spreadsheet: add formula reading/writing support

Minimal support for now, just enough to read table
ranges so they can be used from formulas.

filenames.go

@@ -53,6 +53,9 @@ func RelativeFilename(dt DocType, typ string, index int) string {
 	case VMLDrawingType, VMLDrawingContentType:
 		return fmt.Sprintf("../drawings/vmlDrawing%d.vml", index)
 
+	case TableType, TableContentType:
+		return fmt.Sprintf("../tables/table%d.xml", index)
+
 	case ThemeType, ThemeContentType:
 		return fmt.Sprintf("theme/theme%d.xml", index)
 	case OfficeDocumentType:
@@ -144,6 +147,8 @@ func AbsoluteFilename(dt DocType, typ string, index int) string {
 		default:
 			log.Printf("unsupported type %s pair and %v", typ, dt)
 		}
+	case TableType, TableContentType:
+		return fmt.Sprintf("xl/tables/table%d.xml", index)
 
 	case DrawingType, DrawingContentType:
 		switch dt {

schemas.go

@@ -33,6 +33,8 @@ const (
 	SharedStingsType         = "http://schemas.openxmlformats.org/officeDocument/2006/relationships/sharedStrings"
 	SharedStringsContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sharedStrings+xml"
 	SMLStyleSheetContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.styles+xml"
+	TableType                = "http://schemas.openxmlformats.org/officeDocument/2006/relationships/table"
+	TableContentType         = "application/vnd.openxmlformats-officedocument.spreadsheetml.table+xml"
 
 	// WML
 	HeaderType      = "http://schemas.openxmlformats.org/officeDocument/2006/relationships/header"

spreadsheet/sheet.go

@@ -598,6 +598,8 @@ func (s *Sheet) SetFrozen(firstRow, firstCol bool) {
 
 }
 
+// FormulaContext returns a formula evaluation context that can be used to
+// evaluate formaulas.
 func (s *Sheet) FormulaContext() formula.Context {
 	return newEvalContext(s)
 }

spreadsheet/table.go

@@ -0,0 +1,32 @@
+// Copyright 2017 Baliance. All rights reserved.
+//
+// Use of this source code is governed by the terms of the Affero GNU General
+// Public License version 3.0 as published by the Free Software Foundation and
+// appearing in the file LICENSE included in the packaging of this file. A
+// commercial license can be purchased by contacting sales@baliance.com.
+
+package spreadsheet
+
+import sml "baliance.com/gooxml/schema/schemas.openxmlformats.org/spreadsheetml"
+
+type Table struct {
+	x *sml.Table
+}
+
+// X returns the inner wrapped XML type.
+func (t Table) X() *sml.Table {
+	return t.x
+}
+
+// Name returns the name of the table
+func (t Table) Name() string {
+	if t.x.NameAttr != nil {
+		return *t.x.NameAttr
+	}
+	return ""
+}
+
+// Reference returns the table reference (the cells within the table)
+func (t Table) Reference() string {
+	return t.x.RefAttr
+}

spreadsheet/workbook.go

@@ -47,6 +47,7 @@ type Workbook struct {
 	drawingRels []common.Relationships
 	vmlDrawings []*vmldrawing.Container
 	charts      []*crt.ChartSpace
+	tables      []*sml.Table
 }
 
 // X returns the inner wrapped XML type.
@@ -176,6 +177,10 @@ func (wb *Workbook) Save(w io.Writer) error {
 		fn := gooxml.AbsoluteFilename(dt, gooxml.ChartType, i+1)
 		zippkg.MarshalXML(z, fn, chart)
 	}
+	for i, tbl := range wb.tables {
+		fn := gooxml.AbsoluteFilename(dt, gooxml.TableType, i+1)
+		zippkg.MarshalXML(z, fn, tbl)
+	}
 	for i, drawing := range wb.drawings {
 		fn := gooxml.AbsoluteFilename(dt, gooxml.DrawingType, i+1)
 		zippkg.MarshalXML(z, fn, drawing)
@@ -389,6 +394,13 @@ func (wb *Workbook) onNewRelationship(decMap *zippkg.DecodeMap, target, typ stri
 		wb.charts = append(wb.charts, chart)
 		rel.TargetAttr = gooxml.RelativeFilename(dt, typ, len(wb.charts))
 
+	case gooxml.TableType:
+		tbl := sml.NewTable()
+		idx := uint32(len(wb.tables))
+		decMap.AddTarget(zippkg.Target{Path: target, Ifc: tbl, Index: idx})
+		wb.tables = append(wb.tables, tbl)
+		rel.TargetAttr = gooxml.RelativeFilename(dt, typ, len(wb.charts))
+
 	default:
 		log.Printf("unsupported relationship %s %s", target, typ)
 	}
@@ -500,3 +512,15 @@ func (wb *Workbook) SetActiveSheetIndex(idx uint32) {
 
 	wb.x.BookViews.WorkbookView[0].ActiveTabAttr = gooxml.Uint32(idx)
 }
+
+// Tables returns a slice of all defined tables in the workbook.
+func (w *Workbook) Tables() []Table {
+	if w.tables == nil {
+		return nil
+	}
+	ret := []Table{}
+	for _, t := range w.tables {
+		ret = append(ret, Table{t})
+	}
+	return ret
+}