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);
126 calculated_number eval_and(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
127 return eval_value(exp, &op->ops[0], error) && eval_value(exp, &op->ops[1], error);
129 calculated_number eval_or(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
130 return eval_value(exp, &op->ops[0], error) || eval_value(exp, &op->ops[1], error);
132 calculated_number eval_greater_than_or_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
133 return eval_value(exp, &op->ops[0], error) >= eval_value(exp, &op->ops[1], error);
135 calculated_number eval_less_than_or_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
136 return eval_value(exp, &op->ops[0], error) <= eval_value(exp, &op->ops[1], error);
138 calculated_number eval_not_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
139 return eval_value(exp, &op->ops[0], error) != eval_value(exp, &op->ops[1], error);
141 calculated_number eval_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
142 return eval_value(exp, &op->ops[0], error) == eval_value(exp, &op->ops[1], error);
144 calculated_number eval_less(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
145 return eval_value(exp, &op->ops[0], error) < eval_value(exp, &op->ops[1], error);
147 calculated_number eval_greater(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
148 return eval_value(exp, &op->ops[0], error) > eval_value(exp, &op->ops[1], error);
150 calculated_number eval_plus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
151 return eval_value(exp, &op->ops[0], error) + eval_value(exp, &op->ops[1], error);
153 calculated_number eval_minus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
154 return eval_value(exp, &op->ops[0], error) - eval_value(exp, &op->ops[1], error);
156 calculated_number eval_multiply(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
157 return eval_value(exp, &op->ops[0], error) * eval_value(exp, &op->ops[1], error);
159 calculated_number eval_divide(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
160 return eval_value(exp, &op->ops[0], error) / eval_value(exp, &op->ops[1], error);
162 calculated_number eval_nop(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
163 return eval_value(exp, &op->ops[0], error);
165 calculated_number eval_not(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
166 return !eval_value(exp, &op->ops[0], error);
168 calculated_number eval_sign_plus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
169 return eval_value(exp, &op->ops[0], error);
171 calculated_number eval_sign_minus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
172 return -eval_value(exp, &op->ops[0], error);
175 static struct operator {
176 const char *print_as;
179 calculated_number (*eval)(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error);
181 // this is a random access array
182 // we always access it with a known EVAL_OPERATOR_X
184 [EVAL_OPERATOR_AND] = { "&&", 2, 2, eval_and },
185 [EVAL_OPERATOR_OR] = { "||", 2, 2, eval_or },
186 [EVAL_OPERATOR_GREATER_THAN_OR_EQUAL] = { ">=", 3, 2, eval_greater_than_or_equal },
187 [EVAL_OPERATOR_LESS_THAN_OR_EQUAL] = { "<=", 3, 2, eval_less_than_or_equal },
188 [EVAL_OPERATOR_NOT_EQUAL] = { "!=", 3, 2, eval_not_equal },
189 [EVAL_OPERATOR_EQUAL] = { "==", 3, 2, eval_equal },
190 [EVAL_OPERATOR_LESS] = { "<", 3, 2, eval_less },
191 [EVAL_OPERATOR_GREATER] = { ">", 3, 2, eval_greater },
192 [EVAL_OPERATOR_PLUS] = { "+", 4, 2, eval_plus },
193 [EVAL_OPERATOR_MINUS] = { "-", 4, 2, eval_minus },
194 [EVAL_OPERATOR_MULTIPLY] = { "*", 5, 2, eval_multiply },
195 [EVAL_OPERATOR_DIVIDE] = { "/", 5, 2, eval_divide },
196 [EVAL_OPERATOR_NOT] = { "!", 6, 1, eval_not },
197 [EVAL_OPERATOR_SIGN_PLUS] = { "+", 6, 1, eval_sign_plus },
198 [EVAL_OPERATOR_SIGN_MINUS] = { "-", 6, 1, eval_sign_minus },
199 [EVAL_OPERATOR_NOP] = { NULL, 7, 1, eval_nop },
200 [EVAL_OPERATOR_EXPRESSION_OPEN] = { NULL, 7, 1, eval_nop },
202 // this should exist in our evaluation list
203 [EVAL_OPERATOR_EXPRESSION_CLOSE] = { NULL, 7, 1, eval_nop }
206 #define eval_precedence(operator) (operators[(unsigned char)(operator)].precedence)
208 static inline calculated_number eval_node(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
209 if(unlikely(op->count != operators[op->operator].parameters)) {
210 *error = EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS;
214 calculated_number n = operators[op->operator].eval(exp, op, error);
216 // return eval_check_number(n, error);
220 // ----------------------------------------------------------------------------
221 // parsed-as generation
223 static inline void print_parsed_as_variable(BUFFER *out, EVAL_VARIABLE *v, int *error) {
225 buffer_sprintf(out, "$%s", v->name);
228 static inline void print_parsed_as_constant(BUFFER *out, calculated_number n) {
229 if(unlikely(isnan(n))) {
230 buffer_strcat(out, "nan");
234 if(unlikely(isinf(n))) {
235 buffer_strcat(out, "inf");
240 snprintfz(b, 100, CALCULATED_NUMBER_FORMAT, n);
242 s = &b[strlen(b) - 1];
243 while(s > b && *s == '0') {
248 if(s > b && *s == '.')
