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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Eclipse Public License, Version 1.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.eclipse.org/org/documents/epl-v10.php
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.ide.eclipse.adt.internal.editors;
     18 
     19 import static com.android.ide.common.layout.LayoutConstants.ATTR_LAYOUT_PREFIX;
     20 import static com.android.ide.common.resources.ResourceResolver.PREFIX_RESOURCE_REF;
     21 import static com.android.ide.eclipse.adt.internal.editors.descriptors.AttributeDescriptor.ATTRIBUTE_ICON_FILENAME;
     22 
     23 import com.android.ide.common.api.IAttributeInfo;
     24 import com.android.ide.common.api.IAttributeInfo.Format;
     25 import com.android.ide.eclipse.adt.AdtPlugin;
     26 import com.android.ide.eclipse.adt.internal.editors.descriptors.AttributeDescriptor;
     27 import com.android.ide.eclipse.adt.internal.editors.descriptors.DescriptorsUtils;
     28 import com.android.ide.eclipse.adt.internal.editors.descriptors.ElementDescriptor;
     29 import com.android.ide.eclipse.adt.internal.editors.descriptors.IDescriptorProvider;
     30 import com.android.ide.eclipse.adt.internal.editors.descriptors.SeparatorAttributeDescriptor;
     31 import com.android.ide.eclipse.adt.internal.editors.descriptors.TextAttributeDescriptor;
     32 import com.android.ide.eclipse.adt.internal.editors.descriptors.TextValueDescriptor;
     33 import com.android.ide.eclipse.adt.internal.editors.descriptors.XmlnsAttributeDescriptor;
     34 import com.android.ide.eclipse.adt.internal.editors.layout.gle2.DomUtilities;
     35 import com.android.ide.eclipse.adt.internal.editors.uimodel.UiAttributeNode;
     36 import com.android.ide.eclipse.adt.internal.editors.uimodel.UiElementNode;
     37 import com.android.ide.eclipse.adt.internal.editors.uimodel.UiFlagAttributeNode;
     38 import com.android.ide.eclipse.adt.internal.editors.uimodel.UiResourceAttributeNode;
     39 import com.android.ide.eclipse.adt.internal.sdk.AndroidTargetData;
     40 import com.android.sdklib.SdkConstants;
     41 import com.android.util.Pair;
     42 
     43 import org.eclipse.core.runtime.IStatus;
     44 import org.eclipse.jface.text.BadLocationException;
     45 import org.eclipse.jface.text.IDocument;
     46 import org.eclipse.jface.text.IRegion;
     47 import org.eclipse.jface.text.ITextViewer;
     48 import org.eclipse.jface.text.contentassist.CompletionProposal;
     49 import org.eclipse.jface.text.contentassist.ICompletionProposal;
     50 import org.eclipse.jface.text.contentassist.IContentAssistProcessor;
     51 import org.eclipse.jface.text.contentassist.IContextInformation;
     52 import org.eclipse.jface.text.contentassist.IContextInformationValidator;
     53 import org.eclipse.jface.text.source.ISourceViewer;
     54 import org.eclipse.swt.graphics.Image;
     55 import org.eclipse.wst.sse.core.internal.provisional.IndexedRegion;
     56 import org.w3c.dom.NamedNodeMap;
     57 import org.w3c.dom.Node;
     58 
     59 import java.util.ArrayList;
     60 import java.util.Arrays;
     61 import java.util.Comparator;
     62 import java.util.HashMap;
     63 import java.util.HashSet;
     64 import java.util.List;
     65 import java.util.Map;
     66 import java.util.regex.Pattern;
     67 
     68 /**
     69  * Content Assist Processor for Android XML files
     70  * <p>
     71  * Remaining corner cases:
     72  * <ul>
     73  * <li>Completion does not work right if there is a space between the = and the opening
     74  *   quote.
     75  * <li>Replacement completion does not work right if the caret is to the left of the
     76  *   opening quote, where the opening quote is a single quote, and the replacement items use
     77  *   double quotes.
     78  * </ul>
     79  */
     80 @SuppressWarnings("restriction") // XML model
     81 public abstract class AndroidContentAssist implements IContentAssistProcessor {
     82 
     83     /** Regexp to detect a full attribute after an element tag.
     84      * <pre>Syntax:
     85      *    name = "..." quoted string with all but < and "
     86      * or:
     87      *    name = '...' quoted string with all but < and '
     88      * </pre>
     89      */
     90     private static Pattern sFirstAttribute = Pattern.compile(
     91             "^ *[a-zA-Z_:]+ *= *(?:\"[^<\"]*\"|'[^<']*')");  //$NON-NLS-1$
     92 
     93     /** Regexp to detect an element tag name */
     94     private static Pattern sFirstElementWord = Pattern.compile("^[a-zA-Z0-9_:.-]+"); //$NON-NLS-1$
     95 
     96     /** Regexp to detect whitespace */
     97     private static Pattern sWhitespace = Pattern.compile("\\s+"); //$NON-NLS-1$
     98 
     99     protected final static String ROOT_ELEMENT = "";
    100 
    101     /** Descriptor of the root of the XML hierarchy. This a "fake" ElementDescriptor which
    102      *  is used to list all the possible roots given by actual implementations.
    103      *  DO NOT USE DIRECTLY. Call {@link #getRootDescriptor()} instead. */
    104     private ElementDescriptor mRootDescriptor;
    105 
    106     private final int mDescriptorId;
    107 
    108     protected AndroidXmlEditor mEditor;
    109 
    110     /**
    111      * Constructor for AndroidContentAssist
    112      * @param descriptorId An id for {@link AndroidTargetData#getDescriptorProvider(int)}.
    113      *      The Id can be one of {@link AndroidTargetData#DESCRIPTOR_MANIFEST},
    114      *      {@link AndroidTargetData#DESCRIPTOR_LAYOUT},
    115      *      {@link AndroidTargetData#DESCRIPTOR_MENU},
    116      *      or {@link AndroidTargetData#DESCRIPTOR_XML}.
    117      *      All other values will throw an {@link IllegalArgumentException} later at runtime.
    118      */
    119     public AndroidContentAssist(int descriptorId) {
    120         mDescriptorId = descriptorId;
    121     }
    122 
    123     /**
    124      * Returns a list of completion proposals based on the
    125      * specified location within the document that corresponds
    126      * to the current cursor position within the text viewer.
    127      *
    128      * @param viewer the viewer whose document is used to compute the proposals
    129      * @param offset an offset within the document for which completions should be computed
    130      * @return an array of completion proposals or <code>null</code> if no proposals are possible
    131      *
    132      * @see org.eclipse.jface.text.contentassist.IContentAssistProcessor#computeCompletionProposals(org.eclipse.jface.text.ITextViewer, int)
    133      */
    134     public ICompletionProposal[] computeCompletionProposals(ITextViewer viewer, int offset) {
    135         String wordPrefix = extractElementPrefix(viewer, offset);
    136 
    137         if (mEditor == null) {
    138             mEditor = AndroidXmlEditor.getAndroidXmlEditor(viewer);
    139             if (mEditor == null) {
    140                 // This should not happen. Duck and forget.
