Issue #2335: Backport set literals syntax from Python 3.x.

4 files changed, 40 insertions, 8 deletions

diff --git a/Lib/compiler/ast.py b/Lib/compiler/ast.py
index f923077..f47434c 100644
--- a/Lib/compiler/ast.py
+++ b/Lib/compiler/ast.py
@@ -1107,6 +1107,22 @@ class RightShift(Node):
     def __repr__(self):
         return "RightShift((%s, %s))" % (repr(self.left), repr(self.right))
 
+class Set(Node):
+    def __init__(self, nodes, lineno=None):
+        self.nodes = nodes
+        self.lineno = lineno
+
+    def getChildren(self):
+        return tuple(flatten(self.nodes))
+
+    def getChildNodes(self):
+        nodelist = []
+        nodelist.extend(flatten_nodes(self.nodes))
+        return tuple(nodelist)
+
+    def __repr__(self):
+        return "Set(%s)" % (repr(self.nodes),)
+
 class Slice(Node):
     def __init__(self, expr, flags, lower, upper, lineno=None):
         self.expr = expr
diff --git a/Lib/compiler/pyassem.py b/Lib/compiler/pyassem.py
index be0255d..88510de 100644
--- a/Lib/compiler/pyassem.py
+++ b/Lib/compiler/pyassem.py
@@ -734,6 +734,8 @@ class StackDepthTracker:
         return -count+1
     def BUILD_LIST(self, count):
         return -count+1
+    def BUILD_SET(self, count):
+        return -count+1
     def CALL_FUNCTION(self, argc):
         hi, lo = divmod(argc, 256)
         return -(lo + hi * 2)
diff --git a/Lib/compiler/pycodegen.py b/Lib/compiler/pycodegen.py
index 960c4fc..bef9c70 100644
--- a/Lib/compiler/pycodegen.py
+++ b/Lib/compiler/pycodegen.py
@@ -1215,6 +1215,12 @@ class CodeGenerator:
             self.visit(elt)
         self.emit('BUILD_LIST', len(node.nodes))
 
+    def visitSet(self, node):
+        self.set_lineno(node)
+        for elt in node.nodes:
+            self.visit(elt)
+        self.emit('BUILD_SET', len(node.nodes))
+
     def visitSliceobj(self, node):
         for child in node.nodes:
             self.visit(child)
diff --git a/Lib/compiler/transformer.py b/Lib/compiler/transformer.py
index 2a156d3..816f13b 100644
--- a/Lib/compiler/transformer.py
+++ b/Lib/compiler/transformer.py
@@ -749,7 +749,7 @@ class Transformer:
     def atom_lbrace(self, nodelist):
         if nodelist[1][0] == token.RBRACE:
             return Dict((), lineno=nodelist[0][2])
-        return self.com_dictmaker(nodelist[1])
+        return self.com_dictorsetmaker(nodelist[1])
 
     def atom_backquote(self, nodelist):
         return Backquote(self.com_node(nodelist[1]))
@@ -1197,13 +1197,21 @@ class Transformer:
             assert node[0] == symbol.gen_iter
             return node[1]
 
-    def com_dictmaker(self, nodelist):
-        # dictmaker: test ':' test (',' test ':' value)* [',']
-        items = []
-        for i in range(1, len(nodelist), 4):
-            items.append((self.com_node(nodelist[i]),
-                          self.com_node(nodelist[i+2])))
-        return Dict(items, lineno=items[0][0].lineno)
+    def com_dictorsetmaker(self, nodelist):
+        # dictorsetmaker: ( (test ':' test (',' test ':' test)* [',']) |
+        #                   (test (',' test)* [',']) )
+        assert nodelist[0] == symbol.dictorsetmaker
+        if len(nodelist) == 2 or nodelist[2][0] == token.COMMA:
+            items = []
+            for i in range(1, len(nodelist), 2):
+                items.append(self.com_node(nodelist[i]))
+            return Set(items, lineno=items[0].lineno)
+        else:
+            items = []
+            for i in range(1, len(nodelist), 4):
+                items.append((self.com_node(nodelist[i]),
+                              self.com_node(nodelist[i+2])))
+            return Dict(items, lineno=items[0][0].lineno)
 
     def com_apply_trailer(self, primaryNode, nodelist):
         t = nodelist[1][0]