
+
+    comprehension = (expr target, expr iter, expr* ifs, int is_async)
+
+    excepthandler = ExceptHandler(expr? type, identifier? name, stmt* body)
+                    attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)
+
+    arguments = (arg* posonlyargs,
+                 arg* args,
+                 arg? vararg,
+                 arg* kwonlyargs,
+                 expr* kw_defaults,
+                 arg? kwarg,
+                 expr* defaults)
+
+    arg = (identifier arg, expr? annotation, string? type_comment)
+          attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)
+
+    -- keyword arguments supplied to call (NULL identifier for **kwargs)
+    keyword = (identifier? arg, expr value)
+              attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)
+
+    -- import name with optional 'as' alias.
+    alias = (identifier name, identifier? asname)
+
+    withitem = (expr context_expr, expr? optional_vars)
+
+    type_ignore = TypeIgnore(int lineno, string tag)
+}

docs/contributing/changes_from38to39.rst

@@ -0,0 +1,5 @@
+Changes from Python 3.8 to Python 3.9
+-------------------------------------
+
+.. literalinclude:: ast/python3_9.ast
+   :diff: ast/python3_8.ast

docs/contributing/index.rst

@@ -61,10 +61,11 @@ Technical Backgrounds - Links to External Documentation
 
   * AST Grammar of Python
 
+    * `Python 3.9 AST`_
     * `Python 3.8 AST`_
     * `Python 3.7 AST`_
     * `Python 3.6 AST`_
-    * `Python 3.5 AST`_
+    * `Python 3.5 AST`_ (becoming obsolete)
     * `Python 3.4 AST`_ (obsolete)
     * `Python 3.3 AST`_ (obsolete)
     * `Python 3.2 AST`_ (obsolete)
@@ -73,9 +74,9 @@ Technical Backgrounds - Links to External Documentation
     * `Python 2.7 AST`_
     * `Python 2.6 AST`_ (obsolete)
 
-  * `AST NodeVistiors Class`_  (https://docs.python.org/3.5/library/ast.html#ast.NodeVisitor)
-  * `AST NodeTransformer Class`_  (https://docs.python.org/3.5/library/ast.html#ast.NodeTransformer)
-  * `AST dump method`_ (https://docs.python.org/3.5/library/ast.html#ast.dump)
+  * `AST NodeVistiors Class`_  (https://docs.python.org/3.9/library/ast.html#ast.NodeVisitor)
+  * `AST NodeTransformer Class`_  (https://docs.python.org/3.9/library/ast.html#ast.NodeTransformer)
+  * `AST dump method`_ (https://docs.python.org/3.9/library/ast.html#ast.dump)
 
 * `In detail Documentation on the Python AST module (Green Tree Snakes)`_
 * `Example how to Instrumenting the Python AST`_
@@ -97,7 +98,7 @@ A (modified style) Copy of all Abstract Grammar Definitions for the Python versi
    changes_from35to36
    changes_from36to37
    changes_from37to38
-
+   changes_from38to39
 
 .. Links
 

tox.ini

@@ -7,6 +7,7 @@ envlist =
     py37,
     py38,
     py39,
+    #py310,
     docs,
     lint,
     coverage,