251 buffer_strcat(out, b);
254 static inline void print_parsed_as_value(BUFFER *out, EVAL_VALUE *v, int *error) {
256 case EVAL_VALUE_EXPRESSION:
257 print_parsed_as_node(out, v->expression, error);
260 case EVAL_VALUE_NUMBER:
261 print_parsed_as_constant(out, v->number);
264 case EVAL_VALUE_VARIABLE:
265 print_parsed_as_variable(out, v->variable, error);
269 *error = EVAL_ERROR_INVALID_VALUE;
274 static inline void print_parsed_as_node(BUFFER *out, EVAL_NODE *op, int *error) {
275 if(unlikely(op->count != operators[op->operator].parameters)) {
276 *error = EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS;
280 if(operators[op->operator].parameters == 1) {
282 if(operators[op->operator].print_as)
283 buffer_sprintf(out, "%s", operators[op->operator].print_as);
285 //if(op->operator == EVAL_OPERATOR_EXPRESSION_OPEN)
286 // buffer_strcat(out, "(");
288 print_parsed_as_value(out, &op->ops[0], error);
290 //if(op->operator == EVAL_OPERATOR_EXPRESSION_OPEN)
291 // buffer_strcat(out, ")");
294 else if(operators[op->operator].parameters == 2) {
295 buffer_strcat(out, "(");
296 print_parsed_as_value(out, &op->ops[0], error);
298 if(operators[op->operator].print_as)
299 buffer_sprintf(out, " %s ", operators[op->operator].print_as);
301 print_parsed_as_value(out, &op->ops[1], error);
302 buffer_strcat(out, ")");
306 // ----------------------------------------------------------------------------
307 // parsing expressions
310 static inline void skip_spaces(const char **string) {
311 const char *s = *string;
312 while(isspace(*s)) s++;
316 // what character can appear just after an operator keyword
318 static inline int isoperatorterm_word(const char s) {
319 if(isspace(s) || s == '(' || s == '$' || s == '!' || s == '-' || s == '+' || isdigit(s) || !s)
325 // what character can appear just after an operator symbol?
326 static inline int isoperatorterm_symbol(const char s) {
327 if(isoperatorterm_word(s) || isalpha(s))
333 // return 1 if the character should never appear in a variable
334 static inline int isvariableterm(const char s) {
335 if(isalnum(s) || s == '.' || s == '_')
341 // ----------------------------------------------------------------------------
344 static inline int parse_and(const char **string) {
345 const char *s = *string;
348 if((s[0] == 'A' || s[0] == 'a') && (s[1] == 'N' || s[1] == 'n') && (s[2] == 'D' || s[2] == 'd') && isoperatorterm_word(s[3])) {
354 if(s[0] == '&' && s[1] == '&' && isoperatorterm_symbol(s[2])) {
362 static inline int parse_or(const char **string) {
363 const char *s = *string;
366 if((s[0] == 'O' || s[0] == 'o') && (s[1] == 'R' || s[1] == 'r') && isoperatorterm_word(s[2])) {
372 if(s[0] == '|' && s[1] == '|' && isoperatorterm_symbol(s[2])) {
380 static inline int parse_greater_than_or_equal(const char **string) {
381 const char *s = *string;
384 if(s[0] == '>' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
392 static inline int parse_less_than_or_equal(const char **string) {
393 const char *s = *string;
396 if (s[0] == '<' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
404 static inline int parse_greater(const char **string) {
405 const char *s = *string;
408 if(s[0] == '>' && isoperatorterm_symbol(s[1])) {
416 static inline int parse_less(const char **string) {
417 const char *s = *string;
420 if(s[0] == '<' && isoperatorterm_symbol(s[1])) {
428 static inline int parse_equal(const char **string) {
429 const char *s = *string;
432 if(s[0] == '=' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
438 if(s[0] == '=' && isoperatorterm_symbol(s[1])) {
446 static inline int parse_not_equal(const char **string) {
447 const char *s = *string;
