package yqlib import ( "container/list" "io" "os" yaml "gopkg.in/yaml.v3" ) // A yaml expression evaluator that runs the expression multiple times for each given yaml document. // Uses less memory than loading all documents and running the expression once, but this cannot process // cross document expressions. type StreamEvaluator interface { Evaluate(filename string, reader io.Reader, node *ExpressionNode, printer Printer, leadingContent string) (uint, error) EvaluateFiles(expression string, filenames []string, printer Printer) error EvaluateNew(expression string, printer Printer, leadingContent string) error } type streamEvaluator struct { treeNavigator DataTreeNavigator treeCreator ExpressionParser fileIndex int } func NewStreamEvaluator() StreamEvaluator { return &streamEvaluator{treeNavigator: NewDataTreeNavigator(), treeCreator: NewExpressionParser()} } func (s *streamEvaluator) EvaluateNew(expression string, printer Printer, leadingContent string) error { node, err := s.treeCreator.ParseExpression(expression) if err != nil { return err } candidateNode := &CandidateNode{ Document: 0, Filename: "", Node: &yaml.Node{Tag: "!!null", Kind: yaml.ScalarNode}, FileIndex: 0, } inputList := list.New() inputList.PushBack(candidateNode) result, errorParsing := s.treeNavigator.GetMatchingNodes(Context{MatchingNodes: inputList}, node) if errorParsing != nil { return errorParsing } return printer.PrintResults(result.MatchingNodes, leadingContent) } func (s *streamEvaluator) EvaluateFiles(expression string, filenames []string, printer Printer) error { var totalProcessDocs uint = 0 node, err := s.treeCreator.ParseExpression(expression) if err != nil { return err } var firstFileLeadingContent string for index, filename := range filenames { reader, leadingContent, err := readStream(filename) if index == 0 { firstFileLeadingContent = leadingContent } if err != nil { return err } processedDocs, err := s.Evaluate(filename, reader, node, printer, leadingContent) if err != nil { return err } totalProcessDocs = totalProcessDocs + processedDocs switch reader := reader.(type) { case *os.File: safelyCloseFile(reader) } } if totalProcessDocs == 0 { return s.EvaluateNew(expression, printer, firstFileLeadingContent) } return nil } func (s *streamEvaluator) Evaluate(filename string, reader io.Reader, node *ExpressionNode, printer Printer, leadingContent string) (uint, error) { var currentIndex uint decoder := yaml.NewDecoder(reader) for { var dataBucket yaml.Node errorReading := decoder.Decode(&dataBucket) if errorReading == io.EOF { s.fileIndex = s.fileIndex + 1 return currentIndex, nil } else if errorReading != nil { return currentIndex, errorReading } candidateNode := &CandidateNode{ Document: currentIndex, Filename: filename, Node: &dataBucket, FileIndex: s.fileIndex, } inputList := list.New() inputList.PushBack(candidateNode) result, errorParsing := s.treeNavigator.GetMatchingNodes(Context{MatchingNodes: inputList}, node) if errorParsing != nil { return currentIndex, errorParsing } var err error if currentIndex == 0 { err = printer.PrintResults(result.MatchingNodes, leadingContent) } else { err = printer.PrintResults(result.MatchingNodes, "") } if err != nil { return currentIndex, err } currentIndex = currentIndex + 1 } }