/// <summary>
/// This method split the equation (string) into a tree of equations (string) according the parentheses
/// </summary>
/// <param name="eq">equation</param>
/// <param name="index">starting index of the equation in the string</param>
/// <returns>tree</returns>
public static UnparsedEq DivideStr(string eq, ref int index)
{
UnparsedEq result = new UnparsedEq();
result.str = "";
result.subEqs = new List <UnparsedEq>();
int nbSubEq = 0;
while (eq[index] != ')')
{
char current = eq[index];
if (current == '(')
{
index++;
//We generate an unique id for each subtree to link it in the main string
result.str += "%" + nbSubEq.ToString("000");
nbSubEq++;
result.subEqs.Add(DivideStr(eq, ref index));
}
else
{
result.str += current;
}
index++;
}
return(result);
}
/// <summary>
/// Returns an equation from the given string, and other stuff
/// </summary>
/// <param name="str">equation to parse</param>
/// <param name="currentUnparsed">current tree</param>
/// <param name="registeredVars">the variables</param>
/// <returns>output equation</returns>
public static Equation Parse(string str, UnparsedEq currentUnparsed, List <string> registeredVars)
{
//this is a recursive function that parse every level of a tree at a time
//we operate everything according to the priority order from lower to higher priority
int index = str.IndexOf("*");//<->
if (index == -1)
{
index = str.IndexOf("→");
if (index == -1)
{
index = str.IndexOf("|");
if (index == -1)
{
index = str.IndexOf("&");
if (index == -1)
{
//at this point there is no dual part operators
index = 0;
//we skip blanks chars to get to the first important char
SkipBlank(str, ref index);
if (str[index] == '!')
{
//if it's the not operator
index++;
var eq = new Not();
//we have to parse the inner equation everytime the current equation is NOT a constant
eq.InternalEquation = Parse(str.Substring(index), currentUnparsed, registeredVars);
return(eq);
}
else if (char.IsLetter(str[index]))
{
//if it starts with a letter, it's a constant
var variableName = "";
char currentChar = str[index];
while (char.IsLetterOrDigit(currentChar) && index < str.Length)
{
//we extract the name of the constant
variableName += currentChar;
index++;
if (index < str.Length)
{
currentChar = str[index];
}
}
SkipBlank(str, ref index);
if (index < str.Length)
{
throw new Exception("Unexpected char :" + str[index]);
}
//we add the discovered constant if it doesn't already exists
if (!registeredVars.Contains(variableName))
{
registeredVars.Add(variableName);
}
var eq = new Constant();
eq.Name = variableName;
return(eq);
}
else if (str[index] == '%')
{
//if it starts with %, it's a sub tree (parentheses)
//we extract the id of the subtree
var nbStr = str.Substring(index + 1, 3);
index += 4;
SkipBlank(str, ref index);
if (index < str.Length)
{
throw new Exception("Unexpected char :" + str[index]);
}
var nextUnparsed = currentUnparsed.subEqs[int.Parse(nbStr)];
//aaaand we parse the subtree
var eq = Parse(nextUnparsed.str, nextUnparsed, registeredVars);
return(eq);
}
else
{
throw new Exception("wrong var starting char");
}
}
else
{
//we have to reverse the string because when there is an equal priority (same operator), we parse from left to right, and not the other way around
//if we isolate the first item every time, it means we parse from right to left
var strs = new List <string>();
foreach (var item in new string(str.Reverse().ToArray()).Split(new string[] { "&" }, 2, StringSplitOptions.None))
{
strs.Add(new string(item.Reverse().ToArray()));
}
//and we just fill the parts of the equation, parsing each side
var eq = new OperatorEquation();
eq.Operator = OperatorEquation.OperatorType.AND;
eq.Right = Parse(strs[0], currentUnparsed, registeredVars);
eq.Left = Parse(strs[1], currentUnparsed, registeredVars);
return(eq);
}
}
else
{
//same things for all the others operators
var strs = new List <string>();
foreach (var item in new string(str.Reverse().ToArray()).Split(new string[] { "|" }, 2, StringSplitOptions.None))
{
strs.Add(new string(item.Reverse().ToArray()));
}
var eq = new OperatorEquation();
eq.Operator = OperatorEquation.OperatorType.OR;
eq.Right = Parse(strs[0], currentUnparsed, registeredVars);
eq.Left = Parse(strs[1], currentUnparsed, registeredVars);
return(eq);
}
}
else
{
var strs = new List <string>();
foreach (var item in new string(str.Reverse().ToArray()).Split(new string[] { "→" }, 2, StringSplitOptions.None))
{
strs.Add(new string(item.Reverse().ToArray()));
}
var eq = new OperatorEquation();
eq.Operator = OperatorEquation.OperatorType.INVOLVING;
eq.Right = Parse(strs[0], currentUnparsed, registeredVars);
eq.Left = Parse(strs[1], currentUnparsed, registeredVars);
return(eq);
}
}
else
{
//<->
var strs = new List <string>();
foreach (var item in new string(str.Reverse().ToArray()).Split(new string[] { "*" }, 2, StringSplitOptions.None))
{
strs.Add(new string(item.Reverse().ToArray()));
}
var eq = new OperatorEquation();
eq.Operator = OperatorEquation.OperatorType.EQUIVALENT;
eq.Right = Parse(strs[0], currentUnparsed, registeredVars);
eq.Left = Parse(strs[1], currentUnparsed, registeredVars);
return(eq);
}
}
public static Equation Parse(string str, UnparsedEq currentUnparsed, List <string> registeredVars)
{
int index = str.IndexOf("*");
if (index == -1)
{
index = str.IndexOf("→");
if (index == -1)
{
index = str.IndexOf("|");
if (index == -1)
{
index = str.IndexOf("&");
if (index == -1)
{
index = 0;
SkipBlank(str, ref index);
if (str[index] == '!')
