/// <summary>
/// Takes an arithmetical or logical expression and returns the corresponding variable
/// <para/>Examples:
/// <para/>* "5 + 6" : returns Integer (11)
/// <para/>* "$l[5 * (1 - $i)]" : returns the elements at index 5*(1-i) in the list "l"
/// <para/>* "$l" : returns the list variable l
/// </summary>
/// <param name="expr_string"> expression to parse</param>
/// <returns> Variable object containing the value of the evaluated expression value (at time t)</returns>
public static Variable parse(string expr_string)
{
/* Order of operations:
* checking expression string integrity
* raw dynamic list
* clean redundant symbols
* raw integer value
* raw boolean value (not done yet)
* raw float value (not done yet)
* mathematical or logical operation
* function call
* variable access (e.g. $name or in list by index)
*/
// clean expression
expr_string = StringUtils.normalizeWhiteSpaces(expr_string);
Exception invalid_expr_exception =
new AquilaExceptions.SyntaxExceptions.SyntaxError($"The sentence \"{expr_string}\" is not understood");
Debugging.print("input expression: " + expr_string);
// matching parentheses & brackets
Debugging.assert(StringUtils.checkMatchingDelimiters(expr_string, '(', ')'),
new AquilaExceptions.SyntaxExceptions.UnclosedTagError("Unclosed parenthesis"));
Debugging.assert(StringUtils.checkMatchingDelimiters(expr_string, '[', ']'),
new AquilaExceptions.SyntaxExceptions.UnclosedTagError("Unclosed bracket"));
expr_string = StringUtils.removeRedundantMatchingDelimiters(expr_string, '(', ')');
Debugging.print("dynamic list ?");
// dynamic list
{
DynamicList list = StringUtils.parseListExpression(expr_string);
if (list != null)
{
return(list);
}
}
// now that lists are over, check for redundant brackets
expr_string = StringUtils.removeRedundantMatchingDelimiters(expr_string, '[', ']');
if (expr_string == null)
{
throw new AquilaExceptions.SyntaxExceptions.SyntaxError("Null Expression");
}
Debugging.assert(expr_string != ""); //! NullValue here, instead of Exception
Debugging.print("int ?");
// try evaluating expression as an integer
if (int.TryParse(expr_string, out int int_value))
{
return(new Integer(int_value, true));
}
Debugging.print("bool ?");
// try evaluating expression as a boolean
if (expr_string == "true")
{
return(new BooleanVar(true, true));
}
if (expr_string == "false")
{
return(new BooleanVar(false, true));
}
Debugging.print("float ?");
// try evaluating expression as float
if (!expr_string.Contains(' '))
{
if (float.TryParse(expr_string, out float float_value))
{
Debugging.print("french/classic float");
return(new FloatVar(float_value, true));
}
if (float.TryParse(expr_string.Replace('.', ','), out float_value))
{
Debugging.print("normalized float");
return(new FloatVar(float_value, true));
}
if (expr_string.EndsWith("f") &&
float.TryParse(expr_string.Substring(0, expr_string.Length - 1), out float_value))
{
Debugging.print("f-float");
return(new FloatVar(float_value, true));
}
if (expr_string.EndsWith("f") &&
float.TryParse(expr_string.Replace('.', ',').Substring(0, expr_string.Length - 1), out float_value))
{
Debugging.print("f-float");
return(new FloatVar(float_value, true));
}
}
Debugging.print("checking for negative expression");
// special step: check for -(expr)
if (expr_string.StartsWith("-"))
{
Debugging.print("evaluating expression without \"-\" sign");
string opposite_sign_expr = expr_string.Substring(1); // take away the "-"
Variable opposite_sign_var = parse(opposite_sign_expr);
Debugging.print("evaluated expression without the \"-\" symbol is of type ", opposite_sign_var.getTypeString(), " and value ", opposite_sign_var.getValue());
// ReSharper disable once ConvertIfStatementToSwitchExpression
if (opposite_sign_var is Integer)
{
return(new Integer(-opposite_sign_var.getValue()));
}
if (opposite_sign_var is FloatVar)
{
return(new FloatVar(-opposite_sign_var.getValue()));
}
throw new AquilaExceptions.InvalidTypeError($"Cannot cast \"-\" on a {opposite_sign_var.getTypeString()} variable");
}
Debugging.print("AL operations ?");
// mathematical and logical operations
foreach (char op in Global.al_operations)
{
// ReSharper disable once PossibleNullReferenceException
if (expr_string.Contains(op.ToString()))
{
string simplified = StringUtils.simplifyExpr(expr_string, new [] { op }); // only look for specific delimiter
// more than one simplified expression ?
if (simplified.Split(op).Length > 1)
{
Debugging.print("operation ", expr_string, " and op: ", op);
List <string> splitted_str =
StringUtils.splitStringKeepingStructureIntegrity(expr_string, op, Global.base_delimiters);
// custom: logic operations laziness here (tmp) //!
