io.github.szhittech.format.MessageFormatter Maven / Gradle / Ivy
package io.github.szhittech.format;
import java.text.MessageFormat;
import java.util.HashMap;
import java.util.Map;
// contributors: lizongbo: proposed special treatment of array parameter values
// Joern Huxhorn: pointed out double[] omission, suggested deep array copy
/**
* Formats messages according to very simple substitution rules. Substitutions
* can be made 1, 2 or more arguments.
*
*
* For example,
*
*
* MessageFormatter.format("Hi {}.", "there")
*
*
* will return the string "Hi there.".
*
* The {} pair is called the formatting anchor. It serves to designate
* the location where arguments need to be substituted within the message
* pattern.
*
* In case your message contains the '{' or the '}' character, you do not have
* to do anything special unless the '}' character immediately follows '{'. For
* example,
*
*
* MessageFormatter.format("Set {1,2,3} is not equal to {}.", "1,2");
*
*
* will return the string "Set {1,2,3} is not equal to 1,2.".
*
*
* If for whatever reason you need to place the string "{}" in the message
* without its formatting anchor meaning, then you need to escape the
* '{' character with '\', that is the backslash character. Only the '{'
* character should be escaped. There is no need to escape the '}' character.
* For example,
*
*
* MessageFormatter.format("Set \\{} is not equal to {}.", "1,2");
*
*
* will return the string "Set {} is not equal to 1,2.".
*
*
* The escaping behavior just described can be overridden by escaping the escape
* character '\'. Calling
*
*
* MessageFormatter.format("File name is C:\\\\{}.", "file.zip");
*
*
* will return the string "File name is C:\file.zip".
*
*
* The formatting conventions are different than those of {@link MessageFormat}
* which ships with the Java platform. This is justified by the fact that
* SLF4J's implementation is 10 times faster than that of {@link MessageFormat}.
* This local performance difference is both measurable and significant in the
* larger context of the complete logging processing chain.
*
*
* See also {@link #format(String, Object)},
* {@link #format(String, Object, Object)} and
* {@link #arrayFormat(String, Object[])} methods for more details.
*
* @author Ceki Gülcü
* @author Joern Huxhorn
*/
final public class MessageFormatter {
static final char DELIM_START = '{';
static final char DELIM_STOP = '}';
static final String DELIM_STR = "{}";
private static final char ESCAPE_CHAR = '\\';
/**
* Performs single argument substitution for the 'messagePattern' passed as
* parameter.
*
* For example,
*
*
* MessageFormatter.format("Hi {}.", "there");
*
*
* will return the string "Hi there.".
*
*
* @param messagePattern
* The message pattern which will be parsed and formatted
* @param arg
* The argument to be substituted in place of the formatting anchor
* @return The formatted message
*/
final public static FormattingTuple format(String messagePattern, Object arg) {
return arrayFormat(messagePattern, new Object[] { arg });
}
/**
*
* Performs a two argument substitution for the 'messagePattern' passed as
* parameter.
*
* For example,
*
*
* MessageFormatter.format("Hi {}. My name is {}.", "Alice", "Bob");
*
*
* will return the string "Hi Alice. My name is Bob.".
*
* @param messagePattern
* The message pattern which will be parsed and formatted
* @param arg1
* The argument to be substituted in place of the first formatting
* anchor
* @param arg2
* The argument to be substituted in place of the second formatting
* anchor
* @return The formatted message
*/
final public static FormattingTuple format(final String messagePattern, Object arg1, Object arg2) {
return arrayFormat(messagePattern, new Object[] { arg1, arg2 });
}
final public static FormattingTuple arrayFormat(final String messagePattern, final Object[] argArray) {
Throwable throwableCandidate = MessageFormatter.getThrowableCandidate(argArray);
Object[] args = argArray;
if (throwableCandidate != null) {
args = MessageFormatter.trimmedCopy(argArray);
}
return arrayFormat(messagePattern, args, throwableCandidate);
}
final public static FormattingTuple arrayFormat(final String messagePattern, final Object[] argArray, Throwable throwable) {
if (messagePattern == null) {
return new FormattingTuple(null, argArray, throwable);
}
if (argArray == null) {
return new FormattingTuple(messagePattern);
}
int i = 0;
int j;
// use string builder for better multicore performance
StringBuilder sbuf = new StringBuilder(messagePattern.length() + 50);
int L;
for (L = 0; L < argArray.length; L++) {
j = messagePattern.indexOf(DELIM_STR, i);
if (j == -1) {
// no more variables
if (i == 0) { // this is a simple string
return new FormattingTuple(messagePattern, argArray, throwable);
} else { // add the tail string which contains no variables and return
// the result.
