From 3e9a2178c52faa3f89a4b4af4ba10675515657cb Mon Sep 17 00:00:00 2001
From: Julien Danjou <julien@danjou.info>
Date: Sat, 6 Apr 2013 10:37:21 +0200
Subject: [PATCH] Add support for unary operators (not, ~)

Signed-off-by: Julien Danjou <julien@danjou.info>
---
 hy/compiler.py                 | 16 ++++++++++++++++
 tests/compilers/test_ast.py    | 23 +++++++++++++++++++++++
 tests/native_tests/language.hy | 13 +++++++++++++
 3 files changed, 52 insertions(+)

diff --git a/hy/compiler.py b/hy/compiler.py
index 4a72b1a..d6168a5 100644
--- a/hy/compiler.py
+++ b/hy/compiler.py
@@ -415,6 +415,22 @@ class HyASTCompiler(object):
 
         return call
 
+    @builds("not")
+    @builds("~")
+    def compile_unary_operator(self, expression):
+        if len(expression) != 2:
+            raise TypeError("Unary operator expects only 1 argument, got %d"
+                            % (len(expression) - 1))
+        ops = {"not": ast.Not,
+               "~": ast.Invert}
+        operator = expression.pop(0)
+        operand = expression.pop(0)
+        return ast.UnaryOp(op=ops[operator](),
+                           operand=self.compile(operand),
+                           lineno=operator.start_line,
+                           col_offset=operator.start_column)
+
+
     @builds("=")
     @builds("!=")
     @builds("<")
diff --git a/tests/compilers/test_ast.py b/tests/compilers/test_ast.py
index 88208d1..7db9b57 100644
--- a/tests/compilers/test_ast.py
+++ b/tests/compilers/test_ast.py
@@ -34,6 +34,14 @@ def _ast_spotcheck(arg, root, secondary):
     assert getattr(root, arg) == getattr(secondary, arg)
 
 
+def cant_compile(expr):
+    try:
+        hy_compile(tokenize(expr))
+        assert False
+    except TypeError:
+        pass
+
+
 def test_ast_bad_type():
     "Make sure AST breakage can happen"
     try:
@@ -66,6 +74,21 @@ def test_ast_valid_if():
     hy_compile(tokenize("(if foo bar)"))
 
 
+def test_ast_valid_unary_op():
+    "Make sure AST can compile valid unary operator"
+    hy_compile(tokenize("(not 2)"))
+    hy_compile(tokenize("(~ 1)"))
+
+
+def test_ast_invalid_unary_op():
+    "Make sure AST can't compile invalid unary operator"
+    cant_compile("(not 2 3 4)")
+    cant_compile("(not)")
+    cant_compile("(not 2 3 4)")
+    cant_compile("(~ 2 2 3 4)")
+    cant_compile("(~)")
+
+
 def test_ast_bad_while_0_arg():
     "Make sure AST can't compile invalid while"
     try:
diff --git a/tests/native_tests/language.hy b/tests/native_tests/language.hy
index 4366d06..3d320c6 100644
--- a/tests/native_tests/language.hy
+++ b/tests/native_tests/language.hy
@@ -43,6 +43,19 @@
   (assert (= fact 120)))
 
 
+(defn test-not []
+  "NATIVE: test not"
+  (assert (not (= 1 2)))
+  (assert (= true (not false)))
+  (assert (= false (not 42))) )
+
+
+(defn test-inv []
+  "NATIVE: test inv"
+  (assert (= (~ 1) -2))
+  (assert (= (~ -2) 1)))
+
+
 (defn test-in []
   "NATIVE: test in"
   (assert (in "a" ["a" "b" "c" "d"]))