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package org.checkerframework.checker.index.qual;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.checkerframework.framework.qual.ConditionalPostconditionAnnotation;
import org.checkerframework.framework.qual.InheritedAnnotation;
import org.checkerframework.framework.qual.JavaExpression;
import org.checkerframework.framework.qual.QualifierArgument;
/**
* Indicates that the given expressions evaluate to an integer whose value is less than the lengths
* of all the given sequences, if the method returns the given result (either true or false).
*
* As an example, consider the following method:
*
*
* @EnsuresLTLengthOfIf(
* expression = "end",
* result = true,
* targetValue = "array",
* offset = "#1 - 1"
* )
* public boolean tryShiftIndex(@NonNegative int x) {
* int newEnd = end - x;
* if (newEnd < 0) {
* return false;
* }
* end = newEnd;
* return true;
* }
*
*
* Calling this function ensures that the field {@code end} of the {@code this} object is of type
* {@code @LTLengthOf(value = "array", offset = "x - 1")}, for the value {@code x} that is passed as
* the argument. This allows the Index Checker to verify that {@code end + x} is an index into
* {@code array} in the following code:
*
*
* public void useTryShiftIndex(@NonNegative int x) {
* if (tryShiftIndex(x)) {
* Arrays.fill(array, end, end + x, null);
* }
* }
*
*
* @see LTLengthOf
* @see EnsuresLTLengthOf
* @checker_framework.manual #index-checker Index Checker
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD, ElementType.CONSTRUCTOR})
@ConditionalPostconditionAnnotation(qualifier = LTLengthOf.class)
@InheritedAnnotation
@Repeatable(EnsuresLTLengthOfIf.List.class)
public @interface EnsuresLTLengthOfIf {
/**
* The return value of the method that needs to hold for the postcondition to hold.
*
* @return the return value of the method that needs to hold for the postcondition to hold
*/
boolean result();
/**
* Java expression(s) that are less than the length of the given sequences after the method
* returns the given result.
*
* @return Java expression(s) that are less than the length of the given sequences after the
* method returns the given result
* @checker_framework.manual #java-expressions-as-arguments Syntax of Java expressions
*/
String[] expression();
/**
* Sequences, each of which is longer than each of the expressions' value after the method returns
* the given result.
*/
@JavaExpression
@QualifierArgument("value")
String[] targetValue();
/**
* This expression plus each of the expressions is less than the length of the sequence after the
* method returns the given result. The {@code offset} element must ether be empty or the same
* length as {@code targetValue}.
*
* @return the offset expressions
*/
@JavaExpression
@QualifierArgument("offset")
String[] offset() default {};
/**
* A wrapper annotation that makes the {@link EnsuresLTLengthOfIf} annotation repeatable.
*
* Programmers generally do not need to write this. It is created by Java when a programmer
* writes more than one {@link EnsuresLTLengthOfIf} annotation at the same location.
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD, ElementType.CONSTRUCTOR})
@ConditionalPostconditionAnnotation(qualifier = LTLengthOf.class)
@InheritedAnnotation
public static @interface List {
/**
* Return the repeatable annotations.
*
* @return the repeatable annotations
*/
EnsuresLTLengthOfIf[] value();
}
}