// This function will go through a pre-compiled expression and resolve all periods (e.g. "yem#y + 300#y" => "yem#y + 300/12")
void ResolvePeriods(ref Calculator_Expression exp)
{
if (exp is BinaryExpression) // if binary, look for footnote
{
if (exp._token.ID == TKID.FOOT) // if there is one, copy it to the parts and continue deeper
{
if ((exp as BinaryExpression)._rgt is VariableExpression)
{
string foot = ((exp as BinaryExpression)._rgt as VariableExpression)._name;
if (periods.ContainsKey("#" + foot)) // got a period footnote
{
// consider better handling or better message
if (!((exp as BinaryExpression)._lft is Calculator_Expression))
{
throw new Exception("Period footnotes are only allowed on numbers.");
}
// reduce the usage count
_vars[foot]--;
// if no usage left, then remove variable
if (_vars[foot] == 0)
{
_vars.Remove(foot);
}
exp = (exp as BinaryExpression)._lft;
exp._token.Value = double.Parse(exp._token.Value.ToString()) * periods["#" + foot];
}
else
{
// consider better handling or better message
throw new Exception($"Unrecognised period footnote '{foot}'.");
}
}
else // else dig deeper
{
ResolvePeriods(ref (exp as BinaryExpression)._lft);
ResolvePeriods(ref (exp as BinaryExpression)._rgt);
}
}
else // else dig deeper
{
ResolvePeriods(ref (exp as BinaryExpression)._lft);
ResolvePeriods(ref (exp as BinaryExpression)._rgt);
}
}
else if (exp is UnaryExpression) // if not binary, just dig deeper
{
ResolvePeriods(ref (exp as UnaryExpression)._expr);
}
else if (exp is FunctionExpression)
{
for (int i = 0; i < (exp as FunctionExpression)._parms.Count; i++)
{
Calculator_Expression expr = (exp as FunctionExpression)._parms[i];
ResolvePeriods(ref expr);
(exp as FunctionExpression)._parms[i] = expr;
}
}
}
// This function will go through a pre-compiled expression and propagate _level footnotes (e.g. "{yem + bch > 400}#1" => "{yem#1 + bch#1 > 400}")
void PropagateFootnotes(ref Calculator_Expression exp)
{
if (exp is BinaryExpression) // if binary, look for footnote
{
if (exp._token.ID == TKID.FOOT) // if there is one, copy it to the parts and continue deeper
{
string foot = (exp as BinaryExpression)._rgt._token.Value.ToString();
exp = (exp as BinaryExpression)._lft;
CopyFootnote(ref exp, foot);
PropagateFootnotes(ref exp);
}
else // else dig deeper
{
PropagateFootnotes(ref (exp as BinaryExpression)._lft);
PropagateFootnotes(ref (exp as BinaryExpression)._rgt);
}
}
else if (exp is UnaryExpression) // if not binary, just dig deeper
{
PropagateFootnotes(ref (exp as UnaryExpression)._expr);
}
else if (exp is FunctionExpression)
{
for (int i = 0; i < (exp as FunctionExpression)._parms.Count; i++)
{
Calculator_Expression expr = (exp as FunctionExpression)._parms[i];
PropagateFootnotes(ref expr);
(exp as FunctionExpression)._parms[i] = expr;
}
}
}
public override Calculator_Expression Optimize()
{
_expr = _expr.Optimize();
return(_expr._token.Type == TKTYPE.LITERAL
? new Calculator_Expression(this.Evaluate(null))
: this);
}
public override Calculator_Expression Optimize()
{
_lft = _lft.Optimize();
_rgt = _rgt.Optimize();
return(_lft._token.Type == TKTYPE.LITERAL && _rgt._token.Type == TKTYPE.LITERAL
? new Calculator_Expression(this.Evaluate(null))
: this);
}
/// <summary>
/// Evaluates an expression.
