org.eclipse.tracecompass.ctf.core/src/org/eclipse/tracecompass/internal/ctf/core/event/types/StructDeclarationFlattener.java

   1 /*******************************************************************************
   2  * Copyright (c) 2014 Ericsson
   3  *
   4  * All rights reserved. This program and the accompanying materials are made
   5  * available under the terms of the Eclipse Public License v1.0 which
   6  * accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *      Matthew Khouzam - Initial API and implementation
  11  *******************************************************************************/
  12
  13 package org.eclipse.tracecompass.internal.ctf.core.event.types;
  14
  15 import org.eclipse.jdt.annotation.NonNull;
  16 import org.eclipse.tracecompass.ctf.core.event.types.IDeclaration;
  17 import org.eclipse.tracecompass.ctf.core.event.types.ISimpleDatatypeDeclaration;
  18 import org.eclipse.tracecompass.ctf.core.event.types.StructDeclaration;
  19
  20 /**
  21  * A fixed size struct declaration is a declaration of a structure that has no
  22  * variant or sequence fields. This will accelerate reading of the trace.
  23  *
  24  * @author Matthew Khouzam
  25  */
  26 public final class StructDeclarationFlattener {
  27
  28     private StructDeclarationFlattener() {}
  29
  30     /**
  31      * Flatten a {@link StructDeclaration}, if it can be (which means if it
  32      * contains only fixed-size elements).
  33      *
  34      * This does not modify the declaration passed in parameter, you need to use
  35      * the return value.
  36      *
  37      * @param sd
  38      *            The initial StructDeclaration
  39      * @return The flattened struct. Or if it couldn't be flattened, the 'sd'
  40      *         struct itself
  41      */
  42     public static StructDeclaration tryFlattenStruct(@NonNull StructDeclaration sd) {
  43         if (canBeFlattened(sd)) {
  44             return newFlattenedStruct(sd);
  45         }
  46         return sd;
  47     }
  48
  49     /**
  50      * Check if this struct is fixed size
  51      *
  52      * @param sd
  53      *            the struct
  54      * @return if the struct is of fixed size
  55      */
  56     private static boolean canBeFlattened(@NonNull StructDeclaration sd) {
  57         for (String field : sd.getFieldsList()) {
  58             IDeclaration dec = sd.getField(field);
  59             if (!isFixedSize(dec)) {
  60                 return false;
  61             }
  62         }
  63         return true;
  64     }
  65
  66     private static boolean isFixedSize(IDeclaration dec) {
  67         if (dec instanceof ISimpleDatatypeDeclaration) {
  68             return true;
  69         }
  70         if (dec instanceof ArrayDeclaration) {
  71             return isFixedSize(((ArrayDeclaration) dec).getElementType());
  72         }
  73         if (dec instanceof StructDeclaration) {
  74             StructDeclaration sDec = ((StructDeclaration) dec);
  75             return canBeFlattened(sDec);
  76         }
  77         return false;
  78     }
  79
  80     private static StructDeclaration newFlattenedStruct(@NonNull StructDeclaration sd) {
  81         StructDeclaration flatStruct = new StructDeclaration(sd.getAlignment());
  82         for (String name : sd.getFieldsList()) {
  83             depthFirstAdd(name, flatStruct, sd.getField(name));
  84         }
  85         return flatStruct;
  86     }
  87
  88     private static void depthFirstAdd(String path, StructDeclaration flatStruct, IDeclaration dec) {
  89         if (dec instanceof ISimpleDatatypeDeclaration) {
  90             flatStruct.addField(path, dec);
  91         } else if (dec instanceof ArrayDeclaration) {
  92             ArrayDeclaration ad = (ArrayDeclaration) dec;
  93             int lastIndexOf = path.lastIndexOf('.');
  94
  95             String name = (lastIndexOf > 0) ? path.substring(lastIndexOf) : path;
  96             if (((ArrayDeclaration) dec).isString()) {
  97                 flatStruct.addField(path, dec);
  98             } else {
  99                 for (int i = 0; i < ad.getLength(); i++) {
 100                     depthFirstAdd(path + '.' + name + '[' + i + ']', flatStruct, ad.getElementType());
 101                 }
 102             }
 103         } else if (dec instanceof StructDeclaration) {
 104             StructDeclaration sDec = ((StructDeclaration) dec);
 105             for (String name : sDec.getFieldsList()) {
 106                 depthFirstAdd(path + '.' + name, flatStruct, sDec.getField(name));
 107             }
 108         }
 109     }
 110
 111 }