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tinyexpr: Make te_expr a class

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Removes some #define weirdness.
This commit is contained in:
Fabian Homborg 2018-11-04 13:13:03 +01:00
parent b8697e7795
commit 2e11e6c692
1 changed files with 78 additions and 124 deletions
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202
src/tinyexpr.cpp
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@ -33,6 +33,7 @@
#include <algorithm>
#include <iterator>
#include <utility>
#include <vector>
// TODO: It would be nice not to rely on a typedef for this, especially one that can only do functions with two args.
typedef double (*te_fun2)(double, double);
@ -46,18 +47,32 @@ enum {
TOK_OPEN, TOK_CLOSE, TOK_NUMBER, TOK_INFIX
};
int get_arity(const int type) {
if (type == TE_FUNCTION3) return 3;
if (type == TE_FUNCTION2) return 2;
if (type == TE_FUNCTION1) return 1;
return 0;
}
typedef struct te_expr {
class te_expr {
public:
int type;
union {double value; const void *function;};
te_expr *parameters[1];
} te_expr;
double value;
const void *function;
int arity = 0;
std::vector<te_expr> parameters;
te_expr(int t, const void *fun, te_expr *params) : type(t), value(0), function(fun)
{
// We fill in the arity automatically, because we need it here anyway.
switch (t) {
case TE_FUNCTION0: arity = 0; break;
case TE_FUNCTION1: arity = 1; break;
case TE_FUNCTION2: arity = 2; break;
case TE_FUNCTION3: arity = 3; break;
default: arity = 0;
}
// We allow filling the parameters later.
if (params) {
for (int i = 0; i < arity; i++) parameters.push_back(params[i]);
}
}
te_expr(int t, double val) : type(t), value(val), function(NULL) {}
};
// TODO: Rename since variables have been removed.
typedef struct te_builtin {
@ -77,51 +92,10 @@ typedef struct state {
/* Parses the input expression and binds variables. */
/* Returns NULL on error. */
te_expr *te_compile(const char *expression, te_error_t *error);
te_expr te_compile(const char *expression, te_error_t *error);
/* Evaluates the expression. */
double te_eval(const te_expr *n);
/* Frees the expression. */
/* This is safe to call on NULL pointers. */
void te_free(te_expr *n);
// TODO: That move there? Ouch. Replace with a proper class with a constructor.
#define NEW_EXPR(type, ...) new_expr((type), std::move((const te_expr*[]){__VA_ARGS__}))
static te_expr *new_expr(const int type, const te_expr *parameters[]) {
const int arity = get_arity(type);
const int psize = sizeof(te_expr*) * arity;
const int size = (sizeof(te_expr) - sizeof(void*)) + psize;
te_expr *ret = (te_expr *)malloc(size);
// This sets float to 0, which depends on the implementation.
// We rely on IEEE-754 floats anyway, so it's okay.
memset(ret, 0, size);
if (arity && parameters) {
memcpy(ret->parameters, parameters, psize);
}
ret->type = type;
return ret;
}
void te_free_parameters(te_expr *n) {
if (!n) return;
int arity = get_arity(n->type);
// Free all parameters from the back to the front.
