org.eclipse.tracecompass.ctf.core/src/org/eclipse/linuxtools/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.linuxtools.internal.ctf.core.event.types;
  14
  15 import org.eclipse.jdt.annotation.NonNull;
  16 import org.eclipse.linuxtools.ctf.core.event.types.IDeclaration;
  17 import org.eclipse.linuxtools.ctf.core.event.types.ISimpleDatatypeDeclaration;
  18 import org.eclipse.linuxtools.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  * @since 3.0
  26  */
  27 public final class StructDeclarationFlattener {
  28
  29     private StructDeclarationFlattener() {}
  30
  31     /**
  32      * Flatten a {@link StructDeclaration}, if it can be (which means if it
  33      * contains only fixed-size elements).
  34      *
  35      * This does not modify the declaration passed in parameter, you need to use
  36      * the return value.
  37      *
  38      * @param sd
  39      *            The initial StructDeclaration
  40      * @return The flattened struct. Or if it couldn't be flattened, the 'sd'
  41      *         struct itself
  42      */
  43     public static StructDeclaration tryFlattenStruct(@NonNull StructDeclaration sd) {
  44         if (canBeFlattened(sd)) {
  45             return newFlattenedStruct(sd);
  46         }
  47         return sd;
  48     }
  49
  50     /**
  51      * Check if this struct is fixed size
  52      *
  53      * @param sd
  54      *            the struct
  55      * @return if the struct is of fixed size
  56      */
  57     private static boolean canBeFlattened(@NonNull StructDeclaration sd) {
  58         for (String field : sd.getFieldsList()) {
  59             IDeclaration dec = sd.getField(field);
  60             if (!isFixedSize(dec)) {
  61                 return false;
  62             }
  63         }
  64         return true;
  65     }
  66
  67     private static boolean isFixedSize(IDeclaration dec) {
  68         if (dec instanceof ISimpleDatatypeDeclaration) {
  69             return true;
  70         }
  71         if (dec instanceof ArrayDeclaration) {
  72             return isFixedSize(((ArrayDeclaration) dec).getElementType());
  73         }
  74         if (dec instanceof StructDeclaration) {
  75             StructDeclaration sDec = ((StructDeclaration) dec);
  76             return canBeFlattened(sDec);
  77         }
  78         return false;
  79     }
  80
  81     private static StructDeclaration newFlattenedStruct(@NonNull StructDeclaration sd) {
  82         StructDeclaration flatStruct = new StructDeclaration(sd.getAlignment());
  83         for (String name : sd.getFieldsList()) {
  84             depthFirstAdd(name, flatStruct, sd.getField(name));
  85         }
  86         return flatStruct;
  87     }
  88
  89     private static void depthFirstAdd(String path, StructDeclaration flatStruct, IDeclaration dec) {
  90         if (dec instanceof ISimpleDatatypeDeclaration) {
  91             flatStruct.addField(path, dec);
  92         } else if (dec instanceof ArrayDeclaration) {
  93             ArrayDeclaration ad = (ArrayDeclaration) dec;
  94             int lastIndexOf = path.lastIndexOf('.');
  95
  96             String name = (lastIndexOf > 0) ? path.substring(lastIndexOf) : path;
  97             if (((ArrayDeclaration) dec).isString()) {
  98                 flatStruct.addField(path, dec);
  99             } else {
 100                 for (int i = 0; i < ad.getLength(); i++) {
 101                     depthFirstAdd(path + '.' + name + '[' + i + ']', flatStruct, ad.getElementType());
 102                 }
 103             }
 104         } else if (dec instanceof StructDeclaration) {
 105             StructDeclaration sDec = ((StructDeclaration) dec);
 106             for (String name : sDec.getFieldsList()) {
 107                 depthFirstAdd(path + '.' + name, flatStruct, sDec.getField(name));
 108             }
 109         }
 110     }
 111
 112 }