readd some of the documentation that helps to understand how RestrictedPython works internally (#177)

* readd some of the documentation that helps to understand how RestrictedPython works internally, and the AST Grammars for comparision

* formating and diff for ast files

Author: loechel

docs/contributing/ast/python2_6.ast

@@ -0,0 +1,143 @@
+-- Python 2.6 AST
+-- ASDL's five builtin types are identifier, int, string, object, bool
+
+module Python version "2.6"
+{
+  mod = Module(stmt* body)
+      | Interactive(stmt* body)
+      | Expression(expr body)
+
+      -- not really an actual node but useful in Jython's typesystem.
+      | Suite(stmt* body)
+
+  stmt = FunctionDef(identifier name,
+                     arguments args,
+                     stmt* body,
+                     expr* decorator_list)
+        | ClassDef(identifier name, expr* bases, stmt* body, expr *decorator_list)
+        | Return(expr? value)
+
+        | Delete(expr* targets)
+        | Assign(expr* targets, expr value)
+        | AugAssign(expr target, operator op, expr value)
+
+        -- not sure if bool is allowed, can always use int
+ 	  | Print(expr? dest, expr* values, bool nl)
+
+        -- use 'orelse' because else is a keyword in target languages
+        | For(expr target, expr iter, stmt* body, stmt* orelse)
+        | While(expr test, stmt* body, stmt* orelse)
+        | If(expr test, stmt* body, stmt* orelse)
+        | With(expr context_expr, expr? optional_vars, stmt* body)
+
+        -- 'type' is a bad name
+        | Raise(expr? type, expr? inst, expr? tback)
+        | TryExcept(stmt* body, excepthandler* handlers, stmt* orelse)
+        | TryFinally(stmt* body, stmt* finalbody)
+        | Assert(expr test, expr? msg)
+
+        | Import(alias* names)
+        | ImportFrom(identifier module, alias* names, int? level)
+
+        -- Doesn't capture requirement that locals must be
+        -- defined if globals is
+        -- still supports use as a function!
+        | Exec(expr body, expr? globals, expr? locals)
+
+        | Global(identifier* names)
+        | Expr(expr value)
+        | Pass | Break | Continue
+
+        -- XXX Jython will be different
+        -- col_offset is the byte offset in the utf8 string the parser uses
+        attributes (int lineno, int col_offset)
+
+        -- BoolOp() can use left & right?
+  expr = BoolOp(boolop op, expr* values)
+       | 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)
+       | ListComp(expr elt, comprehension* generators)
+       | GeneratorExp(expr elt, comprehension* generators)
+       -- the grammar constrains where yield expressions can occur
+       | Yield(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, expr? starargs, expr? kwargs)
+       | Repr(expr value)
+       | Num(object n) -- a number as a PyObject.
+       | Str(string s) -- need to specify raw, unicode, etc?
+       -- other literals? bools?
+
+       -- the following expression can appear in assignment context
+       | Attribute(expr value, identifier attr, expr_context ctx)
+       | Subscript(expr value, slice slice, expr_context ctx)
+       | Name(identifier id, expr_context ctx)
+       | List(expr* elts, expr_context ctx)
+       | Tuple(expr* elts, expr_context ctx)
+
+        -- col_offset is the byte offset in the utf8 string the parser uses
+        attributes (int lineno, int col_offset)
+
+  expr_context = Load
+               | Store
+               | Del
+               | AugLoad
+               | AugStore
+               | Param
+
+  slice = Ellipsis
+        | Slice(expr? lower, expr? upper, expr? step)
+        | ExtSlice(slice* dims)
+        | Index(expr value)
+
+  boolop = And
+         | Or
+
+  operator = Add
+           | Sub
+           | Mult
+           | 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)
+
+  -- not sure what to call the first argument for raise and except
+  excepthandler = ExceptHandler(expr? type, expr? name, stmt* body)
+                  attributes (int lineno, int col_offset)
+
+  arguments = (expr* args, identifier? vararg,
+               identifier? kwarg, expr* defaults)
+
+  -- keyword arguments supplied to call
+  keyword = (identifier arg, expr value)
+
+  -- import name with optional 'as' alias.
+  alias = (identifier name, identifier? asname)
+}