while (arity > 0) {
te_free(n->parameters[arity - 1]);
arity--;
}
}
void te_free(te_expr *n) {
if (!n) return;
te_free_parameters(n);
free(n);
}
double te_eval(const te_expr &n);
static double pi() {return 3.14159265358979323846;}
static double e() {return 2.71828182845904523536;}
@ -261,24 +235,21 @@ void next_token(state *s) {
}
static te_expr *expr(state *s);
static te_expr *power(state *s);
static te_expr expr(state *s);
static te_expr power(state *s);
static te_expr *base(state *s) {
static te_expr base(state *s) {
/* <base> = <constant> | <variable> | <function-0> {"(" ")"} | <function-1> <power> | <function-X> "(" <expr> {"," <expr>} ")" | "(" <list> ")" */
te_expr *ret;
int arity;
te_expr ret(0, NULL, NULL);
switch (s->type) {
case TOK_NUMBER:
ret = new_expr(TE_CONSTANT, 0);
ret->value = s->value;
ret = te_expr(TE_CONSTANT, s->value);
next_token(s);
break;
case TE_FUNCTION0:
ret = new_expr(s->type, 0);
ret->function = s->function;
ret = te_expr(s->type, s->function, NULL);
next_token(s);
if (s->type == TOK_OPEN) {
next_token(s);
@ -294,27 +265,24 @@ static te_expr *base(state *s) {
case TE_FUNCTION1:
case TE_FUNCTION2: case TE_FUNCTION3:
arity = get_arity(s->type);
ret = new_expr(s->type, 0);
ret->function = s->function;
ret = te_expr(s->type, s->function, NULL);
next_token(s);
if (s->type == TOK_OPEN) {
int i;
for(i = 0; i < arity; i++) {
for(i = 0; i < ret.arity; i++) {
next_token(s);
ret->parameters[i] = expr(s);
ret.parameters.push_back(expr(s));
if(s->type != TOK_SEP) {
break;
}
}
if(s->type == TOK_CLOSE && i == arity - 1) {
if(s->type == TOK_CLOSE && i == ret.arity - 1) {
next_token(s);
} else if (s->type != TOK_ERROR
|| s->error == TE_ERROR_UNKNOWN) {
s->type = TOK_ERROR;
s->error = i < arity ? TE_ERROR_TOO_FEW_ARGS
s->error = i < ret.arity ? TE_ERROR_TOO_FEW_ARGS
: TE_ERROR_TOO_MANY_ARGS;
}
} else if (s->type != TOK_ERROR
@ -343,16 +311,14 @@ static te_expr *base(state *s) {
// This means we have too few things.
// Instead of introducing another error, just call it
// "too few args".
ret = new_expr(0, 0);
ret = te_expr(TE_CONSTANT, NAN);
s->type = TOK_ERROR;
s->error = TE_ERROR_TOO_FEW_ARGS;
ret->value = NAN;
break;
default:
ret = new_expr(0, 0);
ret = te_expr(TE_CONSTANT, NAN);
s->type = TOK_ERROR;
s->error = TE_ERROR_UNKNOWN;
ret->value = NAN;
break;
}
@ -360,7 +326,7 @@ static te_expr *base(state *s) {
}
static te_expr *power(state *s) {
static te_expr power(state *s) {
/* <power> = {("-" | "+")} <base> */
int sign = 1;
while (s->type == TOK_INFIX && (s->function == add || s->function == sub)) {
@ -368,72 +334,70 @@ static te_expr *power(state *s) {
next_token(s);
}
te_expr *ret;
if (sign == 1) {
ret = base(s);
te_expr ret = base(s);
return ret;
} else {
ret = NEW_EXPR(TE_FUNCTION1, base(s));
ret->function = (const void *) negate;
te_expr params[1] = { base(s) };
te_expr ret = te_expr(TE_FUNCTION1, (const void *) negate, params);
return ret;
}
return ret;
}
static te_expr *factor(state *s) {
static te_expr factor(state *s) {
/* <factor> = <power> {"^" <power>} */
te_expr *ret = power(s);
te_expr ret = power(s);
while (s->type == TOK_INFIX && (s->function == (const void*)(te_fun2)pow)) {
te_fun2 t = (te_fun2) s->function;
next_token(s);
ret = NEW_EXPR(TE_FUNCTION2, ret, power(s));
