private static IEnumerable <RuleMatch> GetMatches(
IRule rule,
ExplorerContext context)
{
var leftMatches = context.InvokeRule(rule);
foreach (var m in leftMatches)
{
var newContext = context.MoveForward(m);
var interleaveLength = newContext.MatchInterleave();
var fullMatch = m.AddInterleaveLength(interleaveLength);
yield return(fullMatch);
}
}
public IEnumerable <RuleMatch> InvokeRule(IRule rule)
{
if (rule == null)
{
throw new ArgumentNullException(nameof(rule));
}
if (Depth <= 1)
{
throw new ParsingException("Recursion exceeds limits");
}
var newAmbiantRuleProperties = _ambiantRuleProperties.Merge(rule);
var newExcepts = GetNewRuleExceptions(newAmbiantRuleProperties, rule);
if (newExcepts != null)
{
var interleaveLength = _isInterleaveMatched ? 0 : MatchInterleave();
var newText = Text.Skip(interleaveLength);
var newContext = new ExplorerContext(
newText,
_interleaveRule,
true,
Depth - 1,
newExcepts,
newAmbiantRuleProperties);
var ruleMatches = rule.Match(newContext);
var uniqueRuleMatchesWithInterleaves = new UniqueRuleMatchEnumerable(ruleMatches)
.Select(m => m.AddInterleaveLength(interleaveLength));
#if DEBUG
// Useful when debugging and faster than a breakpoint condition
//if (rule.RuleName == "outputDeclaration")
//{
//}
// No yield, easier to debug
var ruleMatchList = uniqueRuleMatchesWithInterleaves.ToArray();
return(ruleMatchList);
#else
return(uniqueRuleMatchesWithInterleaves);
#endif
}
else
{
return(EMPTY_RULE_MATCHES);
}
}
public RuleMatch Match(string?ruleName, SubString text, int?depth = null)
{
if (string.IsNullOrWhiteSpace(ruleName))
{
ruleName = DEFAULT_RULE_NAME;
}
if (!_ruleMap.ContainsKey(ruleName))
{
throw new ParsingException($"Unknown rule to match: '{ruleName}'");
}
var rule = _ruleMap[ruleName];
var context = new ExplorerContext(text, _interleaveRule, depth);
var matches = GetMatches(rule, context);
var exactLengthMatches = from m in matches
where m.LengthWithInterleaves == text.Length
select m;
// Take the first available match (of right length)
var match = exactLengthMatches.FirstOrDefault();
return(match);
}
private int MatchInterleave(ExplorerContext interleaveContext)
{
if (_interleaveRule == null)
{
return(0);
}
else
{
var interleaveMatch = _interleaveRule.Match(interleaveContext).FirstOrDefault();
if (interleaveMatch == null || interleaveMatch.Text.Length == 0)
{
return(0);
}
else
{
var newInterleaveContext = interleaveContext.MoveForward(interleaveMatch);
// Recursion
var remainingLength = MatchInterleave(newInterleaveContext);
return(interleaveMatch.Text.Length + remainingLength);
}
}
}
