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fix all bugs in remove5; now, all remove tests have been ported and they all pass fully; should port other tests from KTrie next too

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This commit is contained in:
Humza Shahid
2024-09-07 21:54:11 +01:00
parent 01d79cd801
commit 738e7d93d1
3 changed files with 25 additions and 16 deletions
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37
src/string-set.sml
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@@ -532,7 +532,8 @@ struct
(* should be called when there is a FULL_SEARCH_MATCH (* should be called when there is a FULL_SEARCH_MATCH
* and child is a terminal FOUND node *) * and child is a terminal FOUND node *)
fun removeWhenChildIsMadeEmpty (idx, keys, children, parentConstructor) = fun removeWhenChildIsMadeEmpty
(idx, keys, children, isFoundWithChildren, parentConstructor) =
(* if child was made empty, then: (* if child was made empty, then:
* - if the parent only has 1 child, it should be MADE_EMPTY too * - if the parent only has 1 child, it should be MADE_EMPTY too
* - otherwise, just remove the key and child at this idx from parent * - otherwise, just remove the key and child at this idx from parent
@@ -570,11 +571,22 @@ struct
CHANGED newNode CHANGED newNode
end end
else else
MADE_EMPTY (* if the caller was from the FOUND_WITH_CHILDREN case,
* then, instead of deleting this node entirely,
* we only delete this node's children, and mark this node
* as found.
* However, in general case where this is a CHILDREN node
* whose key was not inserted into the trie,
* we should fully delete this node as well. *)
if isFoundWithChildren then
CHANGED FOUND
else
MADE_EMPTY
(* should be called when searchKeyMatch returns FULL_MATCH (* should be called when searchKeyMatch returns FULL_MATCH
*in helpRemove function *) *in helpRemove function *)
fun removeWhenFullMatch (idx, keys, children, parentConstructor) = fun removeWhenFullMatch
(idx, keys, children, isFoundWithChildren, parentConstructor) =
(* matching over the child at this idx *) (* matching over the child at this idx *)
case Vector.sub (children, idx) of case Vector.sub (children, idx) of
(* CHILDREN is a not-found case, so have to leave parent unchanged (* CHILDREN is a not-found case, so have to leave parent unchanged
@@ -596,10 +608,11 @@ struct
CHANGED newParent CHANGED newParent
end end
| FOUND => | FOUND =>
removeWhenChildIsMadeEmpty (idx, keys, children, parentConstructor) removeWhenChildIsMadeEmpty
(idx, keys, children, isFoundWithChildren, parentConstructor)
fun removeWhenSearchKeyContainsTrieKey fun removeWhenSearchKeyContainsTrieKey
(childResult, idx, keys, children, parentConstructor) = (childResult, idx, keys, children, isFoundWithChildren, parentConstructor) =
case childResult of case childResult of
(* if result is UNCHANGED, let UNCHANGED bubble to the top. (* if result is UNCHANGED, let UNCHANGED bubble to the top.
* At the top, can return same trie given as input as there was no * At the top, can return same trie given as input as there was no
@@ -619,7 +632,8 @@ struct
CHANGED newNode CHANGED newNode
end end
| MADE_EMPTY => | MADE_EMPTY =>
removeWhenChildIsMadeEmpty (idx, keys, children, parentConstructor) removeWhenChildIsMadeEmpty
(idx, keys, children, isFoundWithChildren, parentConstructor)
fun helpRemove (removeKey, keyPos, trie) = fun helpRemove (removeKey, keyPos, trie) =
case trie of case trie of
@@ -636,7 +650,7 @@ struct
(* no search match means nothing to delete *) (* no search match means nothing to delete *)
NO_SEARCH_MATCH => UNCHANGED NO_SEARCH_MATCH => UNCHANGED
| FULL_SEARCH_MATCH => | FULL_SEARCH_MATCH =>
removeWhenFullMatch (idx, keys, children, CHILDREN) removeWhenFullMatch (idx, keys, children, false, CHILDREN)
| SEARCH_KEY_CONTAINS_TRIE_KEY => | SEARCH_KEY_CONTAINS_TRIE_KEY =>
removeWhenSearchKeyContainsTrieKey removeWhenSearchKeyContainsTrieKey
( helpRemove ( helpRemove
@@ -647,6 +661,7 @@ struct
, idx , idx
, keys , keys
, children , children
, false
, CHILDREN , CHILDREN
) )
| TRIE_KEY_CONTAINS_SEARCH_KEY => UNCHANGED) | TRIE_KEY_CONTAINS_SEARCH_KEY => UNCHANGED)
@@ -667,7 +682,7 @@ struct
NO_SEARCH_MATCH => UNCHANGED NO_SEARCH_MATCH => UNCHANGED
| FULL_SEARCH_MATCH => | FULL_SEARCH_MATCH =>
removeWhenFullMatch removeWhenFullMatch
(idx, keys, children, FOUND_WITH_CHILDREN) (idx, keys, children, true, FOUND_WITH_CHILDREN)
| SEARCH_KEY_CONTAINS_TRIE_KEY => | SEARCH_KEY_CONTAINS_TRIE_KEY =>
removeWhenSearchKeyContainsTrieKey removeWhenSearchKeyContainsTrieKey
( helpRemove ( helpRemove
@@ -678,6 +693,7 @@ struct
, idx , idx
, keys , keys
, children , children
, true
, FOUND_WITH_CHILDREN , FOUND_WITH_CHILDREN
) )
| TRIE_KEY_CONTAINS_SEARCH_KEY => UNCHANGED) | TRIE_KEY_CONTAINS_SEARCH_KEY => UNCHANGED)
@@ -701,9 +717,4 @@ struct
CHANGED trie => trie CHANGED trie => trie
| MADE_EMPTY => empty | MADE_EMPTY => empty
| UNCHANGED => trie | UNCHANGED => trie
(*
* todo:
* test remove functionality
* *)
end end

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tests/string-set-tests
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2
tests/string-set-tests.sml
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@@ -126,8 +126,6 @@ struct
val trie = StringSet.remove ("x", trie) val trie = StringSet.remove ("x", trie)
val _ = assertFalse (StringSet.exists ("x", trie), "x does not exist after remove in remove5") val _ = assertFalse (StringSet.exists ("x", trie), "x does not exist after remove in remove5")
(* error: "abc" should exist at this point, but it seems not to.
* find out why and fix. *)
val _ = assertTrue (StringSet.exists ("abc", trie), "abc exists before remove in remove5") val _ = assertTrue (StringSet.exists ("abc", trie), "abc exists before remove in remove5")
val trie = StringSet.remove ("abc", trie) val trie = StringSet.remove ("abc", trie)
val _ = assertFalse (StringSet.exists ("abc", trie), "abc does not exist after remove in remove5") val _ = assertFalse (StringSet.exists ("abc", trie), "abc does not exist after remove in remove5")