From: Sebastian Harl <sh@tokkee.org>
Date: Fri, 24 Oct 2014 15:51:03 +0000 (+0200)
Subject: data: Added sdb_data_expr_type().
X-Git-Tag: sysdb-0.6.0~65
X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=419b318ff64a7d9048e9692dba7470eab9532d1f;p=sysdb.git

data: Added sdb_data_expr_type().

This function returns the expected type of the result of an arithmetic
expression based on the operator and input types.
---

diff --git a/src/core/data.c b/src/core/data.c
index 2994b5f..8754f88 100644
--- a/src/core/data.c
+++ b/src/core/data.c
@@ -46,6 +46,77 @@
 
 #include <math.h>
 
+/*
+ * Operator support maxtrix.
+ * <type1> <op> <type2> -> op_matrix[<op>][<type1>][<type2>]
+ */
+
+/* add, sub, mul, div, mod, concat */
+
+/* integer, decimal, string, datetime, binary, regex */
+
+static int op_matrix[6][6][6] = {
+	/* SDB_DATA_ADD */
+	{
+		{ SDB_TYPE_INTEGER, -1, -1, -1, -1, -1 },
+		{ -1, SDB_TYPE_DECIMAL, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ -1, -1, -1, SDB_TYPE_DATETIME, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+	},
+
+	/* SDB_DATA_SUB */
+	{
+		{ SDB_TYPE_INTEGER, -1, -1, -1, -1, -1 },
+		{ -1, SDB_TYPE_DECIMAL, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ -1, -1, -1, SDB_TYPE_DATETIME, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+	},
+
+	/* SDB_DATA_MUL */
+	{
+		{ SDB_TYPE_INTEGER, -1, -1, SDB_TYPE_DATETIME, -1, -1 },
+		{ -1, SDB_TYPE_DECIMAL, -1, SDB_TYPE_DATETIME, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ SDB_TYPE_DATETIME, SDB_TYPE_DATETIME, -1, SDB_TYPE_DATETIME, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+	},
+
+	/* SDB_DATA_DIV */
+	{
+		{ SDB_TYPE_INTEGER, -1, -1, -1, -1, -1 },
+		{ -1, SDB_TYPE_DECIMAL, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ SDB_TYPE_DATETIME, SDB_TYPE_DATETIME, -1, SDB_TYPE_DATETIME, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+	},
+
+	/* SDB_DATA_MOD */
+	{
+		{ SDB_TYPE_INTEGER, -1, -1, -1, -1, -1 },
+		{ -1, SDB_TYPE_DECIMAL, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ SDB_TYPE_DATETIME, SDB_TYPE_DATETIME, -1, SDB_TYPE_DATETIME, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+	},
+
+	/* SDB_DATA_CONCAT */
+	{
+		{ -1, -1, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ -1, -1, SDB_TYPE_STRING, -1, -1, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+		{ -1, -1, -1, -1, SDB_TYPE_BINARY, -1 },
+		{ -1, -1, -1, -1, -1, -1 },
+	},
+};
+
 /*
  * private helper functions
  */
@@ -624,6 +695,32 @@ sdb_data_expr_eval(int op, const sdb_data_t *d1, const sdb_data_t *d2,
 	return -1;
 } /* sdb_data_expr_eval */
 