    141                 AdtPlugin.log(IStatus.ERROR, "Editor not found during completion");
    142                 return null;
    143             }
    144         }
    145 
    146         // List of proposals, in the order presented to the user.
    147         List<ICompletionProposal> proposals = new ArrayList<ICompletionProposal>(80);
    148 
    149         // Look up the caret context - where in an element, or between elements, or
    150         // within an element's children, is the given caret offset located?
    151         Pair<Node, Node> context = DomUtilities.getNodeContext(viewer.getDocument(), offset);
    152         if (context == null) {
    153             return null;
    154         }
    155         Node parentNode = context.getFirst();
    156         Node currentNode = context.getSecond();
    157         assert parentNode != null || currentNode != null;
    158 
    159         UiElementNode rootUiNode = mEditor.getUiRootNode();
    160         if (currentNode == null || currentNode.getNodeType() == Node.TEXT_NODE) {
    161              UiElementNode parentUiNode =
    162                  rootUiNode == null ? null : rootUiNode.findXmlNode(parentNode);
    163              computeTextValues(proposals, offset, parentNode, currentNode, parentUiNode,
    164                     wordPrefix);
    165         } else if (currentNode.getNodeType() == Node.ELEMENT_NODE) {
    166             String parent = currentNode.getNodeName();
    167             AttribInfo info = parseAttributeInfo(viewer, offset, offset - wordPrefix.length());
    168             char nextChar = extractChar(viewer, offset);
    169             if (info != null) {
    170                 // check to see if we can find a UiElementNode matching this XML node
    171                 UiElementNode currentUiNode = rootUiNode == null
    172                     ? null : rootUiNode.findXmlNode(currentNode);
    173                 computeAttributeProposals(proposals, viewer, offset, wordPrefix, currentUiNode,
    174                         parentNode, currentNode, parent, info, nextChar);
    175             } else {
    176                 computeNonAttributeProposals(viewer, offset, wordPrefix, proposals, parentNode,
    177                         currentNode, parent, nextChar);
    178             }
    179         }
    180 
    181         return proposals.toArray(new ICompletionProposal[proposals.size()]);
    182     }
    183 
    184     private void computeNonAttributeProposals(ITextViewer viewer, int offset, String wordPrefix,
    185             List<ICompletionProposal> proposals, Node parentNode, Node currentNode, String parent,
    186             char nextChar) {
    187         if (startsWith(parent, wordPrefix)) {
    188             // We are still editing the element's tag name, not the attributes
    189             // (the element's tag name may not even be complete)
    190 
    191             Object[] choices = getChoicesForElement(parent, currentNode);
    192             if (choices == null || choices.length == 0) {
    193                 return;
    194             }
    195 
    196             int replaceLength = parent.length() - wordPrefix.length();
    197             boolean isNew = replaceLength == 0 && nextNonspaceChar(viewer, offset) == '<';
    198             // Special case: if we are right before the beginning of a new
    199             // element, wipe out the replace length such that we insert before it,
    200             // we don't edit the current element.
    201             if (wordPrefix.length() == 0 && nextChar == '<') {
    202                 replaceLength = 0;
    203                 isNew = true;
    204             }
    205 
    206             // If we found some suggestions, do we need to add an opening "<" bracket
    207             // for the element? We don't if the cursor is right after "<" or "</".
    208             // Per XML Spec, there's no whitespace between "<" or "</" and the tag name.
    209             char needTag = computeElementNeedTag(viewer, offset, wordPrefix);
    210 
    211             addMatchingProposals(proposals, choices, offset,
    212                     parentNode != null ? parentNode : null, wordPrefix, needTag,
    213                     false /* isAttribute */, isNew, false /*isComplete*/,
    214                     replaceLength);
    215         }
    216     }
    217 
    218     private void computeAttributeProposals(List<ICompletionProposal> proposals, ITextViewer viewer,
    219             int offset, String wordPrefix, UiElementNode currentUiNode, Node parentNode,
    220             Node currentNode, String parent, AttribInfo info, char nextChar) {
    221         // We're editing attributes in an element node (either the attributes' names
    222         // or their values).
    223 
    224         if (info.isInValue) {
    225             computeAttributeValues(proposals, offset, parent, info.name, currentNode,
    226                     wordPrefix, info.skipEndTag, info.replaceLength);
    227         }
    228 
    229         // Look up attribute proposals based on descriptors
    230         Object[] choices = getChoicesForAttribute(parent, currentNode, currentUiNode,
    231                 info, wordPrefix);
    232         if (choices == null || choices.length == 0) {
    233             return;
    234         }
    235 
    236         int replaceLength = info.replaceLength;
    237         if (info.correctedPrefix != null) {
    238             wordPrefix = info.correctedPrefix;
    239         }
    240         char needTag = info.needTag;
    241         // Look to the right and see if we're followed by whitespace
    242         boolean isNew = replaceLength == 0
    243             && (Character.isWhitespace(nextChar) || nextChar == '>' || nextChar == '/');
    244 
    245         addMatchingProposals(proposals, choices, offset, parentNode != null ? parentNode : null,
    246                 wordPrefix, needTag, true /* isAttribute */, isNew, info.skipEndTag,
    247                 replaceLength);
    248     }
    249 
    250     private char computeElementNeedTag(ITextViewer viewer, int offset, String wordPrefix) {
    251         char needTag = 0;
    252         int offset2 = offset - wordPrefix.length() - 1;
    253         char c1 = extractChar(viewer, offset2);
    254         if (!((c1 == '<') || (c1 == '/' && extractChar(viewer, offset2 - 1) == '<'))) {
    255             needTag = '<';
    256         }
    257         return needTag;
    258     }
    259 
    260     protected int computeTextReplaceLength(Node currentNode, int offset) {
    261         if (currentNode == null) {
    262             return 0;
    263         }
    264 
    265         assert currentNode != null && currentNode.getNodeType() == Node.TEXT_NODE;
    266 
    267         String nodeValue = currentNode.getNodeValue();
    268         int relativeOffset = offset - ((IndexedRegion) currentNode).getStartOffset();
    269         int lineEnd = nodeValue.indexOf('\n', relativeOffset);
    270         if (lineEnd == -1) {
    271             lineEnd = nodeValue.length();
    272         }
    273         return lineEnd - relativeOffset;
    274     }
    275 
    276     /**
    277      * Returns the namespace prefix matching the Android Resource URI.
    278      * If no such declaration is found, returns the default "android" prefix.
    279      *
    280      * @param node The current node. Must not be null.
    281      * @param nsUri The namespace URI of which the prefix is to be found,
    282      *              e.g. {@link SdkConstants#NS_RESOURCES}
    283      * @return The first prefix declared or the default "android" prefix.
