83 lines
1.7 KiB
Go
83 lines
1.7 KiB
Go
// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
|
|
// All rights reserved.
|
|
|
|
// operator-range.go
|
|
package expr
|
|
|
|
import "fmt"
|
|
|
|
// -------- range term
|
|
type intPair struct {
|
|
a, b int
|
|
}
|
|
|
|
func (p *intPair) TypeName() string {
|
|
return TypePair
|
|
}
|
|
|
|
func (p *intPair) ToString(opt FmtOpt) string {
|
|
return fmt.Sprintf("(%d, %d)", p.a, p.b)
|
|
}
|
|
|
|
func isIntPair(v any) bool {
|
|
_, ok := v.(*intPair)
|
|
return ok
|
|
}
|
|
|
|
func newRangeTerm(tk *Token) (inst *term) {
|
|
return &term{
|
|
tk: *tk,
|
|
children: make([]*term, 0, 2),
|
|
position: posInfix,
|
|
priority: priRange,
|
|
evalFunc: evalRange,
|
|
}
|
|
}
|
|
|
|
func changeColonToRange(t *term) {
|
|
if t.tk.IsSymbol(SymColon) {
|
|
t.tk.Sym = SymRange
|
|
t.evalFunc = evalRange
|
|
}
|
|
}
|
|
|
|
func evalRange(ctx ExprContext, opTerm *term) (v any, err error) {
|
|
var leftValue, rightValue any
|
|
|
|
if len(opTerm.children) == 0 {
|
|
leftValue = int64(0)
|
|
rightValue = int64(-1)
|
|
} else if len(opTerm.children) == 1 {
|
|
if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
|
|
return
|
|
}
|
|
rightValue = int64(ConstLastIndex)
|
|
} else if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
|
|
return
|
|
}
|
|
if !(IsInteger(leftValue) && IsInteger(rightValue)) {
|
|
// err = opTerm.errIncompatibleTypes(leftValue, rightValue)
|
|
err = errRangeInvalidSpecification(opTerm)
|
|
return
|
|
}
|
|
|
|
startIndex, _ := leftValue.(int64)
|
|
endIndex, _ := rightValue.(int64)
|
|
|
|
v = &intPair{int(startIndex), int(endIndex)}
|
|
return
|
|
}
|
|
|
|
func errRangeInvalidSpecification(t *term) error {
|
|
return t.Errorf("invalid range specification")
|
|
}
|
|
|
|
func errRangeUnexpectedExpression(t *term) error {
|
|
return t.Errorf("unexpected range expression")
|
|
}
|
|
|
|
// init
|
|
func init() {
|
|
registerTermConstructor(SymRange, newRangeTerm)
|
|
}
|