org.codehaus.groovy.transform.stc

Class TypeCheckingExtension

java.lang.Object

org.codehaus.groovy.transform.stc.TypeCheckingExtension

Direct Known Subclasses:

AbstractTypeCheckingExtension, DefaultTypeCheckingExtension

public class TypeCheckingExtension
extends 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

Author:

Cedric Champeau

Field Summary

Fields

Modifier and Type	Field and Description
protected StaticTypeCheckingVisitor	typeCheckingVisitor

Constructor Summary

Constructors

Constructor and Description
TypeCheckingExtension(StaticTypeCheckingVisitor typeCheckingVisitor)

Method Summary

Methods

Modifier and Type	Method and Description
void	addStaticTypeError(String msg, ASTNode expr) Adds a type checking error, which will be displayed to the user during compilation.
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.
ClassNode	buildListType(ClassNode componentType) Builds a parametrized class node for List, to represent List<X>
ClassNode	buildMapType(ClassNode keyType, ClassNode valueType) Builds a parametrized class node representing the Map<keyType,valueType> type.
ClassNode	classNodeFor(Class type)
ClassNode	classNodeFor(String type)
boolean	existsProperty(PropertyExpression pexp, boolean checkForReadOnly)
boolean	existsProperty(PropertyExpression pexp, boolean checkForReadOnly, ClassCodeVisitorSupport visitor)
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.
void	finish() Subclasses should implement this method if they need to perform additional checks after the type checker has finished its work.
ClassNode[]	getArgumentTypes(ArgumentListExpression args)
MethodNode	getTargetMethod(Expression expression)
ClassNode	getType(ASTNode exp) Returns the inferred type of an expression.
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.
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.
ClassNode	lookupClassNodeFor(String type) Lookup a ClassNode by its name from the source unit
void	onMethodSelection(Expression expression, MethodNode target) Allows the extension to listen to method selection events.
ClassNode	parameterizedType(ClassNode baseType, ClassNode... genericsTypeArguments)
void	setup() Subclasses should implement this method whenever they need to perform special checks before the type checker starts working.
void	storeType(Expression exp, ClassNode cn) Stores an inferred type for an expression.

Methods inherited from class java.lang.Object

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

Field Detail

typeCheckingVisitor

protected final StaticTypeCheckingVisitor typeCheckingVisitor

Constructor Detail

TypeCheckingExtension

public TypeCheckingExtension(StaticTypeCheckingVisitor typeCheckingVisitor)

Method Detail

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 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 avoid the type checker to throw 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 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.

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 or a StaticMethodCallExpression

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 or a StaticMethodCallExpression

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(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(Class type)

classNodeFor

public ClassNode classNodeFor(String type)

lookupClassNodeFor

public ClassNode lookupClassNodeFor(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