Заранее спасибо и извиняюсь за любые ошибки или что-то непонятное в моем посте.
Я получаю ошибки с примерами обхода дерева в разделе 3.4.6 "Концепции, методы и модели компьютерного программирования". Я использую Oz/mozart2-2.0.0-alpha.0 (+build.4091-slitaz-1.01.ova).
Я ввожу приведенные ниже процедуры и функции точно так же, как они описаны в книге (две версии книги с немного другим кодом), и получаю ошибки при попытке выполнить. Я пытался исправить их самостоятельно, но пока ничего не получается. Ниже я приведу код, операторы выполнения, ошибки и объявление тестового дерева (которое кажется действительным, поскольку я могу без проблем выполнить {LookUp}, {Insert} и {Delete}). Ниже я добавлю дополнительные примечания, если сочту нужным.
Итак, мой вопрос: что не так с этими фрагментами кода или как я их использую или с моими деревьями? Я включил функцию и три процедуры, которые дают одну и ту же проблему для решения (и, возможно, помогают в устранении неполадок), но я думаю, что решение одинаково для всех.
Объявление дерева последнее, ниже.
КОД -->
%All of the below errors occur upon execution, not on definition of the proc or function
% version: VanRoyHaridi2003-book.pdf
% section 3.4.6 - "Trees","Tree Traversal", "Depth-first traversal
% p.159 (Adobe Reader p. 202 of 939)
declare
proc {DFS T}
case T
of leaf then skip
[] tree(Key Val L R) then
{DFS L}
{Browse Key#Val}
{DFS R}
end
end
{DFS S}
/*
%******************** Error: conditional failed *****************
%**
%** Missing else clause
%**
%** Matching: tree(key:250 left:tree(key:125 left:tree(key:60 left:tree(key:30 left:leaf right:leaf value:pyramid) right:tree(key:90 left:leaf right:leaf value:cube) value:sphere) right:tree(key:185 left:tree(key:155 left:leaf right:leaf value:wave) right:tree(key:215 left:leaf right:leaf value:plane) value:shadow) value:shape) right:tree(key:375 left:tree(key:315 left:tree(key:285 left:leaf right:leaf value:boing) right:tree(key:345 left:leaf right:leaf value:ring) value:tap) right:tree(key:435 left:tree(key:405 left:leaf right:leaf value:whoosh) right:tree(key:465 left:leaf right:leaf value:ping) value:boom) value:sounds) value:treetop)
%** in file "/mnt/host_folder/trees - traversals", line 39
%**
%** Call Stack:
%** procedure 'DFS' in file "/mnt/host_folder/trees - traversals", line 33, column 1, PC = -1279897415
%**--------------------------------------------------------------
*/
% version: CTMchapters1-3.pdf, "Tree Traversal" p.155 (Adobe Read p. 181 of 226)
% section 3.4.6.2, "Tree Traversal"
declare
proc {DFS T}
case T
of leaf then skip
[] tree(Key Val L R) then
{Browse Key#Val}
{DFS L}
{DFS R}
end
end
{DFS S}
% {DFS T} version two had the same error as the 1st version
% I know they are trivially different, but included it anyway... sorry
% Same page as {DFS T} in CTMchapters1-3.pdf (only).
