Migrate extensible lexer from gentoobrowse-api

1 files changed, 78 insertions, 0 deletions

diff --git a/libadhocutil/lexer.cpp b/libadhocutil/lexer.cpp
new file mode 100644
index 0000000..95e079b
--- /dev/null
+++ b/libadhocutil/lexer.cpp
@@ -0,0 +1,78 @@
+#include "lexer.h"
+
+namespace AdHoc {
+	const Lexer::State Lexer::InitialState = "";
+
+	Lexer::Lexer()
+	{
+	}
+
+	Lexer::Lexer(const Rules & r) : rules(r)
+	{
+	}
+
+	void
+	Lexer::extract(const gchar * string, size_t length) const
+	{
+		ExecuteState es;
+		while (es.position < length) {
+			const Rule * selected = nullptr;
+			for (const auto & r : rules) {
+				const auto & s = boost::get<0>(r);
+				if (s.find(es.getState()) == s.end()) {
+					continue;
+				}
+				const auto & p = boost::get<1>(r);
+				if (p->matches(string, length, es.position)) {
+					selected = &r;
+					break;
+				}
+			}
+			if (!selected) {
+				throw std::runtime_error(std::string("Unexpected input in state (" + es.getState() + ") at ") + (string + es.position));
+			}
+			es.pattern = boost::get<1>(*selected);
+			const auto & h = boost::get<2>(*selected);
+			h(&es);
+			es.position += es.pattern->matchedLength();
+		}
+		
+	}
+
+	Lexer::ExecuteState::ExecuteState() :
+		position(0)
+	{
+		stateStack.push_back(InitialState);
+	}
+
+	void
+	Lexer::ExecuteState::setState(const State & s)
+	{
+		stateStack.back() = s;
+	}
+
+	void
+	Lexer::ExecuteState::pushState(const State & s)
+	{
+		stateStack.push_back(s);
+	}
+
+	void
+	Lexer::ExecuteState::popState()
+	{
+		stateStack.pop_back();
+	}
+
+	const Lexer::State &
+	Lexer::ExecuteState::getState() const
+	{
+		return stateStack.back();
+	}
+
+	size_t
+	Lexer::ExecuteState::depth() const
+	{
+		return stateStack.size();
+	}
+}
+