Generate code to recursively copy an AST into

a tree of Python objects. Expose this through compile().

Include/Python-ast.h

@@ -404,3 +404,4 @@ arguments_ty arguments(asdl_seq * args, identifier vararg, identifier kwarg,
 keyword_ty keyword(identifier arg, expr_ty value, PyArena *arena);
 alias_ty alias(identifier name, identifier asname, PyArena *arena);
 
+PyObject* PyAST_mod2obj(mod_ty t);

Include/pythonrun.h

@@ -11,6 +11,7 @@ extern "C" {
 #define PyCF_MASK_OBSOLETE (CO_NESTED)
 #define PyCF_SOURCE_IS_UTF8  0x0100
 #define PyCF_DONT_IMPLY_DEDENT 0x0200
+#define PyCF_ONLY_AST 0x0400
 
 typedef struct {
 	int cf_flags;  /* bitmask of CO_xxx flags relevant to future */

Lib/test/test_ast.py

+import sys, itertools
+
+def to_tuple(t):
+    if t is None or isinstance(t, (str, int, long)):
+        return t
+    elif isinstance(t, list):
+        return [to_tuple(e) for e in t]
+    result = [t.__class__.__name__]
+    if t._fields is None:
+        return tuple(result)
+    for f in t._fields:
+        result.append(to_tuple(getattr(t, f)))
+    return tuple(result)
+    
+# These tests are compiled through "exec"
+# There should be atleast one test per statement
+exec_tests = [
+    # FunctionDef
+    "def f(): pass",
+    # ClassDef
+    "class C:pass",
+    # Return
+    "def f():return 1",
+    # Delete
+    "del v",
+    # Assign
+    "v = 1",
+    # AugAssign
+    "v += 1",
+    # Print
+    "print >>f, 1, ",
+    # For
+    "for v in v:pass",
+    # While
+    "while v:pass",
+    # If
+    "if v:pass",
+    # Raise
+    "raise Exception, 'string'",
+    # TryExcept
+    "try:\n  pass\nexcept Exception:\n  pass",
+    # TryFinally
+    "try:\n  pass\nfinally:\n  pass",
+    # Assert
+    "assert v",
+    # Import
+    "import sys",
+    # ImportFrom
+    "from sys import v",
+    # Exec
+    "exec 'v'",
+    # Global
+    "global v",
+    # Expr
+    "1",
+    # Pass,
+    "pass",
+    # Break
+    "break",
+    # Continue
+    "continue",
+]
+
+# These are compiled through "single"
+# because of overlap with "eval", it just tests what
+# can't be tested with "eval"
+single_tests = [
+    "1+2"
+]
+
+# These are compiled through "eval"
+# It should test all expressions
+eval_tests = [
+  # BoolOp
+  "a and b",
+  # BinOp
+  "a + b",
+  # UnaryOp
+  "not v",
+  # Lambda
+  "lambda:None",
+  # Dict
+  "{ 1:2 }",
+  # ListComp
+  "[a for b in c if d]",
+  # GeneratorExp
+  "(a for b in c if d)",
+  # Yield
+  #"def f():yield 3",
+  # Compare
+  "1 < 2 < 3",
+  # Call
+  "f(1,2,c=3,*d,**e)",
+  # Repr
+  "`v`",
+  # Num
+  "10L",
+  # Str
+  "'string'",
+  # Attribute
+  "a.b",
+  # Subscript
+  "a[b:c]",
+  # Name
+  "v",
+  # List
+  "[1,2,3]",
+  # Tuple
+  "1,2,3"
+]
+
+# TODO: expr_context, slice, boolop, operator, unaryop, cmpop, comprehension
+# excepthandler, arguments, keywords, alias
+
+if __name__=='__main__' and sys.argv[1:] == ['-g']:
+    for statements, kind in ((exec_tests, "exec"), (single_tests, "single"), (eval_tests, "eval")):
+        print kind+"_results = ["
+        for s in statements:
+            print repr(to_tuple(compile(s, "?", kind, 0x400)))+","
+        print "]"
+    print "run_tests()"
+    raise SystemExit
+
+def run_tests():
+    for input, output, kind in ((exec_tests, exec_results, "exec"), 
+                                        (single_tests, single_results, "single"), 
+                                        (eval_tests, eval_results, "eval")):
+        for i, o in itertools.izip(input, output):
+            assert to_tuple(compile(i, "?", kind, 0x400)) == o
+
+#### EVERYTHING BELOW IS GENERATED ##### 
+exec_results = [
+('Module', [('FunctionDef', 'f', ('arguments', [], None, None, []), [('Pass',)], [])]),
+('Module', [('ClassDef', 'C', [], [('Pass',)])]),
+('Module', [('FunctionDef', 'f', ('arguments', [], None, None, []), [('Return', ('Num', 1))], [])]),
+('Module', [('Delete', [('Name', 'v', ('Del',))])]),
+('Module', [('Assign', [('Name', 'v', ('Store',))], ('Num', 1))]),
+('Module', [('AugAssign', ('Name', 'v', ('Load',)), ('Add',), ('Num', 1))]),
+('Module', [('Print', ('Name', 'f', ('Load',)), [('Num', 1)], False)]),
+('Module', [('For', ('Name', 'v', ('Store',)), ('Name', 'v', ('Load',)), [('Pass',)], [])]),
+('Module', [('While', ('Name', 'v', ('Load',)), [('Pass',)], [])]),
+('Module', [('If', ('Name', 'v', ('Load',)), [('Pass',)], [])]),
+('Module', [('Raise', ('Name', 'Exception', ('Load',)), ('Str', 'string'), None)]),
+('Module', [('TryExcept', [('Pass',)], [('excepthandler', ('Name', 'Exception', ('Load',)), None, [('Pass',)])], [])]),
+('Module', [('TryFinally', [('Pass',)], [('Pass',)])]),
+('Module', [('Assert', ('Name', 'v', ('Load',)), None)]),
+('Module', [('Import', [('alias', 'sys', None)])]),
+('Module', [('ImportFrom', 'sys', [('alias', 'v', None)])]),
+('Module', [('Exec', ('Str', 'v'), None, None)]),
+('Module', [('Global', ['v'])]),
+('Module', [('Expr', ('Num', 1))]),
+('Module', [('Pass',)]),
+('Module', [('Break',)]),
+('Module', [('Continue',)]),
+]
+single_results = [
+('Interactive', [('Expr', ('BinOp', ('Num', 1), ('Add',), ('Num', 2)))]),
+]
+eval_results = [
+('Expression', ('BoolOp', ('And',), [('Name', 'a', ('Load',)), ('Name', 'b', ('Load',))])),
+('Expression', ('BinOp', ('Name', 'a', ('Load',)), ('Add',), ('Name', 'b', ('Load',)))),
+('Expression', ('UnaryOp', ('Not',), ('Name', 'v', ('Load',)))),
+('Expression', ('Lambda', ('arguments', [], None, None, []), ('Name', 'None', ('Load',)))),
+('Expression', ('Dict', [('Num', 1)], [('Num', 2)])),
+('Expression', ('ListComp', ('Name', 'a', ('Load',)), [('comprehension', ('Name', 'b', ('Store',)), ('Name', 'c', ('Load',)), [('Name', 'd', ('Load',))])])),
+('Expression', ('GeneratorExp', ('Name', 'a', ('Load',)), [('comprehension', ('Name', 'b', ('Store',)), ('Name', 'c', ('Load',)), [('Name', 'd', ('Load',))])])),
+('Expression', ('Compare', ('Num', 1), [('Lt',), ('Lt',)], [('Num', 2), ('Num', 3)])),
+('Expression', ('Call', ('Name', 'f', ('Load',)), [('Num', 1), ('Num', 2)], [('keyword', 'c', ('Num', 3))], ('Name', 'd', ('Load',)), ('Name', 'e', ('Load',)))),
+('Expression', ('Repr', ('Name', 'v', ('Load',)))),
+('Expression', ('Num', 10L)),
+('Expression', ('Str', 'string')),
+('Expression', ('Attribute', ('Name', 'a', ('Load',)), 'b', ('Load',))),
+('Expression', ('Subscript', ('Name', 'a', ('Load',)), ('Slice', ('Name', 'b', ('Load',)), ('Name', 'c', ('Load',)), None), ('Load',))),
+('Expression', ('Name', 'v', ('Load',))),
+('Expression', ('List', [('Num', 1), ('Num', 2), ('Num', 3)], ('Load',))),
+('Expression', ('Tuple', [('Num', 1), ('Num', 2), ('Num', 3)], ('Load',))),
+]
+run_tests()
+