{
index++;
var eq = new Not();
eq.InternalEquation = Parse(str.Substring(index), currentUnparsed, registeredVars);
return(eq);
}
else if (char.IsLetter(str[index]))
{
var variableName = "";
char currentChar = str[index];
while (char.IsLetterOrDigit(currentChar) && index < str.Length)
{
variableName += currentChar;
index++;
if (index < str.Length)
{
currentChar = str[index];
}
}
SkipBlank(str, ref index);
if (index < str.Length)
{
throw new Exception("Unexpected char :" + str[index]);
}
if (!registeredVars.Contains(variableName))
{
registeredVars.Add(variableName);
}
var eq = new Constant();
eq.Name = variableName;
return(eq);
}
else if (str[index] == '%')
{
var nbStr = str.Substring(index + 1, 3);
index += 4;
SkipBlank(str, ref index);
if (index < str.Length)
{
throw new Exception("Unexpected char :" + str[index]);
}
var nextUnparsed = currentUnparsed.subEqs[int.Parse(nbStr)];
var eq = Parse(nextUnparsed.str, nextUnparsed, registeredVars);
return(eq);
}
else
{
throw new Exception("wrong var starting char");
}
}
else
{
var strs = new List <string>();
foreach (var item in new string(str.Reverse().ToArray()).Split(new string[] { "&" }, 2, StringSplitOptions.None))
{
strs.Add(new string(item.Reverse().ToArray()));
}
var eq = new OperatorEquation();
eq.Operator = OperatorEquation.OperatorType.AND;
eq.Right = Parse(strs[0], currentUnparsed, registeredVars);
eq.Left = Parse(strs[1], currentUnparsed, registeredVars);
return(eq);
}
}
else
{
var strs = new List <string>();
foreach (var item in new string(str.Reverse().ToArray()).Split(new string[] { "|" }, 2, StringSplitOptions.None))
{
strs.Add(new string(item.Reverse().ToArray()));
}
var eq = new OperatorEquation();
eq.Operator = OperatorEquation.OperatorType.OR;
eq.Right = Parse(strs[0], currentUnparsed, registeredVars);
eq.Left = Parse(strs[1], currentUnparsed, registeredVars);
return(eq);
}
}
else
{
var strs = new List <string>();
foreach (var item in new string(str.Reverse().ToArray()).Split(new string[] { "→" }, 2, StringSplitOptions.None))
{
strs.Add(new string(item.Reverse().ToArray()));
}
var eq = new OperatorEquation();
eq.Operator = OperatorEquation.OperatorType.INVOLVING;
eq.Right = Parse(strs[0], currentUnparsed, registeredVars);
eq.Left = Parse(strs[1], currentUnparsed, registeredVars);
return(eq);
}
}
else
{
var strs = new List <string>();
foreach (var item in new string(str.Reverse().ToArray()).Split(new string[] { "*" }, 2, StringSplitOptions.None))
{
strs.Add(new string(item.Reverse().ToArray()));
}
var eq = new OperatorEquation();
eq.Operator = OperatorEquation.OperatorType.EQUIVALENT;
eq.Right = Parse(strs[0], currentUnparsed, registeredVars);
eq.Left = Parse(strs[1], currentUnparsed, registeredVars);
return(eq);
}
}
