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

add variables/constants + implicit multiplication

Browse Source
This commit is contained in:
r4 2022-07-26 13:29:00 +02:00
parent fca5950f6c
commit f9352abf06
1 changed files with 109 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

146
main.c
View File

@ -9,9 +9,10 @@ typedef double real;
typedef struct Tok { typedef struct Tok {
enum { enum {
TokNull,
TokOp, TokOp,
TokNum, TokNum,
TokFunc, TokIdent,
} kind; } kind;
union { union {
@ -54,6 +55,35 @@ static enum {
#define IS_FLOAT(c) ((c >= '0' && c <= '9') || c == '.') #define IS_FLOAT(c) ((c >= '0' && c <= '9') || c == '.')
#define IS_ALPHA(c) ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) #define IS_ALPHA(c) ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))
typedef struct Var {
const char *name;
real val;
} Var;
#define VARS_CAP 256
static Var vars[VARS_CAP];
static size_t vars_size = 0;
static void set_var(const char *name, real val) {
for (size_t i = 0; i < vars_size; i++) {
if (strcmp(vars[i].name, name) == 0) {
vars[i].val = val;
return;
}
}
vars[vars_size++] = (Var){.name = name, .val = val};
}
static void unset_var(const char *name) {
for (size_t i = 0; i < vars_size; i++) {
if (strcmp(vars[i].name, name) == 0) {
memmove(vars + i, vars + i + 1, sizeof(Var) * (vars_size - (i + 1)));
vars_size--;
return;
}
}
}
typedef struct Function { typedef struct Function {
const char *name; const char *name;
real (*func)(real *args); real (*func)(real *args);
@ -79,8 +109,15 @@ static void tokenize(char *expr) {
size_t paren_depth = 0; size_t paren_depth = 0;
Tok last;
char *curr = expr; char *curr = expr;
for (char c = *curr; c != 0; c = *(++curr)) { for (char c = *curr; c != 0; c = *(++curr)) {
if (toks_size > 0)
last = toks[toks_size-1];
else
last = (Tok){.kind = TokNull};
if (c == ' ') if (c == ' ')
continue; continue;
@ -97,6 +134,9 @@ static void tokenize(char *expr) {
real num = strtod(buf, NULL); real num = strtod(buf, NULL);
if (last.kind == TokIdent || (last.kind == TokOp && last.Char == ')') || last.kind == TokNum)
push_tok((Tok){.kind = TokOp, .Char = '*'});
push_tok((Tok){.kind = TokNum, .Num = num}); push_tok((Tok){.kind = TokNum, .Num = num});
continue; continue;
} }
@ -112,7 +152,10 @@ static void tokenize(char *expr) {
curr += i - 1; curr += i - 1;
buf[i++] = 0; buf[i++] = 0;
push_tok((Tok){.kind = TokFunc, .Str = buf}); if (last.kind == TokIdent || (last.kind == TokOp && last.Char == ')') || last.kind == TokNum)
push_tok((Tok){.kind = TokOp, .Char = '*'});
push_tok((Tok){.kind = TokIdent, .Str = buf});
continue; continue;
} }
@ -135,6 +178,8 @@ static void tokenize(char *expr) {
case '*': case '*':
case '/': case '/':
case '^': { case '^': {
if (c == '(' && ((last.kind == TokOp && last.Char == ')') || last.kind == TokNum))
push_tok((Tok){.kind = TokOp, .Char = '*'});
push_tok((Tok){.kind = TokOp, .Char = c}); push_tok((Tok){.kind = TokOp, .Char = c});
break; break;
} }
@ -165,7 +210,7 @@ static void print_toks() {
case TokNum: case TokNum:
printf("%.2f ", toks[i].Num); printf("%.2f ", toks[i].Num);
break; break;
case TokFunc: case TokIdent:
printf("%s ", toks[i].Str); printf("%s ", toks[i].Str);
break; break;
default: default:
@ -182,42 +227,35 @@ static void del_toks(Tok *begin, Tok *end) {
toks_size -= end - begin; toks_size -= end - begin;
} }
static real eval(Tok *t) { static real eval(Tok *t);
if (!(t[0].kind == TokOp && OP_PREC(t[0].Char) == 0)) {
fprintf(stderr, "Error: expected delimiter at beginning of expression\n"); static void collapse(Tok *t) {
exit(1); /* Collapse factor. */
if (t[1].kind == TokOp && t[1].Char == '-') {
collapse(t + 1);
if (t[2].kind != TokNum) {
fprintf(stderr, "Error: uncollapsable expression after minus factor\n");
