1 files changed, 65 insertions, 0 deletions
diff --git a/sphinx/domains/index.py b/sphinx/domains/index.py
new file mode 100644
index 000000000..4b1fd2bb6
--- /dev/null
+++ b/sphinx/domains/index.py
@@ -0,0 +1,65 @@
+"""
+    sphinx.domains.index
+    ~~~~~~~~~~~~~~~~~~~~
+
+    The index domain.
+
+    :copyright: Copyright 2007-2019 by the Sphinx team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+from typing import Any, Dict, Iterable, List, Tuple
+
+from docutils.nodes import Node
+
+from sphinx import addnodes
+from sphinx.application import Sphinx
+from sphinx.domains import Domain
+from sphinx.environment import BuildEnvironment
+from sphinx.util import logging
+from sphinx.util import split_index_msg
+
+
+logger = logging.getLogger(__name__)
+
+
+class IndexDomain(Domain):
+    """Mathematics domain."""
+    name = 'index'
+    label = 'index'
+
+    @property
+    def entries(self) -> Dict[str, List[Tuple[str, str, str, str, str]]]:
+        return self.data.setdefault('entries', {})
+
+    def clear_doc(self, docname: str) -> None:
+        self.entries.pop(docname, None)
+
+    def merge_domaindata(self, docnames: Iterable[str], otherdata: Dict) -> None:
+        for docname in docnames:
+            self.entries[docname] = otherdata['entries'][docname]
+
+    def process_doc(self, env: BuildEnvironment, docname: str, document: Node) -> None:
+        """Process a document after it is read by the environment."""
+        entries = self.entries.setdefault(env.docname, [])
+        for node in document.traverse(addnodes.index):
+            try:
+                for entry in node['entries']:
+                    split_index_msg(entry[0], entry[1])
+            except ValueError as exc:
+                logger.warning(str(exc), location=node)
+                node.parent.remove(node)
+            else:
+                for entry in node['entries']:
+                    entries.append(entry)
+
+
+def setup(app: Sphinx) -> Dict[str, Any]:
+    app.add_domain(IndexDomain)
+
+    return {
+        'version': 'builtin',
+        'env_version': 1,
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+    }