1 files changed, 71 insertions, 0 deletions
diff --git a/mu4web/html_render.py b/mu4web/html_render.py
new file mode 100644
index 0000000..99140ad
--- /dev/null
+++ b/mu4web/html_render.py
@@ -0,0 +1,71 @@
+import html
+from typing import (
+    Callable,
+    TypeAlias,
+    Union,
+)
+
+HTML: TypeAlias = Union[tuple,
+                        list['HTML'],
+                        Callable[[], str],
+                        None, str, int, float]
+
+
+standalones = ['hr', 'br', 'meta']
+"""Tags which can't have a closing tag."""
+
+
+def _render_document(document: HTML) -> str:
+    if isinstance(document, tuple):
+        tag, *body = document
+        if body and isinstance(body[0], dict):
+            print(body[0])
+            attributes = ' '.join(f'{a}="{html.escape(b)}"'
+                                  for a, b in body[0].items())
+            body = body[1:]
+            start = f'<{tag} {attributes}>'
+        else:
+            start = f'<{tag}>'
+
+        if tag in standalones:
+            return start
+        else:
+            if body:
+                items = ''.join(_render_document(b) for b in body)
+            else:
+                items = ''
+            return start + f'{items}</{tag}>'
+    elif callable(document):
+        return str(document())
+    elif isinstance(document, list):
+        return ''.join(_render_document(e) for e in document)
+    elif document is None:
+        return ''
+    else:
+        # strings, and everything else
+        return html.escape(str(document))
+
+
+def render_document(document: HTML) -> str:
+    """
+    Render an HTML structure to an Html string.
+
+    The following Python types are converted as follows:
+    - Tuples
+      - The first value becomes the tags name
+      - The second value, if a dictionary, becomes the tags attributes
+      - All following values (including the second if not a dictionary)
+        gets individually passed to render_document.
+    - Lists
+      Each element gets passed to render_document
+    - Callable[[], str]
+      Gets called, and its output is included verbatim. Useful for
+      including strings which shouldn't be escaped.
+    - str
+      Gets escaped, and included
+    - int, float
+      Gets included as their default string representation.
+    - None
+      Becomes an empty string
+    """
+    return '<!doctype html>\n' + _render_document(document)