    284      */
    285     private static String lookupNamespacePrefix(Node node, String nsUri) {
    286         // Note: Node.lookupPrefix is not implemented in wst/xml/core NodeImpl.java
    287         // The following emulates this:
    288         //   String prefix = node.lookupPrefix(SdkConstants.NS_RESOURCES);
    289 
    290         if (XmlnsAttributeDescriptor.XMLNS_URI.equals(nsUri)) {
    291             return XmlnsAttributeDescriptor.XMLNS;
    292         }
    293 
    294         HashSet<String> visited = new HashSet<String>();
    295 
    296         String prefix = null;
    297         for (; prefix == null &&
    298                     node != null &&
    299                     node.getNodeType() == Node.ELEMENT_NODE;
    300                node = node.getParentNode()) {
    301             NamedNodeMap attrs = node.getAttributes();
    302             for (int n = attrs.getLength() - 1; n >= 0; --n) {
    303                 Node attr = attrs.item(n);
    304                 if (XmlnsAttributeDescriptor.XMLNS.equals(attr.getPrefix())) {
    305                     String uri = attr.getNodeValue();
    306                     if (SdkConstants.NS_RESOURCES.equals(uri)) {
    307                         return attr.getLocalName();
    308                     }
    309                     visited.add(uri);
    310                 }
    311             }
    312         }
    313 
    314         // Use a sensible default prefix if we can't find one.
    315         // We need to make sure the prefix is not one that was declared in the scope
    316         // visited above.
    317         prefix = SdkConstants.NS_RESOURCES.equals(nsUri) ? "android" : "ns"; //$NON-NLS-1$ //$NON-NLS-2$
    318         String base = prefix;
    319         for (int i = 1; visited.contains(prefix); i++) {
    320             prefix = base + Integer.toString(i);
    321         }
    322         return prefix;
    323     }
    324 
    325     /**
    326      * Gets the choices when the user is editing the name of an XML element.
    327      * <p/>
    328      * The user is editing the name of an element (the "parent").
    329      * Find the grand-parent and if one is found, return its children element list.
    330      * The name which is being edited should be one of those.
    331      * <p/>
    332      * Example: <manifest><applic*cursor* => returns the list of all elements that
    333      * can be found under <manifest>, of which <application> is one of the choices.
    334      *
    335      * @return an ElementDescriptor[] or null if no valid element was found.
    336      */
    337     protected Object[] getChoicesForElement(String parent, Node currentNode) {
    338         ElementDescriptor grandparent = null;
    339         if (currentNode.getParentNode().getNodeType() == Node.ELEMENT_NODE) {
    340             grandparent = getDescriptor(currentNode.getParentNode().getNodeName());
    341         } else if (currentNode.getParentNode().getNodeType() == Node.DOCUMENT_NODE) {
    342             grandparent = getRootDescriptor();
    343         }
    344         if (grandparent != null) {
    345             for (ElementDescriptor e : grandparent.getChildren()) {
    346                 if (e.getXmlName().startsWith(parent)) {
    347                     return sort(grandparent.getChildren());
    348                 }
    349             }
    350         }
    351 
    352         return null;
    353     }
    354 
    355     /** Non-destructively sort a list of ElementDescriptors and return the result */
    356     protected static ElementDescriptor[] sort(ElementDescriptor[] elements) {
    357         if (elements != null && elements.length > 1) {
    358             // Sort alphabetically. Must make copy to not destroy original.
    359             ElementDescriptor[] copy = new ElementDescriptor[elements.length];
    360             System.arraycopy(elements, 0, copy, 0, elements.length);
    361 
    362             Arrays.sort(copy, new Comparator<ElementDescriptor>() {
    363                 public int compare(ElementDescriptor e1, ElementDescriptor e2) {
    364                     return e1.getXmlLocalName().compareTo(e2.getXmlLocalName());
    365                 }
    366             });
    367 
    368             return copy;
    369         }
    370 
    371         return elements;
    372     }
    373 
    374     /**
    375      * Gets the choices when the user is editing an XML attribute.
    376      * <p/>
    377      * In input, attrInfo contains details on the analyzed context, namely whether the
    378      * user is editing an attribute value (isInValue) or an attribute name.
    379      * <p/>
    380      * In output, attrInfo also contains two possible new values (this is a hack to circumvent
    381      * the lack of out-parameters in Java):
    382      * - AttribInfo.correctedPrefix if the user has been editing an attribute value and it has
    383      *   been detected that what the user typed is different from what extractElementPrefix()
    384      *   predicted. This happens because extractElementPrefix() stops when a character that
    385      *   cannot be an element name appears whereas parseAttributeInfo() uses a grammar more
    386      *   lenient as suitable for attribute values.
    387      * - AttribInfo.needTag will be non-zero if we find that the attribute completion proposal
    388      *   must be double-quoted.
    389      * @param currentUiNode
    390      *
    391      * @return an AttributeDescriptor[] if the user is editing an attribute name.
    392      *         a String[] if the user is editing an attribute value with some known values,
    393      *         or null if nothing is known about the context.
    394      */
    395     private Object[] getChoicesForAttribute(
    396             String parent, Node currentNode, UiElementNode currentUiNode, AttribInfo attrInfo,
    397             String wordPrefix) {
    398         Object[] choices = null;
    399         if (attrInfo.isInValue) {
    400             // Editing an attribute's value... Get the attribute name and then the
    401             // possible choices for the tuple(parent,attribute)
    402             String value = attrInfo.valuePrefix;
    403             if (value.startsWith("'") || value.startsWith("\"")) {   //$NON-NLS-1$   //$NON-NLS-2$
    404                 value = value.substring(1);
    405                 // The prefix that was found at the beginning only scan for characters
    406                 // valid for tag name. We now know the real prefix for this attribute's
    407                 // value, which is needed to generate the completion choices below.
    408                 attrInfo.correctedPrefix = value;
    409             } else {
    410                 attrInfo.needTag = '"';
    411             }
    412 
    413             if (currentUiNode != null) {
    414                 // look for an UI attribute matching the current attribute name
    415                 String attrName = attrInfo.name;
    416                 // remove any namespace prefix from the attribute name
    417                 int pos = attrName.indexOf(':');
    418                 if (pos >= 0) {
    419                     attrName = attrName.substring(pos + 1);
    420                 }
    421 
    422                 UiAttributeNode currAttrNode = null;
    423                 for (UiAttributeNode attrNode : currentUiNode.getAllUiAttributes()) {
    424                     if (attrNode.getDescriptor().getXmlLocalName().equals(attrName)) {
    425                         currAttrNode = attrNode;
    426                         break;
    427                     }
    428                 }
    429 
    430                 if (currAttrNode != null) {
    431                     choices = getAttributeValueChoices(currAttrNode, attrInfo, value);
    432                 }
    433             }
    434 
    435             if (choices == null) {
    436                 // fallback on the older descriptor-only based lookup.
    437 
    438                 // in order to properly handle the special case of the name attribute in
    439                 // the action tag, we need the grandparent of the action node, to know
    440                 // what type of actions we need.
    441                 // e.g. activity -> intent-filter -> action[@name]
    442                 String greatGrandParentName = null;
    443                 Node grandParent = currentNode.getParentNode();
    444                 if (grandParent != null) {
    445                     Node greatGrandParent = grandParent.getParentNode();
    446                     if (greatGrandParent != null) {
    447                         greatGrandParentName = greatGrandParent.getLocalName();
    448                     }
    449                 }
    450 
    451                 AndroidTargetData data = mEditor.getTargetData();
    452                 if (data != null) {
    453                     choices = data.getAttributeValues(parent, attrInfo.name, greatGrandParentName);
    454                 }
    455             }
    456         } else {
    457             // Editing an attribute's name... Get attributes valid for the parent node.
