Allow the new API for CMakeBuildConfiguration to be extended

PR eclipse-cdt#1010 added the ability to extend CMakeBuildConfiguration and
CMakeBuildConfigurationProvider by making the classes public
API, they used to be internal API.

This change makes it easier to reuse the code in the provider
and configuration by allowing extenders to provide their own
implementations of CMakeBuildConfiguration. This has been
achieved by adding createCMakeBuildConfiguration methods to
control which CMakeBuildConfiguration is constructed.

Follow up to eclipse-cdt#1010

cmake/org.eclipse.cdt.cmake.core/src/org/eclipse/cdt/cmake/core/CMakeBuildConfigurationProvider.java

@@ -27,6 +27,13 @@
 import org.eclipse.core.runtime.Platform;
 
 /**
+ * A ICBuildConfigurationProvider specialized for CMake
+ *
+ * Extenders can provide their own specialised CMakeConfiguration by extending this class and {@link CMakeBuildConfiguration}.
+ * Extenders need to override at least {@link #getId()}, and the various createCMakeBuildConfiguration methods.
+ * See the example project <a href="https://github.com/eclipse-cdt/cdt/tree/main/cmake/org.eclipse.cdt.cmake.example">
+ * org.eclipse.cdt.cmake.example</a> for a full example.
+ *
  * @since 1.6
  */
 public class CMakeBuildConfigurationProvider implements ICBuildConfigurationProvider {
@@ -41,6 +48,30 @@ public String getId() {
 		return ID;
 	}
 
+	/**
+	 * Extenders should override this method to construct their specialized build configuration.
+	 */
+	protected CMakeBuildConfiguration createCMakeBuildConfiguration(IBuildConfiguration config, String name)
+			throws CoreException {
+		return new CMakeBuildConfiguration(config, name);
+	}
+
+	/**
+	 * Extenders should override this method to construct their specialized build configuration.
+	 */
+	protected CMakeBuildConfiguration createCMakeBuildConfiguration(IBuildConfiguration config, String name,
+			IToolChain toolChain) {
+		return new CMakeBuildConfiguration(config, name, toolChain);
+	}
+
+	/**
+	 * Extenders should override this method to construct their specialized build configuration.
+	 */
+	protected CMakeBuildConfiguration createCMakeBuildConfiguration(IBuildConfiguration config, String name,
+			IToolChain toolChain, ICMakeToolChainFile toolChainFile, String launchMode) {
+		return new CMakeBuildConfiguration(config, name, toolChain, toolChainFile, launchMode);
+	}
+
 	@Override
 	public synchronized ICBuildConfiguration getCBuildConfiguration(IBuildConfiguration config, String name)
 			throws CoreException {
@@ -66,13 +97,13 @@ public synchronized ICBuildConfiguration getCBuildConfiguration(IBuildConfigurat
 			}
 
 			if (toolChain != null) {
-				return new CMakeBuildConfiguration(config, name, toolChain);
+				return createCMakeBuildConfiguration(config, name, toolChain);
 			} else {
 				// No valid combinations
 				return null;
 			}
 		}
-		CMakeBuildConfiguration cmakeConfig = new CMakeBuildConfiguration(config, name);
+		CMakeBuildConfiguration cmakeConfig = createCMakeBuildConfiguration(config, name);
 		ICMakeToolChainFile tcFile = cmakeConfig.getToolChainFile();
 		IToolChain toolChain = cmakeConfig.getToolChain();
 		if (toolChain == null) {
@@ -81,7 +112,7 @@ public synchronized ICBuildConfiguration getCBuildConfiguration(IBuildConfigurat
 		}
 		if (tcFile != null && !toolChain.equals(tcFile.getToolChain())) {
 			// toolchain changed
-			return new CMakeBuildConfiguration(config, name, tcFile.getToolChain(), tcFile,
+			return createCMakeBuildConfiguration(config, name, tcFile.getToolChain(), tcFile,
 					cmakeConfig.getLaunchMode());
 		} else {
 			return cmakeConfig;
@@ -136,7 +167,7 @@ public ICBuildConfiguration createBuildConfiguration(IProject project, IToolChai
 			config = configManager.createBuildConfiguration(this, project, name, monitor);
 		}
 
-		CMakeBuildConfiguration cmakeConfig = new CMakeBuildConfiguration(config, name, toolChain, file, launchMode);
+		CMakeBuildConfiguration cmakeConfig = createCMakeBuildConfiguration(config, name, toolChain, file, launchMode);
 		configManager.addBuildConfiguration(config, cmakeConfig);
 		return cmakeConfig;
 	}