public Evaluator(Instructions instructions, Tokens tokens = null)
{
Memory = new double[instructions.Count];
Variables = new Dictionary<char, double>(30);
Variables.Add('p', Math.PI);
Variables.Add('e', Math.E);
Instructions = instructions;
IsConstantExpression = true;
if (tokens == null)
{
foreach (var token in tokens) {
if (token == TokenType.Variable)
{
IsConstantExpression = false;
break;
}
}
if (IsConstantExpression)
{
IsConstantExpression = false;
Evaluate();
IsConstantExpression = true;
}
}
else
{
IsConstantExpression = false;
}
}
public Tokens GenerateTokens()
{
int N = Expression.Length;
Tokens tokens = new Tokens(N);
StringBuilder tokenValue = new StringBuilder(N);
State currentState = State.BEGIN;
int position = 0;
while (position <= N && !LexicalError)
{
char symbol = position < N ? Expression[position] : EndOfExpression;
switch (currentState)
{
case State.BEGIN:
if (Char.IsLetter(symbol))
{
tokenValue.Append(symbol);
currentState = State.VAR;
}
else if (Char.IsDigit(symbol))
{
tokenValue.Append(symbol);
currentState = State.NUM1;
}
else if ("+-*/^()".Contains(symbol))
{
tokenValue.Append(symbol);
currentState = State.OK;
}
else if (symbol != EndOfExpression)
{
if (position < N)
{
var error = String.Format("Invalid symbol {0}", symbol);
TokenError = new Token(TerminalSymbolType.UnRecognized, position, error);
tokens.Add(TokenError);
LexicalError = true;
}
}
position++;
break;
case State.VAR:
if (Char.IsLetter(symbol))
{
tokenValue.Append(symbol);
position++;
currentState = State.FUNC;
}
else
{
tokens.Add(new Token(TokenType.Variable, position, tokenValue.ToString()));
tokenValue.Clear();
currentState = State.BEGIN;
}
break;
case State.FUNC:
if (Char.IsLetter(symbol))
{
tokenValue.Append(symbol);
position++;
}
else
{
var str = tokenValue.ToString();
if (IsFunction(str))
{
tokens.Add(new Token(TokenType.Function, position, str));
tokenValue.Clear();
currentState = State.BEGIN;
}
else
{
var error = String.Format("Unrecognized {0}", str);
TokenError = new Token(TokenType.UnRecognized, position, error);
tokens.Add(TokenError);
LexicalError = true;
}
}
break;
case State.OK:
tokens.Add(makeOneCharToken(tokenValue.ToString(), position));
tokenValue.Clear();
currentState = State.BEGIN;
break;
case State.NUM1:
if (Char.IsDigit(symbol))
{
tokenValue.Append(symbol);
position++;
}
else if (symbol == '.')
{
tokenValue.Append(symbol);
position++;
currentState = State.TRANS;
}
else
{
tokens.Add(new Token(TokenType.Value, position, tokenValue.ToString()));
tokenValue.Clear();
currentState = State.BEGIN;
}
break;
case State.TRANS:
if (Char.IsDigit(symbol))
{
tokenValue.Append(symbol);
position++;
currentState = State.NUM2;
}
else
{
var error = String.Format("Invalid number format {0}", tokenValue.Append(symbol));
TokenError = new Token(TokenType.UnRecognized, position, error);
tokens.Add(TokenError);
LexicalError = true;
}
break;
case State.NUM2:
if (Char.IsDigit(symbol))
{
tokenValue.Append(symbol);
position++;
}
else
{
tokens.Add(new Token(TokenType.Value, position, tokenValue.ToString()));
tokenValue.Clear();
currentState = State.BEGIN;
}
break;
}
}
return tokens;
}
