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Diffstat (limited to 'src/eval.c')
| -rw-r--r-- | src/eval.c | 1119 |
1 files changed, 1119 insertions, 0 deletions
diff --git a/src/eval.c b/src/eval.c new file mode 100644 index 000000000..8866ee95d --- /dev/null +++ b/src/eval.c @@ -0,0 +1,1119 @@ +#include "common.h" + +// ---------------------------------------------------------------------------- +// 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_check_number(calculated_number n, int *error) { + if(unlikely(isnan(n))) { + *error = EVAL_ERROR_VALUE_IS_NAN; + return 0; + } + + if(unlikely(isinf(n))) { + *error = EVAL_ERROR_VALUE_IS_INFINITE; + return 0; + } + + return n; +} + +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; + 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"); + } + + if(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(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(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(v->hash == now_hash && !strcmp(v->name, "now")) { + n = time(NULL); + buffer_strcat(exp->error_msg, "[ $now = "); + 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, "unknown 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 eval_check_number(n, error); + 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_IF_THEN_ELSE] = { "?", 1, 3, 0, eval_if_then_else }, + [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_NOP] = { NULL, 7, 1, 0, eval_nop }, + [EVAL_OPERATOR_EXPRESSION_OPEN] = { NULL, 7, 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 eval_check_number(n, 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 +static inline void skip_spaces(const char **string) { + const char *s = *string; + while(isspace(*s)) s++; + *string = s; +} + +// what character can appear just after an operator keyword +// like NOT AND OR ? +static inline int isoperatorterm_word(const char s) { + if(isspace(s) || s == '(' || s == '$' || s == '!' || s == '-' || s == '+' || isdigit(s) || !s) + return 1; + + return 0; +} + +// what character can appear just after an operator symbol? +static inline int isoperatorterm_symbol(const char s) { + if(isoperatorterm_word(s) || isalpha(s)) + return 1; + + return 0; +} + +// return 1 if the character should never appear in a variable +static inline int isvariableterm(const char s) { + if(isalnum(s) || s == '.' || s == '_') + return 0; + + return 1; +} + +// ---------------------------------------------------------------------------- +// parse operators + +static inline int parse_and(const char **string) { + const char *s = *string; + + // AND + if((s[0] == 'A' || s[0] == 'a') && (s[1] == 'N' || s[1] == 'n') && (s[2] == 'D' || s[2] == 'd') && isoperatorterm_word(s[3])) { + *string = &s[4]; + return 1; + } + + // && + if(s[0] == '&' && s[1] == '&' && isoperatorterm_symbol(s[2])) { + *string = &s[2]; + return 1; + } + + return 0; +} + +static inline int parse_or(const char **string) { + const char *s = *string; + + // OR + if((s[0] == 'O' || s[0] == 'o') && (s[1] == 'R' || s[1] == 'r') && isoperatorterm_word(s[2])) { + *string = &s[3]; + return 1; + } + + // || + if(s[0] == '|' && s[1] == '|' && isoperatorterm_symbol(s[2])) { + *string = &s[2]; + return 1; + } + + return 0; +} + +static inline int parse_greater_than_or_equal(const char **string) { + const char *s = *string; + + // >= + if(s[0] == '>' && s[1] == '=' && isoperatorterm_symbol(s[2])) { + *string = &s[2]; + return 1; + } + + return 0; +} + +static inline int parse_less_than_or_equal(const char **string) { + const char *s = *string; + + // <= + if (s[0] == '<' && s[1] == '=' && isoperatorterm_symbol(s[2])) { + *string = &s[2]; + return 1; + } + + return 0; +} + +static