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Str.splitFirst should not find match if needle is longer than haystack

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Closes #4064
This commit is contained in:
Ayaz Hafiz 2022-09-28 13:14:36 -05:00
parent 190ff7e21a
commit 1d7dc65800
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1 changed files with 8 additions and 5 deletions
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13
crates/compiler/builtins/roc/Str.roc
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@ -359,6 +359,9 @@ splitFirst = \haystack, needle ->
# splitFirst when needle isn't in haystack
expect splitFirst "foo" "z" == Err NotFound
# splitFirst when needle isn't in haystack, and haystack is empty
expect splitFirst "" "z" == Err NotFound
# splitFirst when haystack ends with needle repeated
expect splitFirst "foo" "o" == Ok { before: "f", after: "o" }
@ -444,17 +447,17 @@ matchesAt = \haystack, haystackIndex, needle ->
needleLength = Str.countUtf8Bytes needle
endIndex = min (haystackIndex + needleLength) haystackLength
matchesAtHelp haystack haystackIndex needle 0 endIndex
matchesAtHelp haystack haystackIndex needle 0 needleLength endIndex
matchesAtHelp : Str, Nat, Str, Nat, Nat -> Bool
matchesAtHelp = \haystack, haystackIndex, needle, needleIndex, endIndex ->
matchesAtHelp : Str, Nat, Str, Nat, Nat, Nat -> Bool
matchesAtHelp = \haystack, haystackIndex, needle, needleIndex, needleLength, endIndex ->
if haystackIndex < endIndex then
if Str.getUnsafe haystack haystackIndex == Str.getUnsafe needle needleIndex then
matchesAtHelp haystack (haystackIndex + 1) needle (needleIndex + 1) endIndex
matchesAtHelp haystack (haystackIndex + 1) needle (needleIndex + 1) needleLength endIndex
else
Bool.false
else
Bool.true
needleIndex == needleLength
## Walks over the string's UTF-8 bytes, calling a function which updates a state using each
## UTF-8 `U8` byte as well as the index of that byte within the string.