io.hekate.util.format.ToString Maven / Gradle / Ivy
/*
* Copyright 2022 The Hekate Project
*
* The Hekate Project licenses this file to you 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 io.hekate.util.format;
import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Optional;
import java.util.OptionalDouble;
import java.util.OptionalInt;
import java.util.OptionalLong;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.regex.Pattern;
/**
* Utility for building {@link Object#toString()} methods.
*/
public final class ToString {
private static class FieldFormat {
private static final Pattern FIELD_NAME_PATTERN = Pattern.compile("([^_A-Z])([A-Z])");
private final String nameEq;
private final Field field;
private final ToStringFormat.Formatter formatter;
public FieldFormat(Field field) {
this.nameEq = formatName(field.getName()) + '=';
this.field = field;
ToStringFormat format = field.getAnnotation(ToStringFormat.class);
if (format == null) {
this.formatter = tryDefaultFormatter(field.getType());
} else {
Class type = format.value();
try {
ToStringFormat.Formatter customFormat = null;
try {
for (Constructor c : type.getDeclaredConstructors()) {
if (c != null && c.getParameterCount() == 0) {
c.setAccessible(true);
customFormat = (ToStringFormat.Formatter)c.newInstance();
}
}
} catch (SecurityException | InvocationTargetException e) {
// No-op.
}
if (customFormat == null) {
customFormat = type.getConstructor().newInstance();
}
this.formatter = customFormat;
} catch (InstantiationException | IllegalAccessException | NoSuchMethodException | InvocationTargetException e) {
throw new IllegalStateException("Failed to instantiate formatter [type=" + type.getName() + ']', e);
}
}
}
public boolean format(Object obj, StringBuilder buf, boolean prependSeparator) throws IllegalAccessException {
Object val = field.get(obj);
if (formatter != null) {
// Try to use custom formatter.
String fmtVal = formatter.format(val);
if (fmtVal != null) {
if (prependSeparator) {
buf.append(", ");
}
buf.append(nameEq).append(fmtVal);
return true;
}
return false;
} else if (val != null) {
// Use default formatting (only if value is not null).
if (prependSeparator) {
buf.append(", ");
}
buf.append(nameEq);
if (val.getClass().isArray()) {
formatArray(buf, val);
} else if (val instanceof Class) {
Class clazz = (Class)val;
buf.append(clazz.getName());
} else {
buf.append(val);
}
return true;
} else {
return false;
}
}
private ToStringFormat.Formatter tryDefaultFormatter(Class type) {
if (Optional.class.isAssignableFrom(type)) {
return val -> val != null ? ((Optional)val).map(String::valueOf).orElse(null) : null;
} else if (OptionalInt.class.isAssignableFrom(type)) {
return val -> {
if (val != null) {
OptionalInt opt = (OptionalInt)val;
return opt.isPresent() ? String.valueOf(opt.getAsInt()) : null;
} else {
return null;
}
};
} else if (OptionalLong.class.isAssignableFrom(type)) {
return val -> {
if (val != null) {
OptionalLong opt = (OptionalLong)val;
return opt.isPresent() ? String.valueOf(opt.getAsLong()) : null;
} else {
return null;
}
};
} else if (OptionalDouble.class.isAssignableFrom(type)) {
return val -> {
if (val != null) {
OptionalDouble opt = (OptionalDouble)val;
return opt.isPresent() ? String.valueOf(opt.getAsDouble()) : null;
} else {
return null;
}
};
} else {
return null;
}
}
private static void formatArray(StringBuilder buf, Object val) {
buf.append('[');
for (int i = 0, size = Array.getLength(val); i < size; i++) {
if (i > 0) {
buf.append(", ");
}
Object arrVal = Array.get(val, i);
if (arrVal.getClass().isArray()) {
formatArray(buf, arrVal);
} else {
buf.append(arrVal);
}
}
buf.append(']');
}
private static String formatName(String name) {
return FIELD_NAME_PATTERN.matcher(name).replaceAll("$1-$2").toLowerCase(Locale.US);
}
}
private static class ClassFormat {
private final String name;
private final int approxSize;
private final List fields;
public ClassFormat(Class type) {
this.name = type.getSimpleName();
int approxSize = 0;
List fields = new ArrayList<>();
do {
Field[] declaredFields = type.getDeclaredFields();
if (declaredFields.length > 0) {
List typeFields = new ArrayList<>(declaredFields.length);
for (Field field : declaredFields) {
if (!field.isSynthetic()) {
int mod = field.getModifiers();
if (!Modifier.isStatic(mod) && field.getAnnotation(ToStringIgnore.class) == null) {
field.setAccessible(true);
typeFields.add(new FieldFormat(field));
// This is really approximate.
