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104 lines
2.5 KiB
Go
104 lines
2.5 KiB
Go
package transformers
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import (
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"fmt"
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"os"
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"strings"
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"github.com/johnkerl/miller/v6/pkg/cli"
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"github.com/johnkerl/miller/v6/pkg/types"
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)
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// ----------------------------------------------------------------
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const verbNameTac = "tac"
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var TacSetup = TransformerSetup{
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Verb: verbNameTac,
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UsageFunc: transformerTacUsage,
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ParseCLIFunc: transformerTacParseCLI,
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IgnoresInput: false,
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}
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func transformerTacUsage(
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o *os.File,
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) {
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fmt.Fprintf(o, "Usage: %s %s [options]\n", "mlr", verbNameTac)
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fmt.Fprintf(o, "Prints records in reverse order from the order in which they were encountered.\n")
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fmt.Fprintf(o, "Options:\n")
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fmt.Fprintf(o, "-h|--help Show this message.\n")
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}
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func transformerTacParseCLI(
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pargi *int,
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argc int,
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args []string,
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_ *cli.TOptions,
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doConstruct bool, // false for first pass of CLI-parse, true for second pass
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) IRecordTransformer {
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// Skip the verb name from the current spot in the mlr command line
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argi := *pargi
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argi++
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for argi < argc /* variable increment: 1 or 2 depending on flag */ {
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opt := args[argi]
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if !strings.HasPrefix(opt, "-") {
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break // No more flag options to process
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}
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if args[argi] == "--" {
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break // All transformers must do this so main-flags can follow verb-flags
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}
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argi++
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if opt == "-h" || opt == "--help" {
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transformerTacUsage(os.Stdout)
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os.Exit(0)
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} else {
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transformerTacUsage(os.Stderr)
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os.Exit(1)
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}
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}
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*pargi = argi
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if !doConstruct { // All transformers must do this for main command-line parsing
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return nil
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}
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transformer, err := NewTransformerTac()
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if err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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return transformer
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}
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// ----------------------------------------------------------------
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type TransformerTac struct {
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recordsAndContexts *list.List
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}
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func NewTransformerTac() (*TransformerTac, error) {
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return &TransformerTac{
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recordsAndContexts: list.New(),
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}, nil
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}
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func (tr *TransformerTac) Transform(
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inrecAndContext *types.RecordAndContext,
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outputRecordsAndContexts *types.List[*types.RecordAndContext],
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inputDownstreamDoneChannel <-chan bool,
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outputDownstreamDoneChannel chan<- bool,
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) {
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HandleDefaultDownstreamDone(inputDownstreamDoneChannel, outputDownstreamDoneChannel)
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if !inrecAndContext.EndOfStream {
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tr.recordsAndContexts.PushFront(inrecAndContext)
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} else {
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// end of stream
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for e := tr.recordsAndContexts.Front(); e != nil; e = e.Next() {
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outputRecordsAndContexts.PushBack(e.Value.(*types.RecordAndContext))
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}
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outputRecordsAndContexts.PushBack(types.NewEndOfStreamMarker(&inrecAndContext.Context))
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}
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}
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