sbuf.append(messagePattern, i, messagePattern.length());
return new FormattingTuple(sbuf.toString(), argArray, throwable);
}
} else {
if (isEscapedDelimeter(messagePattern, j)) {
if (!isDoubleEscaped(messagePattern, j)) {
L--; // DELIM_START was escaped, thus should not be incremented
sbuf.append(messagePattern, i, j - 1);
sbuf.append(DELIM_START);
i = j + 1;
} else {
// The escape character preceding the delimiter start is
// itself escaped: "abc x:\\{}"
// we have to consume one backward slash
sbuf.append(messagePattern, i, j - 1);
deeplyAppendParameter(sbuf, argArray[L], new HashMap());
i = j + 2;
}
} else {
// normal case
sbuf.append(messagePattern, i, j);
deeplyAppendParameter(sbuf, argArray[L], new HashMap());
i = j + 2;
}
}
}
// append the characters following the last {} pair.
sbuf.append(messagePattern, i, messagePattern.length());
return new FormattingTuple(sbuf.toString(), argArray, throwable);
}
final static boolean isEscapedDelimeter(String messagePattern, int delimeterStartIndex) {
if (delimeterStartIndex == 0) {
return false;
}
char potentialEscape = messagePattern.charAt(delimeterStartIndex - 1);
if (potentialEscape == ESCAPE_CHAR) {
return true;
} else {
return false;
}
}
final static boolean isDoubleEscaped(String messagePattern, int delimeterStartIndex) {
if (delimeterStartIndex >= 2 && messagePattern.charAt(delimeterStartIndex - 2) == ESCAPE_CHAR) {
return true;
} else {
return false;
}
}
// special treatment of array values was suggested by 'lizongbo'
private static void deeplyAppendParameter(StringBuilder sbuf, Object o, Map seenMap) {
if (o == null) {
sbuf.append("null");
return;
}
if (!o.getClass().isArray()) {
safeObjectAppend(sbuf, o);
} else {
// check for primitive array types because they
// unfortunately cannot be cast to Object[]
if (o instanceof boolean[]) {
booleanArrayAppend(sbuf, (boolean[]) o);
} else if (o instanceof byte[]) {
byteArrayAppend(sbuf, (byte[]) o);
} else if (o instanceof char[]) {
charArrayAppend(sbuf, (char[]) o);
} else if (o instanceof short[]) {
shortArrayAppend(sbuf, (short[]) o);
} else if (o instanceof int[]) {
intArrayAppend(sbuf, (int[]) o);
} else if (o instanceof long[]) {
longArrayAppend(sbuf, (long[]) o);
} else if (o instanceof float[]) {
floatArrayAppend(sbuf, (float[]) o);
} else if (o instanceof double[]) {
doubleArrayAppend(sbuf, (double[]) o);
} else {
objectArrayAppend(sbuf, (Object[]) o, seenMap);
}
}
}
private static void safeObjectAppend(StringBuilder sbuf, Object o) {
try {
String oAsString = o.toString();
sbuf.append(oAsString);
} catch (Throwable t) {
sbuf.append("[FAILED toString()]");
}
}
private static void objectArrayAppend(StringBuilder sbuf, Object[] a, Map seenMap) {
sbuf.append('[');
if (!seenMap.containsKey(a)) {
seenMap.put(a, null);
final int len = a.length;
for (int i = 0; i < len; i++) {
deeplyAppendParameter(sbuf, a[i], seenMap);
if (i != len - 1)
sbuf.append(", ");
}
// allow repeats in siblings
seenMap.remove(a);
} else {
sbuf.append("...");
}
sbuf.append(']');
}
private static void booleanArrayAppend(StringBuilder sbuf, boolean[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void byteArrayAppend(StringBuilder sbuf, byte[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void charArrayAppend(StringBuilder sbuf, char[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void shortArrayAppend(StringBuilder sbuf, short[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void intArrayAppend(StringBuilder sbuf, int[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void longArrayAppend(StringBuilder sbuf, long[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void floatArrayAppend(StringBuilder sbuf, float[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void doubleArrayAppend(StringBuilder sbuf, double[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
/**
* Helper method to determine if an {@link Object} array contains a {@link Throwable} as last element
*
* @param argArray
* The arguments off which we want to know if it contains a {@link Throwable} as last element
* @return if the last {@link Object} in argArray is a {@link Throwable} this method will return it,
* otherwise it returns null
*/
public static Throwable getThrowableCandidate(final Object[] argArray) {
if (argArray == null || argArray.length == 0) {
return null;
}
final Object lastEntry = argArray[argArray.length - 1];
if (lastEntry instanceof Throwable) {
return (Throwable) lastEntry;
}
return null;
}
/**
* Helper method to get all but the last element of an array
*
* @param argArray
* The arguments from which we want to remove the last element
*
* @return a copy of the array without the last element
*/
public static Object[] trimmedCopy(final Object[] argArray) {
if (argArray == null || argArray.length == 0) {
throw new IllegalStateException("non-sensical empty or null argument array");
}
final int trimmedLen = argArray.length - 1;
Object[] trimmed = new Object[trimmedLen];
if (trimmedLen > 0) {
System.arraycopy(argArray, 0, trimmed, 0, trimmedLen);
}
return trimmed;
}
}