private void Reduce(StackGraph graph)
{
var newHeads = new List <Node>();
var curHeadList = graph.Heads;
while (curHeadList.Count > 0)
{
var headsWithShifts = curHeadList
.Where(h => Table[h.State].ShiftActionsMap.Count > 0)
.ToList();
newHeads.AddRange(headsWithShifts);
var reducedHeads = curHeadList
.Where(h => Table[h.State].ReduceRulesIds.Count > 0)
.SelectMany(h => Table[h.State].ReduceRulesIds
.Select(r => new { Head = h, Rule = Table.Grammar.Rules[r] }))
.SelectMany(t => FindAllPathsBack(t.Head, t.Rule.SourceTokens.Count + 1)
.Select(p => new { Head = t.Head, Rule = t.Rule, Path = p }))
.Select(t => CreateReduceNode(t.Path, t.Rule))
.Where(rn => rn != null)
.ToList();
curHeadList = reducedHeads;
}
newHeads = CombineNodes(newHeads).ToList();
graph.Heads = newHeads;
}
private void Shift(StackGraph graph, GrammarRuleToken token)
{
List <Node> resultNodes = new List <Node>(graph.Heads.Count);
foreach (var head in graph.Heads)
{
if (Table[head.State].ShiftActionsMap.TryGetValue(token, out int nextState))
{
var newNode = new Node(token, nextState);
newNode.PrevNodes.Add(new Edge {
PrevNode = head, Meta = new ParseExplanation {
ResultToken = token, RuleApplied = null, ChildrenExplained = null
}
});
resultNodes.Add(newNode);
}
else if (Table.Grammar.IsSkipGrammar && Table[head.State].ShiftActionsMap.TryGetValue(Table.Grammar.SkipToken, out int skipState))
{
var newNode = new Node(token, nextState);
newNode.PrevNodes.Add(new Edge {
PrevNode = head, Meta = new ParseExplanation {
ResultToken = token, RuleApplied = null, ChildrenExplained = null
}
});
resultNodes.Add(newNode);
}
}
graph.Heads = CombineNodes(resultNodes).ToList();
}
public void Parse(string[] strTokens)
{
var tokens = strTokens.Select(s => new GrammarRuleToken {
IsTerminal = true, Value = s.Trim()
}).ToList();
int curTokenIndex = 0;
var graph = new StackGraph();
graph.Heads.Add(new Node(null, 0));
while (curTokenIndex <= tokens.Count)
{
Reduce(graph);
if (curTokenIndex < tokens.Count)
{
Shift(graph, tokens[curTokenIndex]);
}
curTokenIndex++;
}
}