X-Git-Url: http://git.kpe.io/?a=blobdiff_plain;f=sql%2Fexpressions.lisp;h=28915b5e55c6e5d5960348efda8d70454429e9b1;hb=f3430ff34ef6631daf20cb9c69ecbc7ad84d14df;hp=5967f24e941c707d14a175fb7de02db7365506df;hpb=847beae404b498f4d30c96b0324a3ff81022141c;p=clsql.git

diff --git a/sql/expressions.lisp b/sql/expressions.lisp
index 5967f24..28915b5 100644
--- a/sql/expressions.lisp
+++ b/sql/expressions.lisp
@@ -242,21 +242,34 @@
 ;; should do arity checking of subexpressions
 
 (defmethod output-sql ((expr sql-relational-exp) database)
-  (with-slots (operator sub-expressions)
-      expr
-    (when sub-expressions
-      (let ((subs (if (consp (car sub-expressions))
-		      (car sub-expressions)
-		      sub-expressions)))
-	(write-char #\( *sql-stream*)
-	(do ((sub subs (cdr sub)))
-	    ((null (cdr sub))
-	       (output-sql (car sub) database))
-	  (output-sql (car sub) database)
-	  (write-char #\Space *sql-stream*)
-	  (output-sql operator database)
-	  (write-char #\Space *sql-stream*))
-	(write-char #\) *sql-stream*))))
+  (with-slots (operator sub-expressions) expr
+     ;; we do this as two runs so as not to emit confusing superflous parentheses
+     ;; The first loop renders all the child outputs so that we can skip anding with
+     ;; empty output (which causes sql errors)
+     ;; the next loop simply emits each sub-expression with the appropriate number of
+     ;; parens and operators
+     (flet ((trim (sub)
+	      (string-trim '(#\space #\newline #\return #\tab #\no-break_space)
+			   (with-output-to-string (*sql-stream*)
+			     (output-sql sub database)))))
+       (let ((str-subs (loop for sub in sub-expressions
+			     for str-sub = (trim sub)
+			   when (and str-sub (> (length str-sub) 0))
+			     collect str-sub)))
+	 (case (length str-subs)
+	   (0 nil)
+	   (1 (write-string (first str-subs) *sql-stream*))
+	   (t
+	      (write-char #\( *sql-stream*)
+	      (write-string (first str-subs) *sql-stream*)
+	      (loop for str-sub in (rest str-subs)
+		    do
+		 (write-char #\Space *sql-stream*)
+		 (output-sql operator database)
+		 (write-char #\Space *sql-stream*)
+		 (write-string str-sub *sql-stream*))
+	      (write-char #\) *sql-stream*))
+	   ))))
   t)
 
 (defclass sql-array-exp (sql-relational-exp)