let's enable completion autopopup when typing digits and see if anyone complains (IDEA-123325)

java/java-tests/testSrc/com/intellij/codeInsight/completion/CustomFileTypeAutopopupTest.groovy

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2000-2017 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.codeInsight.completion
+
+/**
+ * @author peter
+ */
+class CustomFileTypeAutopopupTest extends CompletionAutoPopupTestCase {
+  void "test no autopopup when typing just digit in a custom file type"() {
+    myFixture.configureByText 'a.hs', 'a42 = 42\n<caret> }}'
+    type '4'
+    assert !lookup
+  }
+
+  void "test show autopopup when typing digit after letter"() {
+    myFixture.configureByText 'a.hs', 'a42 = 42\na<caret> }}'
+    type '4'
+    assert lookup
+  }
+
+}

java/java-tests/testSrc/com/intellij/codeInsight/completion/JavaAutoPopupTest.groovy

@@ -1833,4 +1833,11 @@ ita<caret>
 
     myFixture.assertPreferredCompletionItems 0, 'KimeFamilyRange'
   }
+
+  void "test show autopopup when typing digit after letter"() {
+    myFixture.configureByText 'a.java', 'class Foo {{ int a42; a<caret> }}'
+    type '4'
+    assert lookup
+  }
+
 }

platform/lang-impl/src/com/intellij/codeInsight/completion/CustomFileTypeCompletionContributor.java

@@ -23,7 +23,6 @@ import com.intellij.openapi.fileTypes.FileType;
 import com.intellij.openapi.fileTypes.impl.CustomSyntaxTableFileType;
 import com.intellij.openapi.project.DumbAware;
 import com.intellij.psi.CustomHighlighterTokenType;
-import com.intellij.psi.PsiElement;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.util.ProcessingContext;
 import org.jetbrains.annotations.NotNull;
@@ -56,7 +55,11 @@ public class CustomFileTypeCompletionContributor extends CompletionContributor i
                }
 
                SyntaxTable syntaxTable = ((CustomSyntaxTableFileType)fileType).getSyntaxTable();
-               String prefix = findPrefix(parameters.getPosition(), parameters.getOffset());
+               String prefix = CompletionUtil.findJavaIdentifierPrefix(parameters);
+               if (prefix.isEmpty() && parameters.isAutoPopup()) {
+                 return;
+               }
+
                CompletionResultSet resultSetWithPrefix = result.withPrefixMatcher(prefix);
 
                addVariants(resultSetWithPrefix, syntaxTable.getKeywords1());
@@ -90,15 +93,4 @@ public class CustomFileTypeCompletionContributor extends CompletionContributor i
     }
   }
 
-  private static String findPrefix(PsiElement insertedElement, int offset) {
-    String text = insertedElement.getText();
-    int offsetInElement = offset - insertedElement.getTextOffset();
-    int start = offsetInElement - 1;
-    while(start >=0 ) {
-      if(!Character.isJavaIdentifierStart(text.charAt(start))) break;
-      --start;
-    }
-    return text.substring(start+1, offsetInElement).trim();
-  }
-
 }

platform/lang-impl/src/com/intellij/codeInsight/editorActions/CompletionAutoPopupHandler.java

@@ -59,7 +59,7 @@ public class CompletionAutoPopupHandler extends TypedHandlerDelegate {
       return Result.STOP;
     }
 
-    if (Character.isLetter(charTyped) || charTyped == '_') {
+    if (Character.isLetterOrDigit(charTyped) || charTyped == '_') {
       AutoPopupController.getInstance(project).scheduleAutoPopup(editor);
       return Result.STOP;
     }