implementation of basic price function

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@407 57a11ea4-9604-0410-9ed3-97b8803252fd

src/register/pricecell.c

@@ -4,11 +4,34 @@
 #include "price.h"
 #include "single.h"
 
+#define DECIMAL_PT  '.'
+
+/* ================================================ */
+/* This callback only allows numbers with a single
+ * decimal point in them */
+
 static const char * 
 PriceMV (const char * old, const char *change, const char *new)
 {
-   printf (" price mv called old:%s change:%s new:%s \n", old, change, new);
+   if (change) {
-   return new; 
+      /* if change is a decimal point, then count decimal points */
+      if (DECIMAL_PT == change[0]) {
+         int i, count=0;
+         for (i=0; 0 != new[i]; i++) {
+            if (DECIMAL_PT == new[i]) count ++;
+         }
+         if (1 >= count) return new;
+         return NULL;
+
+      } else {
+         /* accept numeric, reject non-alpha edits */
+         if (isdigit (change[0])) return new;
+         return NULL;
+      }
+   } else {
+      /* accept the new string if user action was delete, etc. */
+      return new; 
+   }
 }
 
 /* ================================================ */