[C++]: Add sbe.cpp.namespaces.collapse system property

The property optionally (if set to `true`) reverts to backward-compatible collapsed namespaces in generated stubs

Author: didenko

sbe-tool/src/main/java/uk/co/real_logic/sbe/SbeTool.java

@@ -121,6 +121,11 @@ public class SbeTool
  */
  public static final String JAVA_GENERATE_INTERFACES = "sbe.java.generate.interfaces";
 
+ /**
+ * Boolean system property to turn on or off collapsing of nested namespaces in generated C++ stubs. Defaults to false.
+ */
+ public static final String CPP_NAMESPACES_COLLAPSE = "sbe.cpp.namespaces.collapse";
+
  /**
  * Package in which the generated Java interfaces will be placed.
  */

sbe-tool/src/main/java/uk/co/real_logic/sbe/ir/Ir.java

@@ -17,6 +17,8 @@
 
 import org.agrona.Verify;
 
+import uk.co.real_logic.sbe.SbeTool;
+
 import java.util.*;
 import java.util.regex.Pattern;
 
@@ -66,7 +68,14 @@ public Ir(
  this.semanticVersion = semanticVersion;
  this.headerStructure = new HeaderStructure(new ArrayList<>(headerTokens));
 
- this.namespaces = Pattern.compile("\\.").split(namespaceName == null ? packageName : namespaceName);
+ if (Boolean.getBoolean(SbeTool.CPP_NAMESPACES_COLLAPSE))
+ {
+ this.namespaces = new String[]{ (namespaceName == null ? packageName : namespaceName).replace(".", "_") };
+ }
+ else
+ {
+ this.namespaces = Pattern.compile("\\.").split(namespaceName == null ? packageName : namespaceName);
+ }
  }
 
  /**