Boost Trie

8/16/2019 Boost Trie

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Boost TrieFrom Data Structure to C++

Library

Cosmin Boacă

[email protected]


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About e

• Cosmin Boaca

• !assionate about algorit"ms# $atastructures an$ big $ata

• Sil%er & Bron'e me$al at (ational)lym*ia$ in n,ormatics

•

nterns"i*s at ntel# Faceboo- an$A$obe

• C++ ,ananatic/


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Trie

• n memory $ata structure use$ ,orstoring strings in sorte$ or$er


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Trie

• n memory $ata structure use$ ,orstoring strings in sorte$ or$er

• )*erations su**orte$ – nsert-ey/

– Fin$-ey/

– 0rase-ey/

– LongestCommon!re2-ey/

– terating o%er t"e -eys in ascen$ing &$escen$ing or$er


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Trie

• 02ecution time ,or all o*erations is*ro*ortional to t"e lengt" o, t"e -ey#regar$less o, t"e number o, -eys t"atare currently store$ in t"e $atastructure


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Trie


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Trie

(o$e structure3

struct Trie bool is6ey0n$7

Trie 8sons :;


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Trie

• Do>nsi$es – ?ig" memory consum*tion eac" no$e

"as SA sons/ >"ere SA is t"e

$imension o, t"e al*"abet – ost o, t"ose sons arent e%en use$


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From $ata structure tolibrary

• euirements ,or a C++ library – Fle2ibility

• T"e user s"oul$ be able to $ene "is o>n

allocators an$ *lug t"em into t"e library>it"out too muc" eort use,ul in embe$$e$systems es*ecially/

• A$%ance$ ,eatures suc" t"e one abo%e/

s"oul$ be trans*arent to users t"at $ontnee$ t"em


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• euirements ,or a C++ library – enerality

• T"e library s"oul$ >or- >it" most o, i$eally

all/ t"e user $ene$ ty*es reuiring aminimal eort ,rom t"e user *ers*ecti%e


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• euirements ,or a C++ library – 0Eciency

• T"e library co$e s"oul$ *er,orm as goo$ as

a co$e t"at is >ritten ,or sol%ing a s*ecic*roblem

• Abstractions use$ s"oul$ bring as lo>*enalty as *ossible


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• euirements ,or a C++ library – ntero*erability >it" stan$ar$ library

• , one >ants to s>itc" ,rom e2isting co$e

using st$33ma* to boost33triema* "e s"oul$be able to $o t"is by Gust te2tually re*lacingma* >it" triema*

• Algorit"ms ,rom Halgorit"mI "ea$er s"oul$

>or- >it" t"e $ata structures ,rom t"elibrary

• terators e2*ose$ s"oul$ com*ly to C++iterator stan$ar$ "ar$er t"an you >oul$

e%er imagine/


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C++ iterator s*ecication


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• euirements ,or Boost Trie – T"e same $ata structure s"oul$ be

Je2ible enoug" to be use$ as container

,or triema*&multima*# set&multiset – 6eys inserte$ s"oul$ be any -in$ o,

iterable structures inclu$ing user

$ene$ structures/ >"ic" iterate o%erany -in$ o, com*arable ty*es

– Better *er,ormance in terms o, time an$memory t"an t"e eui%alent stan$ar$

containers


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• C"allenges – !er,ormance

• n *ractice# >"en -eys arent c"aracters t"e

usual Trie "as *oor *er,ormance in terms o,bot" memory consum*tion an$ e2ecutiontime

• aintaining bot" *er,ormance an$

generality is "ar$ an$ it reuires a lot o,tec"nical $e*t" an$ $ee* un$erstan$ing o,t"e language.


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• C"allenges – terators

• T"e most com*licate$ ,eature to im*lement

an$ su**ort are C++ iterators• T"ere are $e$icate$ libraries ,or t"is

Boost.terator/


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• C"allenges – enerality

• ?an$ling o, alocation & $ealocation using

allocators instea$ o, ne> & $elete• ?an$ling %alue ty*es >"ic" are not $e,ault

constructible

• ?an$ling -ey ty*es >"ic" are not

com*arable & $e,ault constructible


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• )*timi'ations – Ksing Boost.ntrusi%e.Set as no$e

container instea$ o, st$33set

– aritions o, Trie• Com*act Trie

• Burst Trie

• Some ot"er Trie t"at "a%e im*lemente$ att"e moment


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Boost %s Cor*orate

Boost

• Best *eo*le in C++o%er t"e >orl$

• A lot to learn about C++ an$ *rogramming ingeneral

• ?ar$core co$e re%ie>

• nsanely "ig" co$euality stan$ar$s

• emote collaboration

Corporate• A%erage *rogrammers

• Ksing only a smallsubset o, C++,eatures

• ore rela2e$ co$ere%ie>

• Co$e uality

stan$ar$s em*"asi'erea$ability an$maintainability

• Por- en%ironment

Boost Trie

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