com.google.appengine.repackaged.com.google.common.flogger.parameter.ParameterVisitor Maven / Gradle / Ivy
/*
* Copyright (C) 2017 The Flogger Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.flogger.parameter;
import com.google.common.flogger.backend.FormatChar;
import com.google.common.flogger.backend.FormatOptions;
/**
* A visitor of log message arguments, dispatched by {@code Parameter} instances.
*/
// TODO: When all other refactoring done, rename to ArgumentVisitor
public interface ParameterVisitor {
/**
* Visits a log message argument with formatting specified by {@code %s}, {@code %d} etc...
*
* Note that this method may still visit arguments which represent date/time values if the format
* is not explicit (e.g. {@code log("time=%s", dateTime)}).
*
* @param value the non-null log message argument.
* @param format the printf format specifier.
* @param options formatting options.
*/
void visit(Object value, FormatChar format, FormatOptions options);
/**
* Visits a date/time log message argument with formatting specified by {@code %t} or similar.
*
* Note that because this method is called based on the specified format (and not the argument
* type) it may visit arguments whose type is not a known date/time value. This is necessary to
* permit new date/time types to be supported by different logging backends (e.g. JodaTime).
*
* @param value the non-null log message argument.
* @param format the date/time format specifier.
* @param options formatting options.
*/
void visitDateTime(Object value, DateTimeFormat format, FormatOptions options);
/**
* Visits a log message argument for which formatting has already occurred. This method is only
* invoked when non-printf message formatting is used (e.g. brace style formatting).
*
* This method is intended for use by {@code Parameter} implementations which describe formatting
* rules which cannot by represented by either {@link FormatChar} or {@link DateTimeFormat}. This
* method discards formatting and type information, and the visitor implementation may choose to
* reexamine the type of the original argument if doing structural logging.
*
* @param value the original non-null log message argument.
* @param formatted the formatted representation of the argument
*/
void visitPreformatted(Object value, String formatted);
/**
* Visits a missing argument. This method is called when there is no corresponding value for the
* parameter's argument index.
*/
void visitMissing();
/** Visits a null argument. */
void visitNull();
}