70 lines
1.4 KiB
Go
70 lines
1.4 KiB
Go
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// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
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// All rights reserved.
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// operator-range.go
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package expr
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import "fmt"
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// -------- range term
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type intPair struct {
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a, b int
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}
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func (p *intPair) TypeName() string {
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return typePair
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}
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func (p *intPair) ToString(opt FmtOpt) string {
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return fmt.Sprintf("(%d, %d)", p.a, p.b)
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}
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func isIntPair(v any) bool {
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_, ok := v.(*intPair)
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return ok
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}
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func newRangeTerm(tk *Token) (inst *term) {
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return &term{
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tk: *tk,
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children: make([]*term, 0, 2),
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position: posInfix,
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priority: priDot,
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evalFunc: evalRange,
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}
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}
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func evalRange(ctx ExprContext, self *term) (v any, err error) {
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var leftValue, rightValue any
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// if err = self.checkOperands(); err != nil {
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// return
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// }
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if len(self.children) == 0 {
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leftValue = int64(0)
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rightValue = int64(-1)
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} else if len(self.children) == 1 {
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if leftValue, err = self.children[0].compute(ctx); err != nil {
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return
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}
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rightValue = int64(-1)
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} else if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
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return
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}
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if !(IsInteger(leftValue) && IsInteger(rightValue)) {
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err = self.errIncompatibleTypes(leftValue, rightValue)
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return
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}
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startIndex, _ := leftValue.(int64)
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endIndex, _ := rightValue.(int64)
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v = &intPair{int(startIndex), int(endIndex)}
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return
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}
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// init
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func init() {
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registerTermConstructor(SymColon, newRangeTerm)
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}
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