ConstraintSystem (Kotlin Compiler)

All Known Implementing Classes:

ConstraintSystemImpl
```
public interface ConstraintSystem
```

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`addSubtypeConstraint(JetType constrainingType, JetType subjectType, ConstraintPosition constraintPosition)` Adds a constraint that the constraining type is a subtype of the subject type. Asserts that only subject type may contain registered type variables.
`void`	`addSupertypeConstraint(JetType constrainingType, JetType subjectType, ConstraintPosition constraintPosition)` Adds a constraint that the constraining type is a supertype of the subject type.
`ConstraintSystem`	`copy()`
`TypeSubstitutor`	`getCurrentSubstitutor()` Returns a current result of solving the constraint system (mapping from the type variable to the resulting type projection).
`TypeSubstitutor`	`getResultingSubstitutor()` Returns a result of solving the constraint system (mapping from the type variable to the resulting type projection).
`TypeConstraints`	`getTypeConstraints(TypeParameterDescriptor typeVariable)` Returns the resulting type constraints of solving the constraint system for specific type variable.
`java.util.Set<TypeParameterDescriptor>`	`getTypeVariables()` Returns a set of all registered type variables.
`boolean`	`hasConflictingConstraints()` Returns `true` if type constraints for some type variable are contradicting.
`boolean`	`hasContradiction()` Return `true` if constraint system has no contradiction (it can be not successful because of the lack of information for a type variable).
`boolean`	`hasErrorInConstrainingTypes()` Returns `true` if there is an error in constraining types.
`boolean`	`hasOnlyExpectedTypeMismatch()` Returns `true` if there is type constructor mismatch only in `ConstraintPosition.EXPECTED_TYPE_POSITION`.
`boolean`	`hasTypeConstructorMismatch()` Returns `true` if some constraint cannot be processed because of type constructor mismatch.
`boolean`	`hasTypeConstructorMismatchAt(ConstraintPosition constraintPosition)` Returns `true` if there is type constructor mismatch error at a specific `constraintPosition`.
`boolean`	`hasUnknownParameters()` Returns `true` if there is no information for some registered type variable.
`boolean`	`isSuccessful()` Returns `true` if constraint system has a solution (has no contradiction and has enough information to infer each registered type variable).
`void`	`registerTypeVariable(TypeParameterDescriptor typeVariable, Variance positionVariance)` Registers a variable in a constraint system.

- Method Detail
  - registerTypeVariable
```
void registerTypeVariable(@NotNull
                        TypeParameterDescriptor typeVariable,
                        @NotNull
                        Variance positionVariance)
```
    Registers a variable in a constraint system.
  - getTypeVariables
```
@NotNull
java.util.Set<TypeParameterDescriptor> getTypeVariables()
```
    Returns a set of all registered type variables.
  - addSubtypeConstraint
```
void addSubtypeConstraint(@Nullable
                        JetType constrainingType,
                        @NotNull
                        JetType subjectType,
                        @NotNull
                        ConstraintPosition constraintPosition)
```
    Adds a constraint that the constraining type is a subtype of the subject type.
    Asserts that only subject type may contain registered type variables.
    For example, for "fun <T> id(t: T) {}" to infer T in invocation "id(1)" should be generated a constraint "Int is a subtype of T" where T is a subject type, and Int is a constraining type.
  - addSupertypeConstraint
```
void addSupertypeConstraint(@Nullable
                          JetType constrainingType,
                          @NotNull
                          JetType subjectType,
                          @NotNull
                          ConstraintPosition constraintPosition)
```
    Adds a constraint that the constraining type is a supertype of the subject type.
    Asserts that only subject type may contain registered type variables.
    For example, for "fun <T> create() : T" to infer T in invocation "val i: Int = create()" should be generated a constraint "Int is a supertype of T" where T is a subject type, and Int is a constraining type.
  - isSuccessful
```
boolean isSuccessful()
```
    Returns true if constraint system has a solution (has no contradiction and has enough information to infer each registered type variable).
  - hasContradiction
```
boolean hasContradiction()
```
    Return true if constraint system has no contradiction (it can be not successful because of the lack of information for a type variable).
  - hasConflictingConstraints
```
boolean hasConflictingConstraints()
```
    Returns true if type constraints for some type variable are contradicting.
    For example, for
```
fun <R> foo(r: R, t: java.util.List<R>) {}
```
    in invocation foo(1, arrayList("s")) type variable R has two conflicting constraints:
    - "R is a supertype of Int"
    - "List<R> is a supertype of List<String>" which leads to "R is equal to String"
  - hasUnknownParameters
```
boolean hasUnknownParameters()
```
    Returns true if there is no information for some registered type variable. For example, for
```
fun <E> newList()
```
    in invocation "val nl = newList()" there is no information to infer type variable E.
  - hasTypeConstructorMismatch
```
boolean hasTypeConstructorMismatch()
```
    Returns true if some constraint cannot be processed because of type constructor mismatch. For example, for
```
fun <R> foo(t: List<R>) {}
```
    in invocation foo(hashSet("s")) there is type constructor mismatch: "HashSet<String> cannot be a subtype of List<R>".
  - hasTypeConstructorMismatchAt
```
boolean hasTypeConstructorMismatchAt(@NotNull
                                   ConstraintPosition constraintPosition)
```
    Returns true if there is type constructor mismatch error at a specific constraintPosition. For example, for
```
fun <R> foo(t: List<R>) {}
```
    in invocation foo(hashSet("s")) there is type constructor mismatch: "HashSet<String> cannot be a subtype of List<R>" at a constraint position ConstraintPosition.getValueParameterPosition(0).
  - hasOnlyExpectedTypeMismatch
```
boolean hasOnlyExpectedTypeMismatch()
```
    Returns true if there is type constructor mismatch only in ConstraintPosition.EXPECTED_TYPE_POSITION.
  - hasErrorInConstrainingTypes
```
boolean hasErrorInConstrainingTypes()
```
    Returns true if there is an error in constraining types.
    Is used not to generate type inference error if there was one in argument types.
  - getTypeConstraints
```
@Nullable
TypeConstraints getTypeConstraints(@NotNull
                                          TypeParameterDescriptor typeVariable)
```
    Returns the resulting type constraints of solving the constraint system for specific type variable.
    Returns null if the type variable was not registered.
  - getResultingSubstitutor
```
@NotNull
TypeSubstitutor getResultingSubstitutor()
```
    Returns a result of solving the constraint system (mapping from the type variable to the resulting type projection).
    In the resulting substitution should be concerned:
    - type constraints
    - variance of the type variable // not implemented yet
    - type parameter bounds (that can bind type variables with each other). // not implemented yet If the addition of the 'expected type' constraint made the system fail, this constraint is not included in the resulting substitution.
  - getCurrentSubstitutor
```
@NotNull
TypeSubstitutor getCurrentSubstitutor()
```
    Returns a current result of solving the constraint system (mapping from the type variable to the resulting type projection). If there is no information for type parameter, returns type projection for DONT_CARE type.
  - copy
```
ConstraintSystem copy()
```

Interface ConstraintSystem

Method Summary

Method Detail

registerTypeVariable

getTypeVariables

addSubtypeConstraint

addSupertypeConstraint

isSuccessful

hasContradiction

hasConflictingConstraints

hasUnknownParameters

hasTypeConstructorMismatch

hasTypeConstructorMismatchAt

hasOnlyExpectedTypeMismatch

hasErrorInConstrainingTypes

getTypeConstraints

getResultingSubstitutor

getCurrentSubstitutor

copy