+// ----------------------------------------------------------------------------
+// data structures for storing the parsed expression in memory
+
+typedef struct eval_value {
+ int type;
+
+ union {
+ calculated_number number;
+ EVAL_VARIABLE *variable;
+ struct eval_node *expression;
+ };
+} EVAL_VALUE;
+
+typedef struct eval_node {
+ int id;
+ unsigned char operator;
+ int precedence;
+
+ int count;
+ EVAL_VALUE ops[];
+} EVAL_NODE;
+
+// these are used for EVAL_NODE.operator
+// they are used as internal IDs to identify an operator
+// THEY ARE NOT USED FOR PARSING OPERATORS LIKE THAT
+#define EVAL_OPERATOR_NOP '\0'
+#define EVAL_OPERATOR_EXPRESSION_OPEN '('
+#define EVAL_OPERATOR_EXPRESSION_CLOSE ')'
+#define EVAL_OPERATOR_NOT '!'
+#define EVAL_OPERATOR_PLUS '+'
+#define EVAL_OPERATOR_MINUS '-'
+#define EVAL_OPERATOR_AND '&'
+#define EVAL_OPERATOR_OR '|'
+#define EVAL_OPERATOR_GREATER_THAN_OR_EQUAL 'G'
+#define EVAL_OPERATOR_LESS_THAN_OR_EQUAL 'L'
+#define EVAL_OPERATOR_NOT_EQUAL '~'
+#define EVAL_OPERATOR_EQUAL '='
+#define EVAL_OPERATOR_LESS '<'
+#define EVAL_OPERATOR_GREATER '>'
+#define EVAL_OPERATOR_MULTIPLY '*'
+#define EVAL_OPERATOR_DIVIDE '/'
+#define EVAL_OPERATOR_SIGN_PLUS 'P'
+#define EVAL_OPERATOR_SIGN_MINUS 'M'
+#define EVAL_OPERATOR_ABS 'A'
+#define EVAL_OPERATOR_IF_THEN_ELSE '?'
+
+// ----------------------------------------------------------------------------
+// forward function definitions
+
+static inline void eval_node_free(EVAL_NODE *op);
+static inline EVAL_NODE *parse_full_expression(const char **string, int *error);
+static inline EVAL_NODE *parse_one_full_operand(const char **string, int *error);
+static inline calculated_number eval_node(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error);
+static inline void print_parsed_as_node(BUFFER *out, EVAL_NODE *op, int *error);
+static inline void print_parsed_as_constant(BUFFER *out, calculated_number n);
+
+// ----------------------------------------------------------------------------
+// evaluation of expressions
+
+static inline calculated_number eval_variable(EVAL_EXPRESSION *exp, EVAL_VARIABLE *v, int *error) {
+ static uint32_t this_hash = 0, now_hash = 0, after_hash = 0, before_hash = 0, status_hash = 0, removed_hash = 0, uninitialized_hash = 0, undefined_hash = 0, clear_hash = 0, warning_hash = 0, critical_hash = 0;
+ calculated_number n;
+
+ if(unlikely(this_hash == 0)) {
+ this_hash = simple_hash("this");
+ now_hash = simple_hash("now");
+ after_hash = simple_hash("after");
+ before_hash = simple_hash("before");
+ status_hash = simple_hash("status");
+ removed_hash = simple_hash("REMOVED");
+ uninitialized_hash = simple_hash("UNINITIALIZED");
+ undefined_hash = simple_hash("UNDEFINED");
+ clear_hash = simple_hash("CLEAR");
+ warning_hash = simple_hash("WARNING");
+ critical_hash = simple_hash("CRITICAL");
+ }
+
+ if(unlikely(v->hash == this_hash && !strcmp(v->name, "this"))) {
+ n = (exp->this)?*exp->this:NAN;
+ buffer_strcat(exp->error_msg, "[ $this = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(unlikely(v->hash == after_hash && !strcmp(v->name, "after"))) {
+ n = (exp->after && *exp->after)?*exp->after:NAN;
+ buffer_strcat(exp->error_msg, "[ $after = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(unlikely(v->hash == before_hash && !strcmp(v->name, "before"))) {
+ n = (exp->before && *exp->before)?*exp->before:NAN;
+ buffer_strcat(exp->error_msg, "[ $before = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(unlikely(v->hash == now_hash && !strcmp(v->name, "now"))) {
+ n = now_realtime_sec();
