Add an utility module for operating on sequences.

diff --git a/seqtools.py b/seqtools.py
new file mode 100644 (file)
index 0000000..22d0283
--- /dev/null
+++ b/seqtools.py
@@ -0,0 +1,97 @@
+# vim: set encoding=utf-8 et sw=4 sts=4 :
+
+r"""
+Sequence utilities.
+
+This module provides some tools to ease working with sequences.
+"""
+
+class Sequence:
+    r"""Sequence() -> Sequence instance.
+
+    This is an abstract class to ease the implementation of sequences. You can
+    inherit your objects from this class and implement just a method called
+    as_tuple() which returns a tuple representation of the object.
+
+    Example:
+
+    >>> class A(Sequence):
+    >>>     def __init__(self):
+    >>>         self.a = 1
+    >>>         self.b = 2
+    >>>     def as_tuple(self):
+    >>>         return (self.a, self.b)
+    >>> for i in A():
+    >>>     print i
+    >>> print A()[1]
+    """
+
+    def __iter__(self):
+        r"iter(obj) -> iterator object :: Get iterator."
+        for i in self.as_tuple():
+            yield i
+
+    def __len__(self):
+        r"len(obj) -> int :: Get object length."
+        return len(self.as_tuple())
+
+    def __getitem__(self, i):
+        r"obj[i] -> object :: Get item with the index i."
+        return self.as_tuple()[i]
+
+    def __repr__(self):
+        return '%s%r' % (self.__class__.__name__, self.as_tuple())
+
+def as_tuple(obj):
+    if isinstance(obj, basestring):
+        return (obj,)
+    if hasattr(obj, 'items'):
+        return tuple(obj.items())
+    if hasattr(obj, '__iter__'):
+        return tuple(obj)
+    return (obj,)
+
+def as_table(obj):
+    obj = as_tuple(obj)
+    for i in obj:
+        if isinstance(i, basestring):
+            return (obj,)
+        if hasattr(i, '__iter__'):
+            return obj
+        return (obj,)
+
+
+if __name__ == '__main__':
+
+    class A(Sequence):
+        def __init__(self):
+            self.a = 1
+            self.b = 2
+        def as_tuple(self):
+            return (self.a, self.b)
+
+    class B:
+        def __repr__(self):
+            return 'B()'
+
+    for i in A():
+        print i
+
+    print A()[1]
+
+    for f in (as_tuple, as_table):
+
+        print f.__name__
+
+        print f(A())
+
+        print f("hello")
+
+        print f([1,2,3])
+
+        print f([[1,2,3],[6,7,8]])
+
+        print f(B())
+
+        print f(dict(a=1, b=2))
+