yq/pkg/yqlib/printer.go

package yqlib

import (
	"bufio"
	"container/list"
	"fmt"
	"io"
	"regexp"

	yaml "gopkg.in/yaml.v3"
)

type Printer interface {
	PrintResults(matchingNodes *list.List) error
	PrintedAnything() bool
	//e.g. when given a front-matter doc, like jekyll
	SetAppendix(reader io.Reader)
}

type PrinterOutputFormat uint32

const (
	YamlOutputFormat = 1 << iota
	JsonOutputFormat
	PropsOutputFormat
	CsvOutputFormat
	TsvOutputFormat
	XmlOutputFormat
)

func OutputFormatFromString(format string) (PrinterOutputFormat, error) {
	switch format {
	case "yaml", "y":
		return YamlOutputFormat, nil
	case "json", "j":
		return JsonOutputFormat, nil
	case "props", "p":
		return PropsOutputFormat, nil
	case "csv", "c":
		return CsvOutputFormat, nil
	case "tsv", "t":
		return TsvOutputFormat, nil
	case "xml", "x":
		return XmlOutputFormat, nil
	default:
		return 0, fmt.Errorf("unknown format '%v' please use [yaml|json|props|csv|tsv|xml]", format)
	}
}

type resultsPrinter struct {
	encoder           Encoder
	printerWriter     PrinterWriter
	firstTimePrinting bool
	previousDocIndex  uint
	previousFileIndex int
	printedMatches    bool
	treeNavigator     DataTreeNavigator
	appendixReader    io.Reader
}

func NewPrinter(encoder Encoder, printerWriter PrinterWriter) Printer {
	return &resultsPrinter{
		encoder:           encoder,
		printerWriter:     printerWriter,
		firstTimePrinting: true,
		treeNavigator:     NewDataTreeNavigator(),
	}
}

func (p *resultsPrinter) SetAppendix(reader io.Reader) {
	p.appendixReader = reader
}

func (p *resultsPrinter) PrintedAnything() bool {
	return p.printedMatches
}

func (p *resultsPrinter) printNode(node *yaml.Node, writer io.Writer) error {
	p.printedMatches = p.printedMatches || (node.Tag != "!!null" &&
		(node.Tag != "!!bool" || node.Value != "false"))
	return p.encoder.Encode(writer, node)
}

func (p *resultsPrinter) PrintResults(matchingNodes *list.List) error {
	log.Debug("PrintResults for %v matches", matchingNodes.Len())

	if matchingNodes.Len() == 0 {
		log.Debug("no matching results, nothing to print")
		return nil
	}

	if !p.encoder.CanHandleAliases() {
		explodeOp := Operation{OperationType: explodeOpType}
		explodeNode := ExpressionNode{Operation: &explodeOp}
		context, err := p.treeNavigator.GetMatchingNodes(Context{MatchingNodes: matchingNodes}, &explodeNode)
		if err != nil {
			return err
		}
		matchingNodes = context.MatchingNodes
	}

	if p.firstTimePrinting {
		node := matchingNodes.Front().Value.(*CandidateNode)
		p.previousDocIndex = node.Document
		p.previousFileIndex = node.FileIndex
		p.firstTimePrinting = false
	}

	for el := matchingNodes.Front(); el != nil; el = el.Next() {

		mappedDoc := el.Value.(*CandidateNode)
		log.Debug("-- print sep logic: p.firstTimePrinting: %v, previousDocIndex: %v, mappedDoc.Document: %v", p.firstTimePrinting, p.previousDocIndex, mappedDoc.Document)

		writer, errorWriting := p.printerWriter.GetWriter(mappedDoc)
		if errorWriting != nil {
			return errorWriting
		}

		commentsStartWithSepExp := regexp.MustCompile(`^\$yqDocSeperator\$`)
		commentStartsWithSeparator := commentsStartWithSepExp.MatchString(mappedDoc.LeadingContent)

		if (p.previousDocIndex != mappedDoc.Document || p.previousFileIndex != mappedDoc.FileIndex) && !commentStartsWithSeparator {
			if err := p.encoder.PrintDocumentSeparator(writer); err != nil {
				return err
			}
		}

		if err := p.encoder.PrintLeadingContent(writer, mappedDoc.LeadingContent); err != nil {
			return err
		}

		if err := p.printNode(mappedDoc.Node, writer); err != nil {
			return err
		}

		p.previousDocIndex = mappedDoc.Document
		if err := writer.Flush(); err != nil {
			return err
		}
		log.Debugf("done printing results")
	}

	// what happens if I remove output format check?
	if p.appendixReader != nil {
		writer, err := p.printerWriter.GetWriter(nil)
		if err != nil {
			return err
		}

		log.Debug("Piping appendix reader...")
		betterReader := bufio.NewReader(p.appendixReader)
		_, err = io.Copy(writer, betterReader)
		if err != nil {
			return err
		}
		if err := writer.Flush(); err != nil {
			return err
		}
	}

	return nil
}