/// <summary>
/// Creates new instance of <strong>ExpressionTree</strong> with specified
/// expression.
/// </summary>
/// <exception cref="System.ArgumentNullException" caption="">expression is null</exception>
/// <exception cref="System.ArgumentException" caption="">expression has unknown lexemes</exception>
/// <exception cref="ExpressionSyntaxException" caption="ExpressionSyntaxException Class">expression has syntax errors</exception>
/// <example>
/// <code lang="CS">
/// ExpressionTree tree = new ExpressionTree("sin(x^2) + 10/x");
/// </code>
/// </example>
/// <remarks></remarks>
/// <param name="expression">An symbpolic mathematical expression.</param>
public ExpressionTree(string expression)
{
if (expression == null)
{
throw new ArgumentNullException("expression");
}
if (expression == "")
{
throw new ArgumentException("Blank expression not allowed");
}
_expression = expression;
ExpressionLexeme[] lexemes = ExpressionLexeme.GetLexemes(expression);
foreach (ExpressionLexeme lex in lexemes)
{
if (lex.Lexeme == Lexeme.Unknown)
{
throw new ArgumentException(
string.Format("Expression {0} has unknown lexeme \"{1}\"", _expression, lex.LexemeName),
"expression");
}
}
_parsedExpression = "";
CreateTree(lexemes);
_variables = (string[])new ArrayList(FindVariables(_root).Keys).ToArray(typeof(string));
}
// unary + - operators
private ExpressionTreeNode ExprLevel4()
{
ExpressionTreeNode temp = null;
ExpressionLexeme lex;
switch (CurrentLexeme.Lexeme)
{
case Lexeme.Plus:
NextLexeme();
temp = ExprLevel5();
break;
case Lexeme.Minus:
lex = new ExpressionLexeme("", Lexeme.UMinus);
NextLexeme();
ExpressionTreeNode right = ExprLevel5();
if (right == null)
{
throw new ExpressionSyntaxException("expression expected", _expression, _parsedExpression);
}
temp = new ExpressionTreeNode(lex, right);
break;
default:
temp = ExprLevel5();
break;
}
return(temp);
}
private void CreateTree(ExpressionLexeme[] lexemes)
{
_root = null;
_lexemesQueue = new Queue (lexemes);
NextLexeme();
_root = ExprLevel1();
if (CurrentLexeme.Lexeme != ExpressionLexeme.EndLexeme.Lexeme)
throw new ExpressionSyntaxException("operator expected", _expression, _parsedExpression);
}
private void NextLexeme()
{
if (_lexemesQueue.Count > 0)
{
_parsedExpression += CurrentLexeme.LexemeName;
_curLexeme = (ExpressionLexeme)_lexemesQueue.Dequeue();
}
else
{
_curLexeme = ExpressionLexeme.EndLexeme;
}
}
public ExpressionTreeNode(ExpressionLexeme lexeme,ExpressionTreeNode leftNode,ExpressionTreeNode rightNode )
{
ExpressionLexeme = lexeme;
Left = leftNode;
Right = rightNode;
}
public ExpressionTreeNode(ExpressionLexeme lexeme,ExpressionTreeNode leftNode) :
this (lexeme, leftNode,null)
{
}
public ExpressionTreeNode(ExpressionLexeme lexeme) :
this (lexeme, null,null)
{
}
public ExpressionTreeNode(ExpressionLexeme lexeme, ExpressionTreeNode leftNode, ExpressionTreeNode rightNode)
{
ExpressionLexeme = lexeme;
Left = leftNode;
Right = rightNode;
}
public ExpressionTreeNode(ExpressionLexeme lexeme, ExpressionTreeNode leftNode) :
this(lexeme, leftNode, null)
{
}
public ExpressionTreeNode(ExpressionLexeme lexeme) :
this(lexeme, null, null)
{
}
private void NextLexeme()
{
if (_lexemesQueue.Count > 0)
{
_parsedExpression += CurrentLexeme.LexemeName;
_curLexeme = (ExpressionLexeme)_lexemesQueue.Dequeue();
}
else
_curLexeme = ExpressionLexeme.EndLexeme;
}
// unary + - operators
private ExpressionTreeNode ExprLevel4()
{
ExpressionTreeNode temp = null;
ExpressionLexeme lex;
switch (CurrentLexeme.Lexeme)
{
case Lexeme.Plus:
NextLexeme();
temp = ExprLevel5();
break;
case Lexeme.Minus:
lex = new ExpressionLexeme("",Lexeme.UMinus);
NextLexeme();
ExpressionTreeNode right = ExprLevel5();
if (right == null) throw new ExpressionSyntaxException("expression expected", _expression, _parsedExpression);
temp = new ExpressionTreeNode(lex,right);
break;
default:
temp = ExprLevel5();
break;
}
return temp;
}