450 if(s[0] == '!' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
456 if(s[0] == '<' && s[1] == '>' && isoperatorterm_symbol(s[2])) {
463 static inline int parse_not(const char **string) {
464 const char *s = *string;
467 if((s[0] == 'N' || s[0] == 'n') && (s[1] == 'O' || s[1] == 'o') && (s[2] == 'T' || s[2] == 't') && isoperatorterm_word(s[3])) {
480 static inline int parse_multiply(const char **string) {
481 const char *s = *string;
484 if(s[0] == '*' && isoperatorterm_symbol(s[1])) {
492 static inline int parse_divide(const char **string) {
493 const char *s = *string;
496 if(s[0] == '/' && isoperatorterm_symbol(s[1])) {
504 static inline int parse_minus(const char **string) {
505 const char *s = *string;
508 if(s[0] == '-' && isoperatorterm_symbol(s[1])) {
516 static inline int parse_plus(const char **string) {
517 const char *s = *string;
520 if(s[0] == '+' && isoperatorterm_symbol(s[1])) {
528 static inline int parse_open_subexpression(const char **string) {
529 const char *s = *string;
540 static inline int parse_close_subexpression(const char **string) {
541 const char *s = *string;
552 static inline int parse_variable(const char **string, char *buffer, size_t len) {
553 const char *s = *string;
560 while(*s && !isvariableterm(*s) && i < len)
574 static inline int parse_constant(const char **string, calculated_number *number) {
576 calculated_number n = strtold(*string, &end);
577 if(unlikely(!end || *string == end)) {
586 static struct operator_parser {
588 int (*parse)(const char **);
589 } operator_parsers[] = {
590 // the order in this list is important!
591 // the first matching will be used
592 // so place the longer of overlapping ones
595 { EVAL_OPERATOR_AND, parse_and },
596 { EVAL_OPERATOR_OR, parse_or },
597 { EVAL_OPERATOR_GREATER_THAN_OR_EQUAL, parse_greater_than_or_equal },
598 { EVAL_OPERATOR_LESS_THAN_OR_EQUAL, parse_less_than_or_equal },
599 { EVAL_OPERATOR_NOT_EQUAL, parse_not_equal },
600 { EVAL_OPERATOR_EQUAL, parse_equal },
601 { EVAL_OPERATOR_LESS, parse_less },
602 { EVAL_OPERATOR_GREATER, parse_greater },
603 { EVAL_OPERATOR_PLUS, parse_plus },
604 { EVAL_OPERATOR_MINUS, parse_minus },
605 { EVAL_OPERATOR_MULTIPLY, parse_multiply },
606 { EVAL_OPERATOR_DIVIDE, parse_divide },
608 /* we should not put in this list the following:
614 * these are handled in code
618 { EVAL_OPERATOR_NOP, NULL }
621 static inline unsigned char parse_operator(const char **string, int *precedence) {
625 for(i = 0 ; operator_parsers[i].parse != NULL ; i++)
626 if(operator_parsers[i].parse(string)) {
627 if(precedence) *precedence = eval_precedence(operator_parsers[i].id);
628 return operator_parsers[i].id;
631 return EVAL_OPERATOR_NOP;
634 // ----------------------------------------------------------------------------
637 static inline EVAL_NODE *eval_node_alloc(int count) {
640 EVAL_NODE *op = callocz(1, sizeof(EVAL_NODE) + (sizeof(EVAL_VALUE) * count));
643 op->operator = EVAL_OPERATOR_NOP;
644 op->precedence = eval_precedence(EVAL_OPERATOR_NOP);
649 static inline void eval_node_set_value_to_node(EVAL_NODE *op, int pos, EVAL_NODE *value) {
651 fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1);
653 op->ops[pos].type = EVAL_VALUE_EXPRESSION;
654 op->ops[pos].expression = value;
657 static inline void eval_node_set_value_to_constant(EVAL_NODE *op, int pos, calculated_number value) {
659 fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1);
661 op->ops[pos].type = EVAL_VALUE_NUMBER;
662 op->ops[pos].number = value;
665 static inline void eval_node_set_value_to_variable(EVAL_NODE *op, int pos, const char *variable) {
667 fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1);
