-
Notifications
You must be signed in to change notification settings - Fork 15
/
expr_nary.go
52 lines (45 loc) · 1.12 KB
/
expr_nary.go
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
package rel
import (
"fmt"
"strings"
"github.com/arr-ai/wbnf/parser"
)
type CompareFunc func(a, b Value) bool
// CompareExpr represents a range of operators.
type CompareExpr struct {
ExprScanner
args []Expr
comps []CompareFunc
ops []string
}
func NewCompareExpr(scanner parser.Scanner, args []Expr, comps []CompareFunc, ops []string) CompareExpr {
return CompareExpr{ExprScanner: ExprScanner{Src: scanner}, args: args, comps: comps, ops: ops}
}
// String returns a string representation of the expression.
func (e CompareExpr) String() string {
var sb strings.Builder
fmt.Fprintf(&sb, "(%v ", e.args[0])
for i, arg := range e.args[1:] {
fmt.Fprintf(&sb, " %s %v", e.ops[i], arg)
}
sb.WriteString(")")
return sb.String()
}
// Eval returns the subject
func (e CompareExpr) Eval(local Scope) (Value, error) {
lhs, err := e.args[0].Eval(local)
if err != nil {
return nil, wrapContext(err, e, local)
}
for i, arg := range e.args[1:] {
rhs, err := arg.Eval(local)
if err != nil {
return nil, wrapContext(err, e, local)
}
if !e.comps[i](lhs, rhs) {
return False, nil
}
lhs = rhs
}
return True, nil
}