inline int parse_greater(const char **string) { + const char *s = *string; + + // > + if(s[0] == '>' && isoperatorterm_symbol(s[1])) { + *string = &s[1]; + return 1; + } + + return 0; +} + +static inline int parse_less(const char **string) { + const char *s = *string; + + // < + if(s[0] == '<' && isoperatorterm_symbol(s[1])) { + *string = &s[1]; + return 1; + } + + return 0; +} + +static inline int parse_equal(const char **string) { + const char *s = *string; + + // == + if(s[0] == '=' && s[1] == '=' && isoperatorterm_symbol(s[2])) { + *string = &s[2]; + return 1; + } + + // = + if(s[0] == '=' && isoperatorterm_symbol(s[1])) { + *string = &s[1]; + return 1; + } + + return 0; +} + +static inline int parse_not_equal(const char **string) { + const char *s = *string; + + // != + if(s[0] == '!' && s[1] == '=' && isoperatorterm_symbol(s[2])) { + *string = &s[2]; + return 1; + } + + // <> + if(s[0] == '<' && s[1] == '>' && isoperatorterm_symbol(s[2])) { + *string = &s[2]; + } + + return 0; +} + +static inline int parse_not(const char **string) { + const char *s = *string; + + // NOT + if((s[0] == 'N' || s[0] == 'n') && (s[1] == 'O' || s[1] == 'o') && (s[2] == 'T' || s[2] == 't') && isoperatorterm_word(s[3])) { + *string = &s[3]; + return 1; + } + + if(s[0] == '!') { + *string = &s[1]; + return 1; + } + + return 0; +} + +static inline int parse_multiply(const char **string) { + const char *s = *string; + + // * + if(s[0] == '*' && isoperatorterm_symbol(s[1])) { + *string = &s[1]; + return 1; + } + + return 0; +} + +static inline int parse_divide(const char **string) { + const char *s = *string; + + // / + if(s[0] == '/' && isoperatorterm_symbol(s[1])) { + *string = &s[1]; + return 1; + } + + return 0; +} + +static inline int parse_minus(const char **string) { + const char *s = *string; + + // - + if(s[0] == '-' && isoperatorterm_symbol(s[1])) { + *string = &s[1]; + return 1; + } + + return 0; +} + +static inline int parse_plus(const char **string) { + const char *s = *string; + + // + + if(s[0] == '+' && isoperatorterm_symbol(s[1])) { + *string = &s[1]; + return 1; + } + + return 0; +} + +static inline int parse_open_subexpression(const char **string) { + const char *s = *string; + + // ( + if(s[0] == '(') { + *string = &s[1]; + return 1; + } + + return 0; +} + +#define parse_close_function(x) parse_close_subexpression(x) + +static inline int parse_close_subexpression(const char **string) { + const char *s = *string; + + // ) + if(s[0] == ')') { + *string = &s[1]; + return 1; + } + + return 0; +} + +static inline int parse_variable(const char **string, char *buffer, size_t len) { + const char *s = *string; + + // $ + if(s[0] == '$') { + size_t i = 0; + s++; + + while(*s && !isvariableterm(*s) && i < len) + buffer[i++] = *s++; + + buffer[i] = '\0'; + + if(buffer[0]) { + *string = &s[0]; + return 1; + } + } + + return 0; +} + +static inline int parse_constant(const char **string, calculated_number *number) { + char *end = NULL; + calculated_number n = strtold(*string, &end); + if(unlikely(!end || *string == end)) { + *number = 0; + return 0; + } + *number = n; + *string = end; + return 1; +} + +static inline int parse_abs(const char **string) { + const char *s = *string; + + // ABS + if((s[0] == 'A' || s[0] == 'a') && (s[1] == 'B' || s[1] == 'b') && (s[2] == 'S' || s[2] == 's') && s[3] == '(') { + *string = &s[3]; + return 1; + } + + return 0; +} + +static inline int parse_if_then_else(const char **string) { + const char *s = *string; + + // ? + if(s[0] == '?') { + *string = &s[1]; + return 1; + } + + return 0; +} + +static struct operator_parser { + unsigned char id; + int (*parse)(const char **); +} operator_parsers[] = { + // the order