74 lines
1.7 KiB
Go
74 lines
1.7 KiB
Go
// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
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// All rights reserved.
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// operator-pre-inc-dec.go
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package expr
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import (
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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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// -------- pre increment term
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func newPreIncTerm(tk *scan.Token) *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.PriIncDec,
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EvalFunc: evalPreInc,
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}
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}
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func evalPreInc(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
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var childValue any
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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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if kern.IsInteger(childValue) && opTerm.Children[0].Symbol() == scan.SymVariable {
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i := childValue.(int64) + 1
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ctx.SetVar(opTerm.Children[0].Source(), i)
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v = i
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} else {
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err = opTerm.ErrIncompatiblePrefixPostfixType(childValue)
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}
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return
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}
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// -------- pre decrement term
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func newPreDecTerm(tk *scan.Token) *scan.Term {
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return &scan.Term{
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Tk: *tk,
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Parent: nil,
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Children: make([]*scan.Term, 0, 1),
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Position: scan.PosPrefix,
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Priority: scan.PriIncDec,
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EvalFunc: evalPreDec,
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}
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}
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func evalPreDec(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
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var childValue any
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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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if kern.IsInteger(childValue) && opTerm.Children[0].Symbol() == scan.SymVariable {
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i := childValue.(int64) - 1
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ctx.SetVar(opTerm.Children[0].Source(), i)
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v = i
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} else {
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err = opTerm.ErrIncompatiblePrefixPostfixType(childValue)
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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.SymPreInc, newPreIncTerm)
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scan.RegisterTermConstructor(scan.SymPreDec, newPreDecTerm)
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}
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