1 files changed, 70 insertions, 0 deletions
diff --git a/src/rub/xml.py b/src/rub/xml.py
new file mode 100644
index 0000000..ed61a8b
--- /dev/null
+++ b/src/rub/xml.py
@@ -0,0 +1,70 @@
+# XML processing abstractions
+# Copyright (C) 2023  Nguyễn Gia Phong
+#
+# This file is part of rub.
+#
+# Rub is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published
+# by the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Rub is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with rub.  If not, see <https://www.gnu.org/licenses/>.
+
+from copy import deepcopy
+from functools import partial
+from pathlib import Path
+
+from lxml.etree import QName, XML, XSLT, XSLTExtension
+
+__all__ = ['NS', 'generator', 'recurse']
+
+NS = 'https://rub.parody'
+
+
+def recurse(extension, context, input_node, output_parent):
+    """Apply template recursively on input node."""
+    output = deepcopy(input_node)
+    for i in output: output.remove(i)
+    for i in input_node:
+        for j in extension.apply_templates(context, i):
+            if not isinstance(j, str):
+                output.append(deepcopy(j))
+            elif len(output) == 0:
+                if output.text is None:
+                    output.text = j
+                else:
+                    output.text += j
+            elif output[-1].tail is None:
+                output[-1].tail = j
+            else:
+                output[-1].tail += j
+    output_parent.append(output)
+
+
+class Evaluator(XSLTExtension):
+    def __init__(self, **handlers):
+        self.handlers = {QName(NS, k).text: v for k, v in handlers.items()}
+        super().__init__()
+
+    def execute(self, context, self_node, input_node, output_parent):
+        handle = self.handlers.get(input_node.tag, recurse)
+        handle(self, context, input_node, output_parent)
+
+
+def generator(xslt, **handlers):
+    """Return a function taking an XML file and apply given XSLT."""
+    stylesheet = xslt.read_bytes()
+    extensions = {(NS, 'eval'): Evaluator(**handlers)}
+    transform = XSLT(XML(stylesheet), extensions=extensions)
+
+    def make(src, dest):
+        dest.parent.mkdir(mode=0o755, parents=True, exist_ok=True)
+        dest.write_text(str(transform(XML(src.read_bytes()))))
+
+    return make