3 // ----------------------------------------------------------------------------
4 // data structures for storing the parsed expression in memory
6 typedef struct eval_value {
10 calculated_number number;
11 EVAL_VARIABLE *variable;
12 struct eval_node *expression;
16 typedef struct eval_node {
18 unsigned char operator;
25 // these are used for EVAL_NODE.operator
26 // they are used as internal IDs to identify an operator
27 // THEY ARE NOT USED FOR PARSING OPERATORS LIKE THAT
28 #define EVAL_OPERATOR_NOP '\0'
29 #define EVAL_OPERATOR_EXPRESSION_OPEN '('
30 #define EVAL_OPERATOR_EXPRESSION_CLOSE ')'
31 #define EVAL_OPERATOR_NOT '!'
32 #define EVAL_OPERATOR_PLUS '+'
33 #define EVAL_OPERATOR_MINUS '-'
34 #define EVAL_OPERATOR_AND '&'
35 #define EVAL_OPERATOR_OR '|'
36 #define EVAL_OPERATOR_GREATER_THAN_OR_EQUAL 'G'
37 #define EVAL_OPERATOR_LESS_THAN_OR_EQUAL 'L'
38 #define EVAL_OPERATOR_NOT_EQUAL '~'
39 #define EVAL_OPERATOR_EQUAL '='
40 #define EVAL_OPERATOR_LESS '<'
41 #define EVAL_OPERATOR_GREATER '>'
42 #define EVAL_OPERATOR_MULTIPLY '*'
43 #define EVAL_OPERATOR_DIVIDE '/'
44 #define EVAL_OPERATOR_SIGN_PLUS 'P'
45 #define EVAL_OPERATOR_SIGN_MINUS 'M'
47 // ----------------------------------------------------------------------------
48 // forward function definitions
50 static inline void eval_node_free(EVAL_NODE *op);
51 static inline EVAL_NODE *parse_full_expression(const char **string, int *error);
52 static inline EVAL_NODE *parse_one_full_operand(const char **string, int *error);
53 static inline calculated_number eval_node(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error);
54 static inline void print_parsed_as_node(BUFFER *out, EVAL_NODE *op, int *error);
55 static inline void print_parsed_as_constant(BUFFER *out, calculated_number n);
57 // ----------------------------------------------------------------------------
58 // evaluation of expressions
60 static inline calculated_number eval_check_number(calculated_number n, int *error) {
61 if(unlikely(isnan(n))) {
62 *error = EVAL_ERROR_VALUE_IS_NAN;
66 if(unlikely(isinf(n))) {
67 *error = EVAL_ERROR_VALUE_IS_INFINITE;
74 static inline calculated_number eval_variable(EVAL_EXPRESSION *exp, EVAL_VARIABLE *v, int *error) {
75 static uint32_t this_hash = 0;
77 if(unlikely(this_hash == 0))
78 this_hash = simple_hash("this");
80 if(exp->this && v->hash == this_hash && !strcmp(v->name, "this")) {
81 buffer_strcat(exp->error_msg, "[ $this = ");
82 print_parsed_as_constant(exp->error_msg, *exp->this);
83 buffer_strcat(exp->error_msg, " ] ");
88 if(exp->rrdcalc && health_variable_lookup(v->name, v->hash, exp->rrdcalc, &n)) {
89 buffer_sprintf(exp->error_msg, "[ $%s = ", v->name);
90 print_parsed_as_constant(exp->error_msg, n);
91 buffer_strcat(exp->error_msg, " ] ");
95 *error = EVAL_ERROR_UNKNOWN_VARIABLE;
96 buffer_sprintf(exp->error_msg, "unknown variable '%s'", v->name);
100 static inline calculated_number eval_value(EVAL_EXPRESSION *exp, EVAL_VALUE *v, int *error) {
104 case EVAL_VALUE_EXPRESSION:
105 n = eval_node(exp, v->expression, error);
108 case EVAL_VALUE_NUMBER:
112 case EVAL_VALUE_VARIABLE:
113 n = eval_variable(exp, v->variable, error);
117 *error = EVAL_ERROR_INVALID_VALUE;
122 return eval_check_number(n, error);
125 calculated_number eval_and(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
126 return eval_value(exp, &op->ops[0], error) && eval_value(exp, &op->ops[1], error);
128 calculated_number eval_or(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
129 return eval_value(exp, &op->ops[0], error) || eval_value(exp, &op->ops[1], error);
131 calculated_number eval_greater_than_or_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
132 return eval_value(exp, &op->ops[0], error) >= eval_value(exp, &op->ops[1], error);
134 calculated_number eval_less_than_or_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
135 return eval_value(exp, &op->ops[0], error) <= eval_value(exp, &op->ops[1], error);
137 calculated_number eval_not_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
138 return eval_value(exp, &op->ops[0], error) != eval_value(exp, &op->ops[1], error);
