1 files changed, 101 insertions, 0 deletions
diff --git a/python/mozbuild/mozbuild/action/html_fragment_preprocesor.py b/python/mozbuild/mozbuild/action/html_fragment_preprocesor.py
new file mode 100644
index 0000000000..f957318a7f
--- /dev/null
+++ b/python/mozbuild/mozbuild/action/html_fragment_preprocesor.py
@@ -0,0 +1,101 @@
+import json
+import re
+import xml.etree.ElementTree as ET
+from pathlib import Path
+
+JS_FILE_TEMPLATE = """\
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const EXPORTED_SYMBOLS = ["getHTMLFragment"];
+
+const Fragments = {json_string};
+
+/*
+ * Loads HTML fragment strings pulled from fragment documents.
+ * @param key - key identifying HTML fragment
+ *
+ * @return raw HTML/XHTML string
+ */
+const getHTMLFragment = key => Fragments[key];
+"""
+
+RE_COLLAPSE_WHITESPACE = re.compile(r"\s+")
+
+
+def get_fragment_key(path, template_name=None):
+    key = Path(path).stem
+    if template_name:
+        key += "/" + template_name
+    return key
+
+
+def fill_html_fragments_map(fragment_map, path, template, doctype=None):
+    # collape white space
+    for elm in template.iter():
+        if elm.text:
+            elm.text = RE_COLLAPSE_WHITESPACE.sub(" ", elm.text)
+        if elm.tail:
+            elm.tail = RE_COLLAPSE_WHITESPACE.sub(" ", elm.tail)
+    key = get_fragment_key(path, template.attrib.get("name"))
+    xml = "".join(ET.tostring(elm, encoding="unicode") for elm in template).strip()
+    if doctype:
+        xml = doctype + "\n" + xml
+    fragment_map[key] = xml
+
+
+def get_html_fragments_from_file(fragment_map, path):
+    for _, (name, value) in ET.iterparse(path, events=["start-ns"]):
+        ET.register_namespace(name, value)
+    tree = ET.parse(path)
+    root = tree.getroot()
+    sub_templates = root.findall("{http://www.w3.org/1999/xhtml}template")
+    # if all nested nodes are templates then treat as list of templates
+    if len(sub_templates) == len(root):
+        doctype = ""
+        for template in sub_templates:
+            if template.get("doctype") == "true":
+                doctype = template.text.strip()
+                break
+        for template in sub_templates:
+            if template.get("doctype") != "true":
+                fill_html_fragments_map(fragment_map, path, template, doctype)
+    else:
+        fill_html_fragments_map(fragment_map, path, root, None)
+
+
+def generate(output, *inputs):
+    """Builds an html fragments loader JS file from the input xml file(s)
+
+    The xml files are expected to be in the format of:
+    `<template>...xhtml markup...</template>`
+
+    or `<template><template name="fragment_name">...xhtml markup...</template>...</template>`
+    Where there are multiple templates. All markup is expected to be properly namespaced.
+
+    In the JS file, calling getHTMLFragment(key) will return the HTML string from the xml file
+    that matches the key.
+
+    The key format is `filename_without_extension/template_name` for files with
+    multiple templates, or just `filename_without_extension` for files with one template.
+    `filename_without_extension` is the xml filename without the .xml extension
+    and `template_name` is the name attribute of template node containing the xml fragment.
+
+    Arguments:
+    output -- File handle to JS file being generated
+    inputs -- list of xml filenames to include in loader
+
+    Returns:
+    The set of dependencies which should trigger this command to be re-run.
+    This is ultimately returned to the build system for use by the backend
+    to ensure that incremental rebuilds happen when any dependency changes.
+    """
+
+    fragment_map = {}
+    for file in inputs:
+        get_html_fragments_from_file(fragment_map, file)
+    json_string = json.dumps(fragment_map, separators=(",", ":"))
+    contents = JS_FILE_TEMPLATE.format(json_string=json_string)
+    output.write(contents)
+    return set(inputs)