537217: [C++17] Add support for typename keyword for template template parameters

This patch allows for the 'typename' keyword to be used in
template-template template parameter declarations. Additionally, this
patch also fixes an issue in the writer, which caused the ellipsis in
variadic template-template template parameter declaration to be dropped.

Change-Id: I8f68e6053b2b8848b35d1cf6d25d7f4b5b9d396d
Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=537217
Signed-off-by: Felix Morgner <fmorgner@hsr.ch>

7 files changed, 84 insertions, 31 deletions

diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPASTSimpleTypeTemplateParameter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPASTSimpleTypeTemplateParameter.java
index 0b6373bef39..73d74ba510a 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPASTSimpleTypeTemplateParameter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPASTSimpleTypeTemplateParameter.java
@@ -47,7 +47,7 @@ public interface ICPPASTSimpleTypeTemplateParameter extends ICPPASTTemplateParam
 
 
 	/**
-	 * Get the parameter type.
+	 * Get the type of the type parameter (either {@link #st_class} or {@link #st_typename}).
 	 */
 	public int getParameterType();
 	
@@ -62,7 +62,9 @@ public interface ICPPASTSimpleTypeTemplateParameter extends ICPPASTTemplateParam
 	public IASTTypeId getDefaultType();
 
 	/**
-	 * Set the parameter type.
+	 * Set the type of the type parameter.
+	 * 
+	 * @param value The type of the type parameter (either {@link #st_class} or {@link #st_typename})
 	 */
 	public void setParameterType(int value);
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPASTTemplatedTypeTemplateParameter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPASTTemplatedTypeTemplateParameter.java
index b6901bae13d..8948533e473 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPASTTemplatedTypeTemplateParameter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPASTTemplatedTypeTemplateParameter.java
@@ -44,11 +44,29 @@ public interface ICPPASTTemplatedTypeTemplateParameter extends ICPPASTTemplatePa
 			"ICPPASTTemplateTypeTemplateParameter.DEFAULT_VALUE [IASTExpression]"); //$NON-NLS-1$
 
 	/**
+	 * <code>tt_class</code> represents a class.
+	 * @since 6.6
+	 */
+	public static final int tt_class = 1;
+
+	/**
+	 * <code>tt_typename</code> represents a typename.
+	 * @since 6.6
+	 */
+	public static final int tt_typename = 2;
+
+	/**
 	 * Get the nested template parameters.
 	 */
 	public ICPPASTTemplateParameter[] getTemplateParameters();
 
 	/**
+	 * Get the type of the template-template parameter (either {@link #tt_class} or {@link #tt_typename}).
+	 * @since 6.6
+	 */
+	public int getParameterType();
+
+	/**
 	 * Get the (optional) name of this template template parameter. In case there is no name an
 	 * empty name is returned.
 	 */
@@ -85,6 +103,13 @@ public interface ICPPASTTemplatedTypeTemplateParameter extends ICPPASTTemplatePa
 	public void setIsParameterPack(boolean val);
 
 	/**
+	 * Set the type of the template-template parameter.
+	 * @param type The type of the template-template parameter (either {@link #tt_class} or {@link #tt_typename})
+	 * @since 6.6
+	 */
+	public void setParameterType(int type);
+
+	/**
 	 * Set the name of this template template parameter.
 	 */
 	public void setName(IASTName name);
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPNodeFactory.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPNodeFactory.java
index b33183bd746..d2dae11d327 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPNodeFactory.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/cpp/ICPPNodeFactory.java
@@ -358,6 +358,11 @@ public interface ICPPNodeFactory extends INodeFactory {
 
 	public ICPPASTTemplatedTypeTemplateParameter newTemplatedTypeTemplateParameter(IASTName name, IASTExpression defaultValue);
 
+	/**
+	 * @since 6.6
+	 */
+	public ICPPASTTemplatedTypeTemplateParameter newTemplatedTypeTemplateParameter(int type, IASTName name, IASTExpression defaultValue);
+
 	public ICPPASTTemplateId newTemplateId(IASTName templateName);
 
 	public ICPPASTTemplateSpecialization newTemplateSpecialization(IASTDeclaration declaration);
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPASTTemplatedTypeTemplateParameter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPASTTemplatedTypeTemplateParameter.java
index 5741604b23e..4ba508de060 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPASTTemplatedTypeTemplateParameter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPASTTemplatedTypeTemplateParameter.java
@@ -30,6 +30,7 @@ public class CPPASTTemplatedTypeTemplateParameter extends ASTNode implements
 
