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typedef enum {
VAL_VOID,
VAL_INT,
VAL_FLOAT,
VAL_PTR,
VAL_FN,
VAL_BOOL
} ValueKind;
#define VAL_FLAG_FN_NULL 0x01 /* is this function null? */
typedef double FloatVal;
typedef struct Value {
ValueKind kind;
union {
Integer intv;
FloatVal floatv;
struct Value *points_to;
FnExpr *fn;
bool boolv;
};
} Value;
static bool eval_truthiness(Value *v) {
switch (v->kind) {
case VAL_VOID:
assert(0);
return false;
case VAL_INT:
return v->intv != 0;
case VAL_FLOAT:
return v->floatv != 0;
case VAL_PTR:
return v->points_to != NULL;
case VAL_FN:
return v->fn != NULL;
case VAL_BOOL:
return v->boolv;
}
assert(0);
return false;
}
/* NOTE: expr must be typed before it can be evaluated */
static bool eval_expr(Expression *e, Value *v) {
switch (e->kind) {
case EXPR_LITERAL_FLOAT:
v->kind = VAL_FLOAT;
v->floatv = (FloatVal)e->floatl;
return true;
case EXPR_LITERAL_INT:
v->kind = VAL_INT;
if (e->intl > (UInteger)INTEGER_MAX) { /* TODO: FIXME */
err_print(e->where, "Overflow when evaluating integer.");
return false;
}
v->intv = (Integer)e->intl;
return true;
case EXPR_LITERAL_BOOL:
v->kind = VAL_BOOL;
v->boolv = e->booll;
return true;
case EXPR_UNARY_OP: {
Expression *of_expr = e->unary.of;
switch (e->unary.op) {
case UNARY_MINUS: {
Value of;
if (!eval_expr(of_expr, &of)) return false;
assert(e->type.kind != TYPE_BUILTIN);
v->kind = of.kind;
if (v->kind == VAL_INT) {
v->intv = -of.intv;
} else if (v->kind == VAL_FLOAT) {
v->floatv = -of.floatv;
} else {
assert(0);
return false;
}
return true;
}
case UNARY_NOT:
v->kind = VAL_BOOL;
v->boolv = !eval_truthiness(v);
return true;
case UNARY_ADDRESS:
v->kind = VAL_PTR;
v->points_to = err_malloc(sizeof *v->points_to); /* OPTIM */
return eval_expr(e->unary.of, v->points_to);
case UNARY_DEREF: {
Value ptr;
if (!eval_expr(of_expr, &ptr)) return false;
*v = *ptr.points_to;
return true;
} break;
case UNARY_DEL: /* TODO */
assert(0);
break;
}
} break;
case EXPR_BINARY_OP: {
Value lhs, rhs;
/* NOTE: this will need to change for short-circuiting */
if (!eval_expr(e->binary.lhs, &lhs)) return false;
if (!eval_expr(e->binary.rhs, &rhs)) return false;
if (e->type.kind != TYPE_BUILTIN) {
err_print(e->where, "Operators can only be applied to builtin types.");
return false;
}
bool is_int = type_builtin_is_integer(e->type.builtin);
bool is_float = type_builtin_is_floating(e->type.builtin);
bool is_bool = e->type.builtin == BUILTIN_BOOL;
switch (e->binary.op) {
case BINARY_PLUS:
v->kind = lhs.kind;
if (is_int) {
v->intv = lhs.intv + rhs.intv;
} else if (is_float) {
v->floatv = lhs.floatv + rhs.floatv;
} else assert(0);
return true;
case BINARY_MINUS:
v->kind = lhs.kind;
if (is_int) {
v->intv = lhs.intv - rhs.intv;
} else if (is_float) {
v->floatv = lhs.floatv - rhs.floatv;
} else assert(0);
return true;
case BINARY_MUL:
v->kind = lhs.kind;
if (is_int) {
v->intv = lhs.intv * rhs.intv;
} else if (is_float) {
v->floatv = lhs.floatv * rhs.floatv;
} else assert(0);
return true;
