Move scheme compiler into a separate directory.

1 files changed, 46 insertions, 0 deletions

diff --git a/csc/strings.csc b/csc/strings.csc
new file mode 100644
index 0000000..737c91b
--- /dev/null
+++ b/csc/strings.csc
@@ -0,0 +1,46 @@
+(define-library (csc strings)
+  (export
+    find
+    join
+    not-found-error?
+    prefix?
+    str-quote)
+  (import (scheme base)
+          (only (scheme case-lambda) case-lambda)
+          (only (scheme write) write)
+          (only (csc list) intercalate))
+  (begin
+
+
+    (define prefix?
+      (case-lambda
+        ((prefix str) (prefix? prefix str 0))
+        ((prefix str start)
+         (and (<= (string-length prefix) (- (string-length str) start))
+              (string=? prefix (substring str start (+ start (string-length prefix))))))))
+
+
+    (define (str-quote s)
+      (let ((out (open-output-string)))
+        (write s out)
+        (get-output-string out)))
+
+
+    (define-record-type <not-found-error>
+      (make-not-found-error)
+      not-found-error?)
+
+
+    (define find
+      (case-lambda
+        ((match str) (find match str 0 (string-length str)))
+        ((match str start) (find match str start (string-length str)))
+        ((match str start end)
+         (let loop ((i start))
+           (cond ((>= i end) (raise (make-not-found-error)))
+                 ((prefix? match str i) i)
+                 (else (loop (+ 1 i))))))))
+
+
+    (define (join sep . strings)
+      (apply string-append (intercalate sep strings)))))