Bug 367117 - [formatter] cdt hangs when formatting c++ code.

core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/formatter/CodeFormatterVisitor.java

@@ -2623,31 +2623,32 @@ public class CodeFormatterVisitor extends ASTVisitor implements ICPPASTVisitor,
 			return formatOverloadedLeftShiftChain(node);
 		}
 
+		// To improve speed of the algorithm we flatten homogeneous nested binary expressions
+		// to reduce overall depth of the expression tree.
+		List<IASTExpression> operands = getOperandsOfMultiExpression(node);
+		
 		Runnable tailFormatter = endsWithMacroExpansion(node) ? null : scribe.takeTailFormatter();
 
-		Alignment expressionAlignment= scribe.createAlignment(
+		Alignment alignment= scribe.createAlignment(
 				Alignment.BINARY_EXPRESSION,
 				preferences.alignment_for_binary_expression,
 				Alignment.R_OUTERMOST,
-				2,
+				operands.size(),
 				scribe.scanner.getCurrentPosition());
 
-		scribe.enterAlignment(expressionAlignment);
+		scribe.enterAlignment(alignment);
     	boolean ok = false;
     	do {
     		try {
-    			final IASTExpression op1= node.getOperand1();
+    			for (int i = 0; i < operands.size(); i++) {
-    			// Left operand
+    				final IASTExpression operand = operands.get(i);
-    			op1.accept(this);
-    			scribe.printTrailingComment();
-
         			// In case of macros we may have already passed the operator position.
-    			if (scribe.scanner.getCurrentPosition() < node.getOperand2().getFileLocation().getNodeOffset()) {
+        			if (i > 0 && scribe.scanner.getCurrentPosition() < operand.getFileLocation().getNodeOffset()) {
-    				scribe.alignFragment(expressionAlignment, 1);
+        				scribe.alignFragment(alignment, i);
 
     	    			// Operator
     	    			final int nextToken= peekNextToken();
-	    			// In case of C++ alternative operators, like 'and', 'not', etc. a space
+    	    			// In case of C++ alternative operators, like 'and', 'or', etc. a space
     	    			boolean forceSpace= Character.isJavaIdentifierStart(peekNextChar());
 
     					switch (node.getOperator()) {
@@ -2655,29 +2656,58 @@ public class CodeFormatterVisitor extends ASTVisitor implements ICPPASTVisitor,
     					case IASTBinaryExpression.op_pmarrow:
     	    				scribe.printNextToken(nextToken, false);
     	    				break;
+
     	    			default:
     	    				scribe.printNextToken(nextToken, forceSpace || preferences.insert_space_before_binary_operator);
     	    				if (forceSpace || preferences.insert_space_after_binary_operator) {
     	    					scribe.space();
     	    				}
     	    			}
+						scribe.printTrailingComment();
+        			}
+					if (i == alignment.fragmentCount - 1) {
+						scribe.setTailFormatter(tailFormatter);
+					}
+       				operand.accept(this);
+        			scribe.restartAtOffset(getNodeEndLocation(operand));
+        			scribe.printTrailingComment();
 				}
 
-   				// Right operand
+   				scribe.runTailFormatter();
-   				final IASTExpression op2= node.getOperand2();
-   				op2.accept(this);
-
-   				if (tailFormatter != null)
-   					tailFormatter.run();
     			ok = true;
     		} catch (AlignmentException e) {
     			scribe.redoAlignment(e);
     		}
     	} while (!ok);
-    	scribe.exitAlignment(expressionAlignment, true);
+    	scribe.exitAlignment(alignment, true);
     	return PROCESS_SKIP;
 	}
 
+	/**
+	 * Traverses a chain of nested homogeneous left-to-right-associative binary expressions and
+	 * returns a list of their operands in left-to-right order. For example, for the expression
+	 * a + b * c + d, it will return a list containing expressions: a, b * c, and d.
+	 *  
+	 * @param binaryExpression the top-level binary expression
+	 * @return a list of expression operands from left to right
+	 */
+	private List<IASTExpression> getOperandsOfMultiExpression(IASTBinaryExpression binaryExpression) {
+		int operator = binaryExpression.getOperator();
+		List<IASTExpression> operands = new ArrayList<IASTExpression>(2);
+		IASTExpression node;
+		do {
+			operands.add(binaryExpression.getOperand2());
+			node = binaryExpression.getOperand1();
+			if (!(node instanceof IASTBinaryExpression)) {
+				break;
+			}
+			binaryExpression = (IASTBinaryExpression) node;
+		} while (binaryExpression.getOperator() == operator);
+		operands.add(node);
+		Collections.reverse(operands);
+		return operands;
+	}
+
 	private int formatAssignment(IASTBinaryExpression node) {
 		Runnable tailFormatter = scribe.takeTailFormatter();
 		final IASTExpression op1= node.getOperand1();

core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/formatter/align/Alignment.java

@@ -311,7 +311,7 @@ public class Alignment {
 						this.fragmentIndentations[i] = this.breakIndentationLevel;
 						return wasSplit = true;
 					}
-				} while (--i >= 0);
+				} while ((this.fragmentBreaks[i] != BREAK || (this.mode & M_INDENT_ON_COLUMN) != 0) && --i >= 0); 
 				break;
 
 			/*  # aligned fragment