Start on uri-template based on the provisional API.

Will probably change as python-hyper/uritemplate#36
is merged.

jsonschema/_format.py

@@ -299,6 +299,22 @@ def is_json_pointer(instance):
         return jsonpointer.JsonPointer(instance)
 
 
+try:
+    import uritemplate.exceptions
+except ImportError:
+    pass
+else:
+    @_checks_drafts(
+        draft6="uri-template", raises=uritemplate.exceptions.InvalidTemplate,
+    )
+    def is_uri_template(
+        instance,
+        template_validator=uritemplate.Validator().force_balanced_braces(),
+    ):
+        template = uritemplate.URITemplate(instance)
+        return template_validator.validate(template)
+
+
 draft3_format_checker = FormatChecker(_draft_checkers["draft3"])
 draft4_format_checker = FormatChecker(_draft_checkers["draft4"])
 draft6_format_checker = FormatChecker(_draft_checkers["draft6"])

setup.py

@@ -24,7 +24,13 @@
 ]
 
 extras_require = {
-    "format" : ["jsonpointer>1.13", "rfc3987", "strict-rfc3339", "webcolors"],
+    "format": [
+        "jsonpointer>1.13",
+        "rfc3987",
+        "strict-rfc3339",
+        "uritemplate>3.0.0",
+        "webcolors",
+    ],
     ":python_version=='2.7'": ["functools32"],
 }