hide lookup on typing special characters in a live template expression (IDEA-92139)

java/java-tests/testData/codeInsight/template/AllowTypingRandomExpressionsWithLookupOpen-out.java

@@ -0,0 +1,11 @@
+import java.io.File;
+import java.lang.Object;
+import java.util.Map;
+
+class Foo {
+    void foo(Map<File, Object> files, File file, Object filx) {
+        for (File file1 : file.<caret>) {
+            
+        }
+    }
+}

java/java-tests/testData/codeInsight/template/AllowTypingRandomExpressionsWithLookupOpen.java

@@ -0,0 +1,9 @@
+import java.io.File;
+import java.lang.Object;
+import java.util.Map;
+
+class Foo {
+    void foo(Map<File, Object> files, File file, Object filx) {
+      <caret>
+    }
+}

java/java-tests/testSrc/com/intellij/codeInsight/template/LiveTemplateTest.groovy

@@ -190,6 +190,14 @@ public class LiveTemplateTest extends LightCodeInsightFixtureTestCase {
     assert !state.finished
   }
 
+  public void testAllowTypingRandomExpressionsWithLookupOpen() {
+    configure();
+    startTemplate("iter", "iterations")
+    myFixture.type('file.')
+    checkResult()
+    assert !state.finished
+  }
+
   private TemplateState getState() {
     TemplateManagerImpl.getTemplateState(getEditor())
   }

platform/lang-impl/src/com/intellij/codeInsight/template/impl/LiveTemplateCharFilter.java

@@ -34,6 +34,10 @@ public class LiveTemplateCharFilter extends CharFilter {
       }
       return Result.HIDE_LOOKUP;
     }
+    if (item instanceof TemplateExpressionLookupElement) {
+      if (Character.isJavaIdentifierPart(c)) return Result.ADD_TO_PREFIX;
+      return Result.HIDE_LOOKUP;
+    }
 
     return null;
   }