r4/expression-parser
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

cleaner interface for defining functions

Browse Source
This commit is contained in:
r4 2021-11-23 17:13:59 +01:00
parent dacf01e83e
commit e3c466e321
1 changed files with 42 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
main.c
View File

@ -54,11 +54,26 @@ enum {
#define IS_FLOAT(c) ((c >= '0' && c <= '9') || c == '.')
#define IS_ALPHA(c) ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))
typedef struct Function {
const char *name;
real (*func)(real *args);
size_t n_args;
} Function;
#define FUNCTIONS_CAP 256
Function functions[FUNCTIONS_CAP];
size_t functions_size = 0;
void push_tok(Tok t) {
if (toks_size+1 < TOKS_CAP)
toks[toks_size++] = t;
}
void add_func(const char *name, real (*func)(real *args), size_t n_args) {
if (functions_size+1 < FUNCTIONS_CAP)
functions[functions_size++] = (Function){.name = name, .func = func, .n_args = n_args};
}
void tokenize(char *expr) {
push_tok((Tok){.kind = TokOp, .Char = '('});
@ -222,22 +237,23 @@ real eval(Tok *t) {
t -= 2;
real outer_res;
if (strcmp(t[1].Str, "sqrt") == 0) {
if (arg_results_size != 1) {
fprintf(stderr, "Error: function sqrt() requires exactly 1 argument\n");
exit(1);
bool func_found = false;
for (size_t i = 0; i < functions_size; i++) {
if (strcmp(t[1].Str, functions[i].name) == 0) {
func_found = true;
if (arg_results_size != functions[i].n_args) {
const char *plural = functions[i].n_args == 1 ? "" : "s";
fprintf(stderr, "Error: function %s() requires exactly 1 argument%s\n", functions[i].name, plural);
exit(1);
}
outer_res = functions[i].func(arg_results);
}
outer_res = sqrt(arg_results[0]);
} else if (strcmp(t[1].Str, "pow") == 0) {
if (arg_results_size != 2) {
fprintf(stderr, "Error: function pow() requires exactly 2 arguments\n");
exit(1);
}
outer_res = pow(arg_results[0], arg_results[1]);
} else {
fprintf(stderr, "Error: unknown function name: %s\n", t[1].Str);
}
if (!func_found) {
fprintf(stderr, "Error: unknown function: %s()\n", t[1].Str);
exit(1);
}
t[1].kind = TokNum;
t[1].Num = outer_res;
}
@ -289,11 +305,24 @@ void cleanup() {
}
}
real fn_sqrt(real *args) { return sqrt(args[0]); }
real fn_pow(real *args) { return pow(args[0], args[1]); }
real fn_mod(real *args) { return fmod(args[0], args[1]); }
real fn_round(real *args) { return round(args[0]); }
real fn_floor(real *args) { return floor(args[0]); }
real fn_ceil(real *args) { return ceil(args[0]); }
int main(int argc, char **argv) {
if (argc != 2 || strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0) {
fprintf(stderr, "Usage: ./exp \"<expression>\"\n");
exit(1);
}
add_func("sqrt", fn_sqrt, 1);
add_func("pow", fn_pow, 2);
add_func("mod", fn_mod, 2);
add_func("round", fn_round, 1);
add_func("floor", fn_floor, 1);
add_func("ceil", fn_ceil, 1);
tokenize(argv[1]);
print_toks();
real res = eval(toks);