72 lines
2.6 KiB
Nim
72 lines
2.6 KiB
Nim
# nimbus-eth1
|
|
# Copyright (c) 2023-2024 Status Research & Development GmbH
|
|
# Licensed under either of
|
|
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
|
|
# http://www.apache.org/licenses/LICENSE-2.0)
|
|
# * MIT license ([LICENSE-MIT](LICENSE-MIT) or
|
|
# http://opensource.org/licenses/MIT)
|
|
# at your option. This file may not be copied, modified, or distributed
|
|
# except according to those terms.
|
|
|
|
import
|
|
std/tables,
|
|
eth/common,
|
|
../kvt_desc
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Private functions
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc layersMergeOnto(src: LayerRef; trg: var LayerObj) =
|
|
for (key,val) in src.sTab.pairs:
|
|
trg.sTab[key] = val
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc deltaMerge*(
|
|
upper: LayerRef; # Think of `top`, `nil` is ok
|
|
modUpperOk: bool; # May re-use/modify `upper`
|
|
lower: LayerRef; # Think of `balancer`, `nil` is ok
|
|
modLowerOk: bool; # May re-use/modify `lower`
|
|
): LayerRef =
|
|
## Merge argument `upper` into the `lower` filter instance.
|
|
##
|
|
## Note that the namimg `upper` and `lower` indicate that the filters are
|
|
## stacked and the database access is `upper -> lower -> backend`.
|
|
##
|
|
if lower.isNil:
|
|
# Degenerate case: `upper` is void
|
|
result = upper
|
|
|
|
elif upper.isNil:
|
|
# Degenerate case: `lower` is void
|
|
result = lower
|
|
|
|
elif modLowerOk:
|
|
# Can modify `lower` which is the prefered action mode but applies only
|
|
# in cases where the `lower` argument is not shared.
|
|
layersMergeOnto(upper, lower[])
|
|
result = lower
|
|
|
|
elif not modUpperOk:
|
|
# Cannot modify any argument layers.
|
|
result = LayerRef(sTab: lower.sTab)
|
|
layersMergeOnto(upper, result[])
|
|
|
|
else:
|
|
# Otherwise avoid copying some tables by modifyinh `upper`. This is not
|
|
# completely free as the merge direction changes to merging the `lower`
|
|
# layer up into the higher prioritised `upper` layer (note that the `lower`
|
|
# argument filter is read-only.) Here again, the `upper` argument must not
|
|
# be a shared layer/filter.
|
|
for (key,val) in lower.sTab.pairs:
|
|
if not upper.sTab.hasKey(key):
|
|
upper.sTab[key] = val
|
|
result = upper
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# End
|
|
# ------------------------------------------------------------------------------
|