140 calculated_number eval_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
141 return eval_value(exp, &op->ops[0], error) == eval_value(exp, &op->ops[1], error);
143 calculated_number eval_less(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
144 return eval_value(exp, &op->ops[0], error) < eval_value(exp, &op->ops[1], error);
146 calculated_number eval_greater(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
147 return eval_value(exp, &op->ops[0], error) > eval_value(exp, &op->ops[1], error);
149 calculated_number eval_plus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
150 return eval_value(exp, &op->ops[0], error) + eval_value(exp, &op->ops[1], error);
152 calculated_number eval_minus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
153 return eval_value(exp, &op->ops[0], error) - eval_value(exp, &op->ops[1], error);
155 calculated_number eval_multiply(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
156 return eval_value(exp, &op->ops[0], error) * eval_value(exp, &op->ops[1], error);
158 calculated_number eval_divide(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
159 return eval_value(exp, &op->ops[0], error) / eval_value(exp, &op->ops[1], error);
161 calculated_number eval_nop(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
162 return eval_value(exp, &op->ops[0], error);
164 calculated_number eval_not(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
165 return !eval_value(exp, &op->ops[0], error);
167 calculated_number eval_sign_plus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
168 return eval_value(exp, &op->ops[0], error);
170 calculated_number eval_sign_minus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
171 return -eval_value(exp, &op->ops[0], error);
174 static struct operator {
175 const char *print_as;
178 calculated_number (*eval)(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error);
180 // this is a random access array
181 // we always access it with a known EVAL_OPERATOR_X
183 [EVAL_OPERATOR_AND] = { "&&", 2, 2, eval_and },
184 [EVAL_OPERATOR_OR] = { "||", 2, 2, eval_or },
185 [EVAL_OPERATOR_GREATER_THAN_OR_EQUAL] = { ">=", 3, 2, eval_greater_than_or_equal },
186 [EVAL_OPERATOR_LESS_THAN_OR_EQUAL] = { "<=", 3, 2, eval_less_than_or_equal },
187 [EVAL_OPERATOR_NOT_EQUAL] = { "!=", 3, 2, eval_not_equal },
188 [EVAL_OPERATOR_EQUAL] = { "==", 3, 2, eval_equal },
189 [EVAL_OPERATOR_LESS] = { "<", 3, 2, eval_less },
190 [EVAL_OPERATOR_GREATER] = { ">", 3, 2, eval_greater },
191 [EVAL_OPERATOR_PLUS] = { "+", 4, 2, eval_plus },
192 [EVAL_OPERATOR_MINUS] = { "-", 4, 2, eval_minus },
193 [EVAL_OPERATOR_MULTIPLY] = { "*", 5, 2, eval_multiply },
194 [EVAL_OPERATOR_DIVIDE] = { "/", 5, 2, eval_divide },
195 [EVAL_OPERATOR_NOT] = { "!", 6, 1, eval_not },
196 [EVAL_OPERATOR_SIGN_PLUS] = { "+", 6, 1, eval_sign_plus },
197 [EVAL_OPERATOR_SIGN_MINUS] = { "-", 6, 1, eval_sign_minus },
198 [EVAL_OPERATOR_NOP] = { NULL, 7, 1, eval_nop },
199 [EVAL_OPERATOR_EXPRESSION_OPEN] = { NULL, 7, 1, eval_nop },
201 // this should exist in our evaluation list
202 [EVAL_OPERATOR_EXPRESSION_CLOSE] = { NULL, 7, 1, eval_nop }
205 #define eval_precedence(operator) (operators[(unsigned char)(operator)].precedence)
207 static inline calculated_number eval_node(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
208 if(unlikely(op->count != operators[op->operator].parameters)) {
209 *error = EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS;
213 calculated_number n = operators[op->operator].eval(exp, op, error);
215 return eval_check_number(n, error);
218 // ----------------------------------------------------------------------------
219 // parsed-as generation
221 static inline void print_parsed_as_variable(BUFFER *out, EVAL_VARIABLE *v, int *error) {
223 buffer_sprintf(out, "$%s", v->name);
226 static inline void print_parsed_as_constant(BUFFER *out, calculated_number n) {
227 if(unlikely(isnan(n))) {
228 buffer_strcat(out, "NaN");
232 if(unlikely(isinf(n))) {
233 buffer_strcat(out, "INFINITE");
238 snprintfz(b, 100, CALCULATED_NUMBER_FORMAT, n);
240 s = &b[strlen(b) - 1];
241 while(s > b && *s == '0') {
246 if(s > b && *s == '.')