declare
proc {DFSAccLoop T S1 ?Sn}
case T
of leaf then Sn=S1
[] tree(Key Val L R) then S2 S3 in
S2=Key#Val|S1
{DFSAccLoop L S2 S3}
{DFSAccLoop L S3 Sn}
end
end
fun {DFSAcc T} {Reverse {DFSAccLoop S nil $}} end
{Browse {DFSAcc S}}
/*
%******************** Error: conditional failed *****************
%**
%** Missing else clause
%**
%** Matching: tree(key:250 left:tree(key:125 left:tree(key:60 left:tree(key:30 left:leaf right:leaf value:pyramid) right:tree(key:90 left:leaf right:leaf value:cube) value:sphere) right:tree(key:185 left:tree(key:155 left:leaf right:leaf value:wave) right:tree(key:215 left:leaf right:leaf value:plane) value:shadow) value:shape) right:tree(key:375 left:tree(key:315 left:tree(key:285 left:leaf right:leaf value:boing) right:tree(key:345 left:leaf right:leaf value:ring) value:tap) right:tree(key:435 left:tree(key:405 left:leaf right:leaf value:whoosh) right:tree(key:465 left:leaf right:leaf value:ping) value:boom) value:sounds) value:treetop)
%** in file "/mnt/host_folder/trees - traversals", line 67
%**
%** Call Stack:
%** procedure 'DFSAccLoop' in file "/mnt/host_folder/trees - traversals", line 61, column 1, PC = -1239512161
%** procedure 'DFSAcc' in file "/mnt/host_folder/trees - traversals", line 70, column 1, PC = -1239496575
%** toplevel abstraction in line 1, column 0, PC = -1238883005
%**--------------------------------------------------------------
*/
% One of the versions of {LookUp X T} gives the same error.
% version: CTMchapters1-3.pdf, "Tree Traversal" p.152 (Adobe Read p. 178 of 226)
% section 3.4.6.2, "Storing information in trees"
declare
fun {Lookup X T}
case T
of leaf then notfound
[] tree(Y V T1 T2) then
if X<Y then {Lookup X T1}
elseif X>Y then {Lookup X T2}
else found(V) end
end
end
/*
%******************** Error: conditional failed *****************
%**
%** Missing else clause
%**
%** Matching: tree(key:horse left:tree(key:dog left:tree(key:cat left:leaf right:leaf value:chat) right:tree(key:elephant left:leaf right:leaf value:elephant) value:chien) right:tree(key:mouse left:tree(key:monkey left:leaf right:leaf value:singe) right:tree(key:tiger left:leaf right:leaf value:tigre) value:souris) value:cheval)
%** in file "/mnt/host_folder/Lookup Insert Delete", line 37
%**
%** Call Stack:
%** procedure 'Lookup' in file "/mnt/host_folder/Lookup Insert Delete", line 31, column 1, PC = -1241765194
%** toplevel abstraction in line 1, column 0, PC = -1241110606
%**--------------------------------------------------------------
*/
% the case version works, so I was suprised when the traversals using case are not working for me.
declare
fun {Lookup K T}
case T of leaf then notfound
[] tree(key:X value:V left:T1 right:T2) andthen X==K then found(V)
[] tree(key:X value:V left:T1 right:T2) andthen X<K then {Lookup K T2}
[] tree(key:X value:V left:T1 right:T2) andthen X>K then {Lookup K T1}
end
end
% There are two test trees here
declare
S=tree(key:250 value:treetop
left:tree(key:125 value:dash
left:tree(key:60 value:sphere
left:tree(key:30 value:pyramid left:leaf right:leaf)
right:tree(key:90 value:cube left:leaf right:leaf))
right:tree(key:185 value:shadow
left:tree(key:155 value:wave left:leaf right:leaf)
right:tree(key:215 value:plane left:leaf right:leaf)))
right:tree(key:375 value:hum
left:tree(key:315 value:tap
left:tree(key:285 value:boing left:leaf right:leaf)
right:tree(key:345 value:ring left:leaf right:leaf))
right:tree(key:435 value:boom
left:tree(key:405 value:whoosh left:leaf right:leaf)
right:tree(key:465 value:ping left:leaf right:leaf))))
T=tree(key:horse value:cheval
left:tree(key:dog value:chien
left:tree(key:cat value:chat left:leaf right:leaf)
right:tree(key:elephant value:elephant left:leaf right:leaf))
right:tree(key:mouse value:souris
left:tree(key:monkey value:singe left:leaf right:leaf)
right:tree(key:tiger value:tigre left:leaf right:leaf)))
{Browse S}
{Browse T}