    458             if (currentUiNode != null) {
    459                 choices = currentUiNode.getAttributeDescriptors();
    460             } else {
    461                 ElementDescriptor parentDesc = getDescriptor(parent);
    462                 choices = parentDesc.getAttributes();
    463             }
    464         }
    465         return choices;
    466     }
    467 
    468     protected Object[] getAttributeValueChoices(UiAttributeNode currAttrNode, AttribInfo attrInfo,
    469             String value) {
    470         Object[] choices;
    471         int pos;
    472         choices = currAttrNode.getPossibleValues(value);
    473         if (choices != null && currAttrNode instanceof UiResourceAttributeNode) {
    474             attrInfo.skipEndTag = false;
    475         }
    476 
    477         if (currAttrNode instanceof UiFlagAttributeNode) {
    478             // A "flag" can consist of several values separated by "or" (|).
    479             // If the correct prefix contains such a pipe character, we change
    480             // it so that only the currently edited value is completed.
    481             pos = value.lastIndexOf('|');
    482             if (pos >= 0) {
    483                 attrInfo.correctedPrefix = value = value.substring(pos + 1);
    484                 attrInfo.needTag = 0;
    485             }
    486 
    487             attrInfo.skipEndTag = false;
    488         }
    489 
    490         // Should we do suffix completion on dimension units etc?
    491         choices = completeSuffix(choices, value, currAttrNode);
    492 
    493         // Check to see if the user is attempting resource completion
    494         AttributeDescriptor attributeDescriptor = currAttrNode.getDescriptor();
    495         IAttributeInfo attributeInfo = attributeDescriptor.getAttributeInfo();
    496         if (value.startsWith(PREFIX_RESOURCE_REF)
    497                 && !Format.REFERENCE.in(attributeInfo.getFormats())) {
    498             // Special case: If the attribute value looks like a reference to a
    499             // resource, offer to complete it, since in many cases our metadata
    500             // does not correctly state whether a resource value is allowed. We don't
    501             // offer these for an empty completion context, but if the user has
    502             // actually typed "@", in that case list resource matches.
    503             // For example, for android:minHeight this makes completion on @dimen/
    504             // possible.
    505             choices = UiResourceAttributeNode.computeResourceStringMatches(
    506                     mEditor, attributeDescriptor, value);
    507             attrInfo.skipEndTag = false;
    508         }
    509 
    510         return choices;
    511     }
    512 
    513     protected void computeAttributeValues(List<ICompletionProposal> proposals, int offset,
    514             String parentTagName, String attributeName, Node node, String wordPrefix,
    515             boolean skipEndTag, int replaceLength) {
    516     }
    517 
    518     protected void computeTextValues(List<ICompletionProposal> proposals, int offset,
    519             Node parentNode, Node currentNode, UiElementNode uiParent,
    520             String wordPrefix) {
    521 
    522        if (parentNode != null) {
    523            // Examine the parent of the text node.
    524            Object[] choices = getElementChoicesForTextNode(parentNode);
    525            if (choices != null && choices.length > 0) {
    526                ISourceViewer viewer = mEditor.getStructuredSourceViewer();
    527                char needTag = computeElementNeedTag(viewer, offset, wordPrefix);
    528 
    529                int replaceLength = 0;
    530                addMatchingProposals(proposals, choices,
    531                        offset, parentNode, wordPrefix, needTag,
    532                                false /* isAttribute */,
    533                                false /*isNew*/,
    534                                false /*isComplete*/,
    535                                replaceLength);
    536            }
    537        }
    538     }
    539 
    540     /**
    541      * Gets the choices when the user is editing an XML text node.
    542      * <p/>
    543      * This means the user is editing outside of any XML element or attribute.
    544      * Simply return the list of XML elements that can be present there, based on the
    545      * parent of the current node.
    546      *
    547      * @return An ElementDescriptor[] or null.
    548      */
    549     private Object[] getElementChoicesForTextNode(Node parentNode) {
    550         Object[] choices = null;
    551         String parent;
    552         if (parentNode.getNodeType() == Node.ELEMENT_NODE) {
    553             // We're editing a text node which parent is an element node. Limit
    554             // content assist to elements valid for the parent.
    555             parent = parentNode.getNodeName();
    556             ElementDescriptor desc = getDescriptor(parent);
    557             if (desc == null && parent.indexOf('.') != -1) {
    558                 // The parent is a custom view and we don't have metadata about its
    559                 // allowable children, so just assume any normal layout tag is
    560                 // legal
    561                 desc = mRootDescriptor;
    562             }
    563 
    564             if (desc != null) {
    565                 choices = sort(desc.getChildren());
    566             }
    567         } else if (parentNode.getNodeType() == Node.DOCUMENT_NODE) {
    568             // We're editing a text node at the first level (i.e. root node).
    569             // Limit content assist to the only valid root elements.
    570             choices = sort(getRootDescriptor().getChildren());
    571         }
    572 
    573         return choices;
    574     }
    575 
    576      /**
    577      * Given a list of choices, adds in any that match the current prefix into the
    578      * proposals list.
    579      * <p/>
    580      * Choices is an object array. Items of the array can be:
    581      * - ElementDescriptor: a possible element descriptor which XML name should be completed.
    582      * - AttributeDescriptor: a possible attribute descriptor which XML name should be completed.
    583      * - String: string values to display as-is to the user. Typically those are possible
    584      *           values for a given attribute.
    585      * - Pair of Strings: the first value is the keyword to insert, and the second value
    586      *           is the tooltip/help for the value to be displayed in the documentation popup.
    587      */
    588     protected void addMatchingProposals(List<ICompletionProposal> proposals, Object[] choices,
    589             int offset, Node currentNode, String wordPrefix, char needTag,
    590             boolean isAttribute, boolean isNew, boolean skipEndTag, int replaceLength) {
    591         if (choices == null) {
    592             return;
    593         }
    594 
    595         Map<String, String> nsUriMap = new HashMap<String, String>();
    596 
    597         for (Object choice : choices) {
    598             String keyword = null;
    599             String nsPrefix = null;
    600             Image icon = null;
    601             String tooltip = null;
    602             if (choice instanceof ElementDescriptor) {
    603                 keyword = ((ElementDescriptor)choice).getXmlName();
    604                 icon    = ((ElementDescriptor)choice).getGenericIcon();
    605                 tooltip = DescriptorsUtils.formatTooltip(((ElementDescriptor)choice).getTooltip());
    606             } else if (choice instanceof TextValueDescriptor) {
    607                 continue; // Value nodes are not part of the completion choices
    608             } else if (choice instanceof SeparatorAttributeDescriptor) {
    609                 continue; // not real attribute descriptors
    610             } else if (choice instanceof AttributeDescriptor) {
    611                 keyword = ((AttributeDescriptor)choice).getXmlLocalName();
    612                 icon    = ((AttributeDescriptor)choice).getGenericIcon();
    613                 if (choice instanceof TextAttributeDescriptor) {
    614                     tooltip = ((TextAttributeDescriptor) choice).getTooltip();
    615                 }
    616 
    617                 // Get the namespace URI for the attribute. Note that some attributes
    618                 // do not have a namespace and thus return null here.