     private ICPPASTTemplateParameter [] fNestedParameters = null;
     private boolean fIsParameterPack;
+    private boolean fUsesKeywordClass;
     private IASTName fName;
     private IASTExpression fDefaultValue;
 	private CPPTemplateTemplateParameterScope fScope;
@@ -38,6 +39,11 @@ public class CPPASTTemplatedTypeTemplateParameter extends ASTNode implements
 	}
 
 	public CPPASTTemplatedTypeTemplateParameter(IASTName name, IASTExpression defaultValue) {
+		this(tt_class, name, defaultValue);
+	}
+
+	public CPPASTTemplatedTypeTemplateParameter(int type, IASTName name, IASTExpression defaultValue) {
+		fUsesKeywordClass = type == tt_class;
 		setName(name);
 		setDefaultValue(defaultValue);
 	}
@@ -52,6 +58,7 @@ public class CPPASTTemplatedTypeTemplateParameter extends ASTNode implements
 		CPPASTTemplatedTypeTemplateParameter copy = new CPPASTTemplatedTypeTemplateParameter();
 		copy.setName(fName == null ? null : fName.copy(style));
 		copy.setDefaultValue(fDefaultValue == null ? null : fDefaultValue.copy(style));
+		copy.fUsesKeywordClass = fUsesKeywordClass;
 		copy.fIsParameterPack = fIsParameterPack;
 		for (ICPPASTTemplateParameter param : getTemplateParameters())
 			copy.addTemplateParameter(param == null ? null : param.copy(style));
@@ -96,6 +103,17 @@ public class CPPASTTemplatedTypeTemplateParameter extends ASTNode implements
 	}
 
 	@Override
+	public int getParameterType() {
+		return fUsesKeywordClass ? tt_class : tt_typename;
+	}
+
+	@Override
+	public void setParameterType(int type) {
+		assertNotFrozen();
+		fUsesKeywordClass = type == tt_class;
+	}
+
+	@Override
 	public IASTName getName() {
         return fName;
     }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPNodeFactory.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPNodeFactory.java
index a00303b0749..834f34a25c8 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPNodeFactory.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPNodeFactory.java
@@ -775,6 +775,11 @@ public class CPPNodeFactory extends NodeFactory implements ICPPNodeFactory {
 	}
 
 	@Override
+	public ICPPASTTemplatedTypeTemplateParameter newTemplatedTypeTemplateParameter(int type, IASTName name, IASTExpression defaultValue) {
+		return new CPPASTTemplatedTypeTemplateParameter(type, name, defaultValue);
+	}
+
+	@Override
 	public ICPPASTTemplateId newTemplateId(IASTName templateName) {
 		return new CPPASTTemplateId(templateName);
 	}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/GNUCPPSourceParser.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/GNUCPPSourceParser.java
index 8ba5be4d04e..b47dba36e5f 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/GNUCPPSourceParser.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/GNUCPPSourceParser.java
@@ -2540,7 +2540,13 @@ public class GNUCPPSourceParser extends AbstractGNUSourceCodeParser {
 			consume(IToken.tLT);
 			List<ICPPASTTemplateParameter> tparList = templateParameterList(new ArrayList<>());
 			consume(IToken.tGT, IToken.tGT_in_SHIFTR);
-			int endOffset = consume(IToken.t_class).getEndOffset();
+
+			int kind = LT(1);
+			if(kind != IToken.t_class && kind != IToken.t_typename) {
+				throw backtrack;
+			}
+
+			int endOffset = consume(kind).getEndOffset();
 
 			if (LT(1) == IToken.tELLIPSIS) {
 				parameterPack= true;
@@ -2564,6 +2570,7 @@ public class GNUCPPSourceParser extends AbstractGNUSourceCodeParser {
 
 			ICPPASTTemplatedTypeTemplateParameter tpar = getNodeFactory().newTemplatedTypeTemplateParameter(identifierName, defaultValue);
 			tpar.setIsParameterPack(parameterPack);
+			tpar.setParameterType(kind == IToken.t_class ? ICPPASTTemplatedTypeTemplateParameter.tt_class : ICPPASTTemplatedTypeTemplateParameter.tt_typename);
 			setRange(tpar, start.getOffset(), endOffset);
 
 			for (int i = 0; i < tparList.size(); ++i) {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/rewrite/astwriter/TemplateParameterWriter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/rewrite/astwriter/TemplateParameterWriter.java
index 26de0d27400..34ac4ed0b08 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/rewrite/astwriter/TemplateParameterWriter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/rewrite/astwriter/TemplateParameterWriter.java
@@ -11,6 +11,8 @@
  *******************************************************************************/
 package org.eclipse.cdt.internal.core.dom.rewrite.astwriter;
 
