Class ClosureSignatureHint

    • Constructor Detail

      • ClosureSignatureHint

        public ClosureSignatureHint()
    • Method Detail

      • pickGenericType

        public static ClassNode pickGenericType​(ClassNode type,
                                                int gtIndex)
        A helper method which will extract the n-th generic type from a class node.
        type - the class node from which to pick a generic type
        gtIndex - the index of the generic type to extract
        the n-th generic type, or ClassHelper.OBJECT_TYPE if it doesn't exist.
      • pickGenericType

        public static ClassNode pickGenericType​(MethodNode node,
                                                int parameterIndex,
                                                int gtIndex)
        A helper method which will extract the n-th generic type from the n-th parameter of a method node.
        node - the method node from which the generic type should be picked
        parameterIndex - the index of the parameter in the method parameter list
        gtIndex - the index of the generic type to extract
        the generic type, or ClassHelper.OBJECT_TYPE if it doesn't exist.
      • getClosureSignatures

        public abstract List<ClassNode[]> getClosureSignatures​(MethodNode node,
                                                               SourceUnit sourceUnit,
                                                               CompilationUnit compilationUnit,
                                                               String[] options,
                                                               ASTNode usage)

        Subclasses should implement this method, which returns the list of accepted closure signatures.

        The compiler will call this method each time, in a source file, a method call using a closure literal is encountered and that the target method has the corresponding Closure parameter annotated with ClosureParams. So imagine the following code needs to be compiled:

        @groovy.transform.TypeChecked void doSomething() { println ['a','b'].collect { it.toUpperCase() } }

        The collect method accepts a closure, but normally, the type checker doesn't have enough type information in the sole DefaultGroovyMethods.collect(java.lang.Iterable, groovy.lang.Closure) method signature to infer the type of it. With the annotation, it will now try to find an annotation on the closure parameter. If it finds it, then an instance of the hint class is created and the type checker calls it with the following arguments:

        Now, the hint instance can return the list of expected parameters. Here, it would have to say that the collect method accepts a closure for which the only argument is of the type of the first generic type of the first argument.

        With that type information, the type checker can now infer that the type of it is String, because the first argument (here the receiver of the collect method) is a List<String>

        Subclasses are therefore expected to return the signatures according to the available context, which is only the target method and the potential options.

        node - the method node for which a Closure parameter was annotated with ClosureParams
        sourceUnit - the source unit of the file being compiled
        compilationUnit - the compilation unit of the file being compiled
        options - the options, corresponding to the ClosureParams.options() found on the annotation @return a non-null list of signature, where a signature corresponds to an array of class nodes, each of them matching a parameter.
        usage - the AST node, in the compiled file, which triggered a call to this method. Normally only used for logging/error handling
      • findClassNode

        protected ClassNode findClassNode​(SourceUnit sourceUnit,
                                          CompilationUnit compilationUnit,
                                          String className)
        Finds a class node given a string representing the type. Performs a lookup in the compilation unit to check if it is done in the same source unit.
        sourceUnit - source unit
        compilationUnit - compilation unit
        className - the name of the class we want to get a ClassNode for
        a ClassNode representing the type