249 buffer_strcat(out, b);
252 static inline void print_parsed_as_value(BUFFER *out, EVAL_VALUE *v, int *error) {
254 case EVAL_VALUE_EXPRESSION:
255 print_parsed_as_node(out, v->expression, error);
258 case EVAL_VALUE_NUMBER:
259 print_parsed_as_constant(out, v->number);
262 case EVAL_VALUE_VARIABLE:
263 print_parsed_as_variable(out, v->variable, error);
267 *error = EVAL_ERROR_INVALID_VALUE;
272 static inline void print_parsed_as_node(BUFFER *out, EVAL_NODE *op, int *error) {
273 if(unlikely(op->count != operators[op->operator].parameters)) {
274 *error = EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS;
278 if(operators[op->operator].parameters == 1) {
280 if(operators[op->operator].print_as)
281 buffer_sprintf(out, "%s", operators[op->operator].print_as);
283 //if(op->operator == EVAL_OPERATOR_EXPRESSION_OPEN)
284 // buffer_strcat(out, "(");
286 print_parsed_as_value(out, &op->ops[0], error);
288 //if(op->operator == EVAL_OPERATOR_EXPRESSION_OPEN)
289 // buffer_strcat(out, ")");
292 else if(operators[op->operator].parameters == 2) {
293 buffer_strcat(out, "(");
294 print_parsed_as_value(out, &op->ops[0], error);
296 if(operators[op->operator].print_as)
297 buffer_sprintf(out, " %s ", operators[op->operator].print_as);
299 print_parsed_as_value(out, &op->ops[1], error);
300 buffer_strcat(out, ")");
304 // ----------------------------------------------------------------------------
305 // parsing expressions
308 static inline void skip_spaces(const char **string) {
309 const char *s = *string;
310 while(isspace(*s)) s++;
314 // what character can appear just after an operator keyword
316 static inline int isoperatorterm_word(const char s) {
317 if(isspace(s) || s == '(' || s == '$' || s == '!' || s == '-' || s == '+' || isdigit(s) || !s)
323 // what character can appear just after an operator symbol?
324 static inline int isoperatorterm_symbol(const char s) {
325 if(isoperatorterm_word(s) || isalpha(s))
331 // return 1 if the character should never appear in a variable
332 static inline int isvariableterm(const char s) {
333 if(isalnum(s) || s == '.' || s == '_')
339 // ----------------------------------------------------------------------------
342 static inline int parse_and(const char **string) {
343 const char *s = *string;
346 if((s[0] == 'A' || s[0] == 'a') && (s[1] == 'N' || s[1] == 'n') && (s[2] == 'D' || s[2] == 'd') && isoperatorterm_word(s[3])) {
352 if(s[0] == '&' && s[1] == '&' && isoperatorterm_symbol(s[2])) {
360 static inline int parse_or(const char **string) {
361 const char *s = *string;
364 if((s[0] == 'O' || s[0] == 'o') && (s[1] == 'R' || s[1] == 'r') && isoperatorterm_word(s[2])) {
370 if(s[0] == '|' && s[1] == '|' && isoperatorterm_symbol(s[2])) {
378 static inline int parse_greater_than_or_equal(const char **string) {
379 const char *s = *string;
382 if(s[0] == '>' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
390 static inline int parse_less_than_or_equal(const char **string) {
391 const char *s = *string;
394 if (s[0] == '<' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
402 static inline int parse_greater(const char **string) {
403 const char *s = *string;
406 if(s[0] == '>' && isoperatorterm_symbol(s[1])) {
414 static inline int parse_less(const char **string) {
415 const char *s = *string;
418 if(s[0] == '<' && isoperatorterm_symbol(s[1])) {
426 static inline int parse_equal(const char **string) {
427 const char *s = *string;
430 if(s[0] == '=' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
436 if(s[0] == '=' && isoperatorterm_symbol(s[1])) {
444 static inline int parse_not_equal(const char **string) {
445 const char *s = *string;
