390 lines
13 KiB
Nim
390 lines
13 KiB
Nim
# nimbus-eth1
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# Copyright (c) 2023 Status Research & Development GmbH
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# Licensed under either of
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# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
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# http://www.apache.org/licenses/LICENSE-2.0)
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# * MIT license ([LICENSE-MIT](LICENSE-MIT) or
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# http://opensource.org/licenses/MIT)
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# at your option. This file may not be copied, modified, or distributed
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# except according to those terms.
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## Aristo DB -- Patricia Trie delete funcionality
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## ==============================================
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##
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## Deleate by `Hike` type chain of vertices.
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{.push raises: [].}
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import
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std/[sets, tables],
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chronicles,
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eth/[common, trie/nibbles],
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results,
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"."/[aristo_desc, aristo_get, aristo_hike, aristo_path, aristo_vid]
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logScope:
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topics = "aristo-delete"
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# ------------------------------------------------------------------------------
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# Private heplers
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# ------------------------------------------------------------------------------
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func toVae(err: AristoError): (VertexID,AristoError) =
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## Map single error to error pair with dummy vertex
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(VertexID(0),err)
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func toVae(err: (Hike,AristoError)): (VertexID,AristoError) =
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if 0 < err[0].legs.len:
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(err[0].legs[^1].wp.vid, err[1])
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else:
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(VertexID(0), err[1])
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proc branchStillNeeded(vtx: VertexRef): Result[int,void] =
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## Returns the nibble if there is only one reference left.
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var nibble = -1
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for n in 0 .. 15:
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if vtx.bVid[n].isValid:
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if 0 <= nibble:
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return ok(-1)
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nibble = n
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if 0 <= nibble:
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return ok(nibble)
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# Oops, degenerated branch node
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err()
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proc clearKey(
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db: AristoDbRef; # Database, top layer
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vid: VertexID; # Vertex IDs to clear
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) =
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let lbl = db.top.kMap.getOrVoid vid
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if lbl.isValid:
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db.top.kMap.del vid
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db.top.pAmk.del lbl
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elif db.getKeyBE(vid).isOK:
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# Register for deleting on backend
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db.top.kMap[vid] = VOID_HASH_LABEL
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db.top.pAmk.del lbl
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proc doneWith(
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db: AristoDbRef; # Database, top layer
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vid: VertexID; # Vertex IDs to clear
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) =
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# Remove entry
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if db.getVtxBE(vid).isOk:
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db.top.sTab[vid] = VertexRef(nil) # Will be propagated to backend
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else:
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db.top.sTab.del vid
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db.vidDispose vid
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db.clearKey vid
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# ------------------------------------------------------------------------------
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# Private functions
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# ------------------------------------------------------------------------------
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proc collapseBranch(
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db: AristoDbRef; # Database, top layer
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hike: Hike; # Fully expanded path
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nibble: byte; # Applicable link for `Branch` vertex
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): Result[void,(VertexID,AristoError)] =
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## Convert/merge vertices:
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## ::
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## current | becomes | condition
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## | |
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## ^3 ^2 | ^3 ^2 |
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## -------------------+---------------------+------------------
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## Branch <br> Branch | Branch <ext> Branch | 2 < legs.len (1)
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## Ext <br> Branch | <ext> Branch | 2 < legs.len (2)
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## <br> Branch | <ext> Branch | legs.len == 2 (3)
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##
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## Depending on whether the parent `par` is an extension, merge `br` into
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## `par`. Otherwise replace `br` by an extension.
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##
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let br = hike.legs[^2].wp
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var xt = VidVtxPair( # Rewrite `br`
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vid: br.vid,
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vtx: VertexRef(
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vType: Extension,
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ePfx: @[nibble].initNibbleRange.slice(1),
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eVid: br.vtx.bVid[nibble]))
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if 2 < hike.legs.len: # (1) or (2)
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let par = hike.legs[^3].wp
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case par.vtx.vType:
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of Branch: # (1)
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# Replace `br` (use `xt` as-is)
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discard
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of Extension: # (2)
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# Merge `br` into ^3 (update `xt`)
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db.doneWith xt.vid
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xt.vid = par.vid
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xt.vtx.ePfx = par.vtx.ePfx & xt.vtx.ePfx
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of Leaf:
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return err((par.vid,DelLeafUnexpected))
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else: # (3)
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# Replace `br` (use `xt` as-is)
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discard
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db.top.sTab[xt.vid] = xt.vtx
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ok()
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proc collapseExt(
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db: AristoDbRef; # Database, top layer
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hike: Hike; # Fully expanded path
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nibble: byte; # Link for `Branch` vertex `^2`
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vtx: VertexRef; # Follow up extension vertex (nibble)
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): Result[void,(VertexID,AristoError)] =
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## Convert/merge vertices:
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## ::
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## ^3 ^2 `vtx` | ^3 ^2 |
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## --------------------+-----------------------+------------------
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## Branch <br> Ext | Branch <ext> | 2 < legs.len (1)
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## Ext <br> Ext | <ext> | 2 < legs.len (2)
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## <br> Ext | <ext> | legs.len == 2 (3)
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##
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## Merge `vtx` into `br` and unlink `vtx`.
