Hash join: Difference between revisions

</pre>

=={{header|Forth}}==

{{works with|Forth}}

Works with any ANS Forth

Needs the FMS-SI (single inheritance) library code located here:

http://soton.mpeforth.com/flag/fms/index.html

<lang forth>

include FMS-SI.f

include FMS-SILib.f

: obj ( addr len -- obj )

heap> string+ dup >r !: r> ;

hash-table r 1 r init

s" Jonah" obj s" Whales" r insert:

s" Jonah" obj s" Spiders" r insert:

s" Alan" obj s" Ghosts" r insert:

s" Alan" obj s" Zombies" r insert:

s" Glory" obj s" Buffy" r insert:

o{ o{ 27 'Jonah' }

o{ 18 'Alan' }

o{ 28 'Glory' }

o{ 18 'Popeye' }

o{ 28 'Alan' } } value s

0 value str

0 value val

0 value cur

: probe ( node -- ) dup val@: str =:

if cur if cr val . dup val@: p: space key@: p: false to cur

else space key@: p:

then

else drop

then ;

: probe ( node -- ) dup val@: str =:

if cur if cr val . dup val@: p: space key@: p: false to cur

else space key@: p:

then exit

then drop ;

\ Step through each element of list s.

\ Probe hash-table r for hits on the Name.

\ For each hit show the Age and Name once, but show every Nemesis

: join

begin

s each:

while

true to cur

dup 0 swap at@: to val 1 swap at: ( obj ) to str ['] probe r iterate:

repeat ;

join

s <free \ free the list memory

r free2: \ free the hash-table memory

</lang>

{{out}}

<pre>

27 Jonah Whales Spiders

18 Alan Zombies Ghosts

28 Glory Buffy

28 Alan Zombies Ghosts