IG: new "Lambda parameter naming convention" inspection

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/InspectionGadgetsBundle.properties

@@ -2159,5 +2159,10 @@ array.objects.equals.display.name='Objects.equals()' called on arrays
 array.objects.equals.problem.descriptor=<code>Objects.#ref()</code> on arrays should probably be 'Arrays.equals()' #loc
 array.objects.deep.equals.problem.descriptor=<code>Objects.#ref()</code> on arrays should probably be 'Arrays.deepEquals()' #loc
 extends.throwable.display.name=Class directly extends 'java.lang.Throwable'
-anonymous.extends.throwable.problem.descriptor=Anonymous class directly extends 'java.lang.Throwable' \#loc
-extends.throwable.problem.descriptor=class <code>\#ref</code> directly extends 'java.lang.Throwable' \#loc
+anonymous.extends.throwable.problem.descriptor=Anonymous class directly extends 'java.lang.Throwable' #loc
+extends.throwable.problem.descriptor=class <code>#ref</code> directly extends 'java.lang.Throwable' #loc
+lambda.parameter.naming.convention.display.name=Lambda parameter naming convention
+lambda.parameter.naming.convention.problem.descriptor.short=Lambda parameter name <code>#ref</code> is too short #loc
+lambda.parameter.naming.convention.problem.descriptor.long=Lambda parameter name <code>#ref</code> is too long #loc
+lambda.parameter.naming.convention.problem.descriptor.regex.mismatch=Lambda parameter name <code>#ref</code> doesn''t match regex ''{0}'' #loc
+

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/naming/LambdaParameterNamingConventionInspectionBase.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2000-2015 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.siyeh.ig.naming;
+
+import com.intellij.psi.*;
+import com.siyeh.InspectionGadgetsBundle;
+import com.siyeh.ig.BaseInspectionVisitor;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class LambdaParameterNamingConventionInspectionBase extends ConventionInspection {
+
+  private static final int DEFAULT_MIN_LENGTH = 1;
+  private static final int DEFAULT_MAX_LENGTH = 20;
+
+  @Override
+  @NotNull
+  public String getID() {
+    return "LambdaParameterNamingConvention";
+  }
+
+  @Override
+  @NotNull
+  public String getDisplayName() {
+    return InspectionGadgetsBundle.message("lambda.parameter.naming.convention.display.name");
+  }
+
+  @Override
+  protected boolean buildQuickFixesOnlyForOnTheFlyErrors() {
+    return true;
+  }
+
+  @Override
+  @NotNull
+  public String buildErrorString(Object... infos) {
+    final String parameterName = (String)infos[0];
+    if (parameterName.length() < getMinLength()) {
+      return InspectionGadgetsBundle.message("lambda.parameter.naming.convention.problem.descriptor.short");
+    }
+    else if (parameterName.length() > getMaxLength()) {
+      return InspectionGadgetsBundle.message("lambda.parameter.naming.convention.problem.descriptor.long");
+    }
+    else {
+      return InspectionGadgetsBundle.message("lambda.parameter.naming.convention.problem.descriptor.regex.mismatch", getRegex());
+    }
+  }
+
+  @Override
+  protected String getDefaultRegex() {
+    return "[a-z][A-Za-z\\d]*";
+  }
+
+  @Override
+  protected int getDefaultMinLength() {
+    return DEFAULT_MIN_LENGTH;
+  }
+
+  @Override
+  protected int getDefaultMaxLength() {
+    return DEFAULT_MAX_LENGTH;
+  }
+
+  @Override
+  public BaseInspectionVisitor buildVisitor() {
+    return new NamingConventionsVisitor();
+  }
+
+  private class NamingConventionsVisitor extends BaseInspectionVisitor {
+
+    @Override
+    public void visitParameter(@NotNull PsiParameter variable) {
+      final PsiElement scope = variable.getDeclarationScope();
+      if (!(scope instanceof PsiLambdaExpression)) {
+        return;
+      }
+      final String name = variable.getName();
+      if (name == null || isValid(name)) {
+        return;
+      }
+      registerVariableError(variable, name);
+    }
+  }
+}

plugins/InspectionGadgets/src/com/siyeh/ig/naming/LambdaParameterNamingConventionInspection.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2003-2015 Dave Griffith, Bas Leijdekkers
+ *
+ * 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.siyeh.ig.naming;
+
+import com.siyeh.ig.InspectionGadgetsFix;
+import com.siyeh.ig.fixes.RenameFix;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class LambdaParameterNamingConventionInspection extends LambdaParameterNamingConventionInspectionBase {
+
+  @Override
+  protected InspectionGadgetsFix buildFix(Object... infos) {
+    return new RenameFix();
+  }
+}

plugins/InspectionGadgets/src/inspectionDescriptions/LambdaParameterNamingConvention.html

@@ -0,0 +1,13 @@
+<html>
+<body>
+Reports lambda parameters whose names are either too short, too long, or do not follow
+the specified regular expression pattern.
+<!-- tooltip end -->
+<p>
+Use the fields below to specify minimum length, maximum length and regular expression expected for method parameter names.
+Specify <b>0</b> to not check the length of names. Regular expressions are in standard <b>java.util.regex</b> format.
+<p>
+<small>New in 15</small>
+<p>
+</body>
+</html>

plugins/InspectionGadgets/test/com/siyeh/igtest/naming/lambda_parameter_naming_convention/LambdaParameterNamingConvention.java

@@ -0,0 +1,12 @@
+public class LambdaParameterNamingConvention {
+
+  void m(int a) {}
+  void n(int abcd) {
+    F f = (<warning descr="Lambda parameter name 'i' is too short">i</warning>) -> 10;
+    F g = abc -> 12;
+  }
+
+  interface F {
+    int a(int i);
+  }
+}

plugins/InspectionGadgets/testsrc/com/siyeh/ig/naming/LambdaParameterNamingConventionInspectionTest.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2000-2015 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.siyeh.ig.naming;
+
+import com.intellij.codeInspection.InspectionProfileEntry;
+import com.siyeh.ig.LightInspectionTestCase;
+import junit.framework.TestCase;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class LambdaParameterNamingConventionInspectionTest extends LightInspectionTestCase {
+
+  public void testLambdaParameterNamingConvention() {
+    doTest();
+  }
+
+  @Nullable
+  @Override
+  protected InspectionProfileEntry getInspection() {
+    final LambdaParameterNamingConventionInspection inspection = new LambdaParameterNamingConventionInspection();
+    inspection.m_minLength = 2;
+    return inspection;
+  }
+}