    619                 String nsUri = ((AttributeDescriptor)choice).getNamespaceUri();
    620                 if (nsUri != null) {
    621                     nsPrefix = nsUriMap.get(nsUri);
    622                     if (nsPrefix == null) {
    623                         nsPrefix = lookupNamespacePrefix(currentNode, nsUri);
    624                         nsUriMap.put(nsUri, nsPrefix);
    625                     }
    626                 }
    627                 if (nsPrefix != null) {
    628                     nsPrefix += ":"; //$NON-NLS-1$
    629                 }
    630 
    631             } else if (choice instanceof String) {
    632                 keyword = (String) choice;
    633                 if (isAttribute) {
    634                     icon = IconFactory.getInstance().getIcon(ATTRIBUTE_ICON_FILENAME);
    635                 }
    636             } else if (choice instanceof Pair<?, ?>) {
    637                 @SuppressWarnings("unchecked")
    638                 Pair<String, String> pair = (Pair<String, String>) choice;
    639                 keyword = pair.getFirst();
    640                 tooltip = pair.getSecond();
    641                 if (isAttribute) {
    642                     icon = IconFactory.getInstance().getIcon(ATTRIBUTE_ICON_FILENAME);
    643                 }
    644             } else {
    645                 continue; // discard unknown choice
    646             }
    647 
    648             String nsKeyword = nsPrefix == null ? keyword : (nsPrefix + keyword);
    649 
    650             if (nameStartsWith(nsKeyword, wordPrefix, nsPrefix)) {
    651                 keyword = nsKeyword;
    652                 String endTag = ""; //$NON-NLS-1$
    653                 if (needTag != 0) {
    654                     if (needTag == '"') {
    655                         keyword = needTag + keyword;
    656                         endTag = String.valueOf(needTag);
    657                     } else if (needTag == '<') {
    658                         if (elementCanHaveChildren(choice)) {
    659                             endTag = String.format("></%1$s>", keyword);  //$NON-NLS-1$
    660                         } else {
    661                             endTag = "/>";  //$NON-NLS-1$
    662                         }
    663                         keyword = needTag + keyword + ' ';
    664                     } else if (needTag == ' ') {
    665                         keyword = needTag + keyword;
    666                     }
    667                 } else if (!isAttribute && isNew) {
    668                     if (elementCanHaveChildren(choice)) {
    669                         endTag = String.format("></%1$s>", keyword);  //$NON-NLS-1$
    670                     } else {
    671                         endTag = "/>";  //$NON-NLS-1$
    672                     }
    673                     keyword = keyword + ' ';
    674                 }
    675 
    676                 final String suffix;
    677                 int cursorPosition;
    678                 final String displayString;
    679                 if (choice instanceof AttributeDescriptor && isNew) {
    680                     // Special case for attributes: insert ="" stuff and locate caret inside ""
    681                     suffix = "=\"\""; //$NON-NLS-1$
    682                     cursorPosition = keyword.length() + suffix.length() - 1;
    683                     displayString = keyword + endTag; // don't include suffix;
    684                 } else {
    685                     suffix = endTag;
    686                     cursorPosition = keyword.length();
    687                     displayString = null;
    688                 }
    689 
    690                 if (skipEndTag) {
    691                     assert isAttribute;
    692                     cursorPosition++;
    693                 }
    694 
    695                 // For attributes, automatically insert ns:attribute="" and place the cursor
    696                 // inside the quotes.
    697                 // Special case for attributes: insert ="" stuff and locate caret inside ""
    698                 proposals.add(new CompletionProposal(
    699                     keyword + suffix,                   // String replacementString
    700                     offset - wordPrefix.length(),       // int replacementOffset
    701                     wordPrefix.length() + replaceLength,// int replacementLength
    702                     cursorPosition,                     // cursorPosition
    703                     icon,                               // Image image
    704                     displayString,                      // displayString
    705                     null,                               // IContextInformation contextInformation
    706                     tooltip                             // String additionalProposalInfo
    707                 ));
    708             }
    709         }
    710     }
    711 
    712     /**
    713      * Returns true if the given word starts with the given prefix. The comparison is not
    714      * case sensitive.
    715      *
    716      * @param word the word to test
    717      * @param prefix the prefix the word should start with
    718      * @return true if the given word starts with the given prefix
    719      */
    720     protected static boolean startsWith(String word, String prefix) {
    721         int prefixLength = prefix.length();
    722         int wordLength = word.length();
    723         if (wordLength < prefixLength) {
    724             return false;
    725         }
    726 
    727         for (int i = 0; i < prefixLength; i++) {
    728             if (Character.toLowerCase(prefix.charAt(i))
    729                     != Character.toLowerCase(word.charAt(i))) {
    730                 return false;
    731             }
    732         }
    733 
    734         return true;
    735     }
    736 
    737     /**
    738      * This method performs a prefix match for the given word and prefix, with a couple of
    739      * Android code completion specific twists:
    740      * <ol>
    741      * <li> The match is not case sensitive, so {word="fOo",prefix="FoO"} is a match.
    742      * <li>If the word to be matched has a namespace prefix, the typed prefix doesn't have
    743      * to match it. So {word="android:foo", prefix="foo"} is a match.
    744      * <li>If the attribute name part starts with "layout_" it can be omitted. So
    745      * {word="android:layout_marginTop",prefix="margin"} is a match, as is
    746      * {word="android:layout_marginTop",prefix="android:margin"}.
    747      * </ol>
    748      *
    749      * @param word the full word to be matched, including namespace if any
    750      * @param prefix the prefix to check
    751      * @param nsPrefix the namespace prefix (android: or local definition of android
    752      *            namespace prefix)
    753      * @return true if the prefix matches for code completion
    754      */
    755     protected static boolean nameStartsWith(String word, String prefix, String nsPrefix) {
    756         if (nsPrefix == null) {
    757             nsPrefix = ""; //$NON-NLS-1$
    758         }
    759 
    760         int wordStart = nsPrefix.length();
    761         int prefixStart = 0;
    762 
    763         if (startsWith(prefix, nsPrefix)) {
    764             // Already matches up through the namespace prefix:
    765             prefixStart = wordStart;
    766         } else if (startsWith(nsPrefix, prefix)) {
    767             return true;
    768         }
    769 
    770         int prefixLength = prefix.length();
    771         int wordLength = word.length();
    772 
    773         if (wordLength - wordStart < prefixLength - prefixStart) {
    774             return false;
    775         }
    776 
    777         boolean matches = true;
    778         for (int i = prefixStart, j = wordStart; i < prefixLength; i++, j++) {
    779             char c1 = Character.toLowerCase(prefix.charAt(i));
    780             char c2 = Character.toLowerCase(word.charAt(j));
    781             if (c1 != c2) {
    782                 matches = false;
    783                 break;
    784             }
    785         }
    786 
    787         if (!matches && word.startsWith(ATTR_LAYOUT_PREFIX, wordStart)
    788                 && !prefix.startsWith(ATTR_LAYOUT_PREFIX, prefixStart)) {
    789             wordStart += ATTR_LAYOUT_PREFIX.length();
    790 
    791             if (wordLength - wordStart < prefixLength - prefixStart) {
    792                 return false;
    793             }
    794 
    795             for (int i = prefixStart, j = wordStart; i < prefixLength; i++, j++) {
    796                 char c1 = Character.toLowerCase(prefix.charAt(i));
    797                 char c2 = Character.toLowerCase(word.charAt(j));
    798                 if (c1 != c2) {
    799                     return false;
    800                 }
    801             }
    802 
    803             return true;
    804         }
    805 
    806         return matches;
    807     }
    808 
    809     /**
    810      * Indicates whether this descriptor describes an element that can potentially
    811      * have children (either sub-elements or text value). If an element can have children,
    812      * we want to explicitly write an opening and a separate closing tag.
