Codenarc Revisited: Part 2 Jenn Strater @codeJENNerator

@codeJENNerator Note For Those Viewing Slides Online • Bulleted text like this indicates the key points mentioned on a previous slide. They may not have been included in the official presentation. • If this view does not support links, the links will work in the pdf. Click the ‘download pdf’ button on the right.

@codeJENNerator https://speakerdeck.com/jlstrater/codenarc-part-2-gr8conf-eu-2017 Follow Along

@codeJENNerator About Me

@codeJENNerator About Me Starting at Zenjob in Berlin on Monday June 5!

@codeJENNerator About Me - Took classes at the Technical University of Denmark and worked on a research project - Also explored Danish Culture with funding from the US Fulbright Grant program - Prior to the Fulbright Grant, I was a senior consultant at Object Partners, Inc. in Minneapolis, MN, USA. - Co-founder of Gr8Ladies and talk about women in the Groovy Community all over the world - Passionate about bring new people into the Groovy community through free introductory workshops called Gr8Workshops. - Moving to Berlin and starting at Zenjob in June 2017.

@codeJENNerator Background

@codeJENNerator Background • Uses Codenarc • Has written a Custom Rule • Contributed back to Codenarc

@codeJENNerator Agenda • Part I Recap • What’s New Since Part I • Creating a Custom Rule • Bytecode Analysis and Optimization Project

Recap of Part I https://www.youtube.com/watch?v=3v18NB7pyCY

@codeJENNerator What is ?

@codeJENNerator “CodeNarc is a static analysis tool for Groovy source code, enabling monitoring and enforcement of many coding standards and best practices… CodeNarc is similar to popular static analysis tools such as PMD or Checkstyle. Unlike those tools which analyze Java code, CodeNarc analyzes Groovy code.” What is ?

@codeJENNerator Why use Codenarc? • Improves readability • Saves time with code reviews • Code with fewer bugs • Help onboard new team members

@codeJENNerator Terms Formatting Space After Switch Braces for Class Trailing Whitespace

@codeJENNerator Not Just Formatting • Concurrency • JDBC • Security • Complexity

@codeJENNerator Setup Plugin

One Year Later https://github.com/CodeNarc/CodeNarc/blob/master/CHANGELOG.txt

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@codeJENNerator What coming next?

@codeJENNerator GR8Conf Hackergarten

@codeJENNerator 0.28.0

@codeJENNerator Creating a Custom Rule

@codeJENNerator ->groovy codenarc.groovy create-rule Enter your name:Jenn Strater Enter the rule name:TestExampleRule Enter the rule category. Valid categories are: basic braces concurrency convention design dry exceptions formatting generic grails groovyism imports jdbc junit logging naming security serialization size unnecessary unused unnecessary Enter the rule description:A test example rule that removes some unnecessary piece of code Created ./src/main/groovy/org/codenarc/rule/unnecessary/TestExampleRule.groovy Created ./src/test/groovy/org/codenarc/rule/unnecessary/TestExampleRuleTest.groovy Updated ./src/main/resources/codenarc-base-messages.properties Updated ./src/main/resources/rulesets/unnecessary.xml Updated ./src/site/apt/codenarc-rules-unnecessary.apt Updated ./CHANGELOG.txt adding to git... add 'src/main/groovy/org/codenarc/rule/unnecessary/TestExampleRule.groovy' adding to git... add 'src/test/groovy/org/codenarc/rule/unnecessary/TestExampleRuleTest.groovy' Finished

@codeJENNerator TextExampleRule.groovy /*
 * Copyright 2017 the original author or authors.
 * 
 * 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 org.codenarc.rule.unnecessary
 
 import org.codenarc.rule.AbstractAstVisitorRule
 import org.codenarc.rule.AbstractAstVisitor
 
 /**
 * A test example rule that removes some unnecessary piece of code
 *
 * @author Jenn Strater
 */
 class TestExampleRule extends AbstractAstVisitorRule {
 
 String name = 'TestExample'
 int priority = 2
 Class astVisitorClass = TestExampleAstVisitor
 }
 
 class TestExampleAstVisitor extends AbstractAstVisitor {
 
 }


@codeJENNerator TextExampleRuleTest.groovy package org.codenarc.rule.unnecessary
 
 import org.codenarc.rule.Rule
 import org.junit.Test
 import org.codenarc.rule.AbstractRuleTestCase
 class TestExampleRuleTest extends AbstractRuleTestCase {
 
 @Test
 void testRuleProperties() {
 assert rule.priority == 2
 assert rule.name == 'TestExample'
 }
 
 @Test
 void testNoViolations() {
 final SOURCE = '''
 // todo: replace with source for passing edge case(s)
 '''
 assertNoViolations(SOURCE)
 }
 
 @Test
 void testSingleViolation() {
 final SOURCE = '''
 // todo: replace with source that triggers a violation
 '''
 assertSingleViolation(SOURCE, 1, '...')
 }
 
 @Test
 void testMultipleViolations() {
 final SOURCE = '''
 // todo: replace with source that triggers 2 violations
 '''
 assertViolations(SOURCE,
 [lineNumber:1, sourceLineText:'...', messageText:'...'], // todo: replace line number, source line and message
 [lineNumber:1, sourceLineText:'...', messageText:'...']) // todo: replace line number, source line and message
 }
 
 protected Rule createRule() {
 new TestExampleRule()
 }
 }

@codeJENNerator Could Be Switch Rule

Switch in Groovy http://mrhaki.blogspot.dk/2009/08/groovy-goodness-switch-statement.html

