75 lines
1.6 KiB
Go
75 lines
1.6 KiB
Go
// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
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// All rights reserved.
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// operator-unset.go
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package expr
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import (
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"strings"
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"git.portale-stac.it/go-pkg/expr/kern"
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"git.portale-stac.it/go-pkg/expr/scan"
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)
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//-------- unset term
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func newUnsetTerm(tk *scan.Token) (inst *scan.Term) {
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return &scan.Term{
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Tk: *tk,
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Children: make([]*scan.Term, 0, 1),
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Position: scan.PosPrefix,
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Priority: scan.PriSign,
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EvalFunc: evalUnset,
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}
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}
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func deleteContextItem(ctx kern.ExprContext, opTerm *scan.Term, item any) (deleted bool, err error) {
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if name, ok := item.(string); ok {
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var size int
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if strings.HasSuffix(name, "()") {
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size = ctx.FuncCount()
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ctx.DeleteFunc(strings.TrimRight(name, "()"))
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deleted = ctx.FuncCount() < size
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} else {
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size = ctx.VarCount()
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ctx.DeleteVar(name)
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deleted = ctx.VarCount() < size
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}
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} else {
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err = opTerm.ErrIncompatiblePrefixPostfixType(item)
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}
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return
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}
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func evalUnset(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
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var childValue any
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var deleted bool
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if childValue, err = opTerm.EvalPrefix(ctx); err != nil {
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return
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}
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count := 0
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if kern.IsList(childValue) {
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list, _ := childValue.(*kern.ListType)
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for _, item := range *list {
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if deleted, err = deleteContextItem(ctx, opTerm, item); err != nil {
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break
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} else if deleted {
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count++
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}
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}
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} else if deleted, err = deleteContextItem(ctx, opTerm, childValue); err == nil && deleted {
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count++
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}
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if err == nil {
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v = int64(count)
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}
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return
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}
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// init
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func init() {
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scan.RegisterTermConstructor(scan.SymKwUnset, newUnsetTerm)
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}
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