public void Multiply(Summand summand)
{
Multiplier *= summand.Multiplier;
foreach (var variable in summand.Variables.Keys)
{
AddVariable(variable, summand.Variables[variable]);
}
}
private List <Summand> ParseMultiply()
{
var leftSummands = ParseUnary();
while (true)
{
if (_tokenizer.Token != Token.Multiply &&
_tokenizer.Token != Token.Number &&
_tokenizer.Token != Token.Variable &&
_tokenizer.Token != Token.OpenParens)
{
return(leftSummands);
}
if (_tokenizer.Token == Token.Multiply)
{
_tokenizer.NextToken();
}
var rightSummands = ParseUnary();
Summand localSummand = null;
if (rightSummands.Count == 1)
{
localSummand = rightSummands.First();
}
else if (leftSummands.Count == 1)
{
localSummand = leftSummands.First();
}
// (x + y)(z + y) - for example.
if (localSummand == null)
{
throw new Exception("Multiplying two parent expressions it not supported");
}
if (leftSummands.Count == 1)
{
leftSummands = rightSummands;
}
foreach (var summand in leftSummands)
{
summand.Multiply(localSummand);
}
}
}
public bool IsEqualent(Summand summand)
{
if (summand.Variables.Count != _variables.Count)
{
return(false);
}
foreach (var variable in summand.Variables.Keys)
{
if (!_variables.ContainsKey(variable))
{
return(false);
}
if (_variables[variable] != summand.Variables[variable])
{
return(false);
}
}
return(true);
}
private List <Summand> ParseSummands()
{
if (_tokenizer.Token != Token.Number &&
_tokenizer.Token != Token.Variable &&
_tokenizer.Token != Token.OpenParens)
{
// Upon the village, cross the sky
// Creepy gizmo’s flying by
// There’s excess in those days
// of such gizmos anyways
// http://chastushki.net.ru/texts/22
// P.S. Don't get me wrong...
throw new Exception($"Unexpect token: {_tokenizer.Token}");
}
if (_tokenizer.Token == Token.OpenParens)
{
_tokenizer.NextToken();
var summands = ParseAddAndSubstract();
if (_tokenizer.Token != Token.CloseParens)
{
throw new Exception("Invalid count of parens");
}
_tokenizer.NextToken();
return(summands);
}
var result = new List <Summand>();
var summand = new Summand();
summand.Multiplier = 1;
bool isValidSummand = false;
while (true)
{
if (_tokenizer.Token == Token.Number)
{
summand.Multiplier *= _tokenizer.Number;
isValidSummand = true;
_tokenizer.NextToken();
continue;
}
// skip '*'
if (_tokenizer.Token == Token.Multiply)
{
isValidSummand = false;
_tokenizer.NextToken();
continue;
}
if (_tokenizer.Token == Token.Variable)
{
// TODO: make it with one parameter
summand.AddVariable(_tokenizer.Variable.Name, _tokenizer.Variable.Power);
isValidSummand = true;
_tokenizer.NextToken();
continue;
}
if (isValidSummand)
{
result.Add(summand);
}
else
{
throw new Exception("Invalid multiplication");
}
return(result);
}
}