Misc/NEWS

@@ -74,7 +74,9 @@ Core and builtins
 
 - Speed up some Unicode operations.
 
-- A new AST parser implementation was completed.
+- A new AST parser implementation was completed. The abstract
+  syntax tree is available for read-only (non-compile) access
+  to Python code.
 
 - SF bug #1167751: fix incorrect code being for generator expressions.
   The following code now raises a SyntaxError:  foo(a = i for i in range(10))

Python/bltinmodule.c

@@ -443,7 +443,7 @@ builtin_compile(PyObject *self, PyObject *args)
 	}
 
 	if (supplied_flags &
-	    ~(PyCF_MASK | PyCF_MASK_OBSOLETE | PyCF_DONT_IMPLY_DEDENT))
+	    ~(PyCF_MASK | PyCF_MASK_OBSOLETE | PyCF_DONT_IMPLY_DEDENT | PyCF_ONLY_AST))
 	{
 		PyErr_SetString(PyExc_ValueError,
 				"compile(): unrecognised flags");

Python/pythonrun.c

@@ -1254,6 +1254,11 @@ Py_CompileStringFlags(const char *str, const char *filename, int start,
                 PyArena_Free(arena);
 		return NULL;
         }
+	if (flags->cf_flags & PyCF_ONLY_AST) {
+		PyObject *result = PyAST_mod2obj(mod);
+		PyArena_Free(arena);
+		return result;
+	}
 	co = PyAST_Compile(mod, filename, flags, arena);
         PyArena_Free(arena);
 	return (PyObject *)co;