more stuff that doesn't work
This commit is contained in:
Andreas Rumpf
parent
1f1edeb23f
commit
eb78bc7a51
1 changed files with 154 additions and 51 deletions
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@ -4,11 +4,26 @@
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## Can also use a page manager for allocations. The page manager be used
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## to off load pages to a file system or to send it over the wire.
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## Todo:
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## - Add logic to deal with the fact that keys do not have to be unique.
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## - Ranged queries
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## - Make it generic and low level
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## - Support for external nodes and a page cache
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const
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M = 4 # max children per B-tree node = M-1
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# (must be even and greater than 2)
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Mhalf = M div 2
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SupportFullTableScan = true
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SupportDuplicateKeys = true
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## Due to the fact that leaves are shared among multiple BTrees the following
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## fields in a Node are downright impossible:
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## - parent
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## - next
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## - prev
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type
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Key = string
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Val = string
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@ -24,6 +39,12 @@ type
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root: Node
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height: int ## height
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n: int ## number of key-value pairs
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CmpKind {.pure.} = enum
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eq, le, lt, ge, gt, neq
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Cursor = object
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n: Node
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i, dir: int
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up: seq[(Node, int)]
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proc newBTree(): BTree = BTree(root: Node(m: 0, isInternal: false))
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@ -42,6 +63,86 @@ proc search(x: Node, key: Key, ht: int): Val =
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if j+1 == x.m or less(key, x.keys[j+1]):
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return search(x.links[j], key, ht-1)
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proc `=~`(i: int; k: CmpKind): bool =
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## check if the result of 'cmp' matches what was requested by 'k':
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case k
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of CmpKind.eq: i == 0
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of CmpKind.le: i <= 0
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of CmpKind.lt: i < 0
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of CmpKind.ge: i >= 0
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of CmpKind.gt: i > 0
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of CmpKind.neq: i != 0
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proc canPrune(i: int; k: CmpKind): bool =
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case k
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of CmpKind.eq:
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# we demand equality so if bigger, we can prune:
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i > 0
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of CmpKind.le:
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i > 0
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of CmpKind.lt: i >= 0
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of CmpKind.ge: i < 0
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of CmpKind.gt: i <= 0
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of CmpKind.neq: i != 0
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proc startingPoint(x: Node; key: Key; kind: CmpKind): Cursor =
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if x.isInternal:
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for j in 0 ..< x.m:
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if j+1 == x.m or cmp(key, x.keys[j+1]) =~ kind:
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return startingPoint(x.links[j], key, kind)
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else:
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for j in 0 ..< x.m:
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let cmpRes = cmp(key, x.keys[j])
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if cmpRes =~ kind: return Cursor(n: x, i: j)
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proc dos(x: Node; key: Key; kind: CmpKind; withKey: proc(k: Key; v: Val)) =
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if not x.isInternal:
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echo "came here"
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for j in 0 ..< x.m:
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if cmp(key, x.keys[j]) =~ kind:
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withKey(x.keys[j+1], x.vals[j])
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else:
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for j in 0 ..< x.m-1:
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let cmpRes = cmp(key, x.keys[j+1])
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echo "came here B ", canPrune(cmpRes, kind)
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if not canPrune(cmpRes, kind): #cmpRes =~ kind:
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dos(x.links[j], key, kind, withKey)
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#if canPrune(cmpRes, kind): return
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# XXX j+1==x.m case?
