use isolation

Author: Pike

fluent.runtime/fluent/runtime/__init__.py

@@ -35,7 +35,7 @@ def __init__(self, locales, functions=None, use_isolating=True):
         self._use_isolating = use_isolating
         self._messages_and_terms = {}
         self._compiled = {}
-        self._compiler = Compiler()
+        self._compiler = Compiler(use_isolating=use_isolating)
         self._babel_locale = self._get_babel_locale()
         self._plural_form = babel.plural.to_python(self._babel_locale.plural_form)
 

fluent.runtime/fluent/runtime/prepare.py

@@ -4,8 +4,9 @@
 
 
 class Compiler(object):
-    def __init__(self, bundle=None):
+    def __init__(self, use_isolating=False, bundle=None):
         self.bundle = None
+        self.use_isolating = use_isolating
 
     def __call__(self, item):
         if isinstance(item, FTL.BaseNode):
@@ -28,11 +29,19 @@ def compile_generic(self, nodename, **kwargs):
         return getattr(resolver, nodename)(**kwargs)
 
     def compile_Placeable(self, _, expression, **kwargs):
+        if self.use_isolating:
+            return resolver.IsolatingPlaceable(expression=expression, **kwargs)
         if isinstance(expression, resolver.Literal):
             return expression
         return resolver.Placeable(expression=expression, **kwargs)
 
     def compile_Pattern(self, _, elements, **kwargs):
+        if (
+            len(elements) == 1 and
+            isinstance(elements[0], resolver.IsolatingPlaceable)
+        ):
+            # Don't isolate isolated placeables
+            return elements[0].expression
         if any(
             not isinstance(child, resolver.Literal)
             for child in elements

fluent.runtime/fluent/runtime/resolver.py

@@ -140,15 +140,15 @@ def __call__(self, env):
             return FluentNone()
         self.dirty = True
         retval = ''.join(
-            self.resolve(element(env), env) for element in self.elements
+            resolve(element(env), env) for element in self.elements
         )
         self.dirty = False
         return retval
 
-    def resolve(self, fluentish, env):
-        if isinstance(fluentish, (FluentType, FluentNumber)):
-            return fluentish.format(env.context._babel_locale)
-        return fluentish
+def resolve(fluentish, env):
+    if isinstance(fluentish, (FluentType, FluentNumber)):
+        return fluentish.format(env.context._babel_locale)
+    return fluentish
 
 
 class TextElement(FTL.TextElement, Literal):
@@ -161,6 +161,12 @@ def __call__(self, env):
         return self.expression(env)
 
 
+class IsolatingPlaceable(FTL.Placeable, BaseResolver):
+    def __call__(self, env):
+        inner = self.expression(env)
+        return "\u2068" + resolve(inner, env) + "\u2069"
+
+
 class StringLiteral(FTL.StringLiteral, Literal):
     def __call__(self, env):
         return self.value