Revert "Revert "Import external/python/jinja into master""

This reverts commit 81aec74062b5c629b3408f7f3d18343ec0bbcab8.

Reason for revert: It seems Jinja folder is empty. Revert the revert to add files back.

Third-party review: ag/11821018
Change-Id: I4429a3b3448cdf2eb62ec388392a2a29fa3dbc21

1 files changed, 157 insertions, 0 deletions

diff --git a/src/jinja2/asyncfilters.py b/src/jinja2/asyncfilters.py
new file mode 100644
index 00000000..0aad12c8
--- /dev/null
+++ b/src/jinja2/asyncfilters.py
@@ -0,0 +1,157 @@
+from functools import wraps
+
+from . import filters
+from .asyncsupport import auto_aiter
+from .asyncsupport import auto_await
+
+
+async def auto_to_seq(value):
+    seq = []
+    if hasattr(value, "__aiter__"):
+        async for item in value:
+            seq.append(item)
+    else:
+        for item in value:
+            seq.append(item)
+    return seq
+
+
+async def async_select_or_reject(args, kwargs, modfunc, lookup_attr):
+    seq, func = filters.prepare_select_or_reject(args, kwargs, modfunc, lookup_attr)
+    if seq:
+        async for item in auto_aiter(seq):
+            if func(item):
+                yield item
+
+
+def dualfilter(normal_filter, async_filter):
+    wrap_evalctx = False
+    if getattr(normal_filter, "environmentfilter", False) is True:
+
+        def is_async(args):
+            return args[0].is_async
+
+        wrap_evalctx = False
+    else:
+        has_evalctxfilter = getattr(normal_filter, "evalcontextfilter", False) is True
+        has_ctxfilter = getattr(normal_filter, "contextfilter", False) is True
+        wrap_evalctx = not has_evalctxfilter and not has_ctxfilter
+
+        def is_async(args):
+            return args[0].environment.is_async
+
+    @wraps(normal_filter)
+    def wrapper(*args, **kwargs):
+        b = is_async(args)
+        if wrap_evalctx:
+            args = args[1:]
+        if b:
+            return async_filter(*args, **kwargs)
+        return normal_filter(*args, **kwargs)
+
+    if wrap_evalctx:
+        wrapper.evalcontextfilter = True
+
+    wrapper.asyncfiltervariant = True
+
+    return wrapper
+
+
+def asyncfiltervariant(original):
+    def decorator(f):
+        return dualfilter(original, f)
+
+    return decorator
+
+
+@asyncfiltervariant(filters.do_first)
+async def do_first(environment, seq):
+    try:
+        return await auto_aiter(seq).__anext__()
+    except StopAsyncIteration:
+        return environment.undefined("No first item, sequence was empty.")
+
+
+@asyncfiltervariant(filters.do_groupby)
+async def do_groupby(environment, value, attribute):
+    expr = filters.make_attrgetter(environment, attribute)
+    return [
+        filters._GroupTuple(key, await auto_to_seq(values))
+        for key, values in filters.groupby(
+            sorted(await auto_to_seq(value), key=expr), expr
+        )
+    ]
+
+
+@asyncfiltervariant(filters.do_join)
+async def do_join(eval_ctx, value, d="", attribute=None):
+    return filters.do_join(eval_ctx, await auto_to_seq(value), d, attribute)
+
+
+@asyncfiltervariant(filters.do_list)
+async def do_list(value):
+    return await auto_to_seq(value)
+
+
+@asyncfiltervariant(filters.do_reject)
+async def do_reject(*args, **kwargs):
+    return async_select_or_reject(args, kwargs, lambda x: not x, False)
+
+
+@asyncfiltervariant(filters.do_rejectattr)
+async def do_rejectattr(*args, **kwargs):
+    return async_select_or_reject(args, kwargs, lambda x: not x, True)
+
+
+@asyncfiltervariant(filters.do_select)
+async def do_select(*args, **kwargs):
+    return async_select_or_reject(args, kwargs, lambda x: x, False)
+
+
+@asyncfiltervariant(filters.do_selectattr)
+async def do_selectattr(*args, **kwargs):
+    return async_select_or_reject(args, kwargs, lambda x: x, True)
+
+
+@asyncfiltervariant(filters.do_map)
+async def do_map(*args, **kwargs):
+    seq, func = filters.prepare_map(args, kwargs)
+    if seq:
+        async for item in auto_aiter(seq):
+            yield await auto_await(func(item))
+
+
+@asyncfiltervariant(filters.do_sum)
+async def do_sum(environment, iterable, attribute=None, start=0):
+    rv = start
+    if attribute is not None:
+        func = filters.make_attrgetter(environment, attribute)
+    else:
+
+        def func(x):
+            return x
+
+    async for item in auto_aiter(iterable):
+        rv += func(item)
+    return rv
+
+
+@asyncfiltervariant(filters.do_slice)
+async def do_slice(value, slices, fill_with=None):
+    return filters.do_slice(await auto_to_seq(value), slices, fill_with)
+
+
+ASYNC_FILTERS = {
+    "first": do_first,
+    "groupby": do_groupby,
+    "join": do_join,
+    "list": do_list,
+    # we intentionally do not support do_last because it may not be safe in async
+    "reject": do_reject,
+    "rejectattr": do_rejectattr,
+    "map": do_map,
+    "select": do_select,
+    "selectattr": do_selectattr,
+    "sum": do_sum,
+    "slice": do_slice,
+}