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Package / PackageParser (XUdt-style)

ExcelTk frames Office-defined protocol units — not UI progressive-render DTOs.

Roles

Role Responsibility
Package One Office unit (BIFF record type / SpreadsheetML element). Owns EncodeBody / DecodeBody of Office fields.
PackageParser PushData / Pump / TryFrameOne state machine: recognize complete unit → empty package by type → DecodeBody → queue; HavePackage / PopPackage / HaveUnParsedData / Reset. Does not invent field layout.
Reader Workbook semantics (SST, styles, DataSet) consuming popped packages / cursor records.

Wire layouts are dictated by Office Excel — do not change them for streaming convenience.

Encode / Decode model

Same shape as XUdt:

Layer Binary (BinaryPackage) XML (XmlPackage)
Header framing Base writes/reads 2-byte type + 2-byte body size Element start tag / framer owns fragment bytes
Body Virtual EncodeBody / DecodeBody on each concrete package EncodeBody(XmlWriter) / Decode(XmlReader) (bytes route via IPackage.DecodeBody)
Required size GetRequiredEncodeBodyBufferLength() Encode-to-MemoryStream via EncodeBody(byte[]) helper

Base only frames the header (or element wrapper). Every concrete Package implements body encode/decode. OnBytesReady is gone — field parsing lives in DecodeBody.

Binary (.xls)

OLE/XlsStream (sector assembly)     ← NOT a Package
        │ workbook byte[]
        ▼
BinaryPackageParser.PushData
        │  CreateEmpty(BIFFRECORDTYPE) → concrete XlsBiff* Package
        ▼
BinaryPackage  (base in Reader.Binary)
  ├── EncodePackage = header + EncodeBody
  ├── DecodePackage / IPackage.DecodeBody = header → DecodeBody(body)
  ├── XlsBiffBOF, XlsBiffRKCell, XlsBiffLabelSSTCell, …
  └── BinaryPackage itself (unknown types: raw body passthrough)

Each XlsBiff* record class in Reader/Binary/ is a Package (one Office BIFF command type = one class).

Is a Package Is NOT a Package
BinaryPackage + every XlsBiff* record type XlsStream, XlsHeader, XlsFat, XlsRootDirectory (OLE)
XlsWorksheet, XlsWorkbookGlobals, ExcelBinaryReader (workbook semantics)
BiffWorkbookCursor (Seek/ReadAt index helper)
  • BIFF header = 2-byte type + 2-byte body length; body from Office header.
  • Factory: BinaryPackage.CreateEmpty(type) → typed subclass → DecodePackage / AttachSharedBytes → DecodeBody fills Office fields.
  • Every concrete XlsBiff* owns field-level DecodeBody (buffer → members) and EncodeBody (members → buffer). No raw-body cheat on known types.
  • BinaryPackage base CaptureRawBody remains only for unknown record types.
  • Opaque known types (CONTINUE, QUICKTIP) store byte[] m_payload as the Office body member — still field-level.
  • SST: members m_count, m_uniqueCount, m_stringData (bytes after the 8-byte header). CONTINUE-spanned strings stay Reader-side (Append + ReadStrings).
  • HyperLink: range, GUID, flags, optional description/frame blocks, and URL are members; Encode rebuilds that structure.
  • Formula string results may look ahead to the next STRING package on the shared buffer.
  • XlsBiffBlankCell is a mid-base for shared row/col/xf; subclasses call base.DecodeBody then extend (except types that rewrite the full body).

OpenXML (.xlsx)

worksheet XML stream (file / NetworkStream / PushData buffer)
        │
        ▼
XmlPackageParser (XmlReader tokenize)
        │  complete SpreadsheetML element
        ▼
XmlPackage.CreateEmpty(localName) → Decode(reader) → queue
        │
        EncodeBody(XmlWriter) writes the same Office element shape

Office element packages only:

Element Package
dimension XmlDimensionPackage
row XmlRowPackage (attrs + child c cell packages)
c XmlCellPackage (attrs r/t/s; children v/t/f)
mergeCell XmlMergePackage
hyperlink XmlHyperlinkPackage

worksheet / sheetData / mergeCells / hyperlinks are parser state — not packages.

ExcelOpenXmlReader.ReadSheetGlobals obtains XmlDimensionPackage via XmlPackageParser when present; sheets without dimension still fall back to counting row/cell packages for size.

TCP demo

dotnet run --project src/Exceltk/Exceltk.csproj -- -t tcpstream \
  -xlsx src/test/test1.xlsx -biff src/test/test8.xls
  • BIFF: server sends raw workbook stream chunks; client BinaryPackageParser.PushData pops concrete XlsBiff* packages.
  • XML: server sends worksheet XML chunks; client XmlReader + XmlPackageParser.TryFrameOne / PopPackage.