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 2994b5f50d3e18348dd183a553c719322e48002c..8754f8868a11471fe1e359cee75ac0d52b87721d 100644 (file)
--- 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 7ff111c1f17395218874a5d954b554cc39d02628..9ab5cdabf50936d33f5a494a64456bad3502c6c9 100644 (file)
--- 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 e8567b1ad61c1f2cb2c1a3cf0f72874a93cdfcc9..1129936f1184cea190907b4851be0ede710b60ad 100644 (file)
--- 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;