Fix a couple bugs with interpolation.

- Sometimes whitespace could be lost after an interpolation.

- Null wasn't being correctly interpolated as empty string.

- Removing String.__str__ revealed a tiny bug in apply_vars.

6 files changed, 67 insertions, 35 deletions

diff --git a/scss/ast.py b/scss/ast.py
index 51cb91c..06de23a 100644
--- a/scss/ast.py
+++ b/scss/ast.py
@@ -240,25 +240,6 @@ class Interpolation(Expression):
 
         return Literal(type(parts[0], quotes=quotes, **kwargs))
 
-    def _render_interpolated(self, value):
-        """Return the result of interpolating `value`, which is slightly
-        different than just rendering it, since it's an intermediate thing.
-        """
-        # Strings are taken literally
-        if isinstance(value, String):
-            return value.value
-
-        # Lists are joined recursively
-        if isinstance(value, List):
-            # TODO Ruby /immediately/ respects `compress` here -- need to
-            # inspect the compilation for whether to pass it in (probably in
-            # other places too)
-            return value.delimiter().join(
-                self._render_interpolated(item) for item in value)
-        else:
-            # TODO like here
-            return value.render()
-
     def evaluate(self, calculator, divide=False):
         result = []
         for i, part in enumerate(self.parts):
@@ -268,7 +249,8 @@ class Interpolation(Expression):
             else:
                 # Interspersed (even) parts are nodes
                 value = part.evaluate(calculator, divide)
-                result.append(self._render_interpolated(value))
+                # TODO need to know whether to pass `compress` here
+                result.append(value.render_interpolated())
 
         return self.type(''.join(result), quotes=self.quotes, **self.kwargs)
 
diff --git a/scss/expression.py b/scss/expression.py
index 090e902..39eb623 100644
--- a/scss/expression.py
+++ b/scss/expression.py
@@ -14,6 +14,7 @@ from scss.errors import SassError, SassEvaluationError, SassParseError
 from scss.grammar.expression import SassExpression, SassExpressionScanner
 from scss.rule import Namespace
 from scss.types import String
+from scss.types import Value
 from scss.util import dequote
 
 
@@ -88,8 +89,13 @@ class Calculator(object):
                             return n
                     else:
                         if v:
-                            if not isinstance(v, six.string_types):
-                                v = v.render()
+                            if not isinstance(v, Value):
+                                raise TypeError(
+                                    "Somehow got a variable {0!r} "
+                                    "with a non-Sass value: {1!r}"
+                                    .format(n, v)
+                                )
+                            v = v.render()
                             # TODO this used to test for _dequote
                             if m.group(1):
                                 v = dequote(v)
@@ -98,6 +104,10 @@ class Calculator(object):
                         return v
 
                 cont = _interpolate_re.sub(_av, cont)
+
+            else:
+                # Variable succeeded, so we need to render it
+                cont = cont.render()
         # TODO this is surprising and shouldn't be here
         cont = self.do_glob_math(cont)
         return cont
diff --git a/scss/grammar/expression.g b/scss/grammar/expression.g
index 026f07a..df4d7e0 100644
--- a/scss/grammar/expression.g
+++ b/scss/grammar/expression.g
@@ -38,6 +38,12 @@ from scss.grammar import Scanner
 
 %%
 parser SassExpression:
+    # These need to go before the ignore, so they match first, and we don't
+    # lose spaces inside a string!
+    # Don't allow quotes or # unless they're escaped (or the # is alone)
+    token SINGLE_STRING_GUTS: '([^\'\\\\#]|[\\\\].|#(?![{]))*'
+    token DOUBLE_STRING_GUTS: "([^\"\\\\#]|[\\\\].|#(?![{]))*"
+
     ignore: "[ \r\t\n]+"
     token LPAR: "\\(|\\["
     token RPAR: "\\)|\\]"
@@ -60,11 +66,7 @@ parser SassExpression:
     token DOTDOTDOT: '[.]{3}'
     token SINGLE_QUOTE: "'"
     token DOUBLE_QUOTE: '"'
-    # Don't allow quotes or # unless they're escaped (or the # is alone)
-    token SINGLE_STRING_GUTS: '([^\'\\\\#]|[\\\\].|#(?![{]))*'
-    token DOUBLE_STRING_GUTS: "([^\"\\\\#]|[\\\\].|#(?![{]))*"
-    token STR: "'[^'\\\\]*(?:\\\\.[^'\\\\]*)*'"
-    token QSTR: '"[^"\\\\]*(?:\\\\.[^"\\\\]*)*"'
+
     token UNITS: "(?<!\s)(?:[a-zA-Z]+|%)(?![-\w])"
     token NUM: "(?:\d+(?:\.\d*)?|\.\d+)"
     token COLOR: "#(?:[a-fA-F0-9]{6}|[a-fA-F0-9]{3})(?![a-fA-F0-9])"
@@ -92,6 +94,7 @@ parser SassExpression:
     # FIXME: Also, URLs may not contain $ as it breaks urls with variables?
     token BAREURL: "(?:[\\\\].|[^#$'\"()\\x00-\\x08\\x0b\\x0e-\\x1f\\x7f]|#(?![{]))*"
 