case BINARY_DIV:
v->kind = lhs.kind;
/* TODO(eventually): check div by 0 */
if (is_int) {
v->intv = lhs.intv / rhs.intv;
} else if (is_float) {
v->floatv = lhs.floatv / rhs.floatv;
} else assert(0);
return true;
case BINARY_EQ:
v->kind = VAL_BOOL;
if (is_int) {
v->boolv = lhs.intv == rhs.intv;
} else if (is_float) {
v->boolv = lhs.floatv == rhs.floatv;
} else if (is_bool) {
v->boolv = lhs.boolv == rhs.boolv;
} else assert(0);
return true;
case BINARY_NE:
v->kind = VAL_BOOL;
if (is_int) {
v->boolv = lhs.intv != rhs.intv;
} else if (is_float) {
v->boolv = lhs.floatv != rhs.floatv;
} else if (is_bool) {
v->boolv = lhs.boolv != rhs.boolv;
} else assert(0);
return true;
case BINARY_GT:
v->kind = VAL_BOOL;
if (is_int) {
v->boolv = lhs.intv > rhs.intv;
} else if (is_float) {
v->boolv = lhs.floatv > rhs.floatv;
} else assert(0);
return true;
case BINARY_GE:
v->kind = VAL_BOOL;
if (is_int) {
v->boolv = lhs.intv >= rhs.intv;
} else if (is_float) {
v->boolv = lhs.floatv >= rhs.floatv;
} else assert(0);
return true;
case BINARY_LT:
v->kind = VAL_BOOL;
if (is_int) {
v->boolv = lhs.intv < rhs.intv;
} else if (is_float) {
v->boolv = lhs.floatv < rhs.floatv;
} else assert(0);
return true;
case BINARY_LE:
v->kind = VAL_BOOL;
if (is_int) {
v->boolv = lhs.intv <= rhs.intv;
} else if (is_float) {
v->boolv = lhs.floatv <= rhs.floatv;
} else assert(0);
return true;
case BINARY_SET:
v->kind = VAL_VOID;
return true;
case BINARY_COMMA:
err_print(e->where, "tuples not supported at compile time yet.");
return false;
case BINARY_AT_INDEX:
err_print(e->where, "Cannot get index of array at compile time yet.");
return false;
}
} break;
case EXPR_IDENT: {
Identifier id = e->ident;
IdentDecl *id_decl = ident_decl(id);
if (!id_decl) {
char *id_str = ident_to_str(id);
err_print(e->where, "Undeclared identifier: %s", id_str);
free(id_str);
return false;
}
Declaration *d = id_decl->decl;
if (location_after(d->where, e->where)) {
err_print(e->where, "Use of constant before its declaration.");
info_print(d->where, "Declaration will be here.");
return false;
}
if (!(d->flags & DECL_FLAG_CONST)) {
err_print(e->where, "Use of non-constant identifier in a constant expression.");
info_print(d->where, "Declaration was here.");
return false;
}
if (!d->val) {
d->val = err_malloc(sizeof *d->val); /* OPTIM */
if (!eval_expr(&d->expr, d->val))
return false;
}
*v = *d->val;
return true;
} break;
case EXPR_FN:
v->kind = VAL_FN;
v->fn = &e->fn;
return true;
case EXPR_CAST:
case EXPR_IF:
case EXPR_WHILE:
case EXPR_CALL:
case EXPR_BLOCK:
case EXPR_LITERAL_STR:
case EXPR_LITERAL_CHAR:
case EXPR_NEW:{
err_print(e->where, "operation not supported at compile time yet."); /* TODO */
} break;
case EXPR_DIRECT:
switch (e->direct.which) {
case DIRECT_C:
err_print(e->where, "Can't run C code at compile time.");
return false;
case DIRECT_COUNT: assert(0); break;
}
break;
}
err_print(e->where, "Not implemented yet");
return false;
}
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