ctf/org.eclipse.tracecompass.ctf.core/src/org/eclipse/tracecompass/internal/ctf/core/event/metadata/tsdl/string/StringDeclarationParser.java

   1 /*******************************************************************************
   2  * Copyright (c) 2015 Ericsson
   3  *
   4  * All rights reserved. This program and the accompanying materials
   5  * are made available under the terms of the Eclipse Public License v1.0
   6  * which accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *******************************************************************************/
   9 package org.eclipse.tracecompass.internal.ctf.core.event.metadata.tsdl.string;
  10
  11 import static org.eclipse.tracecompass.internal.ctf.core.event.metadata.tsdl.TsdlUtils.childTypeError;
  12 import static org.eclipse.tracecompass.internal.ctf.core.event.metadata.tsdl.TsdlUtils.concatenateUnaryStrings;
  13 import static org.eclipse.tracecompass.internal.ctf.core.event.metadata.tsdl.TsdlUtils.isAnyUnaryString;
  14
  15 import java.util.List;
  16
  17 import org.antlr.runtime.tree.CommonTree;
  18 import org.eclipse.jdt.annotation.NonNull;
  19 import org.eclipse.tracecompass.ctf.core.event.types.Encoding;
  20 import org.eclipse.tracecompass.ctf.core.event.types.StringDeclaration;
  21 import org.eclipse.tracecompass.ctf.parser.CTFParser;
  22 import org.eclipse.tracecompass.internal.ctf.core.event.metadata.ICommonTreeParser;
  23 import org.eclipse.tracecompass.internal.ctf.core.event.metadata.ParseException;
  24
  25 /**
  26  * Strings are an array of bytes of variable size and are terminated by a '\0'
  27  * “NULL” character. Their encoding is described in the TSDL metadata. In
  28  * absence of encoding attribute information, the default encoding is UTF-8.
  29  *
  30  * TSDL metadata representation of a named string type:
  31  *
  32  * <pre>
  33  * typealias string {
  34  *   encoding = /* UTF8 OR ASCII * /;
  35  * } := name;
  36  * </pre>
  37  *
  38  * A nameless string type can be declared as a field type:
  39  *
  40  * <pre>
  41  * string field_name; /* use default UTF8 encoding * /
  42  * </pre>
  43  *
  44  * Strings are always aligned on byte size.
  45  *
  46  * @author Matthew Khouzam
  47  * @author Efficios - Javadoc Preable
  48  *
  49  */
  50 public class StringDeclarationParser implements ICommonTreeParser {
  51
  52     /**
  53      * Instance
  54      */
  55     public static final StringDeclarationParser INSTANCE = new StringDeclarationParser();
  56
  57     private static final @NonNull String ENCODING = "encoding"; //$NON-NLS-1$
  58
  59     private StringDeclarationParser() {
  60     }
  61
  62     /**
  63      * Parse a string declaration node and return a {@link StringDeclaration}
  64      *
  65      * @param string
  66      *            the string declaration AST node
  67      * @param unused
  68      *            unused
  69      * @return a {@link StringDeclaration} describing the string layout
  70      * @throws ParseException
  71      *             the AST is malformed
  72      */
  73     @Override
  74     public StringDeclaration parse(CommonTree string, ICommonTreeParserParameter unused) throws ParseException {
  75         List<CommonTree> children = string.getChildren();
  76         StringDeclaration stringDeclaration = null;
  77
  78         if (children == null) {
  79             stringDeclaration = StringDeclaration.getStringDeclaration(Encoding.UTF8);
  80         } else {
  81             Encoding encoding = Encoding.UTF8;
  82             for (CommonTree child : children) {
  83                 switch (child.getType()) {
  84                 case CTFParser.CTF_EXPRESSION_VAL:
  85                     /*
  86                      * An assignment expression must have 2 children, left and
  87                      * right
  88                      */
  89
  90                     CommonTree leftNode = (CommonTree) child.getChild(0);
  91                     CommonTree rightNode = (CommonTree) child.getChild(1);
  92
  93                     List<CommonTree> leftStrings = leftNode.getChildren();
  94
  95                     if (!isAnyUnaryString(leftStrings.get(0))) {
  96                         throw new ParseException("Left side of ctf expression must be a string"); //$NON-NLS-1$
  97                     }
  98                     String left = concatenateUnaryStrings(leftStrings);
  99
 100                     if (left.equals(ENCODING)) {
 101                         encoding = EncodingParser.INSTANCE.parse(rightNode, null);
 102                     } else {
 103                         throw new ParseException("String: unknown attribute " //$NON-NLS-1$
 104                                 + left);
 105                     }
 106
 107                     break;
 108                 default:
 109                     throw childTypeError(child);
 110                 }
 111             }
 112
 113             stringDeclaration = StringDeclaration.getStringDeclaration(encoding);
 114         }
 115
 116         return stringDeclaration;
 117     }
 118
 119 }