ouyangpeng / android-lint-checks-studio3.0 Goto Github PK

google 官方源代码地址为：https://android.googlesource.com/platform/tools/base/+/studio-3.0/lint/

参考的官方介绍视频为：https://www.youtube.com/watch?v=p8yX5-lPS6o&index=9&list=PLQ176FUIyIUY6UK1cgVsbdPYA3X5WLam5

Lint官方论坛：https://groups.google.com/forum/#!forum/lint-dev

这个版本的Lint API和原来的版本 有了很大的改版，很多代码都是kotlin来实现的，如果要自定义Lint的话 得好好看看源代码学习学习

https://groups.google.com/forum/#!topic/lint-dev/7nLiXa04baM 一文中有相关的介绍，如下所示：

https://github.com/JetBrains/uast

There are quite a few implications for lint. Here's the javadoc I wrote for the new UastScanner interface (when you port from PSI you'll change the implements JavaPsiScanner declaration to UastScanner, and then the various tips described below:

public static interface Detector.UastScanner

There are several different common patterns for detecting issues:

• Checking calls to a given method. For this see getApplicableMethodNames() and visitMethod(JavaContext, UCallExpression, PsiMethod)
• Instantiating a given class. For this, see getApplicableConstructorTypes() and visitConstructor(JavaContext, UCallExpression, PsiMethod)
• Referencing a given constant. For this, see getApplicableReferenceNames() and visitReference(JavaContext, UReferenceExpression, PsiElement)
• Extending a given class or implementing a given interface. For this, see applicableSuperClasses() and visitClass(JavaContext, UClass)
• More complicated scenarios: perform a general AST traversal with a visitor. In this case, first tell lint which AST node types you're interested in with the getApplicableUastTypes() method, and then provide a UElementHandler from the createUastHandler(JavaContext) where you override the various applicable handler methods. This is done rather than a general visitor from the root node to avoid having to have every single lint detector (there are hundreds) do a full tree traversal on its own.

Detector.UastScanner exposes the UAST API to lint checks. UAST is short for "Universal AST" and is an abstract syntax tree library which abstracts away details about Java versus Kotlin versus other similar languages and lets the client of the library access the AST in a unified way.

UAST isn't actually a full replacement for PSI; it augments PSI. Essentially, UAST is usd for the inside of methods (e.g. method bodies), and things like field initializers. PSI continues to be used at the outer level: for packages, classes, and methods (declarations and signatures). There are also wrappers around some of these for convenience.

The Detector.UastScanner interface reflects this fact. For example, when you indicate that you want to check calls to a method named foo, the call site node is a UAST node (in this case, UCallExpression, but the called method itself is a PsiMethod, since that method might be anywhere (including in a library that we don't have source for, so UAST doesn't make sense.)

PsiMethod

PsiField

However, the visitor methods have all changed, generally to change to UAST types. For example, the signature Detector.JavaPsiScanner.visitMethod(JavaContext, JavaElementVisitor, PsiMethodCallExpression, PsiMethod) should be changed to visitMethod(JavaContext, UCallExpression, PsiMethod).

There are a bunch of new methods on classes like JavaContext which lets you pass in a UElement to match the existing PsiElement methods.

If you have code which does something specific with PSI classes, the following mapping table in alphabetical order might be helpful, since it lists the corresponding UAST classes.

getUastParent

getParent

UMethod

not

PsiMethod.getBody()

     UastContext context = UastUtils.getUastContext(element);
     UExpression body = context.getMethodBody(method);
 

PsiField

     UastContext context = UastUtils.getUastContext(element);
     UExpression initializer = context.getInitializerBody(field);
 

 <    call.getMethodExpression().getReferenceName();
 ---
 >    call.getMethodName()
 

 <    call.getMethodExpression().getQualifierExpression();
 ---
 >    call.getReceiver()
 

 <    PsiExpression[] args = call.getArgumentList().getExpressions();
 ---
 >    List args = call.getValueArguments();
 

arg[i]

arg.get(i)

arg[i]

UastExpressionUtils

UastExpressionUtils.isAssignment(UElement)

ResourceReference

UExpression

        ResourceReference reference = ResourceReference.get(expression);
        if (reference == null || reference.getType() != ResourceType.STYLEABLE) {
            return;
        }
        ...
 

PsiBinaryExpression

UBinaryExpression

UPolyadicExpression

UPolyadicExpression

The following table maps some common method names and what their corresponding names are in UAST.

getApplicableUastTypes()

not

UElementHandler

getApplicableUastTypes()

First read the javadoc on how to convert from the older Detector.JavaScanner interface over to Detector.JavaPsiScanner. While Detector.JavaPsiScanner is itself deprecated, it's a lot closer to Detector.UastScanner so a lot of the same concepts apply; then follow the above section.