org.starchartlabs.alloy.core

Class Preconditions

java.lang.Object

org.starchartlabs.alloy.core.Preconditions

public final class Preconditions
extends java.lang.Object

Utilities intended to streamline verification of expected input conditions by callers.

In general, these utilities allow code of the form

 if (!expression) {
     throw new SomeException();
 }
 

to be replaced with

 Preconditions.check*(expression);
 

for compactness, behavioral clarity, and readability

It is highly recommended to constrain use of these utilities to verifying possible failure conditions which are the caller's fault, as otherwise behavior may be confusing in stack traces, and to future readers of caller implementations

For failure messages which may have non-trivial performance costs to create, it is highly recommended to use method forms which accept a Supplier

Since:

0.1.0

Method Summary

Modifier and Type	Method and Description
static void	checkArgument(boolean expression) Ensures the truth of an expression involving one or more parameters to the calling method.
static void	checkArgument(boolean expression, java.lang.Object errorMessage) Ensures the truth of an expression involving one or more parameters to the calling method.
static void	checkArgument(boolean expression, java.util.function.Supplier<java.lang.String> errorMessageSupplier) Ensures the truth of an expression involving one or more parameters to the calling method.
static void	checkState(boolean expression) Ensures the truth of an expression involving one or more parameters to the calling method.
static void	checkState(boolean expression, java.lang.Object errorMessage) Ensures the truth of an expression involving one or more parameters to the calling method.
static void	checkState(boolean expression, java.util.function.Supplier<java.lang.String> errorMessageSupplier) Ensures the truth of an expression involving one or more parameters to the calling method.

Methods inherited from class java.lang.Object

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

Method Detail

checkArgument

public static void checkArgument(boolean expression)

Ensures the truth of an expression involving one or more parameters to the calling method.

Parameters:

expression - A boolean expression

Throws:

java.lang.IllegalArgumentException - If expression is false

Since:

0.1.0

checkArgument

public static void checkArgument(boolean expression,
                                 @Nullable
                                 java.lang.Object errorMessage)

Ensures the truth of an expression involving one or more parameters to the calling method.

Parameters:

expression - A boolean expression

errorMessage - The message to provide in the exception, if the check fails; will be converted via String.valueOf(java.lang.Object)

Throws:

java.lang.IllegalArgumentException - If expression is false

Since:

0.1.0

checkArgument

public static void checkArgument(boolean expression,
                                 java.util.function.Supplier<java.lang.String> errorMessageSupplier)

Ensures the truth of an expression involving one or more parameters to the calling method.

Preferred to checkArgument(boolean, Object) when elements needs to be substituted or otherwise processed for performance reasons

Parameters:

expression - A boolean expression

errorMessageSupplier - A supplier for the message to provide in the exception, if the check fails; Will not be invoked if expression is true

Throws:

java.lang.IllegalArgumentException - If expression is false

Since:

0.1.0

checkState

public static void checkState(boolean expression)

Ensures the truth of an expression involving one or more parameters to the calling method.

Parameters:

expression - A boolean expression

Throws:

java.lang.IllegalStateException - If expression is false

Since:

0.1.0

checkState

public static void checkState(boolean expression,
                              @Nullable
                              java.lang.Object errorMessage)

Ensures the truth of an expression involving one or more parameters to the calling method.

Parameters:

expression - A boolean expression

errorMessage - The message to provide in the exception, if the check fails; will be converted via String.valueOf(java.lang.Object)

Throws:

java.lang.IllegalStateException - If expression is false

Since:

0.1.0

checkState

public static void checkState(boolean expression,
                              @Nullable
                              java.util.function.Supplier<java.lang.String> errorMessageSupplier)

Ensures the truth of an expression involving one or more parameters to the calling method.

Preferred to checkState(boolean, Object) when elements needs to be substituted or otherwise processed for performance reasons

Parameters:

expression - A boolean expression

errorMessageSupplier - A supplier for the message to provide in the exception, if the check fails; Will not be invoked if expression is true

Throws:

java.lang.IllegalStateException - If expression is false

Since:

0.1.0