669 op->ops[pos].type = EVAL_VALUE_VARIABLE;
670 op->ops[pos].variable = callocz(1, sizeof(EVAL_VARIABLE));
671 op->ops[pos].variable->name = strdupz(variable);
672 op->ops[pos].variable->hash = simple_hash(op->ops[pos].variable->name);
675 static inline void eval_variable_free(EVAL_VARIABLE *v) {
680 static inline void eval_value_free(EVAL_VALUE *v) {
682 case EVAL_VALUE_EXPRESSION:
683 eval_node_free(v->expression);
686 case EVAL_VALUE_VARIABLE:
687 eval_variable_free(v->variable);
695 static inline void eval_node_free(EVAL_NODE *op) {
698 for(i = op->count - 1; i >= 0 ;i--)
699 eval_value_free(&op->ops[i]);
705 // ----------------------------------------------------------------------------
708 // helper function to avoid allocations all over the place
709 static inline EVAL_NODE *parse_next_operand_given_its_operator(const char **string, unsigned char operator_type, int *error) {
710 EVAL_NODE *sub = parse_one_full_operand(string, error);
711 if(!sub) return NULL;
713 EVAL_NODE *op = eval_node_alloc(1);
714 op->operator = operator_type;
715 eval_node_set_value_to_node(op, 0, sub);
719 // parse a full operand, including its sign or other associative operator (e.g. NOT)
720 static inline EVAL_NODE *parse_one_full_operand(const char **string, int *error) {
721 char variable_buffer[EVAL_MAX_VARIABLE_NAME_LENGTH + 1];
722 EVAL_NODE *op1 = NULL;
723 calculated_number number;
725 *error = EVAL_ERROR_OK;
729 *error = EVAL_ERROR_MISSING_OPERAND;
733 if(parse_not(string)) {
734 op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_NOT, error);
735 op1->precedence = eval_precedence(EVAL_OPERATOR_NOT);
737 else if(parse_plus(string)) {
738 op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_SIGN_PLUS, error);
739 op1->precedence = eval_precedence(EVAL_OPERATOR_SIGN_PLUS);
741 else if(parse_minus(string)) {
742 op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_SIGN_MINUS, error);
743 op1->precedence = eval_precedence(EVAL_OPERATOR_SIGN_MINUS);
745 else if(parse_open_subexpression(string)) {
746 EVAL_NODE *sub = parse_full_expression(string, error);
748 op1 = eval_node_alloc(1);
749 op1->operator = EVAL_OPERATOR_EXPRESSION_OPEN;
750 op1->precedence = eval_precedence(EVAL_OPERATOR_EXPRESSION_OPEN);
751 eval_node_set_value_to_node(op1, 0, sub);
752 if(!parse_close_subexpression(string)) {
753 *error = EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION;
759 else if(parse_variable(string, variable_buffer, EVAL_MAX_VARIABLE_NAME_LENGTH)) {
760 op1 = eval_node_alloc(1);
761 op1->operator = EVAL_OPERATOR_NOP;
762 eval_node_set_value_to_variable(op1, 0, variable_buffer);
764 else if(parse_constant(string, &number)) {
765 op1 = eval_node_alloc(1);
766 op1->operator = EVAL_OPERATOR_NOP;
767 eval_node_set_value_to_constant(op1, 0, number);
770 *error = EVAL_ERROR_UNKNOWN_OPERAND;
772 *error = EVAL_ERROR_MISSING_OPERAND;
777 // parse an operator and the rest of the expression
778 // precedence processing is handled here
779 static inline EVAL_NODE *parse_rest_of_expression(const char **string, int *error, EVAL_NODE *op1) {
780 EVAL_NODE *op2 = NULL;
781 unsigned char operator;
784 operator = parse_operator(string, &precedence);
787 if(operator != EVAL_OPERATOR_NOP) {
788 op2 = parse_one_full_operand(string, error);
790 // error is already reported
795 EVAL_NODE *op = eval_node_alloc(2);
796 op->operator = operator;
797 op->precedence = precedence;
799 eval_node_set_value_to_node(op, 1, op2);
801 // precedence processing
802 // if this operator has a higher precedence compared to its next
803 // put the next operator on top of us (top = evaluated later)
804 // function recursion does the rest...