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##
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let br = hike.legs[^2].wp
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var xt = VidVtxPair( # Merge `vtx` into `br`
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vid: br.vid,
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vtx: VertexRef(
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vType: Extension,
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ePfx: @[nibble].initNibbleRange.slice(1) & vtx.ePfx,
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eVid: vtx.eVid))
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db.doneWith br.vtx.bVid[nibble] # `vtx` is obsolete now
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if 2 < hike.legs.len: # (1) or (2)
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let par = hike.legs[^3].wp
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case par.vtx.vType:
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of Branch: # (1)
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# Replace `br` by `^2 & vtx` (use `xt` as-is)
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discard
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of Extension: # (2)
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# Replace ^3 by `^3 & ^2 & vtx` (update `xt`)
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db.doneWith xt.vid
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xt.vid = par.vid
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xt.vtx.ePfx = par.vtx.ePfx & xt.vtx.ePfx
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of Leaf:
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return err((par.vid,DelLeafUnexpected))
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else: # (3)
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# Replace ^2 by `^2 & vtx` (use `xt` as-is)
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discard
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db.top.sTab[xt.vid] = xt.vtx
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ok()
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proc collapseLeaf(
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db: AristoDbRef; # Database, top layer
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hike: Hike; # Fully expanded path
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nibble: byte; # Link for `Branch` vertex `^2`
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vtx: VertexRef; # Follow up leaf vertex (from nibble)
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): Result[void,(VertexID,AristoError)] =
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## Convert/merge vertices:
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## ::
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## current | becomes | condition
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## | |
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## ^4 ^3 ^2 `vtx` | ^4 ^3 ^2 |
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## -------------------------+----------------------------+------------------
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## .. Branch <br> Leaf | .. Branch <Leaf> | 2 < legs.len (1)
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## Branch Ext <br> Leaf | Branch <Leaf> | 3 < legs.len (2)
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## Ext <br> Leaf | <Leaf> | legs.len == 3 (3)
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## <br> Leaf | <Leaf> | legs.len == 2 (4)
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##
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## Merge `<br>` and `Leaf` replacing one and removing the other.
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##
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let br = hike.legs[^2].wp
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var lf = VidVtxPair( # Merge `br` into `vtx`
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vid: br.vtx.bVid[nibble],
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vtx: VertexRef(
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vType: Leaf,
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lPfx: @[nibble].initNibbleRange.slice(1) & vtx.lPfx,
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lData: vtx.lData))
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db.doneWith br.vid # `br` is obsolete now
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db.clearKey lf.vid # `vtx` was modified
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if 2 < hike.legs.len: # (1), (2), or (3)
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# Merge `br` into the leaf `vtx` and unlink `br`.
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let par = hike.legs[^3].wp
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case par.vtx.vType:
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of Branch: # (1)
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# Replace `vtx` by `^2 & vtx` (use `lf` as-is)
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par.vtx.bVid[hike.legs[^3].nibble] = lf.vid
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db.top.sTab[par.vid] = par.vtx
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db.top.sTab[lf.vid] = lf.vtx
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return ok()
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of Extension: # (2) or (3)
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# Merge `^3` into `lf` but keep the leaf vertex ID unchanged. This
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# avoids some `lTab[]` registry update.
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lf.vtx.lPfx = par.vtx.ePfx & lf.vtx.lPfx
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if 3 < hike.legs.len: # (2)
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# Grandparent exists
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let gpr = hike.legs[^4].wp
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if gpr.vtx.vType != Branch:
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return err((gpr.vid,DelBranchExpexted))
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db.doneWith par.vid # `par` is obsolete now
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gpr.vtx.bVid[hike.legs[^4].nibble] = lf.vid
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db.top.sTab[gpr.vid] = gpr.vtx
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db.top.sTab[lf.vid] = lf.vtx
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return ok()
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# No grandparent, so ^3 is root vertex # (3)
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db.top.sTab[par.vid] = lf.vtx
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# Continue below
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of Leaf:
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return err((par.vid,DelLeafUnexpected))
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else: # (4)
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# Replace ^2 by `^2 & vtx` (use `lf` as-is)
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db.top.sTab[br.vid] = lf.vtx
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# Continue below
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# Common part for setting up `lf` as root vertex # Rest of (3) or (4)
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let rc = lf.vtx.lPfx.pathToTag
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if rc.isErr:
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return err((br.vid,rc.error))
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#
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# No need to update the cache unless `lf` is present there. The leaf path
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# as well as the value associated with the leaf path has not been changed.
