/// <summary>
/// read the source field and fill the spread sheet in the field
/// </summary>
/// <param name="source"></param>
/// <param name="newIsValid"></param>
public Spreadsheet(TextReader source, Regex newIsValid)
{
isvalName = newIsValid;
Regex oldIsvail = null;
sheet = new Dictionary <string, cell>();
dependency = new DependencyGraph();
// Create an XmlSchemaSet object.
XmlSchemaSet sc = new XmlSchemaSet();
// NOTE: To read states3.xsd this way, it must be stored in the same folder with the
// executable. To arrange this, I set the "Copy to Output Directory" propery of states3.xsd to
// "Copy If Newer", which will copy states3.xsd as part of each build (if it has changed
// since the last build).
sc.Add(null, "Spreadsheet.xsd");
// Configure validation.
XmlReaderSettings settings = new XmlReaderSettings();
settings.ValidationType = ValidationType.Schema;
settings.Schemas = sc;
settings.ValidationEventHandler += ValidationCallback;
// try to read the field
try
{
// begin to read
using (XmlReader reader = XmlReader.Create(source, settings))
{
// in the each token,
// first check if it is vaild
// then save them into the sheet once it is vaild
while (reader.Read())
{
if (reader.IsStartElement())
{
switch (reader.Name)
{
case "spreadsheet":
try
{
oldIsvail = new Regex(reader["IsValid"]);
}
catch
{
throw new SpreadsheetReadException("wrong regular expression");
}
break;
// checkall the requirements
case "cell":
try
{
string name = reader["name"];
if (!oldIsvail.IsMatch(name))
{
throw new SpreadsheetReadException("the name is ilegal");
}
if (!isvalName.IsMatch(name))
{
throw new SpreadsheetVersionException("the name is ilegal");
}
if (sheet.ContainsKey(name))
{
throw new SpreadsheetReadException("the name is duplicate");
}
SetContentsOfCell(name, reader["contents"]);
}
catch
{
throw new SpreadsheetReadException("can not read name or contents");
}
break;
}
}
}
}
}
// throw exception once it doen't read
catch
{
throw new IOException();
}
}
/// <summary>
/// the spreadsheet will takes no peremeter
/// </summary>
public Spreadsheet()
{
sheet = new Dictionary <string, cell>();
dependency = new DependencyGraph();
constructorUse = 1;
}
/// <summary>
/// it will take a new isVaild check if match the requirement
/// </summary>
/// <param name="isValid"></param>
public Spreadsheet(Regex isValid)
{
isvalName = isValid;
sheet = new Dictionary <string, cell>();
dependency = new DependencyGraph();
}
/// Creates a Spreadsheet that is a duplicate of the spreadsheet saved in source.
public Spreadsheet(TextReader source, Regex newIsValid)
{
this.dg = new DependencyGraph();
this.cellList = new Dictionary <string, Cell>();
IsValid = newIsValid;
this.Changed = false;
Regex r = newIsValid;
XmlSchemaSet schema = new XmlSchemaSet();
schema.Add(null, "Spreadsheet.xsd");
XmlReaderSettings settings = new XmlReaderSettings();
settings.ValidationType = ValidationType.Schema;
settings.Schemas = schema;
settings.ValidationEventHandler += ThrowExceptionValidation;
using (XmlReader reader = XmlReader.Create(source, settings))
{
while (reader.Read())
{
if (reader.IsStartElement())
{
switch (reader.Name)
{
case "spreadsheet":
try
{
r = new Regex(reader["IsValid"]);
}
catch
{
throw new SpreadsheetReadException("Invalid Expression");
}
break;
case "cell":
if (cellList.ContainsKey(reader["name"]))
{
throw new SpreadsheetReadException("");
}
IsValid = r;
try
{
this.SetContentsOfCell(reader["name"], reader["contents"]);
}
catch (Exception e) when(e is FormulaFormatException || e is CircularException || e is InvalidNameException)
{
if (e is FormulaFormatException)
{
throw new SpreadsheetVersionException("");
}
if (e is FormulaFormatException)
{
throw new SpreadsheetVersionException("");
}
if (e is InvalidNameException)
{
throw new SpreadsheetVersionException("");
}
}
IsValid = newIsValid;
try
{
this.SetContentsOfCell(reader["name"], reader["contents"]);
}
catch (Exception ee) when(ee is FormulaFormatException || ee is CircularException || ee is InvalidNameException)
{
if (ee is FormulaFormatException)
{
throw new SpreadsheetVersionException("");
}
if (ee is FormulaFormatException)
{
throw new SpreadsheetVersionException("");
}
if (ee is InvalidNameException)
{
throw new SpreadsheetVersionException("");
}
}
break;
}
}
}
}
}
/// <summary>
/// Three argument constructor.
