Package org.codehaus.groovy.transform.stc

# Class DefaultTypeCheckingExtension

java.lang.Object
org.codehaus.groovy.transform.stc.TypeCheckingExtension
org.codehaus.groovy.transform.stc.DefaultTypeCheckingExtension

public class DefaultTypeCheckingExtension extends TypeCheckingExtension
The default type checking handler is used by the standard type checker and doesn't handle any of the type checking errors by default. This just means that whenever a type checking error is detected, there's no additional information available to the type checker that could help it. The default handler is also capable of handling a collection of delegate handlers. If a list of delegates is set, then the type checker will try all the delegates until one is capable of handling an error.

Since:
  2.1.0

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected final List<TypeCheckingExtension>`
  `handlers`
  Registered delegate extensions consulted by this composite handler.

  ### Fields inherited from class org.codehaus.groovy.transform.stc.TypeCheckingExtension

  `typeCheckingVisitor`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `DefaultTypeCheckingExtension(StaticTypeCheckingVisitor typeCheckingVisitor)`
  Creates the default composite type-checking extension.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `addHandler(TypeCheckingExtension handler)`
  Adds a delegate handler if it is not already registered.
  `void`
  `addHandler$$bridge(TypeCheckingExtension handler)`
  Deprecated.
  `void`
  `afterMethodCall(MethodCall call)`
  Allows the extension to perform additional tasks after the type checker actually visits a method call.
  `void`
  `afterVisitClass(ClassNode node)`
  Allows the extension to perform additional tasks after the type checker actually visited a class node.
  `void`
  `afterVisitMethod(MethodNode node)`
  Allows the extension to perform additional tasks after the type checker actually visited a method node.
  `boolean`
  `beforeMethodCall(MethodCall call)`
  Allows the extension to perform additional tasks before the type checker actually visits a method call.
  `boolean`
  `beforeVisitClass(ClassNode node)`
  Allows the extension to perform additional tasks before the type checker actually visits a class node.
  `boolean`
  `beforeVisitMethod(MethodNode node)`
  Allows the extension to perform additional tasks before the type checker actually visits a method node.
  `void`
  `finish()`
  Subclasses should implement this method if they need to perform additional checks after the type checker has finished its work.
  `List<MethodNode>`
  `handleAmbiguousMethods(List<MethodNode> nodes, Expression origin)`
  This method is called by the type checker before throwing an "ambiguous method" error, giving the chance to the extension to select the method properly.
  `boolean`
  `handleIncompatibleAssignment(ClassNode lhsType, ClassNode rhsType, Expression assignmentExpression)`
  This method is called by the type checker when an assignment is not allowed by the type checker.
  `boolean`
  `handleIncompatibleReturnType(ReturnStatement returnStatement, ClassNode inferredReturnType)`
  Allows the extension to catch incompatible return types.
  `List<MethodNode>`
  `handleMissingMethod(ClassNode receiver, String name, ArgumentListExpression argumentList, ClassNode[] argumentTypes, MethodCall call)`
  This method is called by the type checker when a method call cannot be resolved.
  `boolean`
  `handleUnresolvedAttribute(AttributeExpression aexp)`
  This method is called by the type checker when an attribute expression cannot be resolved (for example, when an attribute doesn't exist).
  `boolean`
  `handleUnresolvedProperty(PropertyExpression pexp)`
  This method is called by the type checker when a property expression cannot be resolved (for example, when a property doesn't exist).
  `boolean`
  `handleUnresolvedVariableExpression(VariableExpression vexp)`
  This method is called by the type checker when a variable expression cannot be resolved.
  `void`
  `onMethodSelection(Expression expression, MethodNode target)`
  Allows the extension to listen to method selection events.
  `void`
  `removeHandler(TypeCheckingExtension handler)`
  Removes a delegate handler.
  `void`
  `setup()`
  Subclasses should implement this method whenever they need to perform special checks before the type checker starts working.

  ### Methods inherited from class org.codehaus.groovy.transform.stc.TypeCheckingExtension

  `addStaticTypeError, buildListType, buildMapType, classNodeFor, classNodeFor, existsProperty, existsProperty, extractStaticReceiver, getArgumentTypes, getOptions, getTargetMethod, getType, isStaticMethodCallOnClass, lookupClassNodeFor, parameterizedType, setOptions, storeType`

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### handlers

    protected final List<TypeCheckingExtension> handlers
    Registered delegate extensions consulted by this composite handler.