+    # -------------------------------------------------------------------------
     # Goals:
     rule goal:          expr_lst END                {{ return expr_lst }}
 
diff --git a/scss/grammar/expression.py b/scss/grammar/expression.py
index 397fa4c..cf3c9e7 100644
--- a/scss/grammar/expression.py
+++ b/scss/grammar/expression.py
@@ -42,6 +42,8 @@ class SassExpressionScanner(Scanner):
     _patterns = [
         ('":"', ':'),
         ('","', ','),
+        ('SINGLE_STRING_GUTS', "([^'\\\\#]|[\\\\].|#(?![{]))*"),
+        ('DOUBLE_STRING_GUTS', '([^"\\\\#]|[\\\\].|#(?![{]))*'),
         ('[ \r\t\n]+', '[ \r\t\n]+'),
         ('LPAR', '\\(|\\['),
         ('RPAR', '\\)|\\]'),
@@ -64,10 +66,6 @@ class SassExpressionScanner(Scanner):
         ('DOTDOTDOT', '[.]{3}'),
         ('SINGLE_QUOTE', "'"),
         ('DOUBLE_QUOTE', '"'),
-        ('SINGLE_STRING_GUTS', "([^'\\\\#]|[\\\\].|#(?![{]))*"),
-        ('DOUBLE_STRING_GUTS', '([^"\\\\#]|[\\\\].|#(?![{]))*'),
-        ('STR', "'[^'\\\\]*(?:\\\\.[^'\\\\]*)*'"),
-        ('QSTR', '"[^"\\\\]*(?:\\\\.[^"\\\\]*)*"'),
         ('UNITS', '(?<!\\s)(?:[a-zA-Z]+|%)(?![-\\w])'),
         ('NUM', '(?:\\d+(?:\\.\\d*)?|\\.\\d+)'),
         ('COLOR', '#(?:[a-fA-F0-9]{6}|[a-fA-F0-9]{3})(?![a-fA-F0-9])'),
diff --git a/scss/grammar/scanner.py b/scss/grammar/scanner.py
index 8e48d2b..5aee227 100644
--- a/scss/grammar/scanner.py
+++ b/scss/grammar/scanner.py
@@ -206,6 +206,9 @@ except ImportError:
             and add the restriction to self.restrictions
             """
             # Keep looking for a token, ignoring any in self.ignore
+            if DEBUG:
+                print()
+                print("Being asked to match with restriction:", repr(restrict))
             token = None
             while True:
                 best_pat = None
diff --git a/scss/types.py b/scss/types.py
index 65406df..a1c07ab 100644
--- a/scss/types.py
+++ b/scss/types.py
@@ -125,7 +125,19 @@ class Value(object):
         raise ValueError("Not a map: {0!r}".format(self))
 
     def render(self, compress=False):
-        return self.__str__()
+        """Return this value's CSS representation as a string (text, i.e.
+        unicode!).
+
+        If `compress` is true, try hard to shorten the string at the cost of
+        readability.
+        """
+        raise NotImplementedError
+
+    def render_interpolated(self, compress=False):
+        """Return this value's string representation as appropriate for
+        returning from an interpolation.
+        """
+        return self.render(compress)
 
 
 class Null(Value):
@@ -156,6 +168,10 @@ class Null(Value):
     def render(self, compress=False):
         return self.sass_type_name
 
+    def render_interpolated(self, compress=False):
+        # Interpolating a null gives you nothing.
+        return ''
+
 
 class Undefined(Null):
     sass_type_name = 'undefined'
@@ -692,6 +708,10 @@ class List(Value):
             for item in value
         )
 
+    def render_interpolated(self, compress=False):
+        return self.delimiter(compress).join(
+            item.render_interpolated(compress) for item in self)
+
     # DEVIATION: binary ops on lists and scalars act element-wise
     def __add__(self, other):
         if isinstance(other, List):
@@ -1107,6 +1127,10 @@ class String(Value):
         else:
             return self._render_quoted()
 
+    def render_interpolated(self, compress=False):
+        # Always render without quotes
+        return self.value
+
     def _render_bareword(self):
         # TODO this is currently unused, and only implemented due to an
         # oversight, but would make for a much better implementation of
@@ -1173,6 +1197,12 @@ class Function(String):
             super(Function, self).render(compress),
         )
 
+    def render_interpolated(self, compress=False):
+        return "{0}({1})".format(
+            self.function_name,
+            super(Function, self).render_interpolated(compress),
+        )
+
 
 class Url(Function):
     # Bare URLs may not contain quotes, parentheses, or unprintables.  Quoted
@@ -1185,11 +1215,17 @@ class Url(Function):
 
     def render(self, compress=False):
         if self.quotes is None:
-            # Need to escape some stuff to keep this as valid CSS
-            inside = self.bad_identifier_rx.sub(
-                self._escape_character, self.value)
+            return self.render_interpolated(compress)
         else:
             inside = self._render_quoted()
+            return "url(" + inside + ")"
+
+    def render_interpolated(self, compress=False):
+        # Always render without quotes.
+        # When doing that, we need to escape some stuff to make sure the result
+        # is valid CSS.
+        inside = self.bad_identifier_rx.sub(
+            self._escape_character, self.value)
 
         return "url(" + inside + ")"