    813      * <p/>
    814      * Elements can have children if the descriptor has children element descriptors
    815      * or if one of the attributes is a TextValueDescriptor.
    816      *
    817      * @param descriptor An ElementDescriptor or an AttributeDescriptor
    818      * @return True if the descriptor is an ElementDescriptor that can have children or a text
    819      *         value
    820      */
    821     private boolean elementCanHaveChildren(Object descriptor) {
    822         if (descriptor instanceof ElementDescriptor) {
    823             ElementDescriptor desc = (ElementDescriptor) descriptor;
    824             if (desc.hasChildren()) {
    825                 return true;
    826             }
    827             for (AttributeDescriptor attrDesc : desc.getAttributes()) {
    828                 if (attrDesc instanceof TextValueDescriptor) {
    829                     return true;
    830                 }
    831             }
    832         }
    833         return false;
    834     }
    835 
    836     /**
    837      * Returns the element descriptor matching a given XML node name or null if it can't be
    838      * found.
    839      * <p/>
    840      * This is simplistic; ideally we should consider the parent's chain to make sure we
    841      * can differentiate between different hierarchy trees. Right now the first match found
    842      * is returned.
    843      */
    844     private ElementDescriptor getDescriptor(String nodeName) {
    845         return getRootDescriptor().findChildrenDescriptor(nodeName, true /* recursive */);
    846     }
    847 
    848     public IContextInformation[] computeContextInformation(ITextViewer viewer, int offset) {
    849         return null;
    850     }
    851 
    852     /**
    853      * Returns the characters which when entered by the user should
    854      * automatically trigger the presentation of possible completions.
    855      *
    856      * In our case, we auto-activate on opening tags and attributes namespace.
    857      *
    858      * @return the auto activation characters for completion proposal or <code>null</code>
    859      *      if no auto activation is desired
    860      */
    861     public char[] getCompletionProposalAutoActivationCharacters() {
    862         return new char[]{ '<', ':', '=' };
    863     }
    864 
    865     public char[] getContextInformationAutoActivationCharacters() {
    866         return null;
    867     }
    868 
    869     public IContextInformationValidator getContextInformationValidator() {
    870         return null;
    871     }
    872 
    873     public String getErrorMessage() {
    874         return null;
    875     }
    876 
    877     /**
    878      * Heuristically extracts the prefix used for determining template relevance
    879      * from the viewer's document. The default implementation returns the String from
    880      * offset backwards that forms a potential XML element name, attribute name or
    881      * attribute value.
    882      *
    883      * The part were we access the document was extracted from
    884      * org.eclipse.jface.text.templatesTemplateCompletionProcessor and adapted to our needs.
    885      *
    886      * @param viewer the viewer
    887      * @param offset offset into document
    888      * @return the prefix to consider
    889      */
    890     protected String extractElementPrefix(ITextViewer viewer, int offset) {
    891         int i = offset;
    892         IDocument document = viewer.getDocument();
    893         if (i > document.getLength()) return ""; //$NON-NLS-1$
    894 
    895         try {
    896             for (; i > 0; --i) {
    897                 char ch = document.getChar(i - 1);
    898 
    899                 // We want all characters that can form a valid:
    900                 // - element name, e.g. anything that is a valid Java class/variable literal.
    901                 // - attribute name, including : for the namespace
    902                 // - attribute value.
    903                 // Before we were inclusive and that made the code fragile. So now we're
    904                 // going to be exclusive: take everything till we get one of:
    905                 // - any form of whitespace
    906                 // - any xml separator, e.g. < > ' " and =
    907                 if (Character.isWhitespace(ch) ||
    908                         ch == '<' || ch == '>' || ch == '\'' || ch == '"' || ch == '=') {
    909                     break;
    910                 }
    911             }
    912 
    913             return document.get(i, offset - i);
    914         } catch (BadLocationException e) {
    915             return ""; //$NON-NLS-1$
    916         }
    917     }
    918 
    919     /**
    920      * Extracts the character at the given offset.
    921      * Returns 0 if the offset is invalid.
    922      */
    923     protected char extractChar(ITextViewer viewer, int offset) {
    924         IDocument document = viewer.getDocument();
    925         if (offset > document.getLength()) return 0;
    926 
    927         try {
    928             return document.getChar(offset);
    929         } catch (BadLocationException e) {
    930             return 0;
    931         }
    932     }
    933 
    934     /**
    935      * Search forward and find the first non-space character and return it. Returns 0 if no
    936      * such character was found.
    937      */
    938     private char nextNonspaceChar(ITextViewer viewer, int offset) {
    939         IDocument document = viewer.getDocument();
    940         int length = document.getLength();
    941         for (; offset < length; offset++) {
    942             try {
    943                 char c = document.getChar(offset);
    944                 if (!Character.isWhitespace(c)) {
    945                     return c;
    946                 }
    947             } catch (BadLocationException e) {
    948                 return 0;
    949             }
    950         }
    951 
    952         return 0;
    953     }
    954 
    955     /**
    956      * Information about the current edit of an attribute as reported by parseAttributeInfo.
    957      */
    958     protected static class AttribInfo {
    959         public AttribInfo() {
    960         }
    961 
    962         /** True if the cursor is located in an attribute's value, false if in an attribute name */
    963         public boolean isInValue = false;
    964         /** The attribute name. Null when not set. */
    965         public String name = null;
    966         /** The attribute value top the left of the cursor. Null when not set. The value
    967          * *may* start with a quote (' or "), in which case we know we don't need to quote
    968          * the string for the user */
    969         public String valuePrefix = null;
    970         /** String typed by the user so far (i.e. right before requesting code completion),
    971          *  which will be corrected if we find a possible completion for an attribute value.
    972          *  See the long comment in getChoicesForAttribute(). */
    973         public String correctedPrefix = null;
    974         /** Non-zero if an attribute value need a start/end tag (i.e. quotes or brackets) */
    975         public char needTag = 0;
    976         /** Number of characters to replace after the prefix */
    977         public int replaceLength = 0;
    978         /** Should the cursor advance through the end tag when inserted? */
    979         public boolean skipEndTag = false;
    980     }
    981 
    982     /**
    983      * Try to guess if the cursor is editing an element's name or an attribute following an
    984      * element. If it's an attribute, try to find if an attribute name is being defined or
    985      * its value.
