Euphoria
Ticket #747:
valid_index(), sequence of indexes
-
Reported by
Insolor
Feb 03, 2012
It would be useful if the valid_index() function could accept a sequence of indexes as a second argument (eg. to check index existence before using it as an argument of fetch() or store() functions)
Desirable behavior:
sequence s = {1,2,{3,4,5,{6,7}},8,9}
? valid_index(s,{1,2}) -- output: 0
? valid_index(s,{3,2}) -- output: 1
? valid_index{s,{3,4,1}) -- output: 1
Details
1. Comment by Insolor
Feb 03, 2012
As a first approach:
public function valid_index(sequence st, object x)
if atom(x) then
if x < 1 then
return 0
end if
if floor(x) > length(st) then
return 0
end if
return 1
else
for i=1 to length(x) do
if atom(st) or sequence(x[i]) or not valid_index(st,x[i]) then
return 0
end if
st = st[x[i]]
end for
return 1
end if
end function
2. Comment by Insolor
Feb 04, 2012
The second approach:
public function valid_index(object st, object x)
if atom(x) then
stdseq:valid_index(st,x)
else
if atom(st) then
return 0
end if
for i=1 to length(x) do
if atom(st) or sequence(x[i]) or not stdseq:valid_index(st,x[i]) then
return 0
end if
st = st[x[i]]
end for
end if
return 1
end function
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