[NONE] DOT Editor - Fixing BadLocationException in DotProposalProvider.

- Modify the content assist proposal calculation logic to avoid throwing
org.eclipse.jface.text.BadLocationException.
- Implement corresponding DotContentAssistTest test cases.

Author: miklossy

org.eclipse.gef.dot.tests/src/org/eclipse/gef/dot/tests/DotContentAssistTest.xtend

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2016, 2020 itemis AG and others.
+ * Copyright (c) 2016, 2021 itemis AG and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
@@ -3019,6 +3019,19 @@ class DotContentAssistTest extends AbstractContentAssistTest {
 			}
 		''')
 
+		'''
+			graph {
+				1[color="blue"«c»]
+			}
+		'''.testContentAssistant(#[",", ";", "]", "color", "colorscheme", "distortion", "fillcolor", "fixedsize", "fontcolor", "fontname", "fontsize",
+								"height", "id", "label", "penwidth", "pos", "shape", "sides", "skew", "style", "tooltip", "width",
+								"xlabel", "xlp"], "fixedsize",
+		'''
+			graph {
+				1[color="blue"fixedsize=]
+			}
+		''')
+
 		// test local attribute names with prefix
 		'''
 			graph {
@@ -3054,6 +3067,16 @@ class DotContentAssistTest extends AbstractContentAssistTest {
 			}
 		''')
 
+		'''
+			graph {
+				1[ color=«c»"" ]
+			}
+		'''.testContentAssistant(combine(expectedX11ColorNames, #["#", "/"]), "#", '''
+			graph {
+				1[ color=#"" ]
+			}
+		''')
+
 		// test local attribute values with quotes
 		'''
 			graph {
@@ -3458,6 +3481,18 @@ class DotContentAssistTest extends AbstractContentAssistTest {
 		''')
 
 		// test html-like label attribute
+		'''
+			graph {
+				1[ label=«c»<> ]
+			}
+		'''.testContentAssistant(#["HTMLLabel - Insert a template"], "HTMLLabel - Insert a template", '''
+			graph {
+				1[ label=<
+					
+				><> ]
+			}
+		''')
+
 		'''
 			graph {
 				1[ label=<

org.eclipse.gef.dot.ui/src/org/eclipse/gef/dot/internal/ui/language/contentassist/DotProposalProvider.java

@@ -21,6 +21,8 @@
  *******************************************************************************/
 package org.eclipse.gef.dot.internal.ui.language.contentassist;
 
+import static org.eclipse.gef.dot.internal.language.dot.DotPackage.Literals.ATTRIBUTE__VALUE;
+
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
 import java.util.ArrayList;
@@ -69,6 +71,7 @@
 import org.eclipse.xtext.EcoreUtil2;
 import org.eclipse.xtext.Keyword;
 import org.eclipse.xtext.nodemodel.INode;
+import org.eclipse.xtext.nodemodel.util.NodeModelUtils;
 import org.eclipse.xtext.ui.IImageHelper;
 import org.eclipse.xtext.ui.editor.contentassist.ConfigurableCompletionProposal;
 import org.eclipse.xtext.ui.editor.contentassist.ConfigurableCompletionProposal.IReplacementTextApplier;
@@ -313,6 +316,28 @@ public void completeAttribute_Value(EObject model, Assignment assignment,
 					.setMatcher(new AttributeValueMatcher(context.getMatcher()))
 					.toContext();
 
+			/*
+			 * do not propose any attribute values if it is already properly
+			 * enclosed with double quotes and the cursor is located directly
+			 * after the closing quote
+			 */
+			ID attributeValue = attribute.getValue();
+			if (attributeValue != null) {
+				String attributeValueText = attributeValue.toString();
+				int cursorPosition = context.getOffset();
+
+				int attributeValueEndOffset = NodeModelUtils
+						.findNodesForFeature(attribute, ATTRIBUTE__VALUE).get(0)
+						.getTotalEndOffset();
+
+				if (attributeValueText.startsWith("\"") //$NON-NLS-1$
+						&& attributeValueText.endsWith("\"") //$NON-NLS-1$
+						&& attributeValueText.length() > 1
+						&& cursorPosition >= attributeValueEndOffset) {
+					return;
+				}
+			}
+
 			switch (attributeContext) {
 			case EDGE:
 				switch (attributeName) {
@@ -600,7 +625,9 @@ private void proposeAttributeValues(String subgrammarName,
 				} else {
 					text = text.substring(1, text.length() - 1);
 				}
-				offset++;
+				if (context.getOffset() > offset) {
+					offset++;
+				}
 			}
 		}
 
@@ -681,11 +708,22 @@ private void proposeHtmlLabelAttributeValues(Attribute attribute,
 		DotColorProposalProvider.globalColorScheme = DotAstHelper
 				.getColorSchemeAttributeValue(attribute);
 
-		if (attribute.getValue() != null
-				&& attribute.getValue().getType() == Type.HTML_STRING) {
-			proposeAttributeValues(
-					DotActivator.ORG_ECLIPSE_GEF_DOT_INTERNAL_LANGUAGE_DOTHTMLLABEL,
-					context, acceptor);
+		ID attributeValue = attribute.getValue();
+		if (attributeValue != null) {
+			int cursorPosition = context.getOffset();
+			int attributeValueStartOffset = NodeModelUtils
+					.findNodesForFeature(attribute, ATTRIBUTE__VALUE).get(0)
+					.getOffset();
+			/*
+			 * do not propose the html-label values if the attribute value is
+			 * set, but the cursor is located before it
+			 */
+			if (cursorPosition > attributeValueStartOffset
+					&& attributeValue.getType() == Type.HTML_STRING) {
+				proposeAttributeValues(
+						DotActivator.ORG_ECLIPSE_GEF_DOT_INTERNAL_LANGUAGE_DOTHTMLLABEL,
+						context, acceptor);
+			}
 		}
 
 		// reset the state of the DotColorProposalProvider