Variable variable = parse(splitted_str[0]);
if (Global.getSetting("lazy logic") && variable is BooleanVar)
{
Debugging.print("lazy logic evaluation");
bool first = (variable as BooleanVar).getValue();
switch (op)
{
case '|': // when first:
if (first)
{
return(new BooleanVar(true, true));
}
break;
case '&': // when !first:
if (!first)
{
return(new BooleanVar(false, true));
}
break;
}
}
var splitted_var = new List <Variable> {
variable
};
splitted_var.AddRange(splitted_str.GetRange(1, splitted_str.Count - 1).Select(parse));
// reduce the list to a list of one element
// e.g. expr1 + expr2 + expr3 => final_expr
while (splitted_var.Count > 1)
{
// merge the two first expressions
Variable expr1_var = splitted_var[0];
Variable expr2_var = splitted_var[1];
Variable result = applyOperator(expr1_var, expr2_var, op);
// merge result of 0 and 1
splitted_var[0] = result;
// remove 1 (part of it found in 0 now)
splitted_var.RemoveAt(1);
}
return(splitted_var[0]);
}
}
}
Debugging.print("not (!) operator ?");
// '!' operator (only one to take one variable)
if (expr_string.StartsWith("!"))
{
Debugging.assert(expr_string[1] == '(');
Debugging.assert(expr_string[expr_string.Length - 1] == ')');
Variable expr = parse(expr_string.Substring(2, expr_string.Length - 3));
Debugging.assert(expr is BooleanVar);
Debugging.print("base val b4 not operator is ", expr.getValue());
return(((BooleanVar)expr).not());
}
Debugging.print("value function call ?");
// value function call
if (expr_string.Contains("("))
{
string function_name = expr_string.Split('(')[0]; // extract function name
int func_call_length = function_name.Length;
function_name = StringUtils.normalizeWhiteSpaces(function_name);
Debugging.print("function name: ", function_name);
Functions.assertFunctionExists(function_name);
expr_string = expr_string.Substring(func_call_length); // remove function name
expr_string = expr_string.Substring(1, expr_string.Length - 2); // remove parenthesis
Debugging.print("expr_string for function call ", expr_string);
var arg_list = new List <Expression>();
foreach (string arg_string in StringUtils.splitStringKeepingStructureIntegrity(expr_string, ',', Global.base_delimiters))
{
string purged_arg_string = StringUtils.normalizeWhiteSpaces(arg_string);
Expression arg_expr = new Expression(purged_arg_string);
arg_list.Add(arg_expr);
}
if (arg_list.Count == 1 && arg_list[0].expr == "")
{
arg_list = new List <Expression>();
}
Debugging.print("creating value function call with ", arg_list.Count, " parameters");
FunctionCall func_call = new FunctionCall(function_name, arg_list);
return(func_call.callFunction());
}
// function call without parenthesis -> no parameters either
if (!expr_string.StartsWith(StringConstants.Other.VARIABLE_PREFIX) && !expr_string.Contains(' '))
{
Debugging.print($"Call the function \"{expr_string}\" with no parameters");
var func_call = new FunctionCall(expr_string, new List <Expression>());
return(func_call.callFunction());
}
Debugging.print("variable ?");
// variable access
// since it is the last possibility for the parse call to return something, assert it is a variable
Debugging.assert(expr_string.StartsWith(StringConstants.Other.VARIABLE_PREFIX), invalid_expr_exception);
Debugging.print("list access ?");
// ReSharper disable once PossibleNullReferenceException
if (expr_string.Contains("["))
{
// brackets
Debugging.assert(expr_string.EndsWith("]"), invalid_expr_exception); // cannot be "$l[0] + 5" bc AL_operations have already been processed
int bracket_start_index = expr_string.IndexOf('[');
Debugging.assert(bracket_start_index > 1, invalid_expr_exception); // "$[$i - 4]" is not valid
// variable
Expression var_name_expr = new Expression(expr_string.Substring(0, bracket_start_index));
Debugging.print("list name: " + var_name_expr.expr);
// index list
IEnumerable <string> index_list = StringUtils.getBracketsContent(expr_string.Substring(bracket_start_index));
string index_list_expr_string = index_list.Aggregate("", (current, s) => current + s + ", ");
index_list_expr_string = "[" + index_list_expr_string.Substring(0, index_list_expr_string.Length - 2) + "]";
var index_list_expr = new Expression(index_list_expr_string);
Debugging.print("index: " + index_list_expr.expr);
// create a value function call (list_at call)
object[] args = { var_name_expr, index_list_expr };
return(Functions.callFunctionByName("list_at", args));
}
// only variable name, no brackets
Debugging.print("var by name: ", expr_string);
return(variableFromName(expr_string));
}