add basic python writer for bmap binding

CodeGen/BMapBindings/CommonHelper.java

@@ -0,0 +1,31 @@
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.nio.charset.StandardCharsets;
+
+public class CommonHelper {
+
+	public static InputStreamReader openReader(String filename) throws Exception {
+		FileInputStream fs = new FileInputStream(filename);
+		return new InputStreamReader(fs, StandardCharsets.UTF_8);
+	}
+
+	public static OutputStreamWriter openWriter(String filename) throws Exception {
+		FileOutputStream fs = new FileOutputStream(filename);
+		return new OutputStreamWriter(fs, StandardCharsets.UTF_8);
+	}
+
+	public static void writeSnippet(OutputStreamWriter writer, String snippet_path) throws Exception {
+		// open snippet
+		InputStreamReader reader = openReader(snippet_path);
+		// write into writer
+		reader.transferTo(writer);
+		reader.close();
+	}
+	
+	public static String getDoxygenInOutStr(boolean isInput) {
+		return isInput ? "in" : "out";
+	}
+
+}