Fixes #1429, add `iri2uri` (#1902)

Add an iri-to-uri conversion utility to encode IRIs to URIs for `Graph.parse()` sources. Added a couple of tests because feeding it with a suite of IRIs to check seems overkill (not that I could find one).

Fixes #1429

Co-authored-by: Iwan Aucamp <aucampia@gmail.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/rdflib/util.py b/rdflib/util.py
index 246b5cc8..b73a9594 100644
--- a/rdflib/util.py
+++ b/rdflib/util.py
@@ -36,6 +36,7 @@ from typing import (
     Tuple,
     TypeVar,
 )
+from urllib.parse import quote, urlsplit, urlunsplit
 
 import rdflib.graph  # avoid circular dependency
 from rdflib.compat import sign
@@ -58,6 +59,7 @@ __all__ = [
     "find_roots",
     "get_tree",
     "_coalesce",
+    "_iri2uri",
 ]
 
 
@@ -476,3 +478,36 @@ def _coalesce(*args: Optional[_AnyT]) -> Optional[_AnyT]:
         if arg is not None:
             return arg
     return None
+
+
+def _iri2uri(iri: str) -> str:
+    """
+    Convert an IRI to a URI (Python 3).
+    https://stackoverflow.com/a/42309027
+    https://stackoverflow.com/a/40654295
+    netloc should be encoded using IDNA;
+    non-ascii URL path should be encoded to UTF-8 and then percent-escaped;
+    non-ascii query parameters should be encoded to the encoding of a page
+    URL was extracted from (or to the encoding server uses), then
+    percent-escaped.
+    >>> _iri2uri("https://dbpedia.org/resource/Almería")
+    'https://dbpedia.org/resource/Almer%C3%ADa'
+    """
+
+    (scheme, netloc, path, query, fragment) = urlsplit(iri)
+
+    # Just support http/https, otherwise return the iri unmolested
+    if scheme not in ["http", "https"]:
+        return iri
+
+    scheme = quote(scheme)
+    netloc = quote(netloc.encode("idna").decode("utf-8"))
+    path = quote(path)
+    query = quote(query)
+    fragment = quote(fragment)
+    uri = urlunsplit((scheme, netloc, path, query, fragment))
+
+    if iri.endswith("#") and not uri.endswith("#"):
+        uri += "#"
+
+    return uri