/// </summary>
/// <param name="isValid"></param>
/// <param name="normalize"></param>
/// <param name="version"></param>
public Spreadsheet(Func <string, bool> isValid, Func <string, string> normalize, string version) : base(isValid, normalize, version)
{
dg = new DependencyGraph();
sd = new Dictionary <string, Cell>();
Changed = false;
}
/// <summary>
/// Constructs an abstract spreadsheet by recording its variable validity test,
/// its normalization method, and its version information. The variable validity
/// test is used throughout to determine whether a string that consists of one or
/// more letters followed by one or more digits is a valid cell name. The variable
/// equality test should be used thoughout to determine whether two variables are
/// equal.
/// </summary>
public Spreadsheet(string filePath, Func <string, bool> isValid, Func <string, string> normalize, string version)
: base(isValid, normalize, version)
{
//read save file from filePath
spreadsheet = new Dictionary <string, Cell> {
};
dependency_graph = new DependencyGraph();
has_changed = false;
try
{
using (XmlReader read_file = XmlReader.Create(filePath))
{
if (GetSavedVersion(filePath) != version)
{
throw new SpreadsheetReadWriteException("File versions are not the same.");
}
try
{
string cell_name = "";
while (read_file.Read())
{
if (read_file.IsStartElement())
{
switch (read_file.Name)
{
case "spreadsheet":
break;
case "cell":
break;
case "name":
read_file.Read();
cell_name = read_file.Value;
break;
case "contents":
read_file.Read();
try
{
SetContentsOfCell(cell_name, read_file.Value);
}
catch (Exception ex)
{
throw new SpreadsheetReadWriteException(ex.Message);
}
break;
}
}
}
}
catch
{
throw new SpreadsheetReadWriteException("Error while reading from file");
}
}
}
catch (Exception ex)
{
throw new SpreadsheetReadWriteException(ex.Message);
}
has_changed = false;
}
/// <summary>
/// zero-argument constructor should create an empty spreadsheet that imposes no
/// extra validity conditions, normalizes every cell name to itself,
/// and has version "default".
/// </summary>
public Spreadsheet() : base(s => true, s => s, "default")
{
Changed = false;
myDG = new DependencyGraph();
mySS = new Dictionary <string, Cell>();
}
/// <summary>
/// A zero-argument constructor that creates an empty spreadsheet.
/// </summary>
public Spreadsheet()
{
Graph = new DependencyGraph();
NonEmptyCells = new Dictionary <string, Cell>();
}
/// <summary>
/// No arguments in constructor. Cell validity has same rule for all
/// spreadsheets, and is determined by IsValid method in this class.
/// Cell name normalization has same rule (all uppercase letters) for all
/// spreadsheets, and is determined by Normalize method in this class.
/// </summary>
public Spreadsheet()
{
cells = new Dictionary <string, Cell>();
dependencyGraph = new DependencyGraph();
}
public Spreadsheet(string path, Func <string, bool> isValid, Func <string, string> normalize, string version) : base(x => true, x => x, version)
{
//declaring a dependency graph.
DG = new DependencyGraph();
//declarign a cell from the cells class.
Cells = new Dictionary <string, Cell>();
//declaring is Valid and Normalize
this.IsValid = isValid;
this.Normalize = normalize;
this.Version = version;
Changed = false;
try
{ //reading a file from the path
using (XmlReader reader = XmlReader.Create(path))
{
while (reader.Read())
{ //if start element is correct.
if (reader.IsStartElement())
{ //if spreadsheet is read.
if (reader.Name == "spreadsheet")
{ //set version to reader version.
version = reader["version"];
}
//if cell is read.
if (reader.Name == "cell")
{
//if reader Name is not equal to name.
while (!reader.Name.Equals("name"))
{
reader.Read();
}
reader.Read();
//storing value in name.
string name = reader.Value;
while (!reader.Name.Equals("contents"))
{
reader.Read();
}
reader.Read();
//set value in content.
string content = reader.Value;
//rerunning setCentent of cell on name and content.
