Implemented ParserStateDeductor which is used to deduce the current ParserState given the Type signature extracted from a ParserScope.

1 files changed, 79 insertions, 0 deletions

diff --git a/src/core/parser/ParserState.cpp b/src/core/parser/ParserState.cpp
index b0b02d2..9d3aa7e 100644
--- a/src/core/parser/ParserState.cpp
+++ b/src/core/parser/ParserState.cpp
@@ -25,10 +25,12 @@ namespace ousia {
 ParserState::ParserState() : elementHandler(nullptr), childHandler(nullptr) {}
 
 ParserState::ParserState(ParserStateSet parents, Arguments arguments,
+                         RttiSet createdNodeTypes,
                          HandlerConstructor elementHandler,
                          HandlerConstructor childHandler)
     : parents(parents),
       arguments(arguments),
+      createdNodeTypes(createdNodeTypes),
       elementHandler(elementHandler),
       childHandler(childHandler)
 {
@@ -65,6 +67,18 @@ ParserStateBuilder &ParserStateBuilder::arguments(const Arguments &arguments)
 	return *this;
 }
 
+ParserStateBuilder &ParserStateBuilder::createdNodeType(const Rtti *type)
+{
+	state.createdNodeTypes = RttiSet{type};
+	return *this;
+}
+
+ParserStateBuilder &ParserStateBuilder::createdNodeTypes(const RttiSet &types)
+{
+	state.createdNodeTypes = types;
+	return *this;
+}
+
 ParserStateBuilder &ParserStateBuilder::elementHandler(
     HandlerConstructor elementHandler)
 {
@@ -81,6 +95,71 @@ ParserStateBuilder &ParserStateBuilder::childHandler(
 
 const ParserState &ParserStateBuilder::build() const { return state; }
 
+/* Class ParserStateDeductor */
+
+ParserStateDeductor::ParserStateDeductor(
+    std::vector<const Rtti *> signature,
+    std::vector<const ParserState *> states)
+    : tbl(signature.size()),
+      signature(std::move(signature)),
+      states(std::move(states))
+{
+}
+
+bool ParserStateDeductor::isActive(size_t d, const ParserState *s)
+{
+	// Lookup the "active" state of (d, s), if it was not already set
+	// (e.second is true) we'll have to calculate it
+	auto e = tbl[d].emplace(s, false);
+	bool &res = e.first->second;
+	if (!e.second) {
+		return res;
+	}
+
+	// Check whether this node is generative (may have produced the Node
+	// described by the current Signature element)
+	bool isGenerative = signature[d]->isOneOf(s->createdNodeTypes);
+
+	if (isGenerative && d == 0) {
+		// End of recursion -- the last signature element is reached and the
+		// node was generative
+		res = true;
+	} else {
+		// Try repetition of this node
+		if (isGenerative && isActive(d - 1, s)) {
+			res = true;
+		} else {
+			// Check whether any of the parent nodes were active -- either for
+			// the previous element (if this one is generative) or for the
+			// current element (assuming this node was not generative)
+			for (const ParserState *parent : s->parents) {
+				if ((isGenerative && isActive(d - 1, parent)) ||
+					isActive(d, parent)) {
+					res = true;
+					break;
+				}
+			}
+		}
+	}
+
+	return res;
+}
+
+std::vector<const ParserState *> ParserStateDeductor::deduce()
+{
+	std::vector<const ParserState *> res;
+	if (!signature.empty()) {
+		const size_t D = signature.size();
+		for (auto s : states) {
+			if (signature[D - 1]->isOneOf(s->createdNodeTypes) &&
+			    isActive(D - 1, s)) {
+				res.push_back(s);
+			}
+		}
+	}
+	return res;
+}
+
 /* Constant initializations */
 
 namespace ParserStates {