docs/contributing/ast/python2_7.ast

@@ -0,0 +1,146 @@
+-- Python 2.7 AST
+-- ASDL's five builtin types are identifier, int, string, object, bool
+
+module Python version "2.7"
+{
+  mod = Module(stmt* body)
+      | Interactive(stmt* body)
+      | Expression(expr body)
+
+      -- not really an actual node but useful in Jython's typesystem.
+      | Suite(stmt* body)
+
+  stmt = FunctionDef(identifier name,
+                     arguments args,
+                     stmt* body,
+                     expr* decorator_list)
+        | ClassDef(identifier name, expr* bases, stmt* body, expr* decorator_list)
+        | Return(expr? value)
+
+        | Delete(expr* targets)
+        | Assign(expr* targets, expr value)
+        | AugAssign(expr target, operator op, expr value)
+
+        -- not sure if bool is allowed, can always use int
+ 	  | Print(expr? dest, expr* values, bool nl)
+
+        -- use 'orelse' because else is a keyword in target languages
+        | For(expr target, expr iter, stmt* body, stmt* orelse)
+        | While(expr test, stmt* body, stmt* orelse)
+        | If(expr test, stmt* body, stmt* orelse)
+        | With(expr context_expr, expr? optional_vars, stmt* body)
+
+        -- 'type' is a bad name
+        | Raise(expr? type, expr? inst, expr? tback)
+        | TryExcept(stmt* body, excepthandler* handlers, stmt* orelse)
+        | TryFinally(stmt* body, stmt* finalbody)
+        | Assert(expr test, expr? msg)
+
+        | Import(alias* names)
+        | ImportFrom(identifier? module, alias* names, int? level)
+
+        -- Doesn't capture requirement that locals must be
+        -- defined if globals is
+        -- still supports use as a function!
+        | Exec(expr body, expr? globals, expr? locals)
+
+        | Global(identifier* names)
+        | Expr(expr value)
+        | Pass | Break | Continue
+
+        -- XXX Jython will be different
+        -- col_offset is the byte offset in the utf8 string the parser uses
+        attributes (int lineno, int col_offset)
+
+        -- BoolOp() can use left & right?
+  expr = BoolOp(boolop op, expr* values)
+       | 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
+       | Yield(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, expr? starargs, expr? kwargs)
+       | Repr(expr value)
+       | Num(object n) -- a number as a PyObject.
+       | Str(string s) -- need to specify raw, unicode, etc?
+       -- other literals? bools?
+
+       -- the following expression can appear in assignment context
+       | Attribute(expr value, identifier attr, expr_context ctx)
+       | Subscript(expr value, slice slice, expr_context ctx)
+       | Name(identifier id, expr_context ctx)
+       | List(expr* elts, expr_context ctx)
+       | Tuple(expr* elts, expr_context ctx)
+
+        -- col_offset is the byte offset in the utf8 string the parser uses
+        attributes (int lineno, int col_offset)
+
+  expr_context = Load
+               | Store
+               | Del
+               | AugLoad
+               | AugStore
+               | Param
+
+  slice = Ellipsis
+        | Slice(expr? lower, expr? upper, expr? step)
+        | ExtSlice(slice* dims)
+        | Index(expr value)
+
+  boolop = And
+         | Or
+
+  operator = Add
+           | Sub
+           | Mult
+           | 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)
+
+  -- not sure what to call the first argument for raise and except
+  excepthandler = ExceptHandler(expr? type, expr? name, stmt* body)
+                  attributes (int lineno, int col_offset)
+
+  arguments = (expr* args, identifier? vararg,
+               identifier? kwarg, expr* defaults)
+
+  -- keyword arguments supplied to call
+  keyword = (identifier arg, expr value)
+
+  -- import name with optional 'as' alias.
+  alias = (identifier name, identifier? asname)
+}