Allow lambda expression as cast rules using functions.

Before that it was necessary to install a function in the lisp environment
either in the source itself in src/utils/transforms.lisp, or in a lisp file
loaded with --load-lisp-file (or -l for shorts).

While this could be good enough, sometimes a very simple combination of
existing features is required to transform a function and so doing some
level of lisp coding directly in the load command is a nice to have.

Fixes #961.

src/parsers/command-cast-rules.lisp

@@ -141,7 +141,12 @@
       (string (intern (string-upcase fname) :pgloader.transforms))
       (symbol fname))))
 
-(defrule cast-function (and kw-using maybe-qualified-function-name)
+(defrule transform-expression sexp
+  (:lambda (sexp)
+    (eval sexp)))
+
+(defrule cast-function (and kw-using (or maybe-qualified-function-name
+                                         transform-expression))
   (:destructure (using symbol) (declare (ignore using)) symbol))
 
 (defun fix-target-type (source target)

src/utils/transforms.lisp

@@ -104,6 +104,7 @@
                  logical-to-boolean
 		 db3-trim-string
                  db3-numeric-to-pgsql-numeric
+                 db3-numeric-to-pgsql-integer
 		 db3-date-to-pgsql-date))
 
 
@@ -505,10 +506,17 @@
 
 (defun db3-numeric-to-pgsql-numeric (value)
   "DB3 numerics should be good to go, but might contain spaces."
-  (let ((trimmed-string (string-right-trim '(#\Space) value)))
+  (let ((trimmed-string (string-trim '(#\Space) value)))
     (unless (string= "" trimmed-string)
       trimmed-string)))
 
+(defun db3-numeric-to-pgsql-integer (value)
+  "DB3 numerics should be good to go, but might contain spaces."
+  (when value
+    (let ((integer-or-nil (parse-integer value :junk-allowed t)))
+      (when integer-or-nil
+        (write-to-string integer-or-nil)))))
+
 (defun db3-date-to-pgsql-date (value)
   "Convert a DB3 date to a PostgreSQL date."
   (when (and value (string/= "" value) (= 8 (length value)))

test/dbf-memo.load

@@ -0,0 +1,12 @@
+LOAD DBF
+    FROM data/DNORDOC.DBF with encoding cp866
+    INTO postgresql:///pgloader
+    TARGET TABLE public.dnordoc
+    WITH truncate, create table, disable triggers
+
+    cast
+      column dnordoc.normdocid
+          to uuid
+      using (lambda (normdocid)
+              (empty-string-to-null (right-trim normdocid))),
+      column dnordoc.doctype to integer using db3-numeric-to-pgsql-integer;