+ buffer_strcat(exp->error_msg, "[ $now = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(unlikely(v->hash == status_hash && !strcmp(v->name, "status"))) {
+ n = (exp->status)?*exp->status:RRDCALC_STATUS_UNINITIALIZED;
+ buffer_strcat(exp->error_msg, "[ $status = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(unlikely(v->hash == removed_hash && !strcmp(v->name, "REMOVED"))) {
+ n = RRDCALC_STATUS_REMOVED;
+ buffer_strcat(exp->error_msg, "[ $REMOVED = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(unlikely(v->hash == uninitialized_hash && !strcmp(v->name, "UNINITIALIZED"))) {
+ n = RRDCALC_STATUS_UNINITIALIZED;
+ buffer_strcat(exp->error_msg, "[ $UNINITIALIZED = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(unlikely(v->hash == undefined_hash && !strcmp(v->name, "UNDEFINED"))) {
+ n = RRDCALC_STATUS_UNDEFINED;
+ buffer_strcat(exp->error_msg, "[ $UNDEFINED = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(unlikely(v->hash == clear_hash && !strcmp(v->name, "CLEAR"))) {
+ n = RRDCALC_STATUS_CLEAR;
+ buffer_strcat(exp->error_msg, "[ $CLEAR = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(unlikely(v->hash == warning_hash && !strcmp(v->name, "WARNING"))) {
+ n = RRDCALC_STATUS_WARNING;
+ buffer_strcat(exp->error_msg, "[ $WARNING = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(unlikely(v->hash == critical_hash && !strcmp(v->name, "CRITICAL"))) {
+ n = RRDCALC_STATUS_CRITICAL;
+ buffer_strcat(exp->error_msg, "[ $CRITICAL = ");
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ if(exp->rrdcalc && health_variable_lookup(v->name, v->hash, exp->rrdcalc, &n)) {
+ buffer_sprintf(exp->error_msg, "[ $%s = ", v->name);
+ print_parsed_as_constant(exp->error_msg, n);
+ buffer_strcat(exp->error_msg, " ] ");
+ return n;
+ }
+
+ *error = EVAL_ERROR_UNKNOWN_VARIABLE;
+ buffer_sprintf(exp->error_msg, "[ undefined variable '%s' ] ", v->name);
+ return 0;
+}
+
+static inline calculated_number eval_value(EVAL_EXPRESSION *exp, EVAL_VALUE *v, int *error) {
+ calculated_number n;
+
+ switch(v->type) {
+ case EVAL_VALUE_EXPRESSION:
+ n = eval_node(exp, v->expression, error);
+ break;
+
+ case EVAL_VALUE_NUMBER:
+ n = v->number;
+ break;
+
+ case EVAL_VALUE_VARIABLE:
+ n = eval_variable(exp, v->variable, error);
+ break;
+
+ default:
+ *error = EVAL_ERROR_INVALID_VALUE;
+ n = 0;
+ break;
+ }
+
+ return n;
+}
+
+static inline int is_true(calculated_number n) {
+ if(isnan(n)) return 0;
+ if(isinf(n)) return 1;
+ if(n == 0) return 0;
+ return 1;
+}
+
+calculated_number eval_and(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ return is_true(eval_value(exp, &op->ops[0], error)) && is_true(eval_value(exp, &op->ops[1], error));
+}
+calculated_number eval_or(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ return is_true(eval_value(exp, &op->ops[0], error)) || is_true(eval_value(exp, &op->ops[1], error));
+}
+calculated_number eval_greater_than_or_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ calculated_number n2 = eval_value(exp, &op->ops[1], error);
+ return isgreaterequal(n1, n2);
+}
+calculated_number eval_less_than_or_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ calculated_number n2 = eval_value(exp, &op->ops[1], error);
+ return islessequal(n1, n2);
+}
+calculated_number eval_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ calculated_number n2 = eval_value(exp, &op->ops[1], error);
+ if(isnan(n1) && isnan(n2)) return 1;
+ if(isinf(n1) && isinf(n2)) return 1;
+ if(isnan(n1) || isnan(n2)) return 0;
+ if(isinf(n1) || isinf(n2)) return 0;
+ return n1 == n2;
+}