+import org.eclipse.cdt.core.dom.ast.IASTName;
+import org.eclipse.cdt.core.dom.ast.IASTNode;
 import org.eclipse.cdt.core.dom.ast.IASTParameterDeclaration;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPASTParameterDeclaration;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPASTSimpleTypeTemplateParameter;
@@ -28,7 +30,7 @@ import org.eclipse.cdt.internal.core.dom.rewrite.commenthandler.NodeCommentMap;
  * @author Emanuel Graf IFS
  */
 public class TemplateParameterWriter extends NodeWriter {
-	private static final String GREATER_THAN_CLASS = "> class"; //$NON-NLS-1$
+	private static final String GREATER_THAN = ">"; //$NON-NLS-1$
 	private static final String TEMPLATE_LESS_THAN = "template <"; //$NON-NLS-1$
 
 	/**
@@ -43,7 +45,9 @@ public class TemplateParameterWriter extends NodeWriter {
 		if (parameter instanceof ICPPASTParameterDeclaration) {
 			((IASTParameterDeclaration)((ICPPASTParameterDeclaration) parameter)).accept(visitor);
 		} else if (parameter instanceof ICPPASTSimpleTypeTemplateParameter) {
-			writeSimpleTypeTemplateParameter((ICPPASTSimpleTypeTemplateParameter) parameter);
+			ICPPASTSimpleTypeTemplateParameter simple = (ICPPASTSimpleTypeTemplateParameter) parameter;
+			writeTemplateParameter(simple.getParameterType() == ICPPASTSimpleTypeTemplateParameter.st_class,
+			simple.isParameterPack(), simple.getName(), simple.getDefaultType());
 		} else if (parameter instanceof ICPPASTTemplatedTypeTemplateParameter) {
 			writeTemplatedTypeTemplateParameter((ICPPASTTemplatedTypeTemplateParameter) parameter);
 		}
@@ -53,38 +57,25 @@ public class TemplateParameterWriter extends NodeWriter {
 		scribe.print(TEMPLATE_LESS_THAN);
 		ICPPASTTemplateParameter[] params = templated.getTemplateParameters();
 		writeNodeList(params);
-		
-		scribe.print(GREATER_THAN_CLASS);
-		
-		if (templated.getName()!=null){
-			scribe.printSpace();
-			templated.getName().accept(visitor);
-		}
-		
-		if (templated.getDefaultValue() != null){
-			scribe.print(EQUALS);
-			templated.getDefaultValue().accept(visitor);
-		}
+		scribe.print(GREATER_THAN);
+		scribe.printSpace();
+
+		writeTemplateParameter(templated.getParameterType() == ICPPASTTemplatedTypeTemplateParameter.tt_class,
+				templated.isParameterPack(), templated.getName(), templated.getDefaultValue());
 	}
 
-	private void writeSimpleTypeTemplateParameter(ICPPASTSimpleTypeTemplateParameter simple) {
-		switch (simple.getParameterType()) {
-		case ICPPASTSimpleTypeTemplateParameter.st_class:
-			scribe.print(Keywords.CLASS);
-			break;
-		case ICPPASTSimpleTypeTemplateParameter.st_typename:
-			scribe.print(Keywords.TYPENAME);
-			break;
-		}
-		if (simple.isParameterPack()) {
+	private void writeTemplateParameter(boolean usesClass, boolean isVariadic, IASTName name, IASTNode defaultArgument) {
+		scribe.print(usesClass ? Keywords.CLASS : Keywords.TYPENAME);
+		if (isVariadic) {
 			scribe.print(VAR_ARGS);
 		}
 		scribe.printSpace();
-		visitNodeIfNotNull(simple.getName());
-		
-		if (simple.getDefaultType() != null){
+		visitNodeIfNotNull(name);
+
+		if (defaultArgument != null){
 			scribe.print(EQUALS);
-			simple.getDefaultType().accept(visitor);
+			defaultArgument.accept(visitor);
 		}
 	}
+
 }