Symbol Tables and Declaration Processing - Crafting a Compiler - page 292

procedure open S cope ()

depth ← depth + 1

scopeDisplay [ depth ] ← null

end

procedure close S cope ()

foreach sym ∈ scopeDisplay [ depth ] do
prevsym ← sym . var

3

call delete ( sym )

4

if prevsym null

5

then call add ( prevsym )

depth ← depth − 1

end

function ( name ) returns Symbol

sym ← HashTable . get( name )

retrieve S ymbol

while sym null do

if sym . name = name
then return sym

6

sym ← sym . hash

7

return ( null )
end

8

procedure enter S ymbol ( name , type )

oldsym ← retrieve S ymbol ( name )

if oldsym null and oldsym . depth = depth

9

then call error (” Duplicate de f inition o f ” , name )

newsym ← create

N ew S ymbol ( name , type )

10

/ Add to scope display /

newsym . level ← scopeDisplay [ depth ]
newsym . depth ← depth
scopeDisplay [ depth ] ← newsym

/ Add to hash table /

if oldsym = null

then call add ( newsym )

else
call delete ( oldsym )

( newsym )
newsym . var ← oldsym
end

call add

function declared L ocally ( name ) returns Boolean

/ See Exercise 7. /

end

Figure 8.7: Symbol table management