MessageFormatter.java

package com.chamago.bison.logger.helper;

import java.io.PrintStream;
import java.util.HashMap;
import java.util.Map;

public final class MessageFormatter
{
  static final char DELIM_START = '{';
  static final char DELIM_STOP = '}';
  static final String DELIM_STR = "{}";
  private static final char ESCAPE_CHAR = '\\';

  public static final FormattingTuple format(String messagePattern, Object arg)
  {
    return arrayFormat(messagePattern, new Object[] { arg });
  }

  public static final FormattingTuple format(String messagePattern, Object arg1, Object arg2)
  {
    return arrayFormat(messagePattern, new Object[] { arg1, arg2 });
  }

  static final Throwable getThrowableCandidate(Object[] argArray) {
    if ((argArray == null) || (argArray.length == 0)) {
      return null;
    }

    Object lastEntry = argArray[(argArray.length - 1)];
    if ((lastEntry instanceof Throwable)) {
      return (Throwable)lastEntry;
    }
    return null;
  }

  public static final FormattingTuple arrayFormat(String messagePattern, Object[] argArray)
  {
    Throwable throwableCandidate = getThrowableCandidate(argArray);

    if (messagePattern == null) {
      return new FormattingTuple(null, argArray, throwableCandidate);
    }

    if (argArray == null) {
      return new FormattingTuple(messagePattern);
    }

    int i = 0;

    StringBuffer sbuf = new StringBuffer(messagePattern.length() + 50);

    for (int L = 0; L < argArray.length; L++)
    {
      int j = messagePattern.indexOf("{}", i);

      if (j == -1)
      {
        if (i == 0) {
          return new FormattingTuple(messagePattern, argArray, throwableCandidate);
        }

        sbuf.append(messagePattern.substring(i, messagePattern.length()));
        return new FormattingTuple(sbuf.toString(), argArray, throwableCandidate);
      }

      if (isEscapedDelimeter(messagePattern, j)) {
        if (!isDoubleEscaped(messagePattern, j)) {
          L--;

          sbuf.append(messagePattern.substring(i, j - 1));
          sbuf.append('{');
          i = j + 1;
        }
        else
        {
          sbuf.append(messagePattern.substring(i, j - 1));
          deeplyAppendParameter(sbuf, argArray[L], new HashMap());
          i = j + 2;
        }
      }
      else {
        sbuf.append(messagePattern.substring(i, j));
        deeplyAppendParameter(sbuf, argArray[L], new HashMap());
        i = j + 2;
      }

    }

    sbuf.append(messagePattern.substring(i, messagePattern.length()));
    if (i < argArray.length - 1) {
      return new FormattingTuple(sbuf.toString(), argArray, throwableCandidate);
    }
    return new FormattingTuple(sbuf.toString(), argArray, null);
  }

  static final boolean isEscapedDelimeter(String messagePattern, int delimeterStartIndex)
  {
    if (delimeterStartIndex == 0) {
      return false;
    }
    char potentialEscape = messagePattern.charAt(delimeterStartIndex - 1);

    return potentialEscape == '\\';
  }

  static final boolean isDoubleEscaped(String messagePattern, int delimeterStartIndex)
  {
    return (delimeterStartIndex >= 2) && (messagePattern.charAt(delimeterStartIndex - 2) == '\\');
  }

  private static void deeplyAppendParameter(StringBuffer sbuf, Object o, Map<Object[], Object> seenMap)
  {
    if (o == null) {
      sbuf.append("null");
      return;
    }
    if (!o.getClass().isArray()) {
      safeObjectAppend(sbuf, o);
    }
    else 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(StringBuffer sbuf, Object o)
  {
    try
    {
      String oAsString = o.toString();
      sbuf.append(oAsString);
    } catch (Throwable t) {
      System.err.println("SLF4J: Failed toString() invocation on an object of type [" + o.getClass().getName() + "]");
      t.printStackTrace();
      sbuf.append("[FAILED toString()]");
    }
  }

  private static void objectArrayAppend(StringBuffer sbuf, Object[] a, Map<Object[], Object> seenMap)
  {
    sbuf.append('[');
    if (!seenMap.containsKey(a)) {
      seenMap.put(a, null);
      int len = a.length;
      for (int i = 0; i < len; i++) {
        deeplyAppendParameter(sbuf, a[i], seenMap);
        if (i != len - 1) {
          sbuf.append(", ");
        }
      }
      seenMap.remove(a);
    } else {
      sbuf.append("...");
    }
    sbuf.append(']');
  }

  private static void booleanArrayAppend(StringBuffer sbuf, boolean[] a) {
    sbuf.append('[');
    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(StringBuffer sbuf, byte[] a) {
    sbuf.append('[');
    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(StringBuffer sbuf, char[] a) {
    sbuf.append('[');
    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(StringBuffer sbuf, short[] a) {
    sbuf.append('[');
    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(StringBuffer sbuf, int[] a) {
    sbuf.append('[');
    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(StringBuffer sbuf, long[] a) {
    sbuf.append('[');
    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(StringBuffer sbuf, float[] a) {
    sbuf.append('[');
    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(StringBuffer sbuf, double[] a) {
    sbuf.append('[');
    int len = a.length;
    for (int i = 0; i < len; i++) {
      sbuf.append(a[i]);
      if (i != len - 1)
        sbuf.append(", ");
    }
    sbuf.append(']');
  }

  public static void main(String[] args) {
    FormattingTuple ft = format("Hello World {}", "chenzhurong");
    System.out.println(ft.getMessage());
    System.out.println(ft.getThrowable());
  }
}