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Expr filtering: conversions and other fixes.

This commit is contained in:
antirez 2025-02-19 13:06:55 +01:00
parent a90d2ea290
commit af6fa6f732
1 changed files with 48 additions and 28 deletions
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76
expr.c
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@ -10,6 +10,7 @@
#include <stdlib.h> #include <stdlib.h>
#include <ctype.h> #include <ctype.h>
#include <math.h> #include <math.h>
#include "cJSON.h"
#define EXPR_TOKEN_EOF 0 #define EXPR_TOKEN_EOF 0
#define EXPR_TOKEN_NUM 1 #define EXPR_TOKEN_NUM 1
@ -173,6 +174,14 @@ void exprStackFree(exprstack *stack) {
free(stack->items); free(stack->items);
} }
/* Just reset the stack removing all the items, but leaving it in a state
* that makes it still usable for new elements. */
void exprStackReset(exprstack *stack) {
for (int j = 0; j < stack->numitems; j++)
exprFreeToken(stack->items[j]);
stack->numitems = 0;
}
/* =========================== Expression compilation ======================= */ /* =========================== Expression compilation ======================= */
void exprConsumeSpaces(exprstate *es) { void exprConsumeSpaces(exprstate *es) {
@ -553,21 +562,31 @@ exprstate *exprCompile(char *expr, int *errpos) {
/* Convert a token to its numeric value. For strings we attempt to parse them /* Convert a token to its numeric value. For strings we attempt to parse them
* as numbers, returning 0 if conversion fails. */ * as numbers, returning 0 if conversion fails. */
double exprTokenToNum(exprtoken *t) { double exprTokenToNum(exprtoken *t) {
char buf[128];
if (t->token_type == EXPR_TOKEN_NUM) { if (t->token_type == EXPR_TOKEN_NUM) {
return t->num; return t->num;
} else if (t->token_type == EXPR_TOKEN_STR) { } else if (t->token_type == EXPR_TOKEN_STR && t->str.len < sizeof(buf)) {
char *str = malloc(t->str.len + 1); memcpy(buf, t->str.start, t->str.len);
memcpy(str, t->str.start, t->str.len); buf[t->str.len] = '\0';
str[t->str.len] = '\0';
char *endptr; char *endptr;
double val = strtod(str, &endptr); double val = strtod(buf, &endptr);
free(str);
return *endptr == '\0' ? val : 0; return *endptr == '\0' ? val : 0;
} else { } else {
return 0; return 0;
} }
} }
/* Conver obejct to true/false (0 or 1) */
double exprTokenToBool(exprtoken *t) {
if (t->token_type == EXPR_TOKEN_NUM) {
return t->num != 0;
} else if (t->token_type == EXPR_TOKEN_STR && t->str.len == 0) {
return 0; // Empty string are false, like in Javascript.
} else {
return 1; // Every non numerical type is true.
}
}
/* Compare two tokens. Returns true if they are equal. */ /* Compare two tokens. Returns true if they are equal. */
int exprTokensEqual(exprtoken *a, exprtoken *b) { int exprTokensEqual(exprtoken *a, exprtoken *b) {
// If both are strings, do string comparison. // If both are strings, do string comparison.
@ -587,9 +606,9 @@ int exprTokensEqual(exprtoken *a, exprtoken *b) {
/* Execute the compiled expression program. Returns 1 if the final stack value /* Execute the compiled expression program. Returns 1 if the final stack value
* evaluates to true, 0 otherwise. Also returns 0 if any selector callback fails. */ * evaluates to true, 0 otherwise. Also returns 0 if any selector callback fails. */
int exprRun(exprstate *es, int (*get_attrib_callback)(void *privdata, char *attrname, size_t attrnamelen, exprtoken *token), void *privdata) { int exprRun(exprstate *es, char *json, size_t json_len) {
// Reset the values stack. exprStackReset(&es->values_stack);
es->values_stack.numitems = 0; cJSON *parsed_json = NULL;
// Execute each instruction in the program. // Execute each instruction in the program.
for (int i = 0; i < es->program.numitems; i++) { for (int i = 0; i < es->program.numitems; i++) {
@ -598,14 +617,17 @@ int exprRun(exprstate *es, int (*get_attrib_callback)(void *privdata, char *attr
// Handle selectors by calling the callback. // Handle selectors by calling the callback.
