1 files changed, 42 insertions, 0 deletions
diff --git a/strings.csc b/strings.csc
new file mode 100644
index 0000000..963565c
--- /dev/null
+++ b/strings.csc
@@ -0,0 +1,42 @@
+(define-library (csc strings)
+  (export
+    str-find
+    str-not-found-error?
+    str-prefix?
+    str-quote)
+  (import (scheme base)
+          (scheme case-lambda)
+          (only (scheme write) write))
+  (begin
+
+
+    (define str-prefix?
+      (let ((str-prefix?' (lambda (prefix str start)
+                            (and (<= (string-length prefix) (- (string-length str) start))
+                                 (string=? prefix (substring str start (+ start (string-length prefix))))))))
+        (case-lambda
+          ((prefix str) (str-prefix?' prefix str 0))
+          ((prefix str start) (str-prefix?' prefix str start)))))
+
+
+    (define (str-quote s)
+      (let ((out (open-output-string)))
+        (write s out)
+        (get-output-string out)))
+
+
+    (define-record-type <str-not-found-error>
+      (make-str-not-found-error)
+      str-not-found-error?)
+
+
+    (define str-find
+      (let ((str-find' (lambda (match str start end)
+                         (let loop ((i start))
+                           (cond ((>= i end) (raise (make-str-not-found-error)))
+                                 ((str-prefix? match str i) i)
+                                 (else (loop (+ 1 i))))))))
+        (case-lambda
+          ((match str) (str-find' match str 0 (string-length str)))
+          ((match str start) (str-find' match str start (string-length str)))
+          ((match str start end) (str-find' match str start end)))))))