+calculated_number eval_not_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ return !eval_equal(exp, op, error);
+}
+calculated_number eval_less(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ calculated_number n2 = eval_value(exp, &op->ops[1], error);
+ return isless(n1, n2);
+}
+calculated_number eval_greater(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ calculated_number n2 = eval_value(exp, &op->ops[1], error);
+ return isgreater(n1, n2);
+}
+calculated_number eval_plus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ calculated_number n2 = eval_value(exp, &op->ops[1], error);
+ if(isnan(n1) || isnan(n2)) return NAN;
+ if(isinf(n1) || isinf(n2)) return INFINITY;
+ return n1 + n2;
+}
+calculated_number eval_minus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ calculated_number n2 = eval_value(exp, &op->ops[1], error);
+ if(isnan(n1) || isnan(n2)) return NAN;
+ if(isinf(n1) || isinf(n2)) return INFINITY;
+ return n1 - n2;
+}
+calculated_number eval_multiply(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ calculated_number n2 = eval_value(exp, &op->ops[1], error);
+ if(isnan(n1) || isnan(n2)) return NAN;
+ if(isinf(n1) || isinf(n2)) return INFINITY;
+ return n1 * n2;
+}
+calculated_number eval_divide(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ calculated_number n2 = eval_value(exp, &op->ops[1], error);
+ if(isnan(n1) || isnan(n2)) return NAN;
+ if(isinf(n1) || isinf(n2)) return INFINITY;
+ return n1 / n2;
+}
+calculated_number eval_nop(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ return eval_value(exp, &op->ops[0], error);
+}
+calculated_number eval_not(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ return !is_true(eval_value(exp, &op->ops[0], error));
+}
+calculated_number eval_sign_plus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ return eval_value(exp, &op->ops[0], error);
+}
+calculated_number eval_sign_minus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ if(isnan(n1)) return NAN;
+ if(isinf(n1)) return INFINITY;
+ return -n1;
+}
+calculated_number eval_abs(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ calculated_number n1 = eval_value(exp, &op->ops[0], error);
+ if(isnan(n1)) return NAN;
+ if(isinf(n1)) return INFINITY;
+ return abs(n1);
+}
+calculated_number eval_if_then_else(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ if(is_true(eval_value(exp, &op->ops[0], error)))
+ return eval_value(exp, &op->ops[1], error);
+ else
+ return eval_value(exp, &op->ops[2], error);
+}
+
+static struct operator {
+ const char *print_as;
+ char precedence;
+ char parameters;
+ char isfunction;
+ calculated_number (*eval)(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error);
+} operators[256] = {
+ // this is a random access array
+ // we always access it with a known EVAL_OPERATOR_X
+
+ [EVAL_OPERATOR_AND] = { "&&", 2, 2, 0, eval_and },
+ [EVAL_OPERATOR_OR] = { "||", 2, 2, 0, eval_or },
+ [EVAL_OPERATOR_GREATER_THAN_OR_EQUAL] = { ">=", 3, 2, 0, eval_greater_than_or_equal },
+ [EVAL_OPERATOR_LESS_THAN_OR_EQUAL] = { "<=", 3, 2, 0, eval_less_than_or_equal },
+ [EVAL_OPERATOR_NOT_EQUAL] = { "!=", 3, 2, 0, eval_not_equal },
+ [EVAL_OPERATOR_EQUAL] = { "==", 3, 2, 0, eval_equal },
+ [EVAL_OPERATOR_LESS] = { "<", 3, 2, 0, eval_less },
+ [EVAL_OPERATOR_GREATER] = { ">", 3, 2, 0, eval_greater },
+ [EVAL_OPERATOR_PLUS] = { "+", 4, 2, 0, eval_plus },
+ [EVAL_OPERATOR_MINUS] = { "-", 4, 2, 0, eval_minus },
+ [EVAL_OPERATOR_MULTIPLY] = { "*", 5, 2, 0, eval_multiply },
+ [EVAL_OPERATOR_DIVIDE] = { "/", 5, 2, 0, eval_divide },
+ [EVAL_OPERATOR_NOT] = { "!", 6, 1, 0, eval_not },
+ [EVAL_OPERATOR_SIGN_PLUS] = { "+", 6, 1, 0, eval_sign_plus },
