New class SparseState for storing lexer state that may not

change on most lines.

1 files changed, 71 insertions, 0 deletions

diff --git a/lexlib/SparseState.h b/lexlib/SparseState.h
new file mode 100644
index 000000000..39b6e605a
--- /dev/null
+++ b/lexlib/SparseState.h
@@ -0,0 +1,71 @@
+// Scintilla source code edit control
+/** @file SparseState.h
+ ** Hold lexer state that may change rarely.
+ ** This is often per-line state such as whether a particular type of section has been entered.
+ ** A state continues until it is changed.
+ **/
+// Copyright 2011 by Neil Hodgson <neilh@scintilla.org>
+// The License.txt file describes the conditions under which this software may be distributed.
+
+#ifndef SPARSESTATE_H
+#define SPARSESTATE_H
+
+#ifdef SCI_NAMESPACE
+namespace Scintilla {
+#endif
+
+template <typename T>
+class SparseState {
+	struct State {
+		int position;
+		T value;
+		State(int position_, T value_) : position(position_), value(value_) {
+		}
+		inline bool operator<(const State &other) const {
+			return position < other.position;
+		}
+	};
+	typedef std::vector<State> stateVector;
+	stateVector states;
+public:
+	void Set(int position, T value) {
+		Delete(position);
+		states.push_back(State(position, value));
+	}
+	T ValueAt(int position) {
+		if (!states.size())
+			return T();
+		if (position < states[0].position)
+			return T();
+		State searchValue(position, T());
+		typename stateVector::iterator low =
+			lower_bound(states.begin(), states.end(), searchValue);
+		if (low == states.end()) {
+			return states[states.size()-1].value;
+		} else {
+			if (low->position > position) {
+				low--;
+			}
+			return low->value;
+		}
+	}
+	bool Delete(int position) {
+		State searchValue(position, T());
+		typename stateVector::iterator low =
+			lower_bound(states.begin(), states.end(), searchValue);
+		if (low != states.end()) {
+			states.erase(low, states.end());
+			return true;
+		}
+		return false;
+	}
+	size_t size() {
+		return states.size();
+	}
+};
+
+#ifdef SCI_NAMESPACE
+}
+#endif
+
+#endif