448 if(s[0] == '!' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
454 if(s[0] == '<' && s[1] == '>' && isoperatorterm_symbol(s[2])) {
461 static inline int parse_not(const char **string) {
462 const char *s = *string;
465 if((s[0] == 'N' || s[0] == 'n') && (s[1] == 'O' || s[1] == 'o') && (s[2] == 'T' || s[2] == 't') && isoperatorterm_word(s[3])) {
478 static inline int parse_multiply(const char **string) {
479 const char *s = *string;
482 if(s[0] == '*' && isoperatorterm_symbol(s[1])) {
490 static inline int parse_divide(const char **string) {
491 const char *s = *string;
494 if(s[0] == '/' && isoperatorterm_symbol(s[1])) {
502 static inline int parse_minus(const char **string) {
503 const char *s = *string;
506 if(s[0] == '-' && isoperatorterm_symbol(s[1])) {
514 static inline int parse_plus(const char **string) {
515 const char *s = *string;
518 if(s[0] == '+' && isoperatorterm_symbol(s[1])) {
526 static inline int parse_open_subexpression(const char **string) {
527 const char *s = *string;
538 static inline int parse_close_subexpression(const char **string) {
539 const char *s = *string;
550 static inline int parse_variable(const char **string, char *buffer, size_t len) {
551 const char *s = *string;
558 while(*s && !isvariableterm(*s) && i < len)
572 static inline int parse_constant(const char **string, calculated_number *number) {
574 calculated_number n = strtold(*string, &end);
575 if(unlikely(!end || *string == end || isnan(n) || isinf(n))) {
584 static struct operator_parser {
586 int (*parse)(const char **);
587 } operator_parsers[] = {
588 // the order in this list is important!
589 // the first matching will be used
590 // so place the longer of overlapping ones
593 { EVAL_OPERATOR_AND, parse_and },
594 { EVAL_OPERATOR_OR, parse_or },
595 { EVAL_OPERATOR_GREATER_THAN_OR_EQUAL, parse_greater_than_or_equal },
596 { EVAL_OPERATOR_LESS_THAN_OR_EQUAL, parse_less_than_or_equal },
597 { EVAL_OPERATOR_NOT_EQUAL, parse_not_equal },
598 { EVAL_OPERATOR_EQUAL, parse_equal },
599 { EVAL_OPERATOR_LESS, parse_less },
600 { EVAL_OPERATOR_GREATER, parse_greater },
601 { EVAL_OPERATOR_PLUS, parse_plus },
602 { EVAL_OPERATOR_MINUS, parse_minus },
603 { EVAL_OPERATOR_MULTIPLY, parse_multiply },
604 { EVAL_OPERATOR_DIVIDE, parse_divide },
606 /* we should not put in this list the following:
612 * these are handled in code
616 { EVAL_OPERATOR_NOP, NULL }
619 static inline unsigned char parse_operator(const char **string, int *precedence) {
623 for(i = 0 ; operator_parsers[i].parse != NULL ; i++)
624 if(operator_parsers[i].parse(string)) {
625 if(precedence) *precedence = eval_precedence(operator_parsers[i].id);
626 return operator_parsers[i].id;
629 return EVAL_OPERATOR_NOP;
632 // ----------------------------------------------------------------------------
635 static inline EVAL_NODE *eval_node_alloc(int count) {
638 EVAL_NODE *op = callocz(1, sizeof(EVAL_NODE) + (sizeof(EVAL_VALUE) * count));
641 op->operator = EVAL_OPERATOR_NOP;
642 op->precedence = eval_precedence(EVAL_OPERATOR_NOP);
647 static inline void eval_node_set_value_to_node(EVAL_NODE *op, int pos, EVAL_NODE *value) {
649 fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1);
651 op->ops[pos].type = EVAL_VALUE_EXPRESSION;
652 op->ops[pos].expression = value;
655 static inline void eval_node_set_value_to_constant(EVAL_NODE *op, int pos, calculated_number value) {
657 fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1);
659 op->ops[pos].type = EVAL_VALUE_NUMBER;
660 op->ops[pos].number = value;
663 static inline void eval_node_set_value_to_variable(EVAL_NODE *op, int pos, const char *variable) {
665 fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1);
