From bf0610a1ca0019f27d37de4a2f11d926297125ce Mon Sep 17 00:00:00 2001 From: Georg Brandl Date: Sat, 7 Jun 2008 16:04:01 +0000 Subject: Revert unwanted changes. --- Doc/library/_ast.rst | 85 ++++++++++++++++++++++++++++++++++++ Doc/library/language.rst | 2 +- Lib/test/test_ast.py | 109 ++++------------------------------------------- 3 files changed, 95 insertions(+), 101 deletions(-) create mode 100644 Doc/library/_ast.rst diff --git a/Doc/library/_ast.rst b/Doc/library/_ast.rst new file mode 100644 index 0000000..80b8a37 --- /dev/null +++ b/Doc/library/_ast.rst @@ -0,0 +1,85 @@ +.. _ast: + +Abstract Syntax Trees +===================== + +.. module:: _ast + :synopsis: Abstract Syntax Tree classes. + +.. sectionauthor:: Martin v. Löwis + + +.. versionadded:: 2.5 + +The ``_ast`` module helps Python applications to process trees of the Python +abstract syntax grammar. The abstract syntax itself might change with each +Python release; this module helps to find out programmatically what the current +grammar looks like. + +An abstract syntax tree can be generated by passing :data:`_ast.PyCF_ONLY_AST` +as a flag to the :func:`compile` builtin function. The result will be a tree of +objects whose classes all inherit from :class:`_ast.AST`. + +A modified abstract syntax tree can be compiled into a Python code object using +the built-in :func:`compile` function. + +The actual classes are derived from the ``Parser/Python.asdl`` file, which is +reproduced below. There is one class defined for each left-hand side symbol in +the abstract grammar (for example, ``_ast.stmt`` or ``_ast.expr``). In addition, +there is one class defined for each constructor on the right-hand side; these +classes inherit from the classes for the left-hand side trees. For example, +``_ast.BinOp`` inherits from ``_ast.expr``. For production rules with +alternatives (aka "sums"), the left-hand side class is abstract: only instances +of specific constructor nodes are ever created. + +Each concrete class has an attribute ``_fields`` which gives the names of all +child nodes. + +Each instance of a concrete class has one attribute for each child node, of the +type as defined in the grammar. For example, ``_ast.BinOp`` instances have an +attribute ``left`` of type ``_ast.expr``. Instances of ``_ast.expr`` and +``_ast.stmt`` subclasses also have lineno and col_offset attributes. The lineno +is the line number of source text (1 indexed so the first line is line 1) and +the col_offset is the utf8 byte offset of the first token that generated the +node. The utf8 offset is recorded because the parser uses utf8 internally. + +If these attributes are marked as optional in the grammar (using a question +mark), the value might be ``None``. If the attributes can have zero-or-more +values (marked with an asterisk), the values are represented as Python lists. +All possible attributes must be present and have valid values when compiling an +AST with :func:`compile`. + +The constructor of a class ``_ast.T`` parses their arguments as follows: + +* If there are positional arguments, there must be as many as there are items in + ``T._fields``; they will be assigned as attributes of these names. +* If there are keyword arguments, they will set the attributes of the same names + to the given values. + +For example, to create and populate a ``UnaryOp`` node, you could use :: + + node = _ast.UnaryOp() + node.op = _ast.USub() + node.operand = _ast.Num() + node.operand.n = 5 + node.operand.lineno = 0 + node.operand.col_offset = 0 + node.lineno = 0 + node.col_offset = 0 + +or the more compact :: + + node = _ast.UnaryOp(_ast.USub(), _ast.Num(5, lineno=0, col_offset=0), + lineno=0, col_offset=0) + + + +Abstract Grammar +---------------- + +The module defines a string constant ``__version__`` which is the decimal +subversion revision number of the file shown below. + +The abstract grammar is currently defined as follows: + +.. literalinclude:: ../../Parser/Python.asdl diff --git a/Doc/library/language.rst b/Doc/library/language.rst index bcf9ac0..7d6af7d 100644 --- a/Doc/library/language.rst +++ b/Doc/library/language.rst @@ -15,7 +15,7 @@ These modules include: .. toctree:: parser.rst - ast.rst + _ast.rst symbol.rst token.rst keyword.rst diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py index ac26656..9d2bd66 100644 --- a/Lib/test/test_ast.py +++ b/Lib/test/test_ast.py @@ -1,6 +1,6 @@ import sys, itertools, unittest from test import test_support -import ast +import _ast def to_tuple(t): if t is None or isinstance(t, (basestring, int, long, complex)): @@ -123,9 +123,9 @@ eval_tests = [ class AST_Tests(unittest.TestCase): def _assert_order(self, ast_node, parent_pos): - if not isinstance(ast_node, ast.AST) or ast_node._fields is None: + if not isinstance(ast_node, _ast.AST) or ast_node._fields is None: return - if isinstance(ast_node, (ast.expr, ast.stmt, ast.excepthandler)): + if isinstance(ast_node, (_ast.expr, _ast.stmt, _ast.excepthandler)): node_pos = (ast_node.lineno, ast_node.col_offset) self.assert_(node_pos >= parent_pos) parent_pos = (ast_node.lineno, ast_node.col_offset) @@ -142,29 +142,29 @@ class AST_Tests(unittest.TestCase): (single_tests, single_results, "single"), (eval_tests, eval_results, "eval")): for i, o in itertools.izip(input, output): - ast_tree = compile(i, "?", kind, ast.PyCF_ONLY_AST) + ast_tree = compile(i, "?", kind, _ast.PyCF_ONLY_AST) self.assertEquals(to_tuple(ast_tree), o) self._assert_order(ast_tree, (0, 0)) def test_nodeclasses(self): - x = ast.BinOp(1, 2, 3, lineno=0) + x = _ast.BinOp(1, 2, 3, lineno=0) self.assertEquals(x.left, 1) self.assertEquals(x.op, 2) self.assertEquals(x.right, 3) self.assertEquals(x.lineno, 0) # node raises exception when not given enough arguments - self.assertRaises(TypeError, ast.BinOp, 1, 2) + self.assertRaises(TypeError, _ast.BinOp, 1, 2) # can set attributes through kwargs too - x = ast.BinOp(left=1, op=2, right=3, lineno=0) + x = _ast.BinOp(left=1, op=2, right=3, lineno=0) self.assertEquals(x.left, 1) self.assertEquals(x.op, 2) self.assertEquals(x.right, 3) self.assertEquals(x.lineno, 0) # this used to fail because Sub._fields was None - x = ast.Sub() + x = _ast.Sub() def test_pickling(self): import pickle @@ -181,99 +181,8 @@ class AST_Tests(unittest.TestCase): ast2 = mod.loads(mod.dumps(ast, protocol)) self.assertEquals(to_tuple(ast2), to_tuple(ast)) - -class ASTHelpers_Test(unittest.TestCase): - - def test_parse(self): - a = ast.parse('foo(1 + 1)') - b = compile('foo(1 + 1)', '', 'exec', ast.PyCF_ONLY_AST) - self.assertEqual(ast.dump(a), ast.dump(b)) - - def test_dump(self): - node = ast.parse('spam(eggs, "and cheese")') - self.assertEqual(ast.dump(node), - "Module(body=[Expr(value=Call(func=Name(id='spam', ctx=Load()), " - "args=[Name(id='eggs', ctx=Load()), Str(s='and