added RRDCALC management; preparation for expression evaluation

1 files changed, 38 insertions, 0 deletions

diff --git a/src/eval.h b/src/eval.h
new file mode 100644
index 0000000000..da3be13097
--- /dev/null
+++ b/src/eval.h
@@ -0,0 +1,38 @@
+#ifndef NETDATA_EVAL_H
+#define NETDATA_EVAL_H
+
+typedef struct variable {
+    char *name;
+    struct rrdvar *rrdvar;
+    struct variable *next;
+} VARIABLE;
+
+#define EVAL_OPERAND_INVALID 0
+#define EVAL_OPERAND_NUMBER 1
+#define EVAL_OPERAND_VARIABLE 2
+#define EVAL_OPERAND_EXPRESSION 3
+
+// these are used for EVAL_OPERAND.operator
+#define EVAL_OPERATOR_NOP   '\0'
+#define EVAL_OPERATOR_NOT   '!'
+#define EVAL_OPERATOR_PLUS  '+'
+#define EVAL_OPERATOR_MINUS '-'
+
+typedef struct eval_value {
+    int type;
+
+    union {
+        calculated_number number;
+        VARIABLE *variable;
+        struct eval_operand *expression;
+    };
+} EVAL_VALUE;
+
+typedef struct eval_operand {
+    char operator;
+
+    int count;
+    EVAL_VALUE ops[];
+} EVAL_OPERAND;
+
+#endif //NETDATA_EVAL_H