MB-27666: Nested Fields

document.go

@@ -124,3 +124,11 @@ type SynonymDocument interface {
 	// The provided visitor function is called for each synonym field.
 	VisitSynonymFields(visitor SynonymFieldVisitor)
 }
+
+// NestedDocument is a document that contains other documents inside it.
+type NestedDocument interface {
+	Document
+	// VisitNestedDocuments allows iteration over all nested documents in the document.
+	// The provided visitor function is called for each nested document.
+	VisitNestedDocuments(visitor func(doc Document))
+}

index.go

@@ -17,6 +17,8 @@ package index
 import (
 	"bytes"
 	"context"
+	"encoding/binary"
+	"fmt"
 	"reflect"
 )
 
@@ -188,6 +190,18 @@ func (tfv *TermFieldVector) Size() int {
 // IndexInternalID is an opaque document identifier interal to the index impl
 type IndexInternalID []byte
 
+func NewIndexInternalID(buf []byte, in uint64) IndexInternalID {
+	if len(buf) != 8 {
+		if cap(buf) >= 8 {
+			buf = buf[0:8]
+		} else {
+			buf = make([]byte, 8)
+		}
+	}
+	binary.BigEndian.PutUint64(buf, in)
+	return buf
+}
+
 func (id IndexInternalID) Equals(other IndexInternalID) bool {
 	return id.Compare(other) == 0
 }
@@ -196,6 +210,13 @@ func (id IndexInternalID) Compare(other IndexInternalID) int {
 	return bytes.Compare(id, other)
 }
 
+func (id IndexInternalID) Value() (uint64, error) {
+	if len(id) != 8 {
+		return 0, fmt.Errorf("wrong len for IndexInternalID: %q", id)
+	}
+	return binary.BigEndian.Uint64(id), nil
+}
+
 type TermFieldDoc struct {
 	Term    string
 	ID      IndexInternalID
@@ -365,3 +386,12 @@ type EligibleDocumentSelector interface {
 	// This must be called after all eligible documents have been added.
 	SegmentEligibleDocs(segmentID int) []uint64
 }
+
+// NestedReader is an extended index reader that supports hierarchical document structures.
+type NestedReader interface {
+	IndexReader
+	// Ancestors returns the ancestral chain for a given document ID in the index.
+	// For nested documents, this method retrieves all parent documents in the hierarchy
+	// leading up to the specified document ID.
+	Ancestors(id IndexInternalID) ([]IndexInternalID, error)
+}