114 lines
2.5 KiB
Go
114 lines
2.5 KiB
Go
// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
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// All rights reserved.
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// operator-groupby.go
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package expr
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import (
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"fmt"
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"io"
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"strconv"
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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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//-------- group by term
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func newGroupByTerm(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, 2),
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Position: scan.PosInfix,
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Priority: scan.PriIterOp,
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EvalFunc: evalGroupBy,
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}
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}
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func evalGroupBy(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
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var leftValue, rightValue any
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var it kern.Iterator
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var item any
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var sKey string
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var keyByIndex bool
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var ok bool
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if err = opTerm.CheckOperands(); err != nil {
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return
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}
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if leftValue, err = opTerm.Children[0].Compute(ctx); err != nil {
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return
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}
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if it, ok = leftValue.(kern.Iterator); !ok {
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if it, err = NewIterator(ctx, leftValue, nil); err != nil {
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return nil, fmt.Errorf("left operand of MAP must be an iterable data-source; got %s", kern.TypeName(leftValue))
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}
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}
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rightTk := opTerm.Children[1].Tk
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if rightTk.IsSymbol(scan.SymVariable) && rightTk.Source() == "__" {
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keyByIndex = true
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} else if rightValue, err = opTerm.Children[1].Compute(ctx); err != nil {
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return
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} else if kern.IsString(rightValue) {
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sKey = rightValue.(string)
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} else {
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return nil, fmt.Errorf("right operand of GROUPBY must be a string or identifier '__'; got %s", kern.TypeName(rightValue))
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}
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values := kern.MakeDict()
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for item, err = it.Next(); err == nil; item, err = it.Next() {
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ctx.SetVar("_", item)
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ctx.SetVar("__", it.Index())
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ctx.SetVar("#", it.Count())
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var sItemKey string
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if d, ok := item.(*kern.DictType); ok {
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if keyByIndex || len(sKey) == 0 {
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sItemKey = strconv.Itoa(int(it.Index()))
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} else if d.HasKey(sKey) {
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if keyValue, exists := d.GetItem(sKey); exists {
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if s, ok := keyValue.(string); ok {
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sItemKey = s
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} else {
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sItemKey = fmt.Sprintf("%v", keyValue)
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}
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} else {
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sItemKey = "_"
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}
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} else {
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sItemKey = "_"
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}
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} else {
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sItemKey = strconv.Itoa(int(it.Index()))
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}
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var ls *kern.ListType
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if lsAny, exists := values.GetItem(sItemKey); exists && lsAny != nil {
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ls = lsAny.(*kern.ListType)
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}
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if ls == nil {
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ls = kern.NewListA()
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}
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ls.AppendItem(item)
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values.SetItem(sItemKey, ls)
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ctx.DeleteVar("#")
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ctx.DeleteVar("__")
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ctx.DeleteVar("_")
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}
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if err == io.EOF {
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err = nil
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}
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v = values
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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.SymKwGroupBy, newGroupByTerm)
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}
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