70 lines
1.4 KiB
Go
70 lines
1.4 KiB
Go
// Copyright (c) 2024 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 "strings"
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//-------- unset term
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func newUnsetTerm(tk *Token) (inst *term) {
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return &term{
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tk: *tk,
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children: make([]*term, 0, 1),
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position: posPrefix,
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priority: priSign,
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evalFunc: evalUnset,
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}
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}
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func deleteContextItem(ctx ExprContext, opTerm *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.errIncompatibleType(item)
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}
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return
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}
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func evalUnset(ctx ExprContext, opTerm *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 IsList(childValue) {
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list, _ := childValue.(*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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registerTermConstructor(SymKwUnset, newUnsetTerm)
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}
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