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let lfTie = LeafTie(root: hike.root, path: rc.value)
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if db.top.lTab.hasKey lfTie:
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db.top.lTab[lfTie] = lf.vid
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# Clean up stale leaf vertex which has moved to root position
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db.doneWith lf.vid
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ok()
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# -------------------------
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proc deleteImpl(
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db: AristoDbRef; # Database, top layer
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hike: Hike; # Fully expanded path
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lty: LeafTie; # `Patricia Trie` path root-to-leaf
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): Result[void,(VertexID,AristoError)] =
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## Implementation of *delete* functionality.
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# Remove leaf entry on the top
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let lf = hike.legs[^1].wp
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if lf.vtx.vType != Leaf:
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return err((lf.vid,DelLeafExpexted))
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if lf.vid in db.top.pPrf:
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return err((lf.vid, DelLeafLocked))
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# Will be needed at the end. Just detect an error early enouhh
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let leafVidBe = block:
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let rc = db.getVtxBE lf.vid
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if rc.isErr:
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if rc.error != GetVtxNotFound:
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return err((lf.vid, rc.error))
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VertexRef(nil)
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else:
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rc.value
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# Will modify top level cache
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db.top.dirty = true
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db.doneWith lf.vid
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if 1 < hike.legs.len:
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# Get current `Branch` vertex `br`
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let br = block:
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var wp = hike.legs[^2].wp
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wp.vtx = wp.vtx.dup # make sure that layers are not impliciteley modified
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wp
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if br.vtx.vType != Branch:
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return err((br.vid,DelBranchExpexted))
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# Unlink child vertex from structural table
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br.vtx.bVid[hike.legs[^2].nibble] = VertexID(0)
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db.top.sTab[br.vid] = br.vtx
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# Clear all keys up to the root key
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for n in 0 .. hike.legs.len - 2:
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let vid = hike.legs[n].wp.vid
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if vid in db.top.pPrf:
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return err((vid, DelBranchLocked))
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db.clearKey vid
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let nibble = block:
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let rc = br.vtx.branchStillNeeded()
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if rc.isErr:
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return err((br.vid,DelBranchWithoutRefs))
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rc.value
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# Convert to `Extension` or `Leaf` vertex
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if 0 <= nibble:
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# Get child vertex (there must be one after a `Branch` node)
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let nxt = block:
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let vid = br.vtx.bVid[nibble]
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VidVtxPair(vid: vid, vtx: db.getVtx vid)
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if not nxt.vtx.isValid:
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return err((nxt.vid, DelVidStaleVtx))
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# Collapse `Branch` vertex `br` depending on `nxt` vertex type
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case nxt.vtx.vType:
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of Branch:
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? db.collapseBranch(hike, nibble.byte)
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of Extension:
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? db.collapseExt(hike, nibble.byte, nxt.vtx)
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of Leaf:
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? db.collapseLeaf(hike, nibble.byte, nxt.vtx)
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# Delete leaf entry
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if leafVidBe.isValid:
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# To be recorded on change history
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db.top.lTab[lty] = VertexID(0)
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else:
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# No need to keep it any longer in cache
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db.top.lTab.del lty
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ok()
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# ------------------------------------------------------------------------------
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# Public functions
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# ------------------------------------------------------------------------------
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proc delete*(
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db: AristoDbRef; # Database, top layer
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hike: Hike; # Fully expanded chain of vertices
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): Result[void,(VertexID,AristoError)] =
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## Delete argument `hike` chain of vertices from the database
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##
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# Need path in order to remove it from `lTab[]`
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let lty = LeafTie(
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root: hike.root,
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path: ? hike.to(NibblesSeq).pathToTag().mapErr toVae)
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db.deleteImpl(hike, lty)
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proc delete*(
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db: AristoDbRef; # Database, top layer
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lty: LeafTie; # `Patricia Trie` path root-to-leaf
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): Result[void,(VertexID,AristoError)] =
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## Variant of `delete()`
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##
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db.deleteImpl(? lty.hikeUp(db).mapErr toVae, lty)
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proc delete*(
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db: AristoDbRef;
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root: VertexID;
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path: openArray[byte];
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): Result[void,(VertexID,AristoError)] =
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## Variant of `fetchPayload()`
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##
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db.delete(? path.initNibbleRange.hikeUp(root, db).mapErr toVae)
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# ------------------------------------------------------------------------------
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# End
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# ------------------------------------------------------------------------------
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