SetContentsOfCell(name, content);
}
}
}
}
}
catch (Exception)
{
throw new SpreadsheetReadWriteException("error");
}
//if version doesnt match throw an exception.
if (!GetSavedVersion(path).Equals(Version))
{
throw new SpreadsheetReadWriteException("the version do not match");
}
}
/// <summary>
/// Requires that all of the variables in formula are valid cell names.
///
/// If name is null or invalid, throws an InvalidNameException.
///
/// Otherwise, if changing the contents of the named cell to be the formula would cause a
/// circular dependency, throws a CircularException.
///
/// Otherwise, the contents of the named cell becomes formula. The method returns a
/// Set consisting of name plus the names of all other cells whose value depends,
/// directly or indirectly, on the named cell.
///
/// For example, if name is A1, B1 contains A1*2, and C1 contains B1+A1, the
/// set {A1, B1, C1} is returned.
/// </summary>
protected override ISet <string> SetCellContents(string name, Formula formula)
{
name = name.ToUpper();
// check if passed in formula contains a dependent of the named cell
// to prevent a ciruclar dependency
//foreach(string token in GetDirectDependents(name))
//{
// if(formula.ToString().Contains(token))
// {
// throw new CircularException();
// }
//}
HashSet <string> set = new HashSet <string>();
// A backup spreadsheet for revert in case a CircularException is thrown
Dictionary <string, Cell> tempDict = new Dictionary <string, Cell>();
// A backup DependencyGraph for revert in case a CircularException is thrown
DependencyGraph tempGraph = new DependencyGraph(graph);
//create a copy for the spreadsheet
foreach (KeyValuePair <string, Cell> key in cellList)
{
tempDict.Add(key.Key, key.Value);
}
// Replace current cell's content for update
graph.ReplaceDependees(name, new List <string>());
// Create dependency relationship between cell and valid variables generated by Formula
foreach (string var in formula.GetVariables())
{
CheckParameters(var);
graph.AddDependency(var, name);
}
// Generate a new cell if such named cell doesn't exists yet, or simply replace the existing
// cell with new information
GenerateCellInfo(name, formula);
set.Add(name);
// This try catch block is used to detect possible Circular dependency by calling GetCellsToRecalculate()
try
{
foreach (string var in GetCellsToRecalculate(name))
{
set.Add(var);
}
}
catch (CircularException e)
{
// If a CircularException is caught, revert the entire operation.
cellList = tempDict;
graph = tempGraph;
Changed = false;
throw e;
}
// Update current named cell's dependee's content, value and dependency
UpdateCellInfo(set, name);
Changed = true;
return(set);
}
/// Creates a Spreadsheet that is a duplicate of the spreadsheet saved in source.
///
/// See the AbstractSpreadsheet.Save method and Spreadsheet.xsd for the file format
/// specification.
///
/// If there's a problem reading source, throws an IOException.
///
/// Else if the contents of source are not consistent with the schema in Spreadsheet.xsd,
/// throws a SpreadsheetReadException.
///
/// Else if the IsValid string contained in source is not a valid C# regular expression, throws
/// a SpreadsheetReadException. (If the exception is not thrown, this regex is referred to
/// below as oldIsValid.)
///
/// Else if there is a duplicate cell name in the source, throws a SpreadsheetReadException.
/// (Two cell names are duplicates if they are identical after being converted to upper case.)
///
/// Else if there is an invalid cell name or an invalid formula in the source, throws a
/// SpreadsheetReadException. (Use oldIsValid in place of IsValid in the definition of
/// cell name validity.)
///
/// Else if there is an invalid cell name or an invalid formula in the source, throws a
/// SpreadsheetVersionException. (Use newIsValid in place of IsValid in the definition of
/// cell name validity.)
///
/// Else if there's a formula that causes a circular dependency, throws a SpreadsheetReadException.