in this list is important! + // the first matching will be used + // so place the longer of overlapping ones + // at the top + + { EVAL_OPERATOR_AND, parse_and }, + { EVAL_OPERATOR_OR, parse_or }, + { EVAL_OPERATOR_GREATER_THAN_OR_EQUAL, parse_greater_than_or_equal }, + { EVAL_OPERATOR_LESS_THAN_OR_EQUAL, parse_less_than_or_equal }, + { EVAL_OPERATOR_NOT_EQUAL, parse_not_equal }, + { EVAL_OPERATOR_EQUAL, parse_equal }, + { EVAL_OPERATOR_LESS, parse_less }, + { EVAL_OPERATOR_GREATER, parse_greater }, + { EVAL_OPERATOR_PLUS, parse_plus }, + { EVAL_OPERATOR_MINUS, parse_minus }, + { EVAL_OPERATOR_MULTIPLY, parse_multiply }, + { EVAL_OPERATOR_DIVIDE, parse_divide }, + { EVAL_OPERATOR_IF_THEN_ELSE, parse_if_then_else }, + + /* we should not put in this list the following: + * + * - NOT + * - ( + * - ) + * + * these are handled in code + */ + + // termination + { EVAL_OPERATOR_NOP, NULL } +}; + +static inline unsigned char parse_operator(const char **string, int *precedence) { + skip_spaces(string); + + int i; + for(i = 0 ; operator_parsers[i].parse != NULL ; i++) + if(operator_parsers[i].parse(string)) { + if(precedence) *precedence = eval_precedence(operator_parsers[i].id); + return operator_parsers[i].id; + } + + return EVAL_OPERATOR_NOP; +} + +// ---------------------------------------------------------------------------- +// memory management + +static inline EVAL_NODE *eval_node_alloc(int count) { + static int id = 1; + + EVAL_NODE *op = callocz(1, sizeof(EVAL_NODE) + (sizeof(EVAL_VALUE) * count)); + + op->id = id++; + op->operator = EVAL_OPERATOR_NOP; + op->precedence = eval_precedence(EVAL_OPERATOR_NOP); + op->count = count; + return op; +} + +static inline void eval_node_set_value_to_node(EVAL_NODE *op, int pos, EVAL_NODE *value) { + if(pos >= op->count) + fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1); + + op->ops[pos].type = EVAL_VALUE_EXPRESSION; + op->ops[pos].expression = value; +} + +static inline void eval_node_set_value_to_constant(EVAL_NODE *op, int pos, calculated_number value) { + if(pos >= op->count) + fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1); + + op->ops[pos].type = EVAL_VALUE_NUMBER; + op->ops[pos].number = value; +} + +static inline void eval_node_set_value_to_variable(EVAL_NODE *op, int pos, const char *variable) { + if(pos >= op->count) + fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1); + + op->ops[pos].type = EVAL_VALUE_VARIABLE; + op->ops[pos].variable = callocz(1, sizeof(EVAL_VARIABLE)); + op->ops[pos].variable->name = strdupz(variable); + op->ops[pos].variable->hash = simple_hash(op->ops[pos].variable->name); +} + +static inline void eval_variable_free(EVAL_VARIABLE *v) { + freez(v->name); + freez(v); +} + +static inline void eval_value_free(EVAL_VALUE *v) { + switch(v->type) { + case EVAL_VALUE_EXPRESSION: + eval_node_free(v->expression); + break; + + case EVAL_VALUE_VARIABLE: + eval_variable_free(v->variable); + break; + + default: + break; + } +} + +static inline void eval_node_free(EVAL_NODE *op) { + if(op->count) { + int i; + for(i = op->count - 1; i >= 0 ;i--) + eval_value_free(&op->ops[i]); + } + + freez(op); +} + +// ---------------------------------------------------------------------------- +// the parsing logic + +// helper function to avoid allocations all over the place +static inline EVAL_NODE *parse_next_operand_given_its_operator(const char **string, unsigned char operator_type, int *error) { + EVAL_NODE *sub = parse_one_full_operand(string, error); + if(!sub) return NULL; + + EVAL_NODE *op = eval_node_alloc(1); + op->operator = operator_type; + eval_node_set_value_to_node(op, 0, sub); + return op; +} + +// parse a full operand, including its sign or other associative operator (e.g. NOT) +static inline EVAL_NODE *parse_one_full_operand(const char **string, int *error) { + char variable_buffer[EVAL_MAX_VARIABLE_NAME_LENGTH + 1]; + EVAL_NODE *op1 = NULL; + calculated_number number; + + *error = EVAL_ERROR_OK; + + skip_spaces(string); + if(!