private Expression ParsePoW(CharIterator it)
{
var exp1 = ParseUnitary(it);
if (it.Valid() && it.Value() == '^')
{
it.MoveNext();
if (it.Valid() && IsNum(it.Value()))
{
char ch = it.Value();
it.MoveNext();
if (it.Valid() && IsNum(it.Value()))
{
throw new Exception("Need a number in range (0-9)");
}
int n = ch - '0';
exp1 = new PowExpression(Op.Pow, exp1, n);
}
else
{
throw new Exception("Need a number after ^!");
}
}
return(exp1);
}
private double ReadNum(CharIterator it)
{
var sb = new StringBuilder();
// read - +
if (it.Value() == '-' || it.Value() == '+')
{
sb.Append(it.Value());
it.MoveNext();
}
// read integer
for (; it.Valid() && IsNum(it.Value());)
{
sb.Append(it.Value());
it.MoveNext();
}
// read faction
if (it.Valid() && it.Value() == '.')
{
sb.Append(it.Value());
it.MoveNext();
// read faction
for (; it.Valid() && IsNum(it.Value());)
{
sb.Append(it.Value());
it.MoveNext();
}
}
// read exponent
if (it.Valid() && (it.Value() == 'E' || it.Value() == 'e'))
{
sb.Append(it.Value());
it.MoveNext();
// read - +
if (it.Valid() && (it.Value() == '-' || it.Value() == '+'))
{
sb.Append(it.Value());
it.MoveNext();
}
// read integer
for (; it.Valid() && IsNum(it.Value());)
{
sb.Append(it.Value());
it.MoveNext();
}
}
double ret = System.Convert.ToDouble(sb.ToString());
return(ret);
}
public Expression ParseExpression(String str)
{
var it = new CharIterator(str);
var exp1 = ParseAdd(it);
if (it.Valid())
{
throw new Exception("should reach end of string");
}
return(exp1);
}
private Expression ParseAdd(CharIterator it)
{
var exp1 = ParseMul(it);
for (; it.Valid() && (it.Value() == '+' || it.Value() == '-');)
{
char ch = it.Value();
Op op = ch == '+' ? Op.Add : Op.Sub;
it.MoveNext();
var exp2 = ParseMul(it);
exp1 = new BinaryExpression(op, exp1, exp2);
}
return(exp1);
}
private Expression ParseMul(CharIterator it)
{
var exp1 = ParsePoW(it);
for (; it.Valid() && (it.Value() == '*' || it.Value() == '/');)
{
char ch = it.Value();
Op op = ch == '*' ? Op.Mul : Op.Div;
it.MoveNext();
var exp2 = ParsePoW(it);
exp1 = new BinaryExpression(op, exp1, exp2);
}
return(exp1);
}
private Expression ParseID(CharIterator it)
{
char ch = it.Value();
if (IsAlpha(ch) || ch == '@')
{
String varname = ReadString(it);
Variable variable;
if (!fVarsDir.TryGetValue(varname, out variable))
{
variable = new Variable(varname);
variable.fIndex = fVars.Count;
variable.fName = varname;
if (fValues.ContainsKey(varname))
{
variable.fVal = fValues[varname];
}
else
{
variable.fVal = gRnd.Next() % 1000 / 1000.0;
}
fVars.Add(variable);
fVarsDir.Add(varname, variable);
}
var id = new IDExpression(variable);
return(id);
}
else if (ch == '-' || ch == '+' || IsNum(ch))
{
double v = ReadNum(it);
var num = new NumberExpression(v);
return(num);
}
else if (ch == '(')
{
it.MoveNext();
var expr = ParseAdd(it);
if (it.Valid() && it.Value() == ')')
{
it.MoveNext();
return(expr);
}
else
{
throw new Exception("Expect ')'");
}
}
throw new Exception("Need a id or number!");
}
private String ReadString(CharIterator it)
{
var sb = new StringBuilder();
for (; it.Valid();)
{
char ch = it.Value();
if (IsAlpha(ch) || ch == '@' || IsNum(ch))
{
sb.Append(ch);
it.MoveNext();
}
else
{
break;
}
}
return(sb.ToString());
}
private Expression ParseUnitary(CharIterator it)
{
if (it.Valid() && (it.Value() == '-' || it.Value() == '+'))
{
var op = it.Value() == '-' ? Op.Negative : Op.Positive;
it.MoveNext();
var exp = ParseUnitary(it);
if (exp is NumberExpression)
{
var ne = (NumberExpression)exp;
if (op == Op.Negative)
{
ne.fValue = -ne.fValue;
}
return(ne);
}
else
{
return(new UnitaryExpression(op, exp));
}
}
return(ParseID(it));
}
