Major restructuring to get automatic decoding/encoding

[pycalendar.git] / pycalendar / property / base.py

diff --git a/pycalendar/property/base.py b/pycalendar/property/base.py
new file mode 100644 (file)
index 0000000..cc66bfb
--- /dev/null
+++ b/pycalendar/property/base.py
@@ -0,0 +1,92 @@
+# Copyright
+
+import io as _io
+import itertools as _itertools
+
+from .. import dtype as _dtype
+
+
+class Property (dict):
+    """An iCalendar property (e.g. VERSION)
+
+    As defined in :RFC:`5545`, section 3.5 (Property).  Property names
+    are defined in sections 3.7 (Calendar Properties) and 3.8
+    (Component Properties).  Parameters are defined in section 3.2
+    (Property Parameters), and value data types are defined in section
+    3.3 (Property Value Data Types).
+    """
+    name = None
+    parameters = []
+    dtypes = []
+    separator = None
+
+    def __init__(self, parameters=None, value=None):
+        if not parameters:
+            parameters = {}
+        super(Property, self).__init__()
+        self.update(parameters)
+        self.value = value
+
+    def __hash__(self):
+        return id(self)
+
+    def __str__(self):
+        with _io.StringIO() as stream:
+            self.write(stream=stream, newline='\n')
+            return stream.getvalue()[:-1]  # strip the trailing newline
+
+    def __repr__(self):
+        return '<{}.{} name:{} at {:#x}>'.format(
+            self.__module__, type(self).__name__, self.name, id(self))
+
+    def decode(self, value):
+        dtype = self._get_dtype()
+        return dtype.decode(property=self, value=value)
+
+    def encode(self, value):
+        dtype = self._get_dtype()
+        return dtype.encode(property=self, value=value)
+
+    def _get_dtype(self, dtype=None):
+        if not dtype:
+            if not self.dtypes:
+                raise NotImplementedError('no default types for {!r}'.format(
+                    self))
+            dtype = self.get('VALUE', self.dtypes[0])
+        if dtype not in self.dtypes:
+            raise ValueError('invalid type {} for {!r}'.format(
+                dtype, self.name))
+        return _dtype.DTYPE[dtype]
+
+    def check_parameters(self):
+        for parameter in self.keys():
+            if parameter not in self.parameters:
+                raise ValueError(
+                    'invalid parameter {} for {!r}'.format(parameter, self))
+
+    def check_value(self):
+        pass
+
+    def write(self, stream, newline='\r\n', width=75):
+        name_param = self.name
+        line = '{}:{}'.format(
+            ';'.join(_itertools.chain(
+                [name_param],
+                ['{}={}'.format(key, value)
+                 for key,value in sorted(self.items())])),
+            self.encode(self.value))
+        lines = []
+        if width:
+            while len(line) > width:
+                front = line[0:width]
+                line = line[width:]
+                if not lines:
+                    width -= 1  # make room for the indent space
+                else:
+                    front = ' {}'.format(front)  # add the indent space
+                lines.append(front)
+            if lines:  # indent the last line
+                line = ' {}'.format(line)
+        lines.append(line)
+        for line in lines:
+            stream.write('{}{}'.format(line, newline))