///
/// Else, create a Spreadsheet that is a duplicate of the one encoded in source except that
/// the new Spreadsheet's IsValid regular expression should be newIsValid.
public Spreadsheet(TextReader source, Regex newIsValid)
{
cells = new Dictionary <string, Cell>();
dependencies = new DependencyGraph();
validator = newIsValid;
XmlSchemaSet sc = new XmlSchemaSet();
sc.Add(null, "Spreadsheet.xsd");
XmlReaderSettings settings = new XmlReaderSettings();
settings.ValidationType = ValidationType.Schema;
settings.Schemas = sc;
settings.ValidationEventHandler += delegate(object sender, ValidationEventArgs e) { throw new SpreadsheetReadException("Validation Error: " + e); };
Regex oldIsValid = new Regex("");
using (XmlReader reader = XmlReader.Create(source, settings))
{
while (reader.Read())
{
if (reader.IsStartElement())
{
switch (reader.Name)
{
case "spreadsheet":
try
{
oldIsValid = new Regex(reader["IsValid"]);
}
catch (Exception e)
{
throw new SpreadsheetReadException(e.Message);
}
break;
case "cell":
if (cells.ContainsKey(reader["name"].ToUpper()))
{
throw new SpreadsheetReadException("Duplicate cell name: " + reader["name"].ToUpper());
}
if (!oldIsValid.IsMatch(reader["name"]))
{
throw new SpreadsheetReadException("According to the old IsValid regex, " + reader["name"] + " is not a valid cell name");
}
if (!validator.IsMatch(reader["name"]))
{
throw new SpreadsheetVersionException("According to the new IsValid regex, " + reader["name"] + " is not a valid cell name");
}
ValidateVarsUsingOld(reader["contents"], oldIsValid);
try
{
SetContentsOfCell(reader["name"], reader["contents"]);
}
catch (CircularException e)
{
throw new SpreadsheetReadException(e.Message);
}
catch (Exception e)
{
throw new SpreadsheetVersionException(e.Message);
}
break;
}
}
}
}
changed = false;
}
/// <summary>
/// Constructor for Spreadsheet to create a new spreadsheetCells dictionary
/// and a dependencies dependency graph object.
/// This constructor creates a Spreadsheet that is a duplicate of the spreadsheet
/// saved in source.
/// If there's a problem reading source, throws an IOException
/// If the contents of source is not formatted properly, throws a SpreadsheetReadException.
/// </summary>
public Spreadsheet(TextReader source)
{
try
{
// Create an empty spreadsheetCells dictionary
spreadsheetCells = new Dictionary <String, Cell>();
// Create an empty dependencies DG
dependencies = new DependencyGraph();
// Read in the XML file
using (XmlReader reader = XmlReader.Create(source))
{
// Create a temporary cell object
Cell readCell = new Cell();
while (reader.Read())
{
if (reader.IsStartElement())
{
switch (reader.Name)
{
// If reader is on spreadsheet, read in and set the isvalid regex
case "spreadsheet":
reader.MoveToFirstAttribute();
reader.ReadAttributeValue();
String regex = reader.Value;
Regex tempRegex = new Regex(regex);
isValidRegex = tempRegex;
break;
// If reader is on cell, initialize a new temporary cell
case "cell":
readCell = new Cell();
break;
// If reader is on name, set the temporary cell's name to name
case "name":
reader.Read();
String name = reader.Value;
readCell.cellName = name;
break;
// If reader is on contents, set the temporary cell's contents to contents
// and add the temporary cell to the spreadsheet
case "contents":
reader.Read();
String contents = reader.Value;
readCell.cellContents = contents;
SetContentsOfCell(readCell.cellName, contents);
break;
}
}
}
}
// Set Changed equal to false
Changed = false;
}
catch (IOException)
{
throw new IOException();
}
catch (XmlException e)
{
throw new SpreadsheetReadException(e.Message);
}
}
/// <summary>
/// Constructor for Spreadsheet with zero arguments
/// </summary>
public Spreadsheet()
{
dependency_graph = new DependencyGraph();
cell = new Dictionary <String, Cell>();
}
/// <summary>
/// Creates a Spreadsheet that is a duplicate of the spreadsheet saved in source.
/// See the AbstractSpreadsheet.Save method for the file format specification.
