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package bjc.utils.funcutils;
import java.util.Deque;
/**
* Utility methods for operations on strings
*
* @author ben
*
*/
public class StringUtils {
/**
* Checks if the given expression contains the specified operator in a
* situation that indicates its use as an infix operator.
*
* @param expression
* The expression to check
* @param operator
* The operator to see if it is contained
* @return Whether or not the given expression contains the specified
* operator as a infix operator
*/
public static boolean containsInfixOperator(String expression, String operator) {
// Bit annoying to have to use a full class name, but what are you
// going to do?
return org.apache.commons.lang3.StringUtils.countMatches(expression, operator) == 1
&& !expression.equalsIgnoreCase(operator)
&& !expression.startsWith(operator);
}
/**
* Check if a string consists only of one or more matches of a regular
* expression
*
* @param input
* The string to check
* @param regex
* The regex to see if the string only contains matches of
* @return Whether or not the string consists only of multiple matches
* of the provided regex
*/
public static boolean containsOnly(String input, String regex) {
/*
* This regular expression is fairly simple.
*
* First, we match the beginning of the string. Then, we start a
* non-capturing group whose contents are the passed in regex. That
* group is then matched one or more times and the pattern matches
* to the end of the string
*/
if (input == null) {
throw new NullPointerException("Input must not be null");
} else if (regex == null) {
throw new NullPointerException("Regex must not be null");
}
return input.matches("\\A(?:" + regex + ")+\\Z");
}
/**
* Indent the string being built in a StringBuilder n levels
*
* @param builder
* The builder to indent in
* @param levels
* The number of levels to indent
*/
public static void indentNLevels(StringBuilder builder, int levels) {
for (int i = 0; i < levels; i++) {
builder.append("\t");
}
}
/**
* Print out a deque with a special case for easily showing a deque is
* empty
*
* @param <ContainedType>
* The type in the deque
* @param queue
* The deque to print
* @return A string version of the deque, with allowance for an empty
* deque
*/
public static <ContainedType> String printDeque(Deque<ContainedType> queue) {
return queue.isEmpty() ? "(none)" : queue.toString();
}
}
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