cheese')], " - "keywords=[], starargs=None, kwargs=None))])" - ) - self.assertEqual(ast.dump(node, annotate_fields=False), - "Module([Expr(Call(Name('spam', Load()), [Name('eggs', Load()), " - "Str('and cheese')], [], None, None))])" - ) - self.assertEqual(ast.dump(node, include_attributes=True), - "Module(body=[Expr(value=Call(func=Name(id='spam', ctx=Load(), " - "lineno=1, col_offset=0), args=[Name(id='eggs', ctx=Load(), " - "lineno=1, col_offset=5), Str(s='and cheese', lineno=1, " - "col_offset=11)], keywords=[], starargs=None, kwargs=None, " - "lineno=1, col_offset=0), lineno=1, col_offset=0)])" - ) - - def test_copy_location(self): - src = ast.parse('1 + 1', mode='eval') - src.body.right = ast.copy_location(ast.Num(2), src.body.right) - self.assertEqual(ast.dump(src, include_attributes=True), - 'Expression(body=BinOp(left=Num(n=1, lineno=1, col_offset=0), ' - 'op=Add(), right=Num(n=2, lineno=1, col_offset=4), lineno=1, ' - 'col_offset=0))' - ) - - def test_fix_missing_locations(self): - src = ast.parse('write("spam")') - src.body.append(ast.Expr(ast.Call(ast.Name('spam', ast.Load()), - [ast.Str('eggs')], [], None, None))) - self.assertEqual(src, ast.fix_missing_locations(src)) - self.assertEqual(ast.dump(src, include_attributes=True), - "Module(body=[Expr(value=Call(func=Name(id='write', ctx=Load(), " - "lineno=1, col_offset=0), args=[Str(s='spam', lineno=1, " - "col_offset=6)], keywords=[], starargs=None, kwargs=None, " - "lineno=1, col_offset=0), lineno=1, col_offset=0), " - "Expr(value=Call(func=Name(id='spam', ctx=Load(), lineno=1, " - "col_offset=0), args=[Str(s='eggs', lineno=1, col_offset=0)], " - "keywords=[], starargs=None, kwargs=None, lineno=1, " - "col_offset=0), lineno=1, col_offset=0)])" - ) - - def test_increment_lineno(self): - src = ast.parse('1 + 1', mode='eval') - self.assertEqual(ast.increment_lineno(src, n=3), src) - self.assertEqual(ast.dump(src, include_attributes=True), - 'Expression(body=BinOp(left=Num(n=1, lineno=4, col_offset=0), ' - 'op=Add(), right=Num(n=1, lineno=4, col_offset=4), lineno=4, ' - 'col_offset=0))' - ) - - def test_iter_fields(self): - node = ast.parse('foo()', mode='eval') - d = dict(ast.iter_fields(node.body)) - self.assertEqual(d.pop('func').id, 'foo') - self.assertEqual(d, {'keywords': [], 'kwargs': None, - 'args': [], 'starargs': None}) - - def test_iter_child_nodes(self): - node = ast.parse("spam(23, 42, eggs='leek')", mode='eval') - self.assertEqual(len(list(ast.iter_child_nodes(node.body))), 4) - iterator = ast.iter_child_nodes(node.body) - self.assertEqual(next(iterator).id, 'spam') - self.assertEqual(next(iterator).n, 23) - self.assertEqual(next(iterator).n, 42) - self.assertEqual(ast.dump(next(iterator)), - "keyword(arg='eggs', value=Str(s='leek'))" - ) - - def test_get_docstring(self): - node = ast.parse('def foo():\n """line one\n line two"""') - self.assertEqual(ast.get_docstring(node.body[0]), - 'line one\n line two') - - def test_literal_eval(self): - self.assertEqual(ast.literal_eval('[1, 2, 3]'), [1, 2, 3]) - self.assertEqual(ast.literal_eval('{"foo": 42}'), {"foo": 42}) - self.assertEqual(ast.literal_eval('(True, False, None)'), (True, False, None)) - self.assertRaises(ValueError, ast.literal_eval, 'foo()') - - def test_main(): - test_support.run_unittest(AST_Tests, ASTHelpers_Test) + test_support.run_unittest(AST_Tests) def main(): if __name__ != '__main__': -- cgit v0.12