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package com.sun.jersey.spi;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Read a string value and convert to a Java type.
 * <p>
 * A {@link StringReaderProvider} is responsible for providing an instance
 * of this interface.
 * <p>
 * If annotated with {@link ValidateDefaultValue} with a value of true or
 * the annotation is absent then the reader will be used to validate a default 
 * value (if any) by calling the fromString method, perhaps at initialization,
 * before any value, default or otherwise, is actually required. This
 * enables the early reporting of errors for default values.
 * If annotated with {@link ValidateDefaultValue} with a value of false then
 * the reader will not be used to validate a default (if any) before any value,
 * default or otherwise, is actually required.
 *
 * @param <T> the Java type to convert to.
 * 
 * @author Paul.Sandoz@Sun.Com
 */
public interface StringReader<T> {

    /**
     * Declares whether validation of a default value should occur before any
     * value, default or otherwise, is actually required.
     */
    @Target({ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public static @interface ValidateDefaultValue {
        boolean value() default true;
    }
    
    /**
     * Read a string value and convert to a Java type.
     *
     * @param value The string value.
     * @return the instance of the Java type.
     */
    T fromString(String value);
}