@codeJENNerator CouldBeSwitchRule.groovy class CouldBeSwitchStatementRule extends AbstractAstVisitorRule { String name = 'CouldBeSwitchStatement' int priority = 3 Class astVisitorClass = CouldBeSwitchStatementAstVisitor String errorMessage = 'Code could use switch statement' }

@codeJENNerator CouldBeSwitchRule.groovy class CouldBeSwitchStatementAstVisitor extends AbstractAstVisitor { private BinaryExpression prev = null private Integer ifCounter = 0 private firstIfNode = null @Override void visitIfElse(IfStatement node) { checkIfStatementCanBeSwitch(node) super.visitIfElse(node) } private void checkIfStatementCanBeSwitch(IfStatement node) { def current = node.booleanExpression?.expression if (current instanceof BinaryExpression && isSupportedLeftExpressionType(current.leftExpression) && inSupportedOperation(current.operation)) { if (isSameLeftExpressionAsPreviousIfStatement(current.leftExpression, prev?.leftExpression)) { ifCounter++ } else { ifCounter = 1 firstIfNode = current } if (ifCounter > 2) { addViolation(firstIfNode, rule.errorMessage) ifCounter = 0 prev = null } prev = current } else { ifCounter = 0 prev = null } } . . .

@codeJENNerator CouldBeSwitchRule.groovy private Boolean inSupportedOperation(Token operation) { operation.type in [Types.COMPARE_EQUAL, Types.KEYWORD_INSTANCEOF] } private Boolean isSupportedLeftExpressionType(def expression) { switch(expression) { case PropertyExpression: case VariableExpression: case ConstantExpression: return true default: return false } } private Boolean isSameLeftExpressionAsPreviousIfStatement(def current, def prev) { if (!prev || current.class != prev.class) { return false } switch(current) { case PropertyExpression: return isSameLeftExpressionAsPreviousIfStatement(current.objectExpression, prev?.objectExpression) && isSameLeftExpressionAsPreviousIfStatement(current.property, prev.property) case VariableExpression: return current.variable == prev?.variable case ConstantExpression: return current.value == prev.value default: false } }

@codeJENNerator codenarc-base-messages.properties 
 # todo: manually sort your messages into the correct location
 TestExample.description=A test example rule that removes some unnecessary piece of code
 TestExample.description.html=A test example rule that removes some unnecessary piece of code

@codeJENNerator codenarc-rules-unnecessary.apt 
 * {TestExample} Rule
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 
 A test example rule that removes some unnecessary piece of code
 
 Example of violations:
 
 ------------------------------------------------------------------------ -------
 // TODO: Add examples
 ------------------------------------------------------------------------ -------


@codeJENNerator Limitations of Codenarc

@codeJENNerator Codenarc Conclusion

@codeJENNerator

@codeJENNerator • Codenarc is a lot more than just formatting

@codeJENNerator • Codenarc is a lot more than just formatting • There is still a lot of work to do

@codeJENNerator • Codenarc is a lot more than just formatting • There is still a lot of work to do • You can add your own custom rules and contribute back

@codeJENNerator Bytecode Analysis and other forms of static analysis in Groovy

Groovy Compiler Project https://jlstrater.github.io/groovy-compiler-project/html/index.html

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@codeJENNerator Legacy

@codeJENNerator Invoke Dynamic

@codeJENNerator Static Compilation

@codeJENNerator Indy vs Static Compilation

@codeJENNerator Potential for Optimization

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@codeJENNerator https://github.com/apache/groovy/blob/master/src/main/ org/codehaus/groovy/classgen/asm/StatementWriter.java

@codeJENNerator Post Pass Optimization Project

@codeJENNerator

@codeJENNerator • Simple Groovy project

@codeJENNerator • Simple Groovy project • Uses an ASM reader and writer to read bytecode compiled using each of the groovy compiler options

@codeJENNerator • Simple Groovy project • Uses an ASM reader and writer to read bytecode compiled using each of the groovy compiler options • Iterates over the method instructions to find the unneccessary instructions

@codeJENNerator • Simple Groovy project • Uses an ASM reader and writer to read bytecode compiled using each of the groovy compiler options • Iterates over the method instructions to find the unneccessary instructions • Removes the instructions and outputs the new bytecode

@codeJENNerator • Simple Groovy project • Uses an ASM reader and writer to read bytecode compiled using each of the groovy compiler options • Iterates over the method instructions to find the unneccessary instructions • Removes the instructions and outputs the new bytecode • https://github.com/jlstrater/groovy-compiler-project

Results https://jlstrater.github.io/groovy-compiler-project/ bytecode/index.html

@codeJENNerator

@codeJENNerator • There was no difference in performance

@codeJENNerator • There was no difference in performance • as explained on the mailing list

@codeJENNerator • There was no difference in performance • as explained on the mailing list • Also probable problem with benchmarking procedure

@codeJENNerator • There was no difference in performance • as explained on the mailing list • Also probable problem with benchmarking procedure • Output file sizes are being reduced. Some by up to 10% or more.

@codeJENNerator Bytecode Analysis Next Steps

@codeJENNerator

@codeJENNerator • Clean up the code and find a way to integrate the optimization and fixes into the existing groovy compiler

@codeJENNerator Conclusion

@codeJENNerator Next Steps • Join the Groovy Community on Slack groovycommunity.com • Join the Codenarc Mailing List • Submit a PR!

@codeJENNerator Questions? https://flic.kr/p/5DeuzB