- ## Constructor Details

  - ### DefaultTypeCheckingExtension

    public DefaultTypeCheckingExtension(StaticTypeCheckingVisitor typeCheckingVisitor)
    Creates the default composite type-checking extension.

- ## Method Details

  - ### addHandler$$bridge

    @Deprecated public void addHandler$$bridge(TypeCheckingExtension handler)
    Deprecated.
    Adds a delegate handler without duplicate checks.

  - ### addHandler

    public boolean addHandler(TypeCheckingExtension handler)
    Adds a delegate handler if it is not already registered.

  - ### removeHandler

    public void removeHandler(TypeCheckingExtension handler)
    Removes a delegate handler.

  - ### handleUnresolvedVariableExpression

    public boolean handleUnresolvedVariableExpression(VariableExpression vexp)
    This method is called by the type checker when a variable expression cannot be resolved. It gives the extension a chance to resolve it for the type checker.
    Overrides:
      `handleUnresolvedVariableExpression` in class `TypeCheckingExtension`
    Parameters:
      `vexp` - the unresolved variable extension
    Returns:
      `boolean` false if the extension doesn't handle it, true if the extension handles this variable.

  - ### handleUnresolvedProperty

    public boolean handleUnresolvedProperty(PropertyExpression pexp)
    This method is called by the type checker when a property expression cannot be resolved (for example, when a property doesn't exist). It gives the extension a chance to resolve it.
    Overrides:
      `handleUnresolvedProperty` in class `TypeCheckingExtension`
    Parameters:
      `pexp` - the unresolved property
    Returns:
      `boolean` false if this extension doesn't resolve the property, true if it resolves the property.

  - ### handleUnresolvedAttribute

    public boolean handleUnresolvedAttribute(AttributeExpression aexp)
    This method is called by the type checker when an attribute expression cannot be resolved (for example, when an attribute doesn't exist). It gives the extension a chance to resolve it.
    Overrides:
      `handleUnresolvedAttribute` in class `TypeCheckingExtension`
    Parameters:
      `aexp` - the unresolved attribute
    Returns:
      `boolean` false if this extension doesn't resolve the attribute, true if it resolves the attribute.

  - ### handleIncompatibleAssignment

    public boolean handleIncompatibleAssignment(ClassNode lhsType, ClassNode rhsType, Expression assignmentExpression)
    This method is called by the type checker when an assignment is not allowed by the type checker. Extensions may override this method to allow such assignments where the type checker normally disallows them.
    Overrides:
      `handleIncompatibleAssignment` in class `TypeCheckingExtension`
    Parameters:
      `lhsType` - the type of the left hand side of the assignment, as found by the type checker
      `rhsType` - the type of the right hand side of the assignment, as found by the type checker
      `assignmentExpression` - the assignment expression which triggered this call
    Returns:
      `boolean` false if the extension does not handle this assignment, true otherwise

  - ### handleIncompatibleReturnType

    public boolean handleIncompatibleReturnType(ReturnStatement returnStatement, ClassNode inferredReturnType)
    Allows the extension to catch incompatible return types. This event is called whenever the type checker finds that an inferred return type is incompatible with the declared return type of a method.
    Overrides:
      `handleIncompatibleReturnType` in class `TypeCheckingExtension`
    Parameters:
      `returnStatement` - the statement that triggered the error
      `inferredReturnType` - the inferred return type for this statement
    Returns:
      false if the extension doesn't handle the error, true otherwise

  - ### handleAmbiguousMethods

    public List<MethodNode> handleAmbiguousMethods(List<MethodNode> nodes, Expression origin)
    This method is called by the type checker before throwing an "ambiguous method" error, giving the chance to the extension to select the method properly. This means that when this method is called, the "nodes" parameter contains at least two methods. If the returned list still contains at least two methods, then the type checker will throw an ambiguous method call error. If the returned method contains 1 element, then the type checker will not throw any error. It is invalid to return an empty list.
    Overrides:
      `handleAmbiguousMethods` in class `TypeCheckingExtension`
    Parameters:
      `nodes` - the list of ambiguous methods
      `origin` - the expression which originated the method selection process
    Returns:
      a single element list of disambiguated selection, or more elements if still ambiguous. It is not allowed to return an empty list.

  - ### handleMissingMethod

    public List<MethodNode> handleMissingMethod(ClassNode receiver, String name, ArgumentListExpression argumentList, ClassNode[] argumentTypes, MethodCall call)
    This method is called by the type checker when a method call cannot be resolved. Extensions may override this method to handle missing methods and prevent the type checker from throwing an error.
    Overrides:
      `handleMissingMethod` in class `TypeCheckingExtension`
    Parameters:
      `receiver` - the type of the receiver
      `name` - the name of the called method
      `argumentList` - the list of arguments of the call
      `argumentTypes` - the types of the arguments of the call
      `call` - the method call itself, if needed
    Returns:
      an empty list if the extension cannot resolve the method, or a list of potential methods if the extension finds candidates. This method must not return null.

