Implement format string parsing.

2 files changed, 90 insertions, 5 deletions

diff --git a/ttystatus/fmt.py b/ttystatus/fmt.py
index 16b2fe0..16b69de 100644
--- a/ttystatus/fmt.py
+++ b/ttystatus/fmt.py
@@ -14,10 +14,53 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 
+import inspect
+import re
+
 import ttystatus
 
 
-widgets = [getattr(ttystatus, x)
-           for x in dir(ttystatus)
-           if isinstance(getattr(ttystatus, x), ttystatus.Widget) and
-              getattr(ttystatus, x) != ttystatus.Widget]
+def _find_widgets():
+    names = dir(ttystatus)
+    objs = [getattr(ttystatus, x) for x in names]
+    classes = [o for o in objs if inspect.isclass(o)]
+    widgets = [c for c in classes if issubclass(c, ttystatus.Widget)]
+    subclasses = [w for w in widgets if w != ttystatus.Widget]
+    return subclasses
+
+widgets = _find_widgets()
+              
+              
+def parse(fmt):
+    '''Parse format string.'''
+    
+    names = [x.__name__ for x in widgets]
+    namespat = '|'.join(names)
+    argspat = r'[0-9a-zA-Z,_-]*'
+    pat = r'%%(?P<class>%s)\((?P<args>%s)\)' % (namespat, argspat)
+    pat = re.compile(pat)
+    
+    result = []
+    prefix = ''
+    while fmt:
+        m = pat.match(fmt)
+        if m:
+            klass = getattr(ttystatus, m.group('class'))
+            argnames = m.group('args').split(',')
+            argnames = [x for x in argnames if x]
+            if prefix:
+                result.append(ttystatus.Literal(prefix))    
+                prefix = ''
+            result.append(klass(*argnames))
+            fmt = fmt[m.end():]
+        elif fmt.startswith('%%'):
+            prefix += '%'
+            fmt = fmt[2:]
+        else:
+            prefix += fmt[0]
+            fmt = fmt[1:]
+
+    if prefix:
+        result.append(ttystatus.Literal(prefix))    
+    return result
+
diff --git a/ttystatus/fmt_tests.py b/ttystatus/fmt_tests.py
index 1848114..af39948 100644
--- a/ttystatus/fmt_tests.py
+++ b/ttystatus/fmt_tests.py
@@ -23,7 +23,49 @@ class FormatTests(unittest.TestCase):
 
     def test_knows_widgets(self):
         self.assertEqual(type(ttystatus.fmt.widgets), list)
+        self.assert_(len(ttystatus.fmt.widgets) > 0)
         for widget in ttystatus.fmt.widgets:
-            self.assert_(isinstance(widget, ttystatus.Widget))
+            self.assert_(issubclass(widget, ttystatus.Widget))
             self.assertNotEqual(widget, ttystatus.Widget)
 
+    def test_parses_string_without_widgets(self):
+        x = ttystatus.fmt.parse('hello, world')
+        self.assertEqual(len(x), 1)
+        self.assertEqual(type(x[0]), ttystatus.Literal)
+        self.assertEqual(str(x[0]), 'hello, world')
+
+    def test_parses_escaped_pecent(self):
+        x = ttystatus.fmt.parse('%%')
+        self.assertEqual(len(x), 1)
+        self.assertEqual(type(x[0]), ttystatus.Literal)
+        self.assertEqual(str(x[0]), '%')
+
+    def test_parses_parameterless_widget(self):
+        x = ttystatus.fmt.parse('%ElapsedTime()')
+
+        self.assertEqual(len(x), 1)
+        self.assertEqual(type(x[0]), ttystatus.ElapsedTime)
+
+    def test_parses_widget_with_one_parameter(self):
+        x = ttystatus.fmt.parse('%String(name)')
+
+        self.assertEqual(len(x), 1)
+
+        self.assertEqual(type(x[0]), ttystatus.String)
+        self.assertEqual(x[0]._key, 'name')
+
+    def test_parses_some_widgets(self):
+        x = ttystatus.fmt.parse('hello, %String(name): %ElapsedTime()')
+
+        self.assertEqual(len(x), 4)
+
+        self.assertEqual(type(x[0]), ttystatus.Literal)
+        self.assertEqual(str(x[0]), 'hello, ')
+
+        self.assertEqual(type(x[1]), ttystatus.String)
+
+        self.assertEqual(type(x[2]), ttystatus.Literal)
+        self.assertEqual(str(x[2]), ': ')
+
+        self.assertEqual(type(x[3]), ttystatus.ElapsedTime)
+