Introduce src dir.

[librarian.git] / src / librarian / embeds / __init__.py

diff --git a/src/librarian/embeds/__init__.py b/src/librarian/embeds/__init__.py
new file mode 100644 (file)
index 0000000..fa74530
--- /dev/null
+++ b/src/librarian/embeds/__init__.py
@@ -0,0 +1,58 @@
+from __future__ import unicode_literals
+
+import importlib
+from lxml import etree
+
+known_types = {
+    'application/mathml+xml': 'librarian.embeds.mathml.MathML',
+    'application/x-latex': 'librarian.embeds.latex.LaTeX',
+}
+
+class Embed():
+    @classmethod
+    def transforms_to(cls, mime_types, downgrade=False):
+        matches = set()
+        for name, method in cls.__dict__.iteritems():
+            if hasattr(method, "embed_converts_to"):
+                conv_type, conv_downgrade = method.embed_converts_to
+                if downgrade == conv_downgrade and conv_type in mime_types:
+                    matches.add(conv_type)
+        return matches
+
+    def transform_to(self, mime_type, downgrade=False):
+        for name, method in type(cls).__dict__.iteritems():
+            if hasattr(method, "embed_converts_to"):
+                conv_type, conv_downgrade = method.embed_converts_to
+                if downgrade == conv_downgrade and conv_type == mime_type:
+                    return method(self)
+
+
+class DataEmbed(Embed):
+    def __init__(self, data=None):
+        self.data = data
+
+class TreeEmbed(Embed):
+    def __init__(self, tree=None):
+        if isinstance(tree, etree._Element):
+            tree = etree.ElementTree(tree)
+        self.tree = tree
+
+def converts_to(mime_type, downgrade=False):
+    def decorator(method):
+        method.embed_converts_to = mime_type, downgrade
+        return method
+    return decorator
+
+def downgrades_to(mime_type):
+    return converts_to(mime_type, True)
+
+def create_embed(mime_type, tree=None, data=None):
+    embed = known_types.get(mime_type)
+    if embed is None:
+        embed = DataEmbed if tree is None else TreeEmbed
+    else:
+        mod_name, cls_name = embed.rsplit('.', 1)
+        mod = importlib.import_module(mod_name)
+        embed = getattr(mod, cls_name)
+
+    return embed(data if tree is None else tree)