add initial simplistic REPL

Makefile

@@ -20,13 +20,16 @@ LIBCS_LIB = libcubescript.a
 .cc.o:
 	$(CXX) $(CXXFLAGS) $(LIBCS_CXXFLAGS) -c -o $@ $<
 
-all: library
+all: library repl
 
 library: $(LIBCS_LIB)
 
 $(LIBCS_LIB): $(LIBCS_OBJ)
 	ar rcs $(LIBCS_LIB) $(LIBCS_OBJ)
 
+repl: $(LIBCS_LIB)
+	$(CXX) $(CXXFLAGS) $(LIBCS_CXXFLAGS) $(LDFLAGS) repl.cc -o repl $(LIBCS_LIB)
+
 clean:
 	rm -f $(LIBCS_LIB) $(LIBCS_OBJ)
 

repl.cc

@@ -0,0 +1,43 @@
+#include <ostd/io.hh>
+#include <ostd/string.hh>
+#include <ostd/maybe.hh>
+
+#include <cubescript.hh>
+
+using namespace cscript;
+
+ostd::ConstCharRange version =
+    "CubeScript 0.0.1 (REPL mode)  Copyright (C) 2016 Daniel \"q66\" Kolesa";
+CsSvar *prompt = nullptr;
+
+static ostd::Maybe<ostd::String> read_line() {
+    ostd::write(prompt->get_value());
+    char buf[512];
+    if (fgets(buf, sizeof(buf), stdin)) {
+        return ostd::String(buf);
+    }
+    return ostd::nothing;
+}
+
+static void do_tty(CsState &cs) {
+    ostd::writeln(version);
+    for (;;) {
+        auto line = read_line();
+        if (!line) {
+            continue;
+        }
+        CsValue ret;
+        ret.set_null();
+        cs.run_ret(line.value(), ret);
+        if (ret.get_type() != CsValueType::null) {
+            ostd::writeln(ret.get_str());
+        }
+    }
+}
+
+int main() {
+    CsState cs;
+    cs.init_libs();
+    prompt = cs.add_ident<CsSvar>("PROMPT", "> ");
+    do_tty(cs);
+}