    986      * <br/>
    987      * This is currently *only* called when we know the cursor is after a complete element
    988      * tag name, so it should never return null.
    989      * <br/>
    990      * Reference for XML syntax: http://www.w3.org/TR/2006/REC-xml-20060816/#sec-starttags
    991      * <br/>
    992      * @return An AttribInfo describing which attribute is being edited or null if the cursor is
    993      *         not editing an attribute (in which case it must be an element's name).
    994      */
    995     private AttribInfo parseAttributeInfo(ITextViewer viewer, int offset, int prefixStartOffset) {
    996         AttribInfo info = new AttribInfo();
    997         int originalOffset = offset;
    998 
    999         IDocument document = viewer.getDocument();
   1000         int n = document.getLength();
   1001         if (offset <= n) {
   1002             try {
   1003                 // Look to the right to make sure we aren't sitting on the boundary of the
   1004                 // beginning of a new element with whitespace before it
   1005                 if (offset < n && document.getChar(offset) == '<') {
   1006                     return null;
   1007                 }
   1008 
   1009                 n = offset;
   1010                 for (;offset > 0; --offset) {
   1011                     char ch = document.getChar(offset - 1);
   1012                     if (ch == '>') break;
   1013                     if (ch == '<') break;
   1014                 }
   1015 
   1016                 // text will contain the full string of the current element,
   1017                 // i.e. whatever is after the "<" to the current cursor
   1018                 String text = document.get(offset, n - offset);
   1019 
   1020                 // Normalize whitespace to single spaces
   1021                 text = sWhitespace.matcher(text).replaceAll(" "); //$NON-NLS-1$
   1022 
   1023                 // Remove the leading element name. By spec, it must be after the < without
   1024                 // any whitespace. If there's nothing left, no attribute has been defined yet.
   1025                 // Be sure to keep any whitespace after the initial word if any, as it matters.
   1026                 text = sFirstElementWord.matcher(text).replaceFirst("");  //$NON-NLS-1$
   1027 
   1028                 // There MUST be space after the element name. If not, the cursor is still
   1029                 // defining the element name.
   1030                 if (!text.startsWith(" ")) { //$NON-NLS-1$
   1031                     return null;
   1032                 }
   1033 
   1034                 // Remove full attributes:
   1035                 // Syntax:
   1036                 //    name = "..." quoted string with all but < and "
   1037                 // or:
   1038                 //    name = '...' quoted string with all but < and '
   1039                 String temp;
   1040                 do {
   1041                     temp = text;
   1042                     text = sFirstAttribute.matcher(temp).replaceFirst("");  //$NON-NLS-1$
   1043                 } while(!temp.equals(text));
   1044 
   1045                 IRegion lineInfo = document.getLineInformationOfOffset(originalOffset);
   1046                 int lineStart = lineInfo.getOffset();
   1047                 String line = document.get(lineStart, lineInfo.getLength());
   1048                 int cursorColumn = originalOffset - lineStart;
   1049                 int prefixLength = originalOffset - prefixStartOffset;
   1050 
   1051                 // Now we're left with 3 cases:
   1052                 // - nothing: either there is no attribute definition or the cursor located after
   1053                 //   a completed attribute definition.
   1054                 // - a string with no =: the user is writing an attribute name. This case can be
   1055                 //   merged with the previous one.
   1056                 // - string with an = sign, optionally followed by a quote (' or "): the user is
   1057                 //   writing the value of the attribute.
   1058                 int posEqual = text.indexOf('=');
   1059                 if (posEqual == -1) {
   1060                     info.isInValue = false;
   1061                     info.name = text.trim();
   1062 
   1063                     // info.name is currently just the prefix of the attribute name.
   1064                     // Look at the text buffer to find the complete name (since we need
   1065                     // to know its bounds in order to replace it when a different attribute
   1066                     // that matches this prefix is chosen)
   1067                     int nameStart = cursorColumn;
   1068                     for (int nameEnd = nameStart; nameEnd < line.length(); nameEnd++) {
   1069                         char c = line.charAt(nameEnd);
   1070                         if (!(Character.isLetter(c) || c == ':' || c == '_')) {
   1071                             String nameSuffix = line.substring(nameStart, nameEnd);
   1072                             info.name = text.trim() + nameSuffix;
   1073                             break;
   1074                         }
   1075                     }
   1076 
   1077                     info.replaceLength = info.name.length() - prefixLength;
   1078 
   1079                     if (info.name.length() == 0 && originalOffset > 0) {
   1080                         // Ensure that attribute names are properly separated
   1081                         char prevChar = extractChar(viewer, originalOffset - 1);
   1082                         if (prevChar == '"' || prevChar == '\'') {
   1083                             // Ensure that the attribute is properly separated from the
   1084                             // previous element
   1085                             info.needTag = ' ';
   1086                         }
   1087                     }
   1088                     info.skipEndTag = false;
   1089                 } else {
   1090                     info.isInValue = true;
   1091                     info.name = text.substring(0, posEqual).trim();
   1092                     info.valuePrefix = text.substring(posEqual + 1);
   1093 
   1094                     char quoteChar = '"'; // Does " or ' surround the XML value?
   1095                     for (int i = posEqual + 1; i < text.length(); i++) {
   1096                         if (!Character.isWhitespace(text.charAt(i))) {
   1097                             quoteChar = text.charAt(i);
   1098                             break;
   1099                         }
   1100                     }
   1101 
   1102                     // Must compute the complete value
   1103                     int valueStart = cursorColumn;
   1104                     int valueEnd = valueStart;
   1105                     for (; valueEnd < line.length(); valueEnd++) {
   1106                         char c = line.charAt(valueEnd);
   1107                         if (c == quoteChar) {
   1108                             // Make sure this isn't the *opening* quote of the value,
   1109                             // which is the case if we invoke code completion with the
   1110                             // caret between the = and the opening quote; in that case
   1111                             // we consider it value completion, and offer items including
   1112                             // the quotes, but we shouldn't bail here thinking we have found
   1113                             // the end of the value.
   1114                             // Look backwards to make sure we find another " before
   1115                             // we find a =
   1116                             boolean isFirst = false;
   1117                             for (int j = valueEnd - 1; j >= 0; j--) {
   1118                                 char pc = line.charAt(j);
   1119                                 if (pc == '=') {
   1120                                     isFirst = true;
   1121                                     break;
   1122                                 } else if (pc == quoteChar) {
   1123                                     valueStart = j;
   1124                                     break;
   1125                                 }
   1126                             }
   1127                             if (!isFirst) {
   1128                                 info.skipEndTag = true;
   1129                                 break;
   1130                             }
   1131                         }
   1132                     }
   1133                     int valueEndOffset = valueEnd + lineStart;
   1134                     info.replaceLength = valueEndOffset - (prefixStartOffset + prefixLength);
   1135                     // Is the caret to the left of the value quote? If so, include it in
   1136                     // the replace length.