approxSize += field.getName().length() * 2;
}
}
}
if (!typeFields.isEmpty()) {
fields.addAll(0, typeFields);
}
}
type = type.getSuperclass();
}
while (type != null && type != Object.class);
this.fields = fields;
this.approxSize = approxSize;
}
public String format(Class alias, boolean propertiesOnly, Object obj) throws IllegalAccessException {
StringBuilder buf;
if (propertiesOnly) {
if (approxSize == 0) {
// There are no fields in this class.
return "";
} else {
buf = new StringBuilder(approxSize);
}
} else {
String realName;
int realApproxSize;
if (alias == null) {
realName = name;
} else {
realName = alias.getSimpleName();
}
realApproxSize = approxSize + realName.length() + 2/* this is for '[' ']' */;
buf = new StringBuilder(realApproxSize);
buf.append(realName);
}
if (!fields.isEmpty()) {
if (!propertiesOnly) {
buf.append('[');
}
boolean appendSeparator = false;
for (FieldFormat field : fields) {
boolean formatted = field.format(obj, buf, appendSeparator);
if (formatted) {
appendSeparator = true;
}
}
if (!propertiesOnly) {
buf.append(']');
}
}
return buf.toString();
}
}
private static final ReentrantReadWriteLock.ReadLock READ_LOCK;
private static final ReentrantReadWriteLock.WriteLock WRITE_LOCK;
private static final Map, ClassFormat> FORMATS = new HashMap<>();
static {
ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
READ_LOCK = lock.readLock();
WRITE_LOCK = lock.writeLock();
}
private ToString() {
// No-op.
}
/**
* Formats the specified object to string including the object's type information.
*
* Example: {@code MyObj[fieldA=1, fieldB=ZZZ]}
*
*
* @param obj Object to be formatted.
*
* @return String representation of the specified object.
*/
public static String format(Object obj) {
return doFormat(null, false, obj);
}
/**
* Formats the specified object to string by prefixing it with the specified type name instead of the original object type.
*
* Example: {@code MyTypeAlias[fieldA=1, fieldB=ZZZ]}
*
*
* @param alias Type who's name should be added to the formatted string.
* @param obj Object to be formatted.
*
* @return String representation of the specified object.
*/
public static String format(Class alias, Object obj) {
return doFormat(alias, false, obj);
}
/**
* Returns the comma-separated list of object's fields and values.
*
* @param obj Object to be formatted.
*
* @return Comma-separated list of object's fields and values.
*/
public static String formatProperties(Object obj) {
return doFormat(null, true, obj);
}
private static String doFormat(Class alias, boolean propertiesOnly, Object obj) {
if (obj == null) {
return "null";
}
Class type = obj.getClass();
ClassFormat format;
READ_LOCK.lock();
try {
format = FORMATS.get(type);
} finally {
READ_LOCK.unlock();
}
if (format == null) {
WRITE_LOCK.lock();
try {
format = FORMATS.computeIfAbsent(type, ClassFormat::new);
} finally {
WRITE_LOCK.unlock();
}
}
try {
return format.format(alias, propertiesOnly, obj);
} catch (IllegalAccessException e) {
return "TO_STRING_FAILURE: " + e;
}
}
}
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