+ [EVAL_OPERATOR_SIGN_MINUS] = { "-", 6, 1, 0, eval_sign_minus },
+ [EVAL_OPERATOR_ABS] = { "abs(",6,1, 1, eval_abs },
+ [EVAL_OPERATOR_IF_THEN_ELSE] = { "?", 7, 3, 0, eval_if_then_else },
+ [EVAL_OPERATOR_NOP] = { NULL, 8, 1, 0, eval_nop },
+ [EVAL_OPERATOR_EXPRESSION_OPEN] = { NULL, 8, 1, 0, eval_nop },
+
+ // this should exist in our evaluation list
+ [EVAL_OPERATOR_EXPRESSION_CLOSE] = { NULL, 99, 1, 0, eval_nop }
+};
+
+#define eval_precedence(operator) (operators[(unsigned char)(operator)].precedence)
+
+static inline calculated_number eval_node(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+ if(unlikely(op->count != operators[op->operator].parameters)) {
+ *error = EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS;
+ return 0;
+ }
+
+ calculated_number n = operators[op->operator].eval(exp, op, error);
+
+ return n;
+}
+
+// ----------------------------------------------------------------------------
+// parsed-as generation
+
+static inline void print_parsed_as_variable(BUFFER *out, EVAL_VARIABLE *v, int *error) {
+ (void)error;
+ buffer_sprintf(out, "$%s", v->name);
+}
+
+static inline void print_parsed_as_constant(BUFFER *out, calculated_number n) {
+ if(unlikely(isnan(n))) {
+ buffer_strcat(out, "nan");
+ return;
+ }
+
+ if(unlikely(isinf(n))) {
+ buffer_strcat(out, "inf");
+ return;
+ }
+
+ char b[100+1], *s;
+ snprintfz(b, 100, CALCULATED_NUMBER_FORMAT, n);
+
+ s = &b[strlen(b) - 1];
+ while(s > b && *s == '0') {
+ *s ='\0';
+ s--;
+ }
+
+ if(s > b && *s == '.')
+ *s = '\0';
+
+ buffer_strcat(out, b);
+}
+
+static inline void print_parsed_as_value(BUFFER *out, EVAL_VALUE *v, int *error) {
+ switch(v->type) {
+ case EVAL_VALUE_EXPRESSION:
+ print_parsed_as_node(out, v->expression, error);
+ break;
+
+ case EVAL_VALUE_NUMBER:
+ print_parsed_as_constant(out, v->number);
+ break;
+
+ case EVAL_VALUE_VARIABLE:
+ print_parsed_as_variable(out, v->variable, error);
+ break;
+
+ default:
+ *error = EVAL_ERROR_INVALID_VALUE;
+ break;
+ }
+}
+
+static inline void print_parsed_as_node(BUFFER *out, EVAL_NODE *op, int *error) {
+ if(unlikely(op->count != operators[op->operator].parameters)) {
+ *error = EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS;
+ return;
+ }
+
+ if(operators[op->operator].parameters == 1) {
+
+ if(operators[op->operator].print_as)
+ buffer_sprintf(out, "%s", operators[op->operator].print_as);
+
+ //if(op->operator == EVAL_OPERATOR_EXPRESSION_OPEN)
+ // buffer_strcat(out, "(");
+
+ print_parsed_as_value(out, &op->ops[0], error);
+
+ //if(op->operator == EVAL_OPERATOR_EXPRESSION_OPEN)
+ // buffer_strcat(out, ")");
+ }
+
+ else if(operators[op->operator].parameters == 2) {
+ buffer_strcat(out, "(");
+ print_parsed_as_value(out, &op->ops[0], error);
+
+ if(operators[op->operator].print_as)
+ buffer_sprintf(out, " %s ", operators[op->operator].print_as);
+
+ print_parsed_as_value(out, &op->ops[1], error);
+ buffer_strcat(out, ")");
+ }
+ else if(op->operator == EVAL_OPERATOR_IF_THEN_ELSE && operators[op->operator].parameters == 3) {
+ buffer_strcat(out, "(");
+ print_parsed_as_value(out, &op->ops[0], error);
+
+ if(operators[op->operator].print_as)
+ buffer_sprintf(out, " %s ", operators[op->operator].print_as);
+
+ print_parsed_as_value(out, &op->ops[1], error);
+ buffer_strcat(out, " : ");
+ print_parsed_as_value(out, &op->ops[2], error);
+ buffer_strcat(out, ")");
+ }
+
+ if(operators[op->operator].isfunction)
+ buffer_strcat(out, ")");
+}
+
+// ----------------------------------------------------------------------------
+// parsing expressions
+
+// skip spaces