if (t->token_type == EXPR_TOKEN_SELECTOR) { if (t->token_type == EXPR_TOKEN_SELECTOR) {
exprtoken *result = malloc(sizeof(exprtoken)); exprtoken *result = malloc(sizeof(exprtoken));
if (result != NULL && if (result != NULL && json != NULL) {
get_attrib_callback(privdata, t->str.start, t->str.len, result)) if (parsed_json == NULL)
{ parsed_json = cJSON_ParseWithLength(json,json_len);
exprStackPush(&es->values_stack, result); if (parsed_json) {
continue; exprStackPush(&es->values_stack, result);
continue;
}
} }
exprFreeToken(result); exprFreeToken(result);
return 0; // Selector not found, expression fails. if (parsed_json) cJSON_Delete(parsed_json);
return 0; // Selector not found or OOM: expression fails.
} }
// Push non-operator values directly onto the stack. // Push non-operator values directly onto the stack.
@ -629,7 +651,7 @@ int exprRun(exprstate *es, int (*get_attrib_callback)(void *privdata, char *attr
switch(t->opcode) { switch(t->opcode) {
case EXPR_OP_NOT: case EXPR_OP_NOT:
result->num = exprTokenToNum(b) == 0 ? 1 : 0; result->num = exprTokenToBool(b) == 0 ? 1 : 0;
break; break;
case EXPR_OP_POW: { case EXPR_OP_POW: {
double base = exprTokenToNum(a); double base = exprTokenToNum(a);
@ -688,11 +710,11 @@ int exprRun(exprstate *es, int (*get_attrib_callback)(void *privdata, char *attr
} }
case EXPR_OP_AND: case EXPR_OP_AND:
result->num = result->num =
exprTokenToNum(a) != 0 && exprTokenToNum(b) != 0 ? 1 : 0; exprTokenToBool(a) != 0 && exprTokenToBool(b) != 0 ? 1 : 0;
break; break;
case EXPR_OP_OR: case EXPR_OP_OR:
result->num = result->num =
exprTokenToNum(a) != 0 || exprTokenToNum(b) != 0 ? 1 : 0; exprTokenToBool(a) != 0 || exprTokenToBool(b) != 0 ? 1 : 0;
break; break;
default: default:
// Do nothing: we don't want runtime errors. // Do nothing: we don't want runtime errors.
@ -705,19 +727,14 @@ int exprRun(exprstate *es, int (*get_attrib_callback)(void *privdata, char *attr
exprStackPush(&es->values_stack, result); exprStackPush(&es->values_stack, result);
} }
if (parsed_json) cJSON_Delete(parsed_json);
// Get final result from stack. // Get final result from stack.
exprtoken *final = exprStackPop(&es->values_stack); exprtoken *final = exprStackPop(&es->values_stack);
if (final == NULL) return 0; if (final == NULL) return 0;
// Convert result to boolean. // Convert result to boolean.
int retval; int retval = exprTokenToBool(final);
if (final->token_type == EXPR_TOKEN_NUM) {
printf("FINAL %f\n", final->num);
retval = final->num != 0;
} else {
retval = 1; // Non-numeric types evaluate to true.
}
exprFreeToken(final); exprFreeToken(final);
return retval; return retval;
} }
@ -765,7 +782,9 @@ void exprPrintStack(exprstack *stack, const char *name) {
int main(int argc, char **argv) { int main(int argc, char **argv) {
char *testexpr = "(5+2)*3 and 'foo'"; char *testexpr = "(5+2)*3 and 'foo'";
char *testjson = "{\"year\": 1984, \"name\": \"The Matrix\"}";
if (argc >= 2) testexpr = argv[1]; if (argc >= 2) testexpr = argv[1];
if (argc >= 3) testjson = argv[2];
printf("Compiling expression: %s\n", testexpr); printf("Compiling expression: %s\n", testexpr);
@ -778,8 +797,9 @@ int main(int argc, char **argv) {
exprPrintStack(&es->tokens, "Tokens"); exprPrintStack(&es->tokens, "Tokens");
exprPrintStack(&es->program, "Program"); exprPrintStack(&es->program, "Program");
int result = exprRun(es,NULL,NULL); printf("Running against object: %s\n", testjson);
printf("Result: %d\n", result); int result = exprRun(es,testjson,strlen(testjson));
printf("Result: %s\n", result ? "True" : "False");
exprFree(es); exprFree(es);
return 0; return 0;
} }