com.badlogic.gdx.utils.TextFormatter Maven / Gradle / Ivy
/*******************************************************************************
* Copyright 2011 See AUTHORS file.
*
* 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.badlogic.gdx.utils;
import java.text.MessageFormat;
import java.util.Locale;
/** {@code TextFormatter} is used by {@link I18NBundle} to perform argument replacement.
*
* @author davebaol */
class TextFormatter {
private MessageFormat messageFormat;
private StringBuilder buffer;
public TextFormatter (Locale locale, boolean useMessageFormat) {
buffer = new StringBuilder();
if (useMessageFormat) messageFormat = new MessageFormat("", locale);
}
/** Formats the given {@code pattern} replacing its placeholders with the actual arguments specified by {@code args}.
*
* If this {@code TextFormatter} has been instantiated with {@link #TextFormatter(Locale, boolean) TextFormatter(locale, true)}
* {@link MessageFormat} is used to process the pattern, meaning that the actual arguments are properly localized with the
* locale of this {@code TextFormatter}.
*
* On the contrary, if this {@code TextFormatter} has been instantiated with {@link #TextFormatter(Locale, boolean)
* TextFormatter(locale, false)} pattern's placeholders are expected to be in the simplified form {0}, {1}, {2} and so on and
* they will be replaced with the corresponding object from {@code args} converted to a string with {@code toString()}, so
* without taking into account the locale.
*
* In both cases, there's only one simple escaping rule, i.e. a left curly bracket must be doubled if you want it to be part of
* your string.
*
* It's worth noting that the rules for using single quotes within {@link MessageFormat} patterns have shown to be somewhat
* confusing. In particular, it isn't always obvious to localizers whether single quotes need to be doubled or not. For this
* very reason we decided to offer the simpler escaping rule above without limiting the expressive power of message format
* patterns. So, if you're used to MessageFormat's syntax, remember that with {@code TextFormatter} single quotes never need to
* be escaped!
*
* @param pattern the pattern
* @param args the arguments
* @return the formatted pattern
* @exception IllegalArgumentException if the pattern is invalid */
public String format (String pattern, Object... args) {
if (messageFormat != null) {
messageFormat.applyPattern(replaceEscapeChars(pattern));
return messageFormat.format(args);
}
return simpleFormat(pattern, args);
}
// This code is needed because a simple replacement like
// pattern.replace("'", "''").replace("{{", "'{'");
// can't properly manage some special cases.
// For example, the expected output for {{{{ is {{ but you get {'{ instead.
// Also this code is optimized since a new string is returned only if something has been replaced.
private String replaceEscapeChars (String pattern) {
buffer.setLength(0);
boolean changed = false;
int len = pattern.length();
for (int i = 0; i < len; i++) {
char ch = pattern.charAt(i);
if (ch == '\'') {
changed = true;
buffer.append("''");
} else if (ch == '{') {
int j = i + 1;
while (j < len && pattern.charAt(j) == '{')
j++;
int escaped = (j - i) / 2;
if (escaped > 0) {
changed = true;
buffer.append('\'');
do {
buffer.append('{');
} while ((--escaped) > 0);
buffer.append('\'');
}
if ((j - i) % 2 != 0) buffer.append('{');
i = j - 1;
} else {
buffer.append(ch);
}
}
return changed ? buffer.toString() : pattern;
}
/** Formats the given {@code pattern} replacing any placeholder of the form {0}, {1}, {2} and so on with the corresponding
* object from {@code args} converted to a string with {@code toString()}, so without taking into account the locale.
*
* This method only implements a small subset of the grammar supported by {@link java.text.MessageFormat}. Especially,
* placeholder are only made up of an index; neither the type nor the style are supported.
*
* If nothing has been replaced this implementation returns the pattern itself.
*
* @param pattern the pattern
* @param args the arguments
* @return the formatted pattern
* @exception IllegalArgumentException if the pattern is invalid */
private String simpleFormat (String pattern, Object... args) {
buffer.setLength(0);
boolean changed = false;
int placeholder = -1;
int patternLength = pattern.length();
for (int i = 0; i < patternLength; ++i) {
char ch = pattern.charAt(i);
if (placeholder < 0) { // processing constant part
if (ch == '{') {
changed = true;
if (i + 1 < patternLength && pattern.charAt(i + 1) == '{') {
buffer.append(ch); // handle escaped '{'
++i;
} else {
placeholder = 0; // switch to placeholder part
}
} else {
buffer.append(ch);
}
} else { // processing placeholder part
if (ch == '}') {
if (placeholder >= args.length)
throw new IllegalArgumentException("Argument index out of bounds: " + placeholder);
if (pattern.charAt(i - 1) == '{')
throw new IllegalArgumentException("Missing argument index after a left curly brace");
if (args[placeholder] == null)
buffer.append("null"); // append null argument
else
buffer.append(args[placeholder].toString()); // append actual argument
placeholder = -1; // switch to constant part
} else {
if (ch < '0' || ch > '9')
throw new IllegalArgumentException("Unexpected '" + ch + "' while parsing argument index");
placeholder = placeholder * 10 + (ch - '0');
}
}
}
if (placeholder >= 0) throw new IllegalArgumentException("Unmatched braces in the pattern.");
return changed ? buffer.toString() : pattern;
}
}