Initial PCRE FFI work.

pcre.sch

@@ -0,0 +1,38 @@
+; This is just the beginnings of pulling in the PCRE library. This
+; isn't very clean yet and surely has some memory leaks at the moment.
+
+(require 'ffi)
+
+(let* ((pcre (ffi:dlopen "libpcre.so"))
+       (compile (ffi:dlsym pcre "pcre_compile"))
+       (free (ffi:dlsym pcre "pcre_free"))
+       (exec (ffi:dlsym pcre "pcre_exec")))
+
+  (define (pcre:compile pattern)
+    "Compile a regexp."
+    (ffi:funcall compile 'ffi-pointer
+                 (ffi:string-to-alien pattern)
+                 (ffi:int-to-alien 0)
+                 (ffi:make-pointer-array 1)
+                 (ffi:make-pointer-array 1)
+                 (ffi:int-to-alien 0)))
+
+  (define (pcre:free re)
+    "Free a compiled regexp. Currently segfaults. :-("
+    (ffi:funcall free 'ffi-void re))
+
+  (define (pcre:exec re str)
+    (ffi:funcall exec 'ffi-uint
+                 re
+                 (ffi:int-to-alien 0)
+                 (ffi:string-to-alien str)
+                 (ffi:int-to-alien (string-length str))
+                 (ffi:int-to-alien 0)
+                 (ffi:int-to-alien 0)
+                 (ffi:make-pointer-array 30)
+                 (ffi:int-to-alien 30)))
+
+  (define (pcre:match regexp-string string)
+    "Convenience function: return #t on match, #f otherwise."
+    ;; The compiled regexp needs to be freed once that works.
+    (< -1 (pcre:exec (pcre:compile regexp-string) string))))