data: Added sdb_data_strlen.

This function provides a worst-case estimate of the number of bytes required
to format a datum as a string.

diff --git a/src/core/data.c b/src/core/data.c
index 54b6d282e6640d755e38457e4dbd497bb995fd32..4c89b43dd179363aa7644a8a35dda5206739d10d 100644 (file)
--- a/src/core/data.c
+++ b/src/core/data.c
@@ -85,6 +85,34 @@ sdb_data_free_datum(sdb_data_t *datum)
        }
 } /* sdb_data_free_datum */
 
+size_t
+sdb_data_strlen(sdb_data_t *datum)
+{
+       if (! datum)
+               return 0;
+
+       switch (datum->type) {
+               case SDB_TYPE_INTEGER:
+                       /* log(64) */
+                       return 20;
+               case SDB_TYPE_DECIMAL:
+                       /* XXX: -0xN.NNNNNNp+NNN */
+                       return 42;
+               case SDB_TYPE_STRING:
+                       if (! datum->data.string)
+                               return 6; /* "NULL" */
+                       /* in the worst case, each character needs to be escaped */
+                       return 2 * strlen(datum->data.string) + 2;
+               case SDB_TYPE_DATETIME:
+                       /* "YYYY-MM-DD HH:MM:SS +zzzz" */
+                       return 27;
+               case SDB_TYPE_BINARY:
+                       /* "\xNN" */
+                       return 4 * datum->data.binary.length + 2;
+       }
+       return 0;
+} /* sdb_data_strlen */
+
 int
 sdb_data_format(sdb_data_t *datum, sdb_strbuf_t *buf)
 {

diff --git a/src/include/core/data.h b/src/include/core/data.h
index c7c51b830c3761f91bb0ff55736a26087fb560e1..54a2ed2d0d703bec5e227dfaafa53ad136753781 100644 (file)
--- a/src/include/core/data.h
+++ b/src/include/core/data.h
@@ -101,6 +101,15 @@ sdb_data_copy(sdb_data_t *dst, const sdb_data_t *src);
 void
 sdb_data_free_datum(sdb_data_t *datum);
 
+/*
+ * sdb_data_strlen:
+ * Returns a (worst-case) estimate for the number of bytes required to format
+ * the datum as a string. Does not take the terminating null byte into
+ * account.
+ */
+size_t
+sdb_data_strlen(sdb_data_t *datum);
+
 /*
  * sdb_data_format:
  * Append the specified datum to the specified string buffer using a default