From d4808fb260537e65936d9dd25e22cdccd5f7fb6d Mon Sep 17 00:00:00 2001
From: Sebastian Harl <sh@tokkee.org>
Date: Thu, 20 Feb 2014 22:24:48 +0100
Subject: [PATCH] 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.
---
 src/core/data.c         | 28 ++++++++++++++++++++++++++++
 src/include/core/data.h |  9 +++++++++
 2 files changed, 37 insertions(+)

diff --git a/src/core/data.c b/src/core/data.c
index 54b6d28..4c89b43 100644
--- 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 c7c51b8..54a2ed2 100644
--- 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
-- 
2.30.2