private static InvalidSyntacticElement CheckForReservedWordsUsage(List <string> lineElements)
{
InvalidSyntacticElement ise = null;
foreach (string word in lineElements)
{
if (word.IsaReservedWord())
{
ise = new InvalidSyntacticElement("Predicate may not contain reserved words",
word + " Found in predicate " + string.Join(" ", lineElements.ToList()));
break;
}
}
return(ise);
}
private static InvalidSyntacticElement CheckForPredicateSymbol(List <string> lineElements)
{
InvalidSyntacticElement ise = null;
int predicateElementIndex = lineElements.IndexOf(">");
if (predicateElementIndex == -1)
{
ise = new InvalidSyntacticElement("predicate symbol not found", "predicate symbol not found");
}
if (predicateElementIndex == 1)
{
ise = new InvalidSyntacticElement("No predicate name", "the predicate symbol must be in position just after predicate 'name' ");
}
if (predicateElementIndex > 2)
{
ise = new InvalidSyntacticElement("A predicate name can only be one word", "the predicate symbol must be in position just after predicate 'name' ");
}
return(ise);
}
public static SyntacticElement Parse(List <string> lineElements)
{
// syntax is
// <predicate> ::= predicate <name> > <predicate text> [= <value>]
// <name> ::= (<letter>|<number>|<symbol>)*
// <symbol> ::= _@&^*$£!
// <value> ::= true|false
// <predicate text> may not contain a reserved word
//string word = line.ContainsaReservedWord();
InvalidSyntacticElement ise = null;
ise = CheckForPredicateSymbol(lineElements);
if (ise != null)
{
return(ise);
}
ise = CheckForReservedWordsUsage(lineElements);
if (ise != null)
{
return(ise);
}
PredicateSyntacticElement pe = new PredicateSyntacticElement();
pe.Name = lineElements[1];
int equalitySymbolPosition = lineElements.IndexOf("=");
if (equalitySymbolPosition < 0)
{
pe.Value = null;
pe.Predicate = string.Join(" ", lineElements.Skip(3).ToArray());
}
else if (equalitySymbolPosition == lineElements.Count() - 2) // 0 1 2 3 4 5 cnt=6
{ // p p > t = v
pe.Predicate = string.Join(" ", lineElements.Skip(3).
Take(lineElements.Count() - ((lineElements.Count() - equalitySymbolPosition) + 3)).ToArray());
int valueElement = equalitySymbolPosition + 1;
if ((lineElements.Count() - 1) == valueElement)
{
bool result;
if (bool.TryParse(lineElements.Last(), out result))
{
pe.Value = result;
}
else
{
int iResult = 0;
if (int.TryParse(lineElements.Last(), out iResult))
{
if (iResult == 0)
{
pe.Value = false;
}
else if (iResult == 1)
{
pe.Value = true;
}
else
{
ise = new InvalidSyntacticElement("Invalid value", "value must be [true|false], numbers or letters are non truth values and aliases for true or false cannot be used");
return(ise);
}
}
else
{
ise = new InvalidSyntacticElement("Invalid value", "value must be [true|false], numbers or letters are non truth values and aliases for true or false cannot be used");
return(ise);
}
}
}
}
else
{
ise = new InvalidSyntacticElement("Equals sign not in the expected place", "the value must be [true|false], numbers or letters are non truth values and aliases for true or false cannot be used and the value must be the last thing on the line");
return(ise);
}
if (string.IsNullOrWhiteSpace(pe.Predicate))
{
ise = new InvalidSyntacticElement("No predicate text found", "a predicate with no words, you must be a buddha if you think that is sensical");
return(ise);
}
return(pe);
}