Improve as_string output of operators, elif, with, return & docs

The precedence and associativity rules of operators are respected
and parens are only wrapped around child nodes when needed

A single If node inside the else block is output as `elif`

Unneccesary parens in with statements are removed

Unneccesary parens in tuple returns are removed

Doc strings in classes and functions no longer get additional indenting

3 files changed, 49 insertions, 21 deletions

diff --git a/astroid/tests/testdata/python2/data/module.py b/astroid/tests/testdata/python2/data/module.py
index 6a67b9b6..1205c1dd 100644
--- a/astroid/tests/testdata/python2/data/module.py
+++ b/astroid/tests/testdata/python2/data/module.py
@@ -23,7 +23,8 @@ def global_access(key, val):
 
 
 class YO:
-    """hehe"""
+    """hehe
+    haha"""
     a = 1
     
     def __init__(self):
@@ -45,7 +46,8 @@ class YOUPI(YO):
         self.member = None
     
     def method(self):
-        """method test"""
+        """method
+        test"""
         global MY_DICT
         try:
             MY_DICT = {}
@@ -53,9 +55,8 @@ class YOUPI(YO):
             autre = [a for (a, b) in MY_DICT if b]
             if b in autre:
                 return b
-            else:
-                if a in autre:
-                    return a
+            elif a in autre:
+                return a
             global_access(local, val=autre)
         finally:
             return local
@@ -81,9 +82,9 @@ def four_args(a, b, c, d):
     else:
         b += -2
     if c:
-        d = ((a) and (b)) or (c)
+        d = a and (b or c)
     else:
-        c = ((a) and (b)) or (d)
+        c = a and b or d
     map(lambda x, y: (y, x), a)
 redirect = four_args
 
diff --git a/astroid/tests/testdata/python2/data/module2.py b/astroid/tests/testdata/python2/data/module2.py
index 0a1bd1ad..7042a4c1 100644
--- a/astroid/tests/testdata/python2/data/module2.py
+++ b/astroid/tests/testdata/python2/data/module2.py
@@ -71,10 +71,10 @@ del YO.member
 del YO
 [SYN1, SYN2] = (Concrete0, Concrete1)
 assert '1'
-b = (1) | (((2) & (3)) ^ (8))
-bb = ((1) | (two)) | (6)
-ccc = ((one) & (two)) & (three)
-dddd = ((x) ^ (o)) ^ (r)
+b = (1 | 2) & (3 ^ 8)
+bb = 1 | (two | 6)
+ccc = one & two & three
+dddd = x ^ (o ^ r)
 exec 'c = 3'
 exec 'c = 3' in {}, {}
 
@@ -82,15 +82,15 @@ def raise_string(a=2, *args, **kwargs):
     raise Exception, 'yo'
     yield 'coucou'
     yield
-a = (b) + (2)
-c = (b) * (2)
-c = (b) / (2)
-c = (b) // (2)
-c = (b) - (2)
-c = (b) % (2)
-c = (b) ** (2)
-c = (b) << (2)
-c = (b) >> (2)
+a = b + 2
+c = b * 2
+c = b / 2
+c = b // 2
+c = b - 2
+c = b % 2
+c = b**2
+c = b << 2
+c = b >> 2
 c = ~b
 c = not b
 d = [c]
@@ -131,7 +131,7 @@ def not_a_generator():
     
     def generator():
         yield
-    genl = lambda : (yield)
+    genl = lambda: (yield)
 
 def with_metaclass(meta, *bases):
     return meta('NewBase', bases, {})
diff --git a/astroid/tests/testdata/python2/data/operator_precedence.py b/astroid/tests/testdata/python2/data/operator_precedence.py
new file mode 100644
index 00000000..07a3c772
--- /dev/null
+++ b/astroid/tests/testdata/python2/data/operator_precedence.py
@@ -0,0 +1,27 @@
+assert not not True == True
+assert (not False or True) == True
+assert True or False and True
+assert (True or False) and True
+
+assert True is not (False is True) == False
+assert True is (not False is True == False)
+
+assert 1 + 2 + 3 == 6
+assert 5 - 4 + 3 == 4
+assert 4 - 5 - 6 == -7
+assert 7 - (8 - 9) == 8
+assert 2**3**4 == 2**81
+assert (2**3)**4 == 8**4
+
+assert 1 + 2 if (0.5 if True else 0.2) else 1 if True else 2 == 3
+assert (0 if True else 1) if False else 2 == 2
+assert lambda x: x if (0 if False else 0) else 0 if False else 0
+assert (lambda x: x) if (0 if True else 0.2) else 1 if True else 2 == 1
+
+assert ('1' + '2').replace('1', '3') == '32'
+assert (lambda x: x)(1) == 1
+assert ([0] + [1])[1] == 1
+assert (lambda x: lambda: x + 1)(2)() == 3
+
+f = lambda x, y, z: y(x, z)
+assert f(1, lambda x, y: x + y[1], (2, 3)) == 4