private static bool TryTakeMatch(RuleTokenKeeper tokenKeeper, out ApplyIfRuleClause clause)
{
var next = tokenKeeper.Next;
if (next.TokenType == ApplyIfTokenType.Match)
{
var work = new RuleTokenKeeper(tokenKeeper);
work.Take();
if (work.Next.TokenType == ApplyIfTokenType.OpenParen)
{
work.Take();
if (EntityReferenceParser.TryTakeEntityReference(work, out var entityReference))
{
if (work.Next.TokenType == ApplyIfTokenType.CloseParen)
{
work.Take();
}
tokenKeeper.Swap(work);
clause = new MatchClause(entityReference);
return(true);
}
}
}
clause = null;
return(false);
}
internal static bool TryTakeEntityReference(RuleTokenKeeper tokenKeeper, out EntityReference clause)
{
var next = tokenKeeper.Next;
if (next.TokenType == ApplyIfTokenType.Identifier)
{
var work = new RuleTokenKeeper(tokenKeeper);
var entity = work.Take().Text;
if (work.Next.TokenType == ApplyIfTokenType.Period)
{
work.Take();
if (work.Next.TokenType == ApplyIfTokenType.Identifier)
{
var field = work.Take().Text;
tokenKeeper.Swap(work);
clause = new EntityReference(entity, field);
return(true);
}
}
clause = null;
return(false);
}
clause = null;
return(false);
}
private static bool TryTakeRuleSequence(RuleTokenKeeper tokenKeeper, out ApplyIfRuleClause clause)
{
var work = new RuleTokenKeeper(tokenKeeper);
if (TryTakeRuleClause(work, out var left))
{
if (work.Next.TokenType == ApplyIfTokenType.Comma)
{
ApplyIfRuleClause right;
work.Take();
if (TryTakeRuleSequence(work, out right) || TryTakeRuleClause(work, out right))
{
if (work.Finished)
{
tokenKeeper.Swap(work);
clause = new RuleSequenceClause(left, right);
return(true);
}
}
}
}
clause = null;
return(false);
}
private static bool TryTakeRuleClause(RuleTokenKeeper tokenKeeper, out ApplyIfRuleClause clause)
{
if (TryTakeCleanInput(tokenKeeper, out clause) ||
TryTakeFirstError(tokenKeeper, out clause) ||
TryTakeMatch(tokenKeeper, out clause))
{
return(true);
}
clause = null;
return(false);
}
public void Swap(RuleTokenKeeper tokenKeeper)
{
var oldTokens = _tokens;
_tokens = tokenKeeper._tokens;
var oldIndex = _index;
_index = tokenKeeper._index;
tokenKeeper._tokens = oldTokens;
tokenKeeper._index = oldIndex;
}
private static bool TryTakeFirstError(RuleTokenKeeper tokenKeeper, out ApplyIfRuleClause clause)
{
var next = tokenKeeper.Next;
if (next.TokenType == ApplyIfTokenType.FirstError)
{
clause = new FirstErrorClause();
tokenKeeper.Take();
return(true);
}
clause = null;
return(false);
}
private static bool TryTakeCleanInput(RuleTokenKeeper tokenKeeper, out ApplyIfRuleClause clause)
{
var next = tokenKeeper.Next;
if (next.TokenType == ApplyIfTokenType.CleanInput)
{
clause = new CleanInputClause();
tokenKeeper.Take();
return(true);
}
clause = null;
return(false);
}
private static ApplyIfRuleClause TakeClause(RuleTokenKeeper tokenKeeper)
{
ApplyIfRuleClause clause;
if (TryTakeRuleSequence(tokenKeeper, out clause) ||
TryTakeRuleClause(tokenKeeper, out clause))
{
if (tokenKeeper.Finished)
{
return(clause);
}
}
return(new ApplyIfRuleErrorClause("Unable to parse ApplyIf rule."));
}
private static EntityReferenceParseResult PerformParse(IEnumerable <ApplyIfToken> tokens, out string error)
{
var tokenKeeper = new RuleTokenKeeper(tokens.ToList());
if (tokenKeeper.Finished)
{
error = "No entity reference found.";
return(null);
}
if (TryTakeEntityReference(tokenKeeper, out var reference))
{
error = null;
return(new EntityReferenceParseResult(reference));
}
error = "Unable to parse entity reference";
return(new EntityReferenceParseResult(error));
}
private static ApplyIfRule PerformParse(IEnumerable <ApplyIfToken> tokens, out string error)
{
var tokenKeeper = new RuleTokenKeeper(tokens.ToList());
if (tokenKeeper.Finished)
{
error = null;
return(null);
}
var clause = TakeClause(tokenKeeper);
if (clause is ApplyIfRuleErrorClause errorClause)
{
error = errorClause.Error;
}
else
{
error = null;
}
return(new ApplyIfRule(clause));
}
public RuleTokenKeeper(RuleTokenKeeper tokenKeeper)
{
_tokens = tokenKeeper._tokens;
_index = tokenKeeper._index;
}