   1137                     int valueStartOffset = valueStart + lineStart;
   1138                     if (valueStartOffset == prefixStartOffset && valueEnd > valueStart) {
   1139                         info.replaceLength++;
   1140                     }
   1141                 }
   1142                 return info;
   1143             } catch (BadLocationException e) {
   1144                 // pass
   1145             }
   1146         }
   1147 
   1148         return null;
   1149     }
   1150 
   1151     /** Returns the root descriptor id to use */
   1152     protected int getRootDescriptorId() {
   1153         return mDescriptorId;
   1154     }
   1155 
   1156     /**
   1157      * Computes (if needed) and returns the root descriptor.
   1158      */
   1159     protected ElementDescriptor getRootDescriptor() {
   1160         if (mRootDescriptor == null) {
   1161             AndroidTargetData data = mEditor.getTargetData();
   1162             if (data != null) {
   1163                 IDescriptorProvider descriptorProvider =
   1164                     data.getDescriptorProvider(getRootDescriptorId());
   1165 
   1166                 if (descriptorProvider != null) {
   1167                     mRootDescriptor = new ElementDescriptor("",     //$NON-NLS-1$
   1168                             descriptorProvider.getRootElementDescriptors());
   1169                 }
   1170             }
   1171         }
   1172 
   1173         return mRootDescriptor;
   1174     }
   1175 
   1176     /**
   1177      * Fixed list of dimension units, along with user documentation, for use by
   1178      * {@link #completeSuffix}.
   1179      */
   1180     private static final String[] sDimensionUnits = new String[] {
   1181         "dp", //$NON-NLS-1$
   1182         "<b>Density-independent Pixels</b> - an abstract unit that is based on the physical "
   1183                 + "density of the screen.",
   1184 
   1185         "sp", //$NON-NLS-1$
   1186         "<b>Scale-independent Pixels</b> - this is like the dp unit, but it is also scaled by "
   1187                 + "the user's font size preference.",
   1188 
   1189         "pt", //$NON-NLS-1$
   1190         "<b>Points</b> - 1/72 of an inch based on the physical size of the screen.",
   1191 
   1192         "mm", //$NON-NLS-1$
   1193         "<b>Millimeters</b> - based on the physical size of the screen.",
   1194 
   1195         "in", //$NON-NLS-1$
   1196         "<b>Inches</b> - based on the physical size of the screen.",
   1197 
   1198         "px", //$NON-NLS-1$
   1199         "<b>Pixels</b> - corresponds to actual pixels on the screen. Not recommended.",
   1200     };
   1201 
   1202     /**
   1203      * Fixed list of fractional units, along with user documentation, for use by
   1204      * {@link #completeSuffix}
   1205      */
   1206     private static final String[] sFractionUnits = new String[] {
   1207         "%",  //$NON-NLS-1$
   1208         "<b>Fraction</b> - a percentage of the base size",
   1209 
   1210         "%p", //$NON-NLS-1$
   1211         "<b>Fraction</b> - a percentage relative to parent container",
   1212     };
   1213 
   1214     /**
   1215      * Completes suffixes for applicable types (like dimensions and fractions) such that
   1216      * after a dimension number you get completion on unit types like "px".
   1217      */
   1218     private Object[] completeSuffix(Object[] choices, String value, UiAttributeNode currAttrNode) {
   1219         IAttributeInfo attributeInfo = currAttrNode.getDescriptor().getAttributeInfo();
   1220         Format[] formats = attributeInfo.getFormats();
   1221         List<Object> suffixes = new ArrayList<Object>();
   1222 
   1223         if (value.length() > 0 && Character.isDigit(value.charAt(0))) {
   1224             boolean hasDimension = Format.DIMENSION.in(formats);
   1225             boolean hasFraction = Format.FRACTION.in(formats);
   1226 
   1227             if (hasDimension || hasFraction) {
   1228                 // Split up the value into a numeric part (the prefix) and the
   1229                 // unit part (the suffix)
   1230                 int suffixBegin = 0;
   1231                 for (; suffixBegin < value.length(); suffixBegin++) {
   1232                     if (!Character.isDigit(value.charAt(suffixBegin))) {
   1233                         break;
   1234                     }
   1235                 }
   1236                 String number = value.substring(0, suffixBegin);
   1237                 String suffix = value.substring(suffixBegin);
   1238 
   1239                 // Add in the matching dimension and/or fraction units, if any
   1240                 if (hasDimension) {
   1241                     // Each item has two entries in the array of strings: the first odd numbered
   1242                     // ones are the unit names and the second even numbered ones are the
   1243                     // corresponding descriptions.
   1244                     for (int i = 0; i < sDimensionUnits.length; i += 2) {
   1245                         String unit = sDimensionUnits[i];
   1246                         if (startsWith(unit, suffix)) {
   1247                             String description = sDimensionUnits[i + 1];
   1248                             suffixes.add(Pair.of(number + unit, description));
   1249                         }
   1250                     }
   1251 
   1252                     // Allow "dip" completion but don't offer it ("dp" is preferred)
   1253                     if (startsWith(suffix, "di") || startsWith(suffix, "dip")) { //$NON-NLS-1$ //$NON-NLS-2$
   1254                         suffixes.add(Pair.of(number + "dip", "Alternative name for \"dp\"")); //$NON-NLS-1$
   1255                     }
   1256                 }
   1257                 if (hasFraction) {
   1258                     for (int i = 0; i < sFractionUnits.length; i += 2) {
   1259                         String unit = sFractionUnits[i];
   1260                         if (startsWith(unit, suffix)) {
   1261                             String description = sFractionUnits[i + 1];
   1262                             suffixes.add(Pair.of(number + unit, description));
   1263                         }
   1264                     }
   1265                 }
   1266             }
   1267         }
   1268 
   1269         boolean hasFlag = Format.FLAG.in(formats);
   1270         if (hasFlag) {
   1271             boolean isDone = false;
   1272             String[] flagValues = attributeInfo.getFlagValues();
   1273             for (String flagValue : flagValues) {
   1274                 if (flagValue.equals(value)) {
   1275                     isDone = true;
   1276                     break;
   1277                 }
   1278             }
   1279             if (isDone) {
   1280                 // Add in all the new values with a separator of |
   1281                 String currentValue = currAttrNode.getCurrentValue();
   1282                 for (String flagValue : flagValues) {
   1283                     if (currentValue == null || !currentValue.contains(flagValue)) {
   1284                         suffixes.add(value + '|' + flagValue);
   1285                     }
   1286                 }
   1287             }
   1288         }
   1289 
   1290         if (suffixes.size() > 0) {
   1291             // Merge previously added choices (from attribute enums etc) with the new matches
   1292             List<Object> all = new ArrayList<Object>();
   1293             if (choices != null) {
   1294                 for (Object s : choices) {
   1295                     all.add(s);
   1296                 }
   1297             }
   1298             all.addAll(suffixes);
   1299             choices = all.toArray();
   1300         }
   1301 
   1302         return choices;
   1303     }
   1304 }
   1305