(**string)) { + *error = EVAL_ERROR_MISSING_OPERAND; + return NULL; + } + + if(parse_not(string)) { + op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_NOT, error); + op1->precedence = eval_precedence(EVAL_OPERATOR_NOT); + } + else if(parse_plus(string)) { + op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_SIGN_PLUS, error); + op1->precedence = eval_precedence(EVAL_OPERATOR_SIGN_PLUS); + } + else if(parse_minus(string)) { + op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_SIGN_MINUS, error); + op1->precedence = eval_precedence(EVAL_OPERATOR_SIGN_MINUS); + } + else if(parse_abs(string)) { + op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_ABS, error); + op1->precedence = eval_precedence(EVAL_OPERATOR_ABS); + } + else if(parse_open_subexpression(string)) { + EVAL_NODE *sub = parse_full_expression(string, error); + if(sub) { + op1 = eval_node_alloc(1); + op1->operator = EVAL_OPERATOR_EXPRESSION_OPEN; + op1->precedence = eval_precedence(EVAL_OPERATOR_EXPRESSION_OPEN); + eval_node_set_value_to_node(op1, 0, sub); + if(!parse_close_subexpression(string)) { + *error = EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION; + eval_node_free(op1); + return NULL; + } + } + } + else if(parse_variable(string, variable_buffer, EVAL_MAX_VARIABLE_NAME_LENGTH)) { + op1 = eval_node_alloc(1); + op1->operator = EVAL_OPERATOR_NOP; + eval_node_set_value_to_variable(op1, 0, variable_buffer); + } + else if(parse_constant(string, &number)) { + op1 = eval_node_alloc(1); + op1->operator = EVAL_OPERATOR_NOP; + eval_node_set_value_to_constant(op1, 0, number); + } + else if(**string) + *error = EVAL_ERROR_UNKNOWN_OPERAND; + else + *error = EVAL_ERROR_MISSING_OPERAND; + + return op1; +} + +// parse an operator and the rest of the expression +// precedence processing is handled here +static inline EVAL_NODE *parse_rest_of_expression(const char **string, int *error, EVAL_NODE *op1) { + EVAL_NODE *op2 = NULL; + unsigned char operator; + int precedence; + + operator = parse_operator(string, &precedence); + skip_spaces(string); + + if(operator != EVAL_OPERATOR_NOP) { + op2 = parse_one_full_operand(string, error); + if(!op2) { + // error is already reported + eval_node_free(op1); + return NULL; + } + + EVAL_NODE *op = eval_node_alloc(operators[operator].parameters); + op->operator = operator; + op->precedence = precedence; + + if(operator == EVAL_OPERATOR_IF_THEN_ELSE && op->count == 3) { + skip_spaces(string); + + if(**string != ':') { + eval_node_free(op); + eval_node_free(op1); + eval_node_free(op2); + *error = EVAL_ERROR_IF_THEN_ELSE_MISSING_ELSE; + return NULL; + } + (*string)++; + + skip_spaces(string); + + EVAL_NODE *op3 = parse_one_full_operand(string, error); + if(!op3) { + eval_node_free(op); + eval_node_free(op1); + eval_node_free(op2); + // error is already reported + return NULL; + } + + eval_node_set_value_to_node(op, 2, op3); + } + + eval_node_set_value_to_node(op, 1, op2); + + // precedence processing + // if this operator has a higher precedence compared to its next + // put the next operator on top of us (top = evaluated later) + // function recursion does the rest... + if(op->precedence > op1->precedence && op1->count == 2 && op1->operator != '(' && op1->ops[1].type == EVAL_VALUE_EXPRESSION) { + eval_node_set_value_to_node(op, 0, op1->ops[1].expression); + op1->ops[1].expression = op; + op = op1; + } + else + eval_node_set_value_to_node(op, 