Add e, pow, log, and sqrt functions from Compass.

3 files changed, 77 insertions, 1 deletions

diff --git a/scss/functions/compass/helpers.py b/scss/functions/compass/helpers.py
index 99e1709..a57616a 100644
--- a/scss/functions/compass/helpers.py
+++ b/scss/functions/compass/helpers.py
@@ -437,6 +437,41 @@ def opposite_position(p):
 def pi():
     return Number(math.pi)
 
+
+@register('e', 0)
+def e():
+    return Number(math.e)
+
+
+@register('log', 1)
+@register('log', 2)
+def log(number, base=None):
+    if not isinstance(number, Number):
+        raise TypeError("Expected number, got %r" % (number,))
+    elif not number.is_unitless:
+        raise ValueError("Expected unitless number, got %r" % (number,))
+
+    if base is None:
+        pass
+    elif not isinstance(base, Number):
+        raise TypeError("Expected number, got %r" % (base,))
+    elif not base.is_unitless:
+        raise ValueError("Expected unitless number, got %r" % (base,))
+
+    if base is None:
+        ret = math.log(number.value)
+    else:
+        ret = math.log(number.value, base.value)
+
+    return Number(ret)
+
+
+@register('pow', 2)
+def pow(number, exponent):
+    return number ** exponent
+
+
+COMPASS_HELPERS_LIBRARY.add(Number.wrap_python_function(math.sqrt), 'sqrt', 1)
 COMPASS_HELPERS_LIBRARY.add(Number.wrap_python_function(math.sin), 'sin', 1)
 COMPASS_HELPERS_LIBRARY.add(Number.wrap_python_function(math.cos), 'cos', 1)
 COMPASS_HELPERS_LIBRARY.add(Number.wrap_python_function(math.tan), 'tan', 1)
diff --git a/scss/tests/functions/compass/test_helpers.py b/scss/tests/functions/compass/test_helpers.py
index bb5dfd3..0d52956 100644
--- a/scss/tests/functions/compass/test_helpers.py
+++ b/scss/tests/functions/compass/test_helpers.py
@@ -116,7 +116,26 @@ def test_opposite_position(calc):
 
 ## Math
 
-# pi
+def test_pi(calc):
+    assert calc('pi()') == calc('3.141592653589793')
+
+
+def test_e(calc):
+    assert calc('e()') == calc('2.718281828459045')
+
+
+def test_sqrt(calc):
+    assert calc('sqrt(9)') == calc('3')
+
+
+def test_log(calc):
+    assert calc('log(9, 3)') == calc('2')
+
+
+def test_pow(calc):
+    assert calc('pow(3, 2)') == calc('9')
+    assert calc('pow(10px, 2) / 1px') == calc('100px')
+
 
 # sin
 
diff --git a/scss/types.py b/scss/types.py
index 2944c71..99ef17c 100644
--- a/scss/types.py
+++ b/scss/types.py
@@ -301,6 +301,28 @@ class Number(Value):
 
         return op(round(left.value, 5), round(right.value, 5))
 
+    def __pow__(self, exp):
+        if not isinstance(exp, Number):
+            raise TypeError("Can't raise %r to power %r" % (self, exp))
+        if not exp.is_unitless:
+            raise TypeError("Exponent %r cannot have units" % (exp,))
+
+        if self.is_unitless:
+            return Number(self.value ** exp.value)
+
+        # Units can only be exponentiated to integral powers -- what's the
+        # square root of 'px'?  (Well, it's sqrt(px), but supporting that is
+        # a bit out of scope.)
+        if exp.value != int(exp.value):
+            raise ValueError("Can't raise units of %r to non-integral power %r" % (self, exp))
+
+        return Number(
+            self.value ** int(exp.value),
+            unit_numer=self.unit_numer * int(exp.value),
+            unit_denom=self.unit_denom * int(exp.value),
+        )
+
+
     def __mul__(self, other):
         if not isinstance(other, Number):
             return NotImplemented