From 1a6261ace44da5b9e6c6807a5b097c58f161d172 Mon Sep 17 00:00:00 2001
From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Aug 13 2018 14:44:19 +0000
Subject: Add some basic linux cfg parsing


---

diff --git a/rustcfg/__init__.py b/rustcfg/__init__.py
index e7e2109..aa3e77e 100644
--- a/rustcfg/__init__.py
+++ b/rustcfg/__init__.py
@@ -30,6 +30,17 @@ def cfg_grammar():
     grammar = (cfg_exp() | multiarch_tuple()) + pp.stringEnd()
     return grammar
 
+def dump_tree(t, level=0, evalf=None):
+    print('{}structure {}{}{}{}'.format('    '*level, t.getName(),
+                                        ' [' if evalf else '',
+                                        evalf(t) if evalf else '',
+                                        ']' if evalf else ''))
+    for item in t:
+        if isinstance(item, str):
+            print('{}{!r}'.format('    '*(level+1), item))
+        else:
+            dump_tree(item, level+1, evalf=evalf)
+
 class Evaluator:
     """Evalutate cfg expressions
 
@@ -43,6 +54,7 @@ class Evaluator:
     """
     def __init__(self, options=()):
         self.options = options
+        self.tree = None
 
     def eval_tree(self, tree):
         kind = tree.getName()
@@ -72,13 +84,20 @@ class Evaluator:
         else:
             assert False, f'Unknown element {kind}'
 
-def dump_tree(t, level=0, evalf=None):
-    print('{}structure {}{}{}{}'.format('    '*level, t.getName(),
-                                        ' [' if evalf else '',
-                                        evalf(t) if evalf else '',
-                                        ']' if evalf else ''))
-    for item in t:
-        if isinstance(item, str):
-            print('{}{!r}'.format('    '*(level+1), item))
-        else:
-            dump_tree(item, level+1, evalf=evalf)
+    def eval_parsed(self):
+        return self.eval_tree(self.tree)
+
+    @classmethod
+    def platform(cls):
+        """An Evaluator populated with some platform options
+
+        I don't see a list that'd specify what the allowed options
+        are, so this is culled from deps used in crates packaged in
+        Fedora 28.
+        """
+        return cls(options=('unix',
+                            ('target_os', 'linux')))
+
+    def parse(self, string):
+        g = cfg_grammar()
+        self.tree = g.parseString(string)
diff --git a/rustcfg/test/test_expressions.py b/rustcfg/test/test_expressions.py
index e7d6f67..4058edd 100644
--- a/rustcfg/test/test_expressions.py
+++ b/rustcfg/test/test_expressions.py
@@ -1,7 +1,7 @@
 import pytest
 import rustcfg
 
-testdata = [
+asdf_data = [
     # None means expression is unparsable
     ('cfg(ok)', True),
     ('cfg(not_ok)', False),
@@ -23,8 +23,7 @@ testdata = [
     ('cfg(foo = "not bar")', False),
     ('cfg(foo=bar)', None),
     ('cfg(foo foo = = " bar ")', None),
-    ('cfg(foo = foo = " bar ")', None),
-]
+    ('cfg(foo = foo = " bar ")', None)]
 
 @pytest.fixture
 def asdf_evaluator():
@@ -36,7 +35,7 @@ def asdf_evaluator():
                ('foo', ' bar '))
     return rustcfg.Evaluator(options=options)
 
-@pytest.mark.parametrize("expression,result", testdata)
+@pytest.mark.parametrize("expression,result", asdf_data)
 def test_parsing(expression, result, asdf_evaluator):
     g = rustcfg.cfg_grammar()
     try:
@@ -50,3 +49,27 @@ def test_parsing(expression, result, asdf_evaluator):
     if result is not None:
         res = asdf_evaluator.eval_tree(t)
         assert res == result
+
+linux_data = [
+    ('cfg(unix)', True),
+    ('cfg(windows)', False),
+
+    ('cfg(all(unix, not(target_os = "fuchsia"), not(target_os = "emscripten"), not(target_os = "macos"), not(target_os = "ios")))', True),
+    ("cfg(all(unix, not(target_os = \"fuchsia\"), not(target_os = \"emscripten\"), not(target_os = \"macos\"), not(target_os = \"ios\")))", True),
+
+    ("cfg(all(unix, not(target_os = \"macos\")))", True),
+    ('cfg(not(any(target_os = "windows", target_os = "macos")))', True),
+    ('cfg(not(target_os = "redox"))', True),
+    ('cfg(not(target_os = "windows"))', True),
+    ("cfg(not(target_os = \"windows\"))", True),
+    ('cfg(target_env = "msvc")', False)]
+
+@pytest.fixture
+def linux_evaluator():
+    return rustcfg.Evaluator.platform()
+
+@pytest.mark.parametrize("expression,result", linux_data)
+def test_linux(expression, result, linux_evaluator):
+    linux_evaluator.parse(expression)
+    res = linux_evaluator.eval_parsed()
+    res == result