spreadsheet: initial shared formula support

_examples/spreadsheet/shared-formula/main.go

@@ -0,0 +1,36 @@
+// Copyright 2017 Baliance. All rights reserved.
+package main
+
+import (
+	"log"
+
+	"baliance.com/gooxml/spreadsheet"
+)
+
+func main() {
+	ss := spreadsheet.New()
+	sheet := ss.AddSheet()
+
+	sheet.Cell("A1").SetNumber(1)
+	sheet.Cell("B1").SetNumber(2)
+	sheet.Cell("C1").SetNumber(3)
+	sheet.Cell("D1").SetNumber(4)
+	sheet.Cell("A2").SetNumber(5)
+	sheet.Cell("B2").SetNumber(6)
+	sheet.Cell("C2").SetNumber(7)
+	sheet.Cell("D2").SetNumber(8)
+	sheet.Cell("A3").SetNumber(9)
+	sheet.Cell("B3").SetNumber(10)
+	sheet.Cell("C3").SetNumber(11)
+	sheet.Cell("D3").SetNumber(12)
+
+	sheet.Cell("A5").SetFormulaShared("=A1+1", 2, 3)
+	sheet.Cell("A9").SetFormulaShared("=$A1+1", 2, 3)
+	sheet.Cell("A13").SetFormulaShared("=$A$1+1", 2, 3)
+
+	ss.RecalculateFormulas()
+	if err := ss.Validate(); err != nil {
+		log.Fatalf("error validating: %s", err)
+	}
+	ss.SaveToFile("shared-formula.xlsx")
+}

spreadsheet/cell.go

@@ -9,6 +9,7 @@ package spreadsheet
 
 import (
 	"errors"
+	"fmt"
 	"math"
 	"math/big"
 	"strconv"
@@ -93,6 +94,50 @@ func (c Cell) SetFormulaArray(s string) {
 	c.x.F.Content = s
 }
 
+// SetFormulaShared sets the cell type to formula shared, and the raw formula to
+// the given string. The range is the range of cells that the formula applies
+// to, and is used to conserve disk space.
+func (c Cell) SetFormulaShared(formula string, rows, cols uint32) error {
+	c.clearValue()
+	c.x.TAttr = sml.ST_CellTypeStr
+	c.x.F = sml.NewCT_CellFormula()
+	c.x.F.TAttr = sml.ST_CellFormulaTypeShared
+	c.x.F.Content = formula
+	col, rowIdx, err := ParseCellReference(c.Reference())
+	if err != nil {
+		return err
+	}
+	colIdx := ColumnToIndex(col)
+
+	sid := uint32(0)
+	for _, r := range c.s.SheetData.Row {
+		for _, c := range r.C {
+			if c.F != nil && c.F.SiAttr != nil && *c.F.SiAttr >= sid {
+				sid = *c.F.SiAttr
+			}
+		}
+	}
+
+	ref := fmt.Sprintf("%s%d:%s%d", col, rowIdx, IndexToColumn(colIdx+cols), rowIdx+rows)
+	fmt.Println("REF IS", ref)
+	c.x.F.RefAttr = gooxml.String(ref)
+	c.x.F.SiAttr = gooxml.Uint32(sid)
+	sheet := Sheet{c.w, nil, c.s}
+	for row := rowIdx; row <= rowIdx+rows; row++ {
+		for col := colIdx; col <= colIdx+cols; col++ {
+			if row == rowIdx && col == colIdx {
+				continue
+			}
+			ref := fmt.Sprintf("%s%d", IndexToColumn(col), row)
+			sheet.Cell(ref).Clear()
+			sheet.Cell(ref).X().F = sml.NewCT_CellFormula()
+			sheet.Cell(ref).X().F.TAttr = sml.ST_CellFormulaTypeShared
+			sheet.Cell(ref).X().F.SiAttr = gooxml.Uint32(sid)
+		}
+	}
+	return nil
+}
+
 // SetString sets the cell type to string, and the value to the given string,
 // returning an ID from the shared strings table. To reuse a string, call
 // SetStringByID with the ID returned.

spreadsheet/sheet.go

@@ -628,6 +628,9 @@ func (s *Sheet) RecalculateFormulas() {
 					// array we need to expand the array out into cells
 					if c.X().F.TAttr == sml.ST_CellFormulaTypeArray && res.Type == formula.ResultTypeArray {
 						s.setArray(c.Reference(), res)
+					} else if c.X().F.TAttr == sml.ST_CellFormulaTypeShared {
+						// shared formula
+						//						s.setShared(c.X().F.RefAttr)
 					}
 				}
 			}