public Alternation(IEBNFItem left, IEBNFItem right)
{
this._left = left;
this._right = right;
this.MinimalLength = this._left.MinimalLength <= this._right.MinimalLength ? this._left.MinimalLength : this._right.MinimalLength;
this.IsOptional = this._left.IsOptional && this._right.IsOptional;
}
/// <summary>
/// Recursive function for finding sequence of Terminals and NonTerminals by rule. Result is IEBNFItem which containst sequence
/// </summary>
private IEBNFItem GetEBNFItem(string rule, List <NonTerminal> listOfExistedTerminals, string endNotation = null)
{
IEBNFItem result = null;
var left = GetStartEBNFItem(rule, listOfExistedTerminals);
var lengthOfLeftRule = left.Rebuild().Length;
var restOfRule = rule.Substring(lengthOfLeftRule, rule.Length - lengthOfLeftRule);
if (string.IsNullOrEmpty(restOfRule))
{
throw new GrammarParseException("Can't find IEBNFItem, rest of rule is null or empty. Check termination charatcter.");
}
var firstChar = restOfRule[0].ToString();
if (!string.IsNullOrEmpty(endNotation) && firstChar.Equals(endNotation))
{
result = left;
}
else if (IsTermination(firstChar))
{
result = left;
}
else
{
var newRule = restOfRule.Substring(1, restOfRule.Length - 1);
var right = GetEBNFItem(newRule, listOfExistedTerminals, endNotation);
switch (firstChar)
{
case Alternation.notation: result = new Alternation(left, right); break;
case Concatenation.notation: result = new Concatenation(left, right, this._cacheLength); break;
}
}
return(result);
}
public Concatenation(IEBNFItem left, IEBNFItem right, int cacheLength)
{
this._left = left;
this._right = right;
this._cache = new SmartFixedCollectionPair <string, CacheItem <string>[]>(cacheLength);
this.MinimalLength = this._left.MinimalLength + this._right.MinimalLength;
this.IsOptional = this._left.IsOptional && this._right.IsOptional;
}
public Optional(IEBNFItem item)
{
this._item = item;
}
public Grouping(IEBNFItem item)
{
this._item = item;
this.MinimalLength = this._item.MinimalLength;
this.IsOptional = this._item.IsOptional;
}
/// <summary>
/// Allows to set right side rule
/// </summary>
internal void SetRightSide(IEBNFItem item)
{
this._rightSide = item;
this.MinimalLength = item.MinimalLength;
this.IsOptional = this._rightSide.IsOptional;
}
public Repetition(IEBNFItem item, int cacheLength)
{
this._item = item;
this._cache = new SmartFixedCollectionPair <string, string[]>(cacheLength);
}
/// <summary>
/// Try to find EBNFItem which can be on right side
/// Its part of recursion it calls GetEBNFItem
/// </summary>
/// <returns></returns>
private IEBNFItem GetStartEBNFItem(string rule, List <NonTerminal> listOfExistedTerminals)
{
IEBNFItem result = null;
switch (rule[0].ToString())
{
case "\"":
{
var builder = new StringBuilder();
for (var i = 1; i < rule.Length; i++)
{
if (rule[i].Equals('"'))
{
break;
}
builder.Append(rule[i]);
}
result = new Terminal(builder.ToString());
}
break;
case var endItem when endItem.Equals(EndRecursion.Current.Notation):
result = EndRecursion.Current;
break;
case var nonItem when Regex.IsMatch(nonItem.ToString(), "[a-zA-Z]"):
{
var builder = new StringBuilder();
foreach (var t in rule)
{
if (Regex.IsMatch(t.ToString(), @"[,;|\[\]\{\}\(\)]"))
{
break;
}
builder.Append(t);
}
result = (from item in listOfExistedTerminals where item.Name.Equals(builder.ToString()) select item).SingleOrDefault();
if (result == null)
{
var emptyNonTerm = this._actualDefinition.GetNewNonTerminalInstance(builder.ToString());
result = emptyNonTerm;
}
}
break;
case var groupItem when Regex.IsMatch(groupItem, @"[\[\{\(]"):
{
var restOfRepRule = rule.Substring(1, rule.Length - 1);
switch (groupItem)
{
case Repetition.notation:
var repItem = GetEBNFItem(restOfRepRule, listOfExistedTerminals, Repetition.endNotation);
result = new Repetition(repItem, this._cacheLength);
break;
case Optional.notation:
var opItem = GetEBNFItem(restOfRepRule, listOfExistedTerminals, Optional.endNotation);
result = new Optional(opItem);
break;
case Grouping.notation:
var grItem = GetEBNFItem(restOfRepRule, listOfExistedTerminals, Grouping.endNotation);
result = new Grouping(grItem);
break;
}
}
break;
default:
throw new GrammarParseException($"Grammar parse error. Can't recognize character: {rule[0]}. Check missing rules characters.", new ArgumentException());
}
return(result);
}
