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| author | Rose Hogenson <rhogenson@posteo.net> | 2022-08-07 15:54:30 -0700 |
|---|---|---|
| committer | Rose Hogenson <rhogenson@posteo.net> | 2022-08-07 15:54:30 -0700 |
| commit | 49e0ce47d4fdd3f41dde1e376977d545fc8c542e (patch) | |
| tree | 372a9c0fe4eb2049670c19da98d7643229f3bce3 | |
| parent | Fix a typo in codegen. (diff) | |
| download | chromatopelma-49e0ce47d4fdd3f41dde1e376977d545fc8c542e.tar.zst | |
Define last-index.
| -rw-r--r-- | lib/csc/strings-test.csc | 18 | ||||
| -rw-r--r-- | lib/csc/strings.csc | 8 |
2 files changed, 26 insertions, 0 deletions
diff --git a/lib/csc/strings-test.csc b/lib/csc/strings-test.csc index 1f981ad..95dbb59 100644 --- a/lib/csc/strings-test.csc +++ b/lib/csc/strings-test.csc @@ -42,6 +42,24 @@ (index "def" "a"))) + (test last-index-last + (assert-equal + 4 + (last-index "ababa" "a"))) + + + (test last-index-penultimate + (assert-equal + 4 + (last-index "ababab" "a"))) + + + (test last-index-notfound + (assert-equal + -1 + (last-index "abcdfads" ";"))) + + (test contains (assert-equal #t diff --git a/lib/csc/strings.csc b/lib/csc/strings.csc index 255a2fd..373f9be 100644 --- a/lib/csc/strings.csc +++ b/lib/csc/strings.csc @@ -4,6 +4,7 @@ has-prefix? index join + last-index split str-quote) (import (scheme base) @@ -36,6 +37,13 @@ finally (return -1))) + (define (last-index s substr) + (loop for i downfrom (- (string-length s) (string-length substr)) to 0 + if (has-prefix? (string-copy s i) substr) + return i + finally (return -1))) + + (define (contains? s substr) (if (string=? "" substr) #t |