805 if(op->precedence > op1->precedence && op1->count == 2 && op1->operator != '(' && op1->ops[1].type == EVAL_VALUE_EXPRESSION) {
806 eval_node_set_value_to_node(op, 0, op1->ops[1].expression);
807 op1->ops[1].expression = op;
811 eval_node_set_value_to_node(op, 0, op1);
813 return parse_rest_of_expression(string, error, op);
815 else if(**string == ')') {
819 if(op1) eval_node_free(op1);
821 *error = EVAL_ERROR_MISSING_OPERATOR;
827 // high level function to parse an expression or a sub-expression
828 static inline EVAL_NODE *parse_full_expression(const char **string, int *error) {
829 EVAL_NODE *op1 = NULL;
831 op1 = parse_one_full_operand(string, error);
833 *error = EVAL_ERROR_MISSING_OPERAND;
837 return parse_rest_of_expression(string, error, op1);
840 // ----------------------------------------------------------------------------
843 int expression_evaluate(EVAL_EXPRESSION *exp) {
844 exp->error = EVAL_ERROR_OK;
846 buffer_reset(exp->error_msg);
847 exp->result = eval_node(exp, (EVAL_NODE *)exp->nodes, &exp->error);
849 if(exp->error == EVAL_ERROR_OK)
850 exp->result = eval_check_number(exp->result, &exp->error);
852 if(exp->error != EVAL_ERROR_OK) {
855 if(buffer_strlen(exp->error_msg))
856 buffer_strcat(exp->error_msg, "; ");
858 buffer_sprintf(exp->error_msg, "failed to evaluate expression with error %d (%s)", exp->error, expression_strerror(exp->error));
865 EVAL_EXPRESSION *expression_parse(const char *string, const char **failed_at, int *error) {
866 const char *s = string;
867 int err = EVAL_ERROR_OK;
868 unsigned long pos = 0;
870 EVAL_NODE *op = parse_full_expression(&s, &err);
877 err = EVAL_ERROR_REMAINING_GARBAGE;
880 if (failed_at) *failed_at = s;
881 if (error) *error = err;
884 pos = s - string + 1;
885 error("failed to parse expression '%s': %s at character %lu (i.e.: '%s').", string, expression_strerror(err), pos, s);
889 BUFFER *out = buffer_create(1024);
890 print_parsed_as_node(out, op, &err);
891 if(err != EVAL_ERROR_OK) {
892 error("failed to re-generate expression '%s' with reason: %s", string, expression_strerror(err));
898 EVAL_EXPRESSION *exp = callocz(1, sizeof(EVAL_EXPRESSION));
900 exp->source = strdupz(string);
901 exp->parsed_as = strdupz(buffer_tostring(out));
904 exp->error_msg = buffer_create(100);
905 exp->nodes = (void *)op;
910 void expression_free(EVAL_EXPRESSION *exp) {
913 if(exp->nodes) eval_node_free((EVAL_NODE *)exp->nodes);
914 freez((void *)exp->source);
915 freez((void *)exp->parsed_as);
916 buffer_free(exp->error_msg);
920 const char *expression_strerror(int error) {
925 case EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION:
926 return "missing closing parenthesis";
928 case EVAL_ERROR_UNKNOWN_OPERAND:
929 return "unknown operand";
931 case EVAL_ERROR_MISSING_OPERAND:
932 return "expected operand";
934 case EVAL_ERROR_MISSING_OPERATOR:
935 return "expected operator";
937 case EVAL_ERROR_REMAINING_GARBAGE:
938 return "remaining characters after expression";
940 case EVAL_ERROR_INVALID_VALUE:
941 return "invalid value structure - internal error";
943 case EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS:
944 return "wrong number of operands for operation - internal error";
946 case EVAL_ERROR_VALUE_IS_NAN:
947 return "value is unset";
949 case EVAL_ERROR_VALUE_IS_INFINITE:
950 return "computed value is infinite";
952 case EVAL_ERROR_UNKNOWN_VARIABLE:
953 return "undefined variable";
956 return "unknown error";