0, op1); + + return parse_rest_of_expression(string, error, op); + } + else if(**string == ')') { + ; + } + else if(**string) { + eval_node_free(op1); + op1 = NULL; + *error = EVAL_ERROR_MISSING_OPERATOR; + } + + return op1; +} + +// high level function to parse an expression or a sub-expression +static inline EVAL_NODE *parse_full_expression(const char **string, int *error) { + EVAL_NODE *op1 = NULL; + + op1 = parse_one_full_operand(string, error); + if(!op1) { + *error = EVAL_ERROR_MISSING_OPERAND; + return NULL; + } + + return parse_rest_of_expression(string, error, op1); +} + +// ---------------------------------------------------------------------------- +// public API + +int expression_evaluate(EVAL_EXPRESSION *exp) { + exp->error = EVAL_ERROR_OK; + + buffer_reset(exp->error_msg); + exp->result = eval_node(exp, (EVAL_NODE *)exp->nodes, &exp->error); + + if(exp->error == EVAL_ERROR_OK) + exp->result = eval_check_number(exp->result, &exp->error); + + if(exp->error != EVAL_ERROR_OK) { + exp->result = NAN; + + if(buffer_strlen(exp->error_msg)) + buffer_strcat(exp->error_msg, "; "); + + buffer_sprintf(exp->error_msg, "failed to evaluate expression with error %d (%s)", exp->error, expression_strerror(exp->error)); + return 0; + } + + return 1; +} + +EVAL_EXPRESSION *expression_parse(const char *string, const char **failed_at, int *error) { + const char *s = string; + int err = EVAL_ERROR_OK; + unsigned long pos = 0; + + EVAL_NODE *op = parse_full_expression(&s, &err); + + if(*s) { + if(op) { + eval_node_free(op); + op = NULL; + } + err = EVAL_ERROR_REMAINING_GARBAGE; + } + + if (failed_at) *failed_at = s; + if (error) *error = err; + + if(!op) { + pos = s - string + 1; + error("failed to parse expression '%s': %s at character %lu (i.e.: '%s').", string, expression_strerror(err), pos, s); + return NULL; + } + + BUFFER *out = buffer_create(1024); + print_parsed_as_node(out, op, &err); + if(err != EVAL_ERROR_OK) { + error("failed to re-generate expression '%s' with reason: %s", string, expression_strerror(err)); + eval_node_free(op); + buffer_free(out); + return NULL; + } + + EVAL_EXPRESSION *exp = callocz(1, sizeof(EVAL_EXPRESSION)); + + exp->source = strdupz(string); + exp->parsed_as = strdupz(buffer_tostring(out)); + buffer_free(out); + + exp->error_msg = buffer_create(100); + exp->nodes = (void *)op; + + return exp; +} + +void expression_free(EVAL_EXPRESSION *exp) { + if(!exp) return; + + if(exp->nodes) eval_node_free((EVAL_NODE *)exp->nodes); + freez((void *)exp->source); + freez((void *)exp->parsed_as); + buffer_free(exp->error_msg); + freez(exp); +} + +const char *expression_strerror(int error) { + switch(error) { + case EVAL_ERROR_OK: + return "success"; + + case EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION: + return "missing closing parenthesis"; + + case EVAL_ERROR_UNKNOWN_OPERAND: + return "unknown operand"; + + case EVAL_ERROR_MISSING_OPERAND: + return "expected operand"; + + case EVAL_ERROR_MISSING_OPERATOR: + return "expected operator"; + + case EVAL_ERROR_REMAINING_GARBAGE: + return "remaining characters after expression"; + + case EVAL_ERROR_INVALID_VALUE: + return "invalid value structure - internal error"; + + case EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS: + return "wrong number of operands for operation - internal error"; + + case EVAL_ERROR_VALUE_IS_NAN: + return "value is unset"; + + case EVAL_ERROR_VALUE_IS_INFINITE: + return "computed value is infinite"; + + case EVAL_ERROR_UNKNOWN_VARIABLE: + return "undefined variable"; + + case EVAL_ERROR_IF_THEN_ELSE_MISSING_ELSE: + return "missing second sub-expression of inline conditional"; + + default: + return "unknown error"; + } +} |