/// If there's a problem reading source, throws an IOException
/// If the contents of source is not formatted properly, throws a SpreadsheetReadException
///
/// Sample reading file:
///
/// <spreadsheet isvalid="IsValid regex goes here">
/// <cell>
/// <name>
/// cell name goes here
/// </name>
/// <contents>
/// cell contents goes here
/// </contents>
/// </cell>
/// </spreadsheet>
///
/// The value of the isvalid attribute should be IsValid.ToString()
/// </summary>
public Spreadsheet(TextReader source)
{
// Initiating our DependencyGraph and our Cells Dictionary
DGSpreadsheet = new DependencyGraph();
cellDictionary = new Dictionary <string, Cell>();
// Local variables to hold the xml data (name of cell and content of cell)
string tempCellName = "";
string tempContent = "";
isValidBool = true;
// Using xml processing to break the different elements of a source reader into
// usuable information to make a spreadsheet. If we have difficulty reading the input file
// we throw a IOException
try
{
using (XmlReader xmlReader = XmlReader.Create(source))
{
// if any elements read are not in an appropriate format,
// we throw a Spreadsheet read exception
try
{
while (xmlReader.Read())
{
if (xmlReader.IsStartElement())
{
switch (xmlReader.Name.ToString())
{
// Checking for the title of the xml file and grabbing
// a regex expression if one exists
case "spreadsheet":
isValid = new Regex(xmlReader.GetAttribute("isvalid"));
break;
// cell is checked only for formatting purposes that were given
// in the assignment description
case "cell":
break;
// Grabing the name of the cell (stored in a temp variable)
case "name":
tempCellName = xmlReader.ReadString();
// Checking if the name is valid
if (!nameValidation(tempCellName))
{
throw new InvalidNameException();
}
break;
// Grabing the content of the cell and setting a cell using SetContentsOfCell
case "contents":
tempContent = xmlReader.ReadString();
SetContentsOfCell(tempCellName, tempContent);
break;
default:
throw new SpreadsheetReadException("Error in reading spreadsheet");
}
}
}
Changed = false;
}
catch (Exception)
{
throw new SpreadsheetReadException("There was a problem reading from the input file.");
}
}
}
catch (IOException) { throw new IOException("There was an issue reading from the source file"); }
}
/// <summary>
/// constructor for spreadsheet with no parameters
///
/// </summary>
public Spreadsheet() : base(s => true, s => s, "default")
{
spreadsheet = new Dictionary <string, Cell>();
graph = new DependencyGraph();
changed = false;
}
/// <summary>
/// creates a Spreadsheet from a saved file
/// </summary>
public Spreadsheet(TextReader source, Regex newIsValid)//CHANGE HERE FOR REGRADE
{
cells = new Dictionary <string, Cell>();
dg = new DependencyGraph();
changed = false;
try
{
XmlSchemaSet sc = new XmlSchemaSet();
sc.Add(null, "Spreadsheet.xsd");
XmlReaderSettings settings = new XmlReaderSettings();
settings.ValidationType = ValidationType.Schema;
settings.Schemas = sc;
//using xml reader to read file
try
{
XmlReader reader = XmlReader.Create(source, settings);//CHANGE HERE
//cell name
string cellName = "";
//cell value
string cellContent = "";
bool RegexMatch = true;
bool setContents;
while (reader.Read())
{
if (reader.IsStartElement())
{
setContents = false;
string name = reader.Name;
switch (name)
{
case "spreadsheet":
string v = reader.GetAttribute("IsValid");
try
{
oldValid = new Regex(v);
}
catch (Exception)
{
throw new SpreadsheetReadException("invalid Regex");
}
if (string.IsNullOrEmpty(oldValid.ToString()))
{
RegexMatch = false;
}
else if (oldValid.ToString().Equals(newIsValid.ToString()))
{
RegexMatch = true;
}
valid = newIsValid;
break;
//read the cell name
case "cell":
string a = reader.GetAttribute("name");
cellName = a;
string b = reader.GetAttribute("contents");
cellContent = b;
setContents = true;
if (!Regex.IsMatch(a, newIsValid.ToString()))
{
throw new SpreadsheetVersionException("Spreadsheet version");
}
if (!Regex.IsMatch(a, oldValid.ToString()))
{
throw new SpreadsheetReadException("invalid regex");
}
break;
}
if (!RegexMatch)
{
throw new SpreadsheetReadException("Regex does not match");
}
if (setContents)
{
if (cells.ContainsKey(cellName))
{
throw new SpreadsheetReadException("duplicate cell");
}
SetContentsOfCell(cellName, cellContent);
}
}
}
reader.Close();
}
catch (XmlException)
{
throw new SpreadsheetReadException("Spreadsheet cannot be read");
}
}
catch (XmlSchemaException)
{
throw new SpreadsheetReadException("Spreadsheet cannot be read");
}
}
/// <summary>
/// Empty argument constructor.