ret->function = (const void *) t;
te_expr param[2] = { ret, power(s) };
ret = te_expr(TE_FUNCTION2, (const void *) t, param);
}
return ret;
}
static te_expr *term(state *s) {
static te_expr term(state *s) {
/* <term> = <factor> {("*" | "/" | "%") <factor>} */
te_expr *ret = factor(s);
te_expr ret = factor(s);
while (s->type == TOK_INFIX && (s->function == (const void*)(te_fun2)mul || s->function == (const void*)(te_fun2)divide || s->function == (const void*)(te_fun2)fmod)) {
te_fun2 t = (te_fun2) s->function;
next_token(s);
ret = NEW_EXPR(TE_FUNCTION2, ret, factor(s));
ret->function = (const void *) t;
te_expr params[2] = { ret, factor(s) };
ret = te_expr(TE_FUNCTION2, (const void *) t, params);
}
return ret;
}
static te_expr *expr(state *s) {
static te_expr expr(state *s) {
/* <expr> = <term> {("+" | "-") <term>} */
te_expr *ret = term(s);
te_expr ret = term(s);
while (s->type == TOK_INFIX && (s->function == add || s->function == sub)) {
te_fun2 t = (te_fun2) s->function;
next_token(s);
ret = NEW_EXPR(TE_FUNCTION2, ret, term(s));
ret->function = (const void *) t;
te_expr params[2] = { ret, term(s) };
ret = te_expr(TE_FUNCTION2, (const void *) t, params);
}
return ret;
}
#define TE_FUN(...) ((double(*)(__VA_ARGS__))n->function)
#define M(e) te_eval(n->parameters[e])
#define TE_FUN(...) ((double(*)(__VA_ARGS__))n.function)
#define M(e) te_eval(n.parameters[e])
double te_eval(const te_expr *n) {
if (!n) return NAN;
switch(n->type) {
case TE_CONSTANT: return n->value;
double te_eval(const te_expr &n) {
switch(n.type) {
case TE_CONSTANT:
return n.value;
case TE_FUNCTION0:
return TE_FUN(void)();
case TE_FUNCTION1:
@ -444,43 +408,39 @@ double te_eval(const te_expr *n) {
return TE_FUN(double, double, double)(M(0), M(1), M(2));
default: return NAN;
}
}
#undef TE_FUN
#undef M
static void optimize(te_expr *n) {
static void optimize(te_expr &n) {
/* Evaluates as much as possible. */
if (n->type == TE_CONSTANT) return;
if (n.type == TE_CONSTANT) return;
const int arity = get_arity(n->type);
bool known = true;
for (int i = 0; i < arity; ++i) {
optimize(n->parameters[i]);
if ((n->parameters[i])->type != TE_CONSTANT) {
for (int i = 0; i < n.arity; ++i) {
optimize(n.parameters[i]);
if ((n.parameters[i]).type != TE_CONSTANT) {
known = false;
}
}
if (known) {
const double value = te_eval(n);
te_free_parameters(n);
n->type = TE_CONSTANT;
n->value = value;
n.type = TE_CONSTANT;
n.value = value;
}
}
te_expr *te_compile(const char *expression, te_error_t *error) {
te_expr te_compile(const char *expression, te_error_t *error) {
state s;
s.start = s.next = expression;
s.error = TE_ERROR_NONE;
next_token(&s);
te_expr *root = expr(&s);
te_expr root = expr(&s);
if (s.type != TOK_END) {
te_free(root);
if (error) {
error->position = (s.next - s.start) + 1;
if (s.error != TE_ERROR_NONE) {
@ -495,22 +455,16 @@ te_expr *te_compile(const char *expression, te_error_t *error) {
error->type = TE_ERROR_TOO_MANY_ARGS;
}
}
return 0;
} else {
optimize(root);
if (error) error->position = 0;
return root;
}
return root;
}
double te_interp(const char *expression, te_error_t *error) {
te_expr *n = te_compile(expression, error);
te_expr n = te_compile(expression, error);
double ret;
if (n) {
ret = te_eval(n);
te_free(n);
} else {
ret = NAN;
}
ret = te_eval(n);
return ret;
}