Extracted out evaluators

pkg/yqlib/stream_evaluator.go

@@ -0,0 +1,85 @@
+package yqlib
+
+import (
+	"container/list"
+	"io"
+	"os"
+
+	yaml "gopkg.in/yaml.v3"
+)
+
+type StreamEvaluator interface {
+	Evaluate(filename string, reader io.Reader, node *PathTreeNode, printer Printer) error
+	EvaluateFiles(expression string, filenames []string, printer Printer) error
+}
+
+type streamEvaluator struct {
+	treeNavigator DataTreeNavigator
+	treeCreator   PathTreeCreator
+	fileIndex     int
+}
+
+func NewStreamEvaluator() StreamEvaluator {
+	return &streamEvaluator{treeNavigator: NewDataTreeNavigator(), treeCreator: NewPathTreeCreator()}
+}
+
+func (s *streamEvaluator) EvaluateFiles(expression string, filenames []string, printer Printer) error {
+
+	node, err := treeCreator.ParsePath(expression)
+	if err != nil {
+		return err
+	}
+
+	for _, filename := range filenames {
+		reader, err := readStream(filename)
+		if err != nil {
+			return err
+		}
+		err = s.Evaluate(filename, reader, node, printer)
+		if err != nil {
+			return err
+		}
+
+		switch reader := reader.(type) {
+		case *os.File:
+			safelyCloseFile(reader)
+		}
+	}
+	return nil
+}
+
+func (s *streamEvaluator) Evaluate(filename string, reader io.Reader, node *PathTreeNode, printer Printer) 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 nil
+		} else if errorReading != nil {
+			return errorReading
+		}
+		candidateNode := &CandidateNode{
+			Document:  currentIndex,
+			Filename:  filename,
+			Node:      &dataBucket,
+			FileIndex: s.fileIndex,
+		}
+		inputList := list.New()
+		inputList.PushBack(candidateNode)
+
+		matches, errorParsing := treeNavigator.GetMatchingNodes(inputList, node)
+		if errorParsing != nil {
+			return errorParsing
+		}
+		err := printer.PrintResults(matches)
+		if err != nil {
+			return err
+		}
+		currentIndex = currentIndex + 1
+	}
+}