blob: 4226078b815521e5df5287c6345a1a3a8dcd7d8d (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
|
#pragma once
#include "error.hpp"
#include "../lexer/token.hpp"
#include "../lexer/token_type.hpp"
namespace math::server::parser {
class BinaryOp {
public:
using Token = lexer::Token;
using Type = Token::Type;
static bool is(const Token& token) {
switch (token.get_type()) {
case Type::PLUS:
case Type::MINUS:
case Type::ASTERISK:
case Type::SLASH:
return true;
default:
return false;
}
}
static BinaryOp from_token(const Token& token) {
if (!is(token)) {
throw ParserError{"internal: token is not a binary operator"};
}
return BinaryOp{token};
}
static constexpr unsigned min_precedence() { return 0; }
unsigned get_precedence() const {
switch (m_type) {
case Type::PLUS:
case Type::MINUS:
return min_precedence();
case Type::ASTERISK:
case Type::SLASH:
return min_precedence() + 1;
default:
throw ParserError{"internal: undefined operator precedence"};
}
}
double exec(double lhs, double rhs) const {
switch (m_type) {
case Type::PLUS:
return lhs + rhs;
case Type::MINUS:
return lhs - rhs;
case Type::ASTERISK:
return lhs * rhs;
case Type::SLASH:
// Trapping the CPU would be better?
if (rhs == 0.) {
throw ParserError{"division by zero"};
}
return lhs / rhs;
default:
throw ParserError{"internal: unsupported operator"};
}
}
private:
explicit BinaryOp(const Token& token)
: m_type{token.get_type()}
{ }
Type m_type;
};
}
|