667 op->ops[pos].type = EVAL_VALUE_VARIABLE;
668 op->ops[pos].variable = callocz(1, sizeof(EVAL_VARIABLE));
669 op->ops[pos].variable->name = strdupz(variable);
670 op->ops[pos].variable->hash = simple_hash(op->ops[pos].variable->name);
673 static inline void eval_variable_free(EVAL_VARIABLE *v) {
678 static inline void eval_value_free(EVAL_VALUE *v) {
680 case EVAL_VALUE_EXPRESSION:
681 eval_node_free(v->expression);
684 case EVAL_VALUE_VARIABLE:
685 eval_variable_free(v->variable);
693 static inline void eval_node_free(EVAL_NODE *op) {
696 for(i = op->count - 1; i >= 0 ;i--)
697 eval_value_free(&op->ops[i]);
703 // ----------------------------------------------------------------------------
706 // helper function to avoid allocations all over the place
707 static inline EVAL_NODE *parse_next_operand_given_its_operator(const char **string, unsigned char operator_type, int *error) {
708 EVAL_NODE *sub = parse_one_full_operand(string, error);
709 if(!sub) return NULL;
711 EVAL_NODE *op = eval_node_alloc(1);
712 op->operator = operator_type;
713 eval_node_set_value_to_node(op, 0, sub);
717 // parse a full operand, including its sign or other associative operator (e.g. NOT)
718 static inline EVAL_NODE *parse_one_full_operand(const char **string, int *error) {
719 char variable_buffer[EVAL_MAX_VARIABLE_NAME_LENGTH + 1];
720 EVAL_NODE *op1 = NULL;
721 calculated_number number;
723 *error = EVAL_ERROR_OK;
727 *error = EVAL_ERROR_MISSING_OPERAND;
731 if(parse_not(string)) {
732 op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_NOT, error);
733 op1->precedence = eval_precedence(EVAL_OPERATOR_NOT);
735 else if(parse_plus(string)) {
736 op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_SIGN_PLUS, error);
737 op1->precedence = eval_precedence(EVAL_OPERATOR_SIGN_PLUS);
739 else if(parse_minus(string)) {
740 op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_SIGN_MINUS, error);
741 op1->precedence = eval_precedence(EVAL_OPERATOR_SIGN_MINUS);
743 else if(parse_open_subexpression(string)) {
744 EVAL_NODE *sub = parse_full_expression(string, error);
746 op1 = eval_node_alloc(1);
747 op1->operator = EVAL_OPERATOR_EXPRESSION_OPEN;
748 op1->precedence = eval_precedence(EVAL_OPERATOR_EXPRESSION_OPEN);
749 eval_node_set_value_to_node(op1, 0, sub);
750 if(!parse_close_subexpression(string)) {
751 *error = EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION;
757 else if(parse_variable(string, variable_buffer, EVAL_MAX_VARIABLE_NAME_LENGTH)) {
758 op1 = eval_node_alloc(1);
759 op1->operator = EVAL_OPERATOR_NOP;
760 eval_node_set_value_to_variable(op1, 0, variable_buffer);
762 else if(parse_constant(string, &number)) {
763 op1 = eval_node_alloc(1);
764 op1->operator = EVAL_OPERATOR_NOP;
765 eval_node_set_value_to_constant(op1, 0, number);
768 *error = EVAL_ERROR_UNKNOWN_OPERAND;
770 *error = EVAL_ERROR_MISSING_OPERAND;
775 // parse an operator and the rest of the expression
776 // precedence processing is handled here
777 static inline EVAL_NODE *parse_rest_of_expression(const char **string, int *error, EVAL_NODE *op1) {
778 EVAL_NODE *op2 = NULL;
779 unsigned char operator;
782 operator = parse_operator(string, &precedence);
785 if(operator != EVAL_OPERATOR_NOP) {
786 op2 = parse_one_full_operand(string, error);
788 // error is already reported
793 EVAL_NODE *op = eval_node_alloc(2);
794 op->operator = operator;
795 op->precedence = precedence;
797 eval_node_set_value_to_node(op, 1, op2);
799 // precedence processing
800 // if this operator has a higher precedence compared to its next
801 // put the next operator on top of us (top = evaluated later)
802 // function recursion does the rest...