/// </summary>
public Spreadsheet() : base(s => true, s => s, "default")
{
graph = new DependencyGraph();
cellMap = new Dictionary <string, Cell>();
}
/// If there's a problem reading source, throws an IOException.
///
/// Else if the contents of source are not consistent with the schema in Spreadsheet.xsd,
/// throws a SpreadsheetReadException.
///
/// Else if the IsValid string contained in source is not a valid C# regular expression, throws
/// a SpreadsheetReadException. (If the exception is not thrown, this regex is referred to
/// below as oldIsValid.)
///
/// Else if there is a duplicate cell name in the source, throws a SpreadsheetReadException.
/// (Two cell names are duplicates if they are identical after being converted to upper case.)
///
/// Else if there is an invalid cell name or an invalid formula in the source, throws a
/// SpreadsheetReadException. (Use oldIsValid in place of IsValid in the definition of
/// cell name validity.)
///
/// Else if there is an invalid cell name or an invalid formula in the source, throws a
/// SpreadsheetVersionException. (Use newIsValid in place of IsValid in the definition of
/// cell name validity.)
///
/// Else if there's a formula that causes a circular dependency, throws a SpreadsheetReadException.
///
/// Else, create a Spreadsheet that is a duplicate of the one encoded in source except that
/// the new Spreadsheet's IsValid regular expression should be newIsValid.
public Spreadsheet(TextReader source, Regex newIsValid)
{
this.dg = new DependencyGraph();
this.cells = new Dictionary <string, Cell>();
Regex checkValid = newIsValid;
XmlSchemaSet schema = new XmlSchemaSet();
schema.Add(null, "Spreadsheet.xsd");
XmlReaderSettings xmlSetting = new XmlReaderSettings();
xmlSetting.ValidationType = ValidationType.Schema;
xmlSetting.Schemas = schema;
xmlSetting.ValidationEventHandler += (object sender, ValidationEventArgs e) => throw new SpreadsheetReadException("not valid");
using (XmlReader xmlReader = XmlReader.Create(source, xmlSetting))
{
while (xmlReader.Read())
{
if (xmlReader.IsStartElement())
{
if (xmlReader.Name == "cell")
{
if (cells.ContainsKey(xmlReader["name"]))
{
throw new SpreadsheetReadException("duplicate cell in the source");
}
IsValid = checkValid;
try
{
this.SetContentsOfCell(xmlReader["name"], xmlReader["contents"]);
}
catch (FormulaFormatException e)
{
throw new SpreadsheetReadException("invalid");
}
catch (CircularException e)
{
throw new SpreadsheetReadException("invalid");
}
catch (InvalidNameException e)
{
throw new SpreadsheetReadException("invalid");
}
IsValid = newIsValid;
try
{
this.SetContentsOfCell(xmlReader["name"], xmlReader["contents"]);
}
catch (FormulaFormatException e)
{
throw new SpreadsheetVersionException("invalid");
}
catch (CircularException e)
{
throw new SpreadsheetVersionException("invalid");
}
catch (InvalidNameException e)
{
throw new SpreadsheetVersionException("invalid");
}
}
else if (xmlReader.Name == "spreadsheet")
{
try
{
checkValid = new Regex(xmlReader["IsValid"]);
}
catch (ArgumentException e)
{
throw new SpreadsheetReadException("invalid");
}
}
}
}
}
}
// ADDED FOR PS5
/// <summary>
/// Constructs a spreadsheet by recording its variable validity test,
/// its normalization method, and its version information. The variable validity
/// test is used throughout to determine whether a string that consists of one or
/// more letters followed by one or more digits is a valid cell name. The variable
/// equality test should be used thoughout to determine whether two variables are
/// equal.
/// </summary>
public Spreadsheet(Func <string, bool> isValid, Func <string, string> normalize, string version) :
base(isValid, normalize, version)
{
usedCells = new Dictionary <string, Cell>();
depGraph = new DependencyGraph();
}
/// <summary>
/// constrctor
/// </summary>
public Spreadsheet()
{
DG = new DependencyGraph();
Sheet = new Dictionary <string, Cell>();
}
/// <summary>
/// Constructor Method, sets all data values to new.
/// </summary>
public Spreadsheet() : base(s => true, s => s, "default")
{
spreadSheetCells = new Dictionary <string, Cell>();
dependencies = new DependencyGraph();
Changed = false;
}