Package org.codehaus.groovy.transform.stc

Class TypeCheckingExtension

java.lang.Object
org.codehaus.groovy.transform.stc.TypeCheckingExtension
Direct Known Subclasses:
AbstractTypeCheckingExtension, DefaultTypeCheckingExtension, EnumTypeCheckingExtension
public class TypeCheckingExtension
extends java.lang.Object
This interface defines a high-level API for handling type checking errors. As a dynamic language and a platform for developing DSLs, the Groovy language provides a lot of means to supply custom bindings or methods that are not possible to find at compile time. However, it is still possible to help the compiler, for example by telling it what is the type of an unresolved property. For basic DSL type checking, implementing those methods would help the type checker and make it silent where it normally throws errors.
Since:
2.1.0

  • Field Details

  • Constructor Details

  • Method Details

    • setup

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

    • 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.

    • 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.
      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.
      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.
      Parameters:
      aexp - the unresolved attribute
      Returns:
      boolean false if this extension doesn't resolve the attribute, true if it resolves the attribute.

    • handleMissingMethod

      public java.util.List<MethodNode> handleMissingMethod​(ClassNode receiver, java.lang.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.
      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.

    • 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.
      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

    • handleAmbiguousMethods

      public java.util.List<MethodNode> handleAmbiguousMethods​(java.util.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.
      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.

    • 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.
      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.

    • 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.
      Parameters:
      node - a method 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.
      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.

    • 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.
      Parameters:
      node - a class node

    • 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.
      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.

    • 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.
      Parameters:
      call - a method call, either a MethodCallExpression, StaticMethodCallExpression, or ConstructorCallExpression

    • 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.
      Parameters:
      expression - the expression for which a corresponding method has been found
      target - the method which has been chosen by the type checker

    • 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.
      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

    • getType

      public ClassNode getType​(ASTNode exp)
      Returns the inferred type of an expression. Delegates to the type checker implementation.
      Parameters:
      exp - the expression for which we want to find the inferred type
      Returns:
      the inferred type of the expression, as found by the type checker

    • addStaticTypeError

      public void addStaticTypeError​(java.lang.String msg, ASTNode expr)
      Adds a type checking error, which will be displayed to the user during compilation.
      Parameters:
      msg - the message for the error
      expr - the expression which is the root cause of the error

    • storeType

      public void storeType​(Expression exp, ClassNode cn)
      Stores an inferred type for an expression. Delegates to the type checker.
      Parameters:
      exp - the expression for which we want to store an inferred type
      cn - the type of the expression

    • existsProperty

      public boolean existsProperty​(PropertyExpression pexp, boolean checkForReadOnly)

    • existsProperty

      public boolean existsProperty​(PropertyExpression pexp, boolean checkForReadOnly, ClassCodeVisitorSupport visitor)

    • getArgumentTypes

      public ClassNode[] getArgumentTypes​(ArgumentListExpression args)

    • getTargetMethod

      public MethodNode getTargetMethod​(Expression expression)

    • classNodeFor

      public ClassNode classNodeFor​(java.lang.Class type)

    • classNodeFor

      public ClassNode classNodeFor​(java.lang.String type)

    • lookupClassNodeFor

      public ClassNode lookupClassNodeFor​(java.lang.String type)
      Lookup a ClassNode by its name from the source unit
      Parameters:
      type - the name of the class whose ClassNode we want to lookup
      Returns:
      a ClassNode representing the class

    • parameterizedType

      public ClassNode parameterizedType​(ClassNode baseType, ClassNode... genericsTypeArguments)

    • buildListType

      public ClassNode buildListType​(ClassNode componentType)
      Builds a parametrized class node for List, to represent List<X>
      Parameters:
      componentType - the classnode for the component type of the list
      Returns:
      a classnode representing List<componentType>
      Since:
      2.2.0

    • buildMapType

      public ClassNode buildMapType​(ClassNode keyType, ClassNode valueType)
      Builds a parametrized class node representing the Map<keyType,valueType> type.
      Parameters:
      keyType - the classnode type of the key
      valueType - the classnode type of the value
      Returns:
      a class node for Map<keyType,valueType>
      Since:
      2.2.0

    • extractStaticReceiver

      public ClassNode extractStaticReceiver​(MethodCall call)
      Given a method call, first checks that it's a static method call, and if it is, returns the class node for the receiver. For example, with the following code: Person.findAll { ... }, it would return the class node for Person. If it's not a static method call, returns null.
      Parameters:
      call - a method call
      Returns:
      null if it's not a static method call, or the class node for the receiver instead.

    • isStaticMethodCallOnClass

      public boolean isStaticMethodCallOnClass​(MethodCall call, ClassNode receiver)
      Given a method call, checks if it's a static method call and if it is, tells if the receiver matches the one supplied as an argument.
      Parameters:
      call - a method call
      receiver - a class node
      Returns:
      true if the method call is a static method call on the receiver