/// </summary>
/// <param name="operants">The formula variables with their values.</param>
/// <param name="expression">The expression to evaluate.</param>
/// <returns>The value of the expression.</returns>
public double CalculateExpression(Dictionary <string, double> operands, Calculator_Expression expression)
{
var x = expression.Evaluate(operands);
if (x is bool)
{
return((bool)x ? 1.0 : 0.0);
}
return((double)x);
}
Calculator_Expression ParseAtom()
{
string id;
Calculator_Expression x = null;
FunctionDefinition fnDef = null;
switch (_token.Type)
{
// literals
case TKTYPE.LITERAL:
x = new Calculator_Expression(_token);
break;
// identifiers
case TKTYPE.IDENTIFIER:
// get identifier
id = (string)_token.Value;
// look for functions
if (_fnTbl.TryGetValue(id, out fnDef))
{
var p = GetParameters();
var pCnt = p == null ? 0 : p.Count;
if (fnDef.ParmMin != -1 && pCnt < fnDef.ParmMin)
{
Throw($"Too few parameters for function {id}.");
}
if (fnDef.ParmMax != -1 && pCnt > fnDef.ParmMax)
{
Throw($"Too many parameters for function {id}.");
}
x = new FunctionExpression(fnDef, p);
break;
}
if (!_vars.ContainsKey(id))
{
_vars.Add(id, 1); // if variable does not exist, add with value 1
}
else
{
_vars[id]++; // else increase value by 1. At this point, value counts usage.
}
x = new VariableExpression(_vars, id);
break;
// sub-expressions
case TKTYPE.GROUP:
// anything other than opening parenthesis is illegal here
if (_token.ID != TKID.OPEN)
{
Throw("Expression expected.");
}
// get expression
GetToken();
x = ParseOr();
// check that the parenthesis was closed
if (_token.ID != TKID.CLOSE)
{
Throw("Unbalanced parenthesis.");
}
break;
// logical sub-expressions
case TKTYPE.LGROUP:
if (!isCond)
{
Throw("Curly brackets are only allowed within condition formulas.");
}
// anything other than opening parenthesis is illegal here
if (_token.ID != TKID.LOPEN)
{
Throw("Expression expected.");
}
// get expression
GetToken();
x = ParseOr();
// check that the parenthesis was closed
if (_token.ID != TKID.LCLOSE)
{
Throw("Unbalanced parenthesis.");
}
break;
}
// make sure we got something...
if (x == null)
{
Throw($"Unexpected token '{_token.Value}' found in position {_ptr} of the formula.");
}
// done
GetToken();
return(x);
}
/// <summary>
/// Evaluates an expression.
/// </summary>
/// <param name="expression">Expression to evaluate.</param>
/// <returns>The value of the expression.</returns>
public double Evaluate(Calculator_Expression expression)
{
return((double)expression.Evaluate(null));
}
// This function will go through a pre-compiled expression and try to super-optimize it
void OptimizeExpression(ref Calculator_Expression exp)
{
if (exp is BinaryExpression) // optimize BinaryExpressions
{
Calculator_Expression lft = (exp as BinaryExpression)._lft;
Calculator_Expression rgt = (exp as BinaryExpression)._rgt;
OptimizeExpression(ref (exp as BinaryExpression)._lft);
OptimizeExpression(ref (exp as BinaryExpression)._rgt);
// if this is a multiplication try to optimize:
// - multiplications by 0
// - multiplications by 1 (e.g. due to #m footnotes)
// - multiplications where the order can be changed to bring literals together (e.g. "2 * b * 3" = "2 * 3 * b" = "6 * b")
if (exp._token.ID == TKID.MUL)
{
if (lft._token.Type == TKTYPE.LITERAL) // check if the left side is literal
{
if ((double)lft._token.Value == 1) // if 1, return the right side
{
exp = rgt;
return;
}
if ((double)lft._token.Value == 0) // if 0, return 0
{
exp = new Calculator_Expression(new Token(0.0, TKID.ATOM, TKTYPE.LITERAL));
return;
}