  - ### afterVisitMethod

    public void afterVisitMethod(MethodNode node)
    Allows the extension to perform additional tasks after the type checker actually visited a method node. Compared to a custom visitor, this method ensures that the node being visited is a node which would have been visited by the type checker. This is in particular important for nodes which are marked with `TypeCheckingMode.SKIP`.
    Overrides:
      `afterVisitMethod` in class `TypeCheckingExtension`
    Parameters:
      `node` - a method node

  - ### beforeVisitMethod

    public boolean beforeVisitMethod(MethodNode node)
    Allows the extension to perform additional tasks before the type checker actually visits a method node. Compared to a custom visitor, this method ensures that the node being visited is a node which would have been visited by the type checker. This is in particular important for nodes which are marked with `TypeCheckingMode.SKIP`.
    Overrides:
      `beforeVisitMethod` in class `TypeCheckingExtension`
    Parameters:
      `node` - a method node
    Returns:
      false if the type checker should visit the node, or true if this extension replaces what the type checker would do with the method.

  - ### afterVisitClass

    public void afterVisitClass(ClassNode node)
    Allows the extension to perform additional tasks after the type checker actually visited a class node. Compared to a custom visitor, this method ensures that the node being visited is a node which would have been visited by the type checker. This is in particular important for nodes which are marked with `TypeCheckingMode.SKIP`.
    Overrides:
      `afterVisitClass` in class `TypeCheckingExtension`
    Parameters:
      `node` - a class node

  - ### beforeVisitClass

    public boolean beforeVisitClass(ClassNode node)
    Allows the extension to perform additional tasks before the type checker actually visits a class node. Compared to a custom visitor, this method ensures that the node being visited is a node which would have been visited by the type checker. This is in particular important for nodes which are marked with `TypeCheckingMode.SKIP`.
    Overrides:
      `beforeVisitClass` in class `TypeCheckingExtension`
    Parameters:
      `node` - a class node
    Returns:
      false if the type checker should visit the node, or true if this extension replaces what the type checker would do with the class.

  - ### afterMethodCall

    public void afterMethodCall(MethodCall call)
    Allows the extension to perform additional tasks after the type checker actually visits a method call. Compared to a custom visitor, this method ensures that the node being visited is a node which would have been visited by the type checker. This is in particular important for nodes which are marked with `TypeCheckingMode.SKIP`.
    Overrides:
      `afterMethodCall` in class `TypeCheckingExtension`
    Parameters:
      `call` - a method call, either a `MethodCallExpression`, `StaticMethodCallExpression`, or `ConstructorCallExpression`

  - ### beforeMethodCall

    public boolean beforeMethodCall(MethodCall call)
    Allows the extension to perform additional tasks before the type checker actually visits a method call. Compared to a custom visitor, this method ensures that the node being visited is a node which would have been visited by the type checker. This is in particular important for nodes which are marked with `TypeCheckingMode.SKIP`.
    Overrides:
      `beforeMethodCall` in class `TypeCheckingExtension`
    Parameters:
      `call` - a method call, either a `MethodCallExpression`, `StaticMethodCallExpression`, or `ConstructorCallExpression`
    Returns:
      false if the type checker should visit the node, or true if this extension replaces what the type checker would do with the method call.

  - ### onMethodSelection

    public void onMethodSelection(Expression expression, MethodNode target)
    Allows the extension to listen to method selection events. Given an expression, which may be a method call expression, a static method call expression, a pre/postfix expression, ..., if a corresponding method is found, this method is called.
    Overrides:
      `onMethodSelection` in class `TypeCheckingExtension`
    Parameters:
      `expression` - the expression for which a corresponding method has been found
      `target` - the method which has been chosen by the type checker

  - ### setup

    public void setup()
    Subclasses should implement this method whenever they need to perform special checks before the type checker starts working.
    Overrides:
      `setup` in class `TypeCheckingExtension`

  - ### finish

    public void finish()
    Subclasses should implement this method if they need to perform additional checks after the type checker has finished its work. This is particularly useful for situations where you need multiple passes. Some checks in that case may be deferred to the end, using this method.
    Overrides:
      `finish` in class `TypeCheckingExtension`