exit(1);
}
t[2].Num *= -1.0;
del_toks(t + 1, t + 2);
} }
while (1) { /* Collapse parentheses. */
/* Collapse factor. */ if (t[1].kind == TokOp && t[1].Char == '(') {
if (t[1].kind == TokOp && t[1].Char == '-') { real res = eval(t + 1);
if (t[2].kind != TokNum) { size_t i;
fprintf(stderr, "Error: expected number token after minus factor\n"); for (i = 2; !(t[i].kind == TokOp && OP_PREC(t[i].Char) == 0); i++);
exit(1); del_toks(t + 2, t + i + 1);
} /* Put the newly evaluated value into place. */
t[2].Num *= -1.0; t[1].kind = TokNum;
del_toks(t + 1, t + 2); t[1].Num = res;
} }
/* Collapse parentheses. */
if (t[1].kind == TokOp && t[1].Char == '(') {
real res = eval(t + 1);
size_t i;
for (i = 2; !(t[i].kind == TokOp && OP_PREC(t[i].Char) == 0); i++);
del_toks(t + 2, t + i + 1);
/* Put the newly evaluated value into place. */
t[1].kind = TokNum;
t[1].Num = res;
}
/* Collapse function. */ if (t[1].kind == TokIdent) {
if (t[1].kind == TokFunc) { if (t + 2 < toks + toks_size && (t[2].kind == TokOp && t[2].Char == '(')) {
if (t + 2 >= toks + toks_size || !(t[2].kind == TokOp && t[2].Char == '(')) { /* Collapse function. */
fprintf(stderr, "Error: expected '(' token after function\n");
exit(1);
}
real arg_results[16]; real arg_results[16];
size_t arg_results_size = 0; size_t arg_results_size = 0;
@ -257,8 +295,35 @@ static real eval(Tok *t) {
t[1].kind = TokNum; t[1].kind = TokNum;
t[1].Num = outer_res; t[1].Num = outer_res;
} else {
/* Collapse variable. */
real res;
bool found = false;
for (size_t i = 0; i < vars_size; i++) {
if (strcmp(t[1].Str, vars[i].name) == 0) {
found = true;
res = vars[i].val;
}
}
if (!found) {
fprintf(stderr, "Error: unknown variable: %s\n", t[1].Str);
exit(1);
}
t[1].kind = TokNum;
t[1].Num = res;
} }
}
}
static real eval(Tok *t) {
if (!(t[0].kind == TokOp && OP_PREC(t[0].Char) == 0)) {
fprintf(stderr, "Error: expected delimiter at beginning of expression\n");
exit(1);
}
while (1) {
collapse(t);
if (!(t[0].kind == TokOp && t[1].kind == TokNum && t[2].kind == TokOp)) { if (!(t[0].kind == TokOp && t[1].kind == TokNum && t[2].kind == TokOp)) {
fprintf(stderr, "Error: invalid token order\n"); fprintf(stderr, "Error: invalid token order\n");
exit(1); exit(1);
@ -301,7 +366,7 @@ static real eval(Tok *t) {
static void cleanup() { static void cleanup() {
for (size_t i = 0; i < toks_size; i++) { for (size_t i = 0; i < toks_size; i++) {
if (toks[i].kind == TokFunc) if (toks[i].kind == TokIdent)
free(toks[i].Str); free(toks[i].Str);
} }
} }
@ -312,6 +377,8 @@ static real fn_mod(real *args) { return fmod(args[0], args[1]); }
static real fn_round(real *args) { return round(args[0]); } static real fn_round(real *args) { return round(args[0]); }
static real fn_floor(real *args) { return floor(args[0]); } static real fn_floor(real *args) { return floor(args[0]); }
static real fn_ceil(real *args) { return ceil(args[0]); } static real fn_ceil(real *args) { return ceil(args[0]); }
static real fn_sin(real *args) { return sin(args[0]); }
static real fn_cos(real *args) { return cos(args[0]); }
int main(int argc, char **argv) { int main(int argc, char **argv) {
if (argc != 2 || strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0) { if (argc != 2 || strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0) {
@ -324,6 +391,11 @@ int main(int argc, char **argv) {
add_func("round", fn_round, 1); add_func("round", fn_round, 1);
add_func("floor", fn_floor, 1); add_func("floor", fn_floor, 1);
add_func("ceil", fn_ceil, 1); add_func("ceil", fn_ceil, 1);
add_func("sin", fn_sin, 1);
add_func("cos", fn_cos, 1);
unset_var("x");
set_var("pi", M_PI);
set_var("e", M_E);
tokenize(argv[1]); tokenize(argv[1]);
print_toks(); print_toks();
real res = eval(toks); real res = eval(toks);