803 if(op->precedence > op1->precedence && op1->count == 2 && op1->operator != '(' && op1->ops[1].type == EVAL_VALUE_EXPRESSION) {
804 eval_node_set_value_to_node(op, 0, op1->ops[1].expression);
805 op1->ops[1].expression = op;
809 eval_node_set_value_to_node(op, 0, op1);
811 return parse_rest_of_expression(string, error, op);
813 else if(**string == ')') {
817 if(op1) eval_node_free(op1);
819 *error = EVAL_ERROR_MISSING_OPERATOR;
825 // high level function to parse an expression or a sub-expression
826 static inline EVAL_NODE *parse_full_expression(const char **string, int *error) {
827 EVAL_NODE *op1 = NULL;
829 op1 = parse_one_full_operand(string, error);
831 *error = EVAL_ERROR_MISSING_OPERAND;
835 return parse_rest_of_expression(string, error, op1);
838 // ----------------------------------------------------------------------------
841 int expression_evaluate(EVAL_EXPRESSION *exp) {
842 exp->error = EVAL_ERROR_OK;
844 buffer_reset(exp->error_msg);
845 exp->result = eval_node(exp, (EVAL_NODE *)exp->nodes, &exp->error);
847 if(exp->error != EVAL_ERROR_OK) {
850 if(buffer_strlen(exp->error_msg))
851 buffer_strcat(exp->error_msg, "; ");
853 buffer_sprintf(exp->error_msg, "failed to evaluate expression with error %d (%s)", exp->error, expression_strerror(exp->error));
860 EVAL_EXPRESSION *expression_parse(const char *string, const char **failed_at, int *error) {
861 const char *s = string;
862 int err = EVAL_ERROR_OK;
863 unsigned long pos = 0;
865 EVAL_NODE *op = parse_full_expression(&s, &err);
872 err = EVAL_ERROR_REMAINING_GARBAGE;
875 if (failed_at) *failed_at = s;
876 if (error) *error = err;
879 pos = s - string + 1;
880 error("failed to parse expression '%s': %s at character %lu (i.e.: '%s').", string, expression_strerror(err), pos, s);
884 BUFFER *out = buffer_create(1024);
885 print_parsed_as_node(out, op, &err);
886 if(err != EVAL_ERROR_OK) {
887 error("failed to re-generate expression '%s' with reason: %s", string, expression_strerror(err));
893 EVAL_EXPRESSION *exp = callocz(1, sizeof(EVAL_EXPRESSION));
895 exp->source = strdupz(string);
896 exp->parsed_as = strdupz(buffer_tostring(out));
899 exp->error_msg = buffer_create(100);
900 exp->nodes = (void *)op;
905 void expression_free(EVAL_EXPRESSION *exp) {
908 if(exp->nodes) eval_node_free((EVAL_NODE *)exp->nodes);
909 freez((void *)exp->source);
910 freez((void *)exp->parsed_as);
911 buffer_free(exp->error_msg);
915 const char *expression_strerror(int error) {
920 case EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION:
921 return "missing closing parenthesis";
923 case EVAL_ERROR_UNKNOWN_OPERAND:
924 return "unknown operand";
926 case EVAL_ERROR_MISSING_OPERAND:
927 return "expected operand";
929 case EVAL_ERROR_MISSING_OPERATOR:
930 return "expected operator";
932 case EVAL_ERROR_REMAINING_GARBAGE:
933 return "remaining characters after expression";
935 case EVAL_ERROR_INVALID_VALUE:
936 return "invalid value structure - internal error";
938 case EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS:
939 return "wrong number of operands for operation - internal error";
941 case EVAL_ERROR_VALUE_IS_NAN:
942 return "value is unset";
944 case EVAL_ERROR_VALUE_IS_INFINITE:
945 return "computed value is infinite";
947 case EVAL_ERROR_UNKNOWN_VARIABLE:
948 return "undefined variable";
951 return "unknown error";