if (rgt._token.ID == TKID.MUL) // check if the right side is also a multiplication, maybe we can move literals around
{
if ((rgt as BinaryExpression)._lft._token.Type == TKTYPE.LITERAL)
{
(exp as BinaryExpression)._lft._token.Value = (double)lft._token.Value * (double)(rgt as BinaryExpression)._lft._token.Value;
(exp as BinaryExpression)._rgt = (rgt as BinaryExpression)._rgt;
}
if ((rgt as BinaryExpression)._rgt._token.Type == TKTYPE.LITERAL)
{
(exp as BinaryExpression)._lft._token.Value = (double)lft._token.Value * (double)(rgt as BinaryExpression)._rgt._token.Value;
(exp as BinaryExpression)._rgt = (rgt as BinaryExpression)._lft;
}
}
}
if (rgt._token.Type == TKTYPE.LITERAL) // check if the right side is literal
{
if ((double)rgt._token.Value == 1) // if 1, return the right side
{
exp = lft;
return;
}
if ((double)rgt._token.Value == 0) // if 0, return 0
{
exp = new Calculator_Expression(new Token(0.0, TKID.ATOM, TKTYPE.LITERAL));
return;
}
if (lft._token.ID == TKID.MUL) // check if the left side is also a multiplication, maybe we can move literals around
{
if ((lft as BinaryExpression)._lft._token.Type == TKTYPE.LITERAL)
{
(exp as BinaryExpression)._rgt._token.Value = (double)rgt._token.Value * (double)(lft as BinaryExpression)._lft._token.Value;
(exp as BinaryExpression)._lft = (lft as BinaryExpression)._rgt;
}
if ((lft as BinaryExpression)._rgt._token.Type == TKTYPE.LITERAL)
{
(exp as BinaryExpression)._rgt._token.Value = (double)rgt._token.Value * (double)(lft as BinaryExpression)._rgt._token.Value;
(exp as BinaryExpression)._lft = (lft as BinaryExpression)._lft;
}
}
}
}
}
exp.Optimize(); // finally, perform standard optimization again for any remaining calculations
}
// helper function for PropagateFootnotes
void CopyFootnote(ref Calculator_Expression exp, string foot)
{
if (exp is VariableExpression) // if variable, then copy footnote
{
// get the variable name
string v = (exp as VariableExpression)._name;
// reduce the usage count
_vars[v]--;
// if no usage left, then remove variable
if (_vars[v] == 0)
{
_vars.Remove(v);
}
// build new name
v += "#" + foot;
// add new variable or increase usage count
if (_vars.ContainsKey(v))
{
_vars[v]++;
}
else
{
_vars.Add(v, 1);
}
// make sure the token is also updated
(exp as VariableExpression)._name = v;
}
else if (exp is BinaryExpression) // else dig deeper
{
Calculator_Expression lft = (exp as BinaryExpression)._lft;
Calculator_Expression rgt = (exp as BinaryExpression)._rgt;
if (lft is VariableExpression || lft is BinaryExpression || lft is UnaryExpression || lft is FunctionExpression)
{
CopyFootnote(ref lft, foot);
}
if (rgt is VariableExpression || rgt is BinaryExpression || rgt is UnaryExpression || rgt is FunctionExpression)
{
CopyFootnote(ref rgt, foot);
}
}
else if (exp is UnaryExpression)
{
Calculator_Expression expr = (exp as UnaryExpression)._expr;
if (expr is VariableExpression || expr is BinaryExpression || expr is UnaryExpression || expr is FunctionExpression)
{
CopyFootnote(ref expr, foot);
}
}
else if (exp is FunctionExpression)
{
for (int i = 0; i < (exp as FunctionExpression)._parms.Count; i++)
{
Calculator_Expression expr = (exp as FunctionExpression)._parms[i];
if (expr is VariableExpression || expr is BinaryExpression || expr is UnaryExpression || expr is FunctionExpression)
{
CopyFootnote(ref expr, foot);
}
}
}
else
{
Throw("Invalid use of footnote.");
}
}
// ** ctor
public BinaryExpression(Token tk, Calculator_Expression exprLeft, Calculator_Expression exprRight) : base(tk)
{
_lft = exprLeft;
_rgt = exprRight;
}
// ** ctor
public UnaryExpression(Token tk, Calculator_Expression expr) : base(tk)
{
_expr = expr;
}