+int
+sdb_data_expr_type(int op, int type1, int type2)
+{
+	int types_num = (int)SDB_STATIC_ARRAY_LEN(op_matrix[0]);
+
+	assert(SDB_STATIC_ARRAY_LEN(op_matrix[0])
+			== SDB_STATIC_ARRAY_LEN(op_matrix[0][0]));
+
+	if ((op <= 0) || (SDB_STATIC_ARRAY_LEN(op_matrix) < (size_t)op))
+		return -1;
+
+	/* arrays only support concat; type has to match */
+	if ((type1 & SDB_TYPE_ARRAY) || (type2 & SDB_TYPE_ARRAY)) {
+		if ((type1 != type2) || (op != SDB_DATA_CONCAT))
+			return -1;
+		return type1;
+	}
+	if ((type1 < 0) || (types_num < type1)
+			|| (type2 < 0) || (types_num < type2))
+		return -1;
+
+	if ((type1 == SDB_TYPE_NULL) || (type2 == SDB_TYPE_NULL))
+		return SDB_TYPE_NULL;
+	return op_matrix[op - 1][type1 - 1][type2 - 1];
+} /* sdb_data_expr_type */
+
 size_t
 sdb_data_strlen(const sdb_data_t *datum)
 {
diff --git a/src/include/core/data.h b/src/include/core/data.h
index 7ff111c..9ab5cda 100644
--- a/src/include/core/data.h
+++ b/src/include/core/data.h
@@ -220,6 +220,23 @@ int
 sdb_data_expr_eval(int op, const sdb_data_t *d1, const sdb_data_t *d2,
 		sdb_data_t *res);
 
+/*
+ * sdb_data_expr_type:
+ * Determine the type of the expression when applying the specified operator
+ * to the specified types. Note that if an actual value is a typed NULL value
+ * (e.g. a NULL string value), the return value of this function does not
+ * match the return type of sdb_data_expr_eval.
+ *
+ * See the documentation of sdb_data_expr_eval() for a description of which
+ * operations are supported.
+ *
+ * Returns:
+ *  - the type id on success
+ *  - a negative value else
+ */
+int
+sdb_data_expr_type(int op, int type1, int type2);
+
 /*
  * sdb_data_strlen:
  * Returns a (worst-case) estimate for the number of bytes required to format
diff --git a/t/unit/core/data_test.c b/t/unit/core/data_test.c
index e8567b1..1129936 100644
--- a/t/unit/core/data_test.c
+++ b/t/unit/core/data_test.c
@@ -1220,6 +1220,7 @@ START_TEST(test_expr_eval)
 		for (j = 0; j < SDB_STATIC_ARRAY_LEN(tests); ++j) {
 			sdb_data_t res;
 			int check;
+			int type1, type2, type;
 
 			char d1_str[64] = "", d2_str[64] = "";
 			sdb_data_format(&golden_data[i].d1, d1_str, sizeof(d1_str),
@@ -1227,12 +1228,29 @@ START_TEST(test_expr_eval)
 			sdb_data_format(&golden_data[i].d2, d2_str, sizeof(d2_str),
 					SDB_DOUBLE_QUOTED);
 
+			type1 = golden_data[i].d1.type;
+			type2 = golden_data[i].d2.type;
+			if (sdb_data_isnull(&golden_data[i].d1))
+				type1 = SDB_TYPE_NULL;
+			if (sdb_data_isnull(&golden_data[i].d2))
+				type2 = SDB_TYPE_NULL;
+			type = sdb_data_expr_type(tests[j].op, type1, type2);
+
 			check = sdb_data_expr_eval(tests[j].op,
 					&golden_data[i].d1, &golden_data[i].d2, &res);
 			fail_unless((check == 0) == (tests[j].expected.type != -1),
 					"sdb_data_expr_eval(%s, %s, %s) = %d; expected: %d",
 					SDB_DATA_OP_TO_STRING(tests[j].op), d1_str, d2_str, check,
 					tests[j].expected.type == -1 ? -1 : 0);
+
+			fail_unless(tests[j].expected.type == type,
+					"sdb_data_expr_eval(%s, %s, %s) expected to evaluate "
+					"to type %d while sdb_data_expr_type(%d, %d, %d) "
+					"predicted type %d", SDB_DATA_OP_TO_STRING(tests[j].op),
+					d1_str, d2_str, tests[j].expected.type,
+					tests[j].op, golden_data[i].d1.type,
+					golden_data[i].d2.type, type);
+
 			if (tests[j].expected.type == -1)
 				continue;