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proc init(x: Node): Cursor =
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result.up = @[]
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result.i = 0
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var it = x
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while it.isInternal:
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result.up.add((it, 0))
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it = it.links[0]
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result.n = it
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proc next(c: var Cursor) =
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assert c.n != nil
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if c.i >= c.n.m:
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# current leaf exhausted, pick the next one:
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if c.up.len > 0:
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(c.n, c.i) = c.up.pop()
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inc c.i
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var u = 1
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while c.i > c.n.m or c.n.isInternal:
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if c.up.len > 0:
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(c.n, c.i) = c.up[c.up.len - u]
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else:
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c.n = nil
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return
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assert(c.n == nil or not c.n.isInternal)
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proc atEnd(c: Cursor): bool = c.n == nil
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proc getKey(c: Cursor): Key = discard
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proc getVal(c: Cursor): Val = discard
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proc get(t: BTree; key: Key): Val = search(t.root, key, t.height)
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proc copyHalf(h, result: Node; offset: int) =
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@ -187,59 +288,61 @@ proc `$`(b: BTree): string =
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result = ""
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toString(b.root, b.height, "", result)
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proc main =
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var st = newBTree()
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st.put("www.cs.princeton.edu", "abc")
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st.put("www.cs.princeton.edu", "xyz")
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st.put("www.princeton.edu", "128.112.128.15")
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st.put("www.yale.edu", "130.132.143.21")
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st.put("www.simpsons.com", "209.052.165.60")
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st.put("www.apple.com", "17.112.152.32")
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st.put("www.amazon.com", "207.171.182.16")
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st.put("www.ebay.com", "66.135.192.87")
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st.put("www.cnn.com", "64.236.16.20")
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st.put("www.google.com", "216.239.41.99")
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st.put("www.nytimes.com", "199.239.136.200")
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st.put("www.microsoft.com", "207.126.99.140")
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st.put("www.dell.com", "143.166.224.230")
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st.put("www.slashdot.org", "66.35.250.151")
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st.put("www.espn.com", "199.181.135.201")
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st.put("www.weather.com", "63.111.66.11")
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st.put("www.yahoo.com", "216.109.118.65")
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when isMainModule:
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proc main =
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var st = newBTree()
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st.put("www.cs.princeton.edu", "abc")
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st.put("www.cs.princeton.edu", "xyz")
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st.put("www.princeton.edu", "128.112.128.15")
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st.put("www.yale.edu", "130.132.143.21")
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st.put("www.simpsons.com", "209.052.165.60")
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st.put("www.apple.com", "17.112.152.32")
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st.put("www.amazon.com", "207.171.182.16")
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st.put("www.ebay.com", "66.135.192.87")
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st.put("www.cnn.com", "64.236.16.20")
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st.put("www.google.com", "216.239.41.99")
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st.put("www.nytimes.com", "199.239.136.200")
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st.put("www.microsoft.com", "207.126.99.140")
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st.put("www.dell.com", "143.166.224.230")
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st.put("www.slashdot.org", "66.35.250.151")
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st.put("www.espn.com", "199.181.135.201")
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st.put("www.weather.com", "63.111.66.11")
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st.put("www.yahoo.com", "216.109.118.65")
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assert st.get("www.cs.princeton.edu") == "abc"
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assert st.get("www.harvardsucks.com") == nil
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assert st.get("www.cs.princeton.edu") == "abc"
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assert st.get("www.harvardsucks.com") == nil
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assert st.get("www.simpsons.com") == "209.052.165.60"
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assert st.get("www.apple.com") == "17.112.152.32"
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assert st.get("www.ebay.com") == "66.135.192.87"
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assert st.get("www.dell.com") == "143.166.224.230"
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assert(st.n == 17)
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assert st.get("www.simpsons.com") == "209.052.165.60"
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assert st.get("www.apple.com") == "17.112.152.32"
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assert st.get("www.ebay.com") == "66.135.192.87"
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assert st.get("www.dell.com") == "143.166.224.230"
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assert(st.n == 17)
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when false:
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var b2 = newBTree()
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const iters = 10_000
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for i in 1..iters:
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b2.put($i, $(iters - i))
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for i in 1..iters:
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let x = b2.get($i)
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if x != $(iters - i):
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echo "got ", x, ", but expected ", iters - i
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echo b2.n
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echo b2.height
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when false:
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var b2 = newBTree()
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const iters = 10_000
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for i in 1..iters:
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b2.put($i, $(iters - i))
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for i in 1..iters:
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let x = b2.get($i)
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if x != $(iters - i):
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echo "got ", x, ", but expected ", iters - i
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echo b2.n
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echo b2.height
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when true:
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var b1 = newBTree()
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var b2 = newBTree()
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const iters = 60_000
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for i in 1..iters:
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b2 = b2.putPs($i, $(iters - i))
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b1.put($i, $(iters - i))
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for i in 1..iters:
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let x = b2.get($i)
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if x != $(iters - i):
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echo i, "th iteration; got ", x, ", but expected ", iters - i
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echo b2.n, " = ", b1.n
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echo b2.height, " = ", b1.height
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when true:
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var b1 = newBTree()
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var b2 = newBTree()
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const iters = 10 #60_000
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for i in 1..iters:
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b2 = b2.putPs($i, $(iters - i))
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b1.put($i, $(iters - i))
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for i in 1..iters:
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let x = b2.get($i)
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if x != $(iters - i):
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echo i, "th iteration; got ", x, ", but expected ", iters - i
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echo b2.n, " = ", b1.n
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echo b2.height, " = ", b1.height
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dos(b1.root, "5", CmpKind.eq, proc(k: Key; v: Val) = echo("k ", k, " = ", v))
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main()
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main()
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Add table
Add a link
Reference in a new issue