Example usage for org.apache.commons.lang3.text StrBuilder charAt

Introduction

In this page you can find the example usage for org.apache.commons.lang3.text StrBuilder charAt.

Prototype

@Override
public char charAt(final int index) 

Source Link

Document

Gets the character at the specified index.

Usage

From source file:com.mgmtp.jfunk.data.generator.util.GeneratingExpression.java

/**
 * Resolves alternations by randomly choosing one at a time and adapting the pattern accordingly
 * //  w w w .  j a  va 2  s  .c  o  m
 * @param expression
 *            the pattern
 * @return the reduced pattern
 */
private String chooseAlternations(final String expression) {
    StrBuilder sb = new StrBuilder(expression);

    int i = 0;
    // Loop until an unescaped pipe symbol appears.
    while (UNESCAPED_PIPE_PATTERN.matcher(sb.toString()).find()) {
        for (; i < sb.length(); ++i) {
            if (sb.charAt(i) == '|') {
                if (sb.charAt(i - 1) == '\\') {
                    // escapet
                    continue;
                }

                int start = i;
                // Backtrack until an opening bracket is found
                // to limit the context of alternatives.
                for (int closingCount = 0; start >= 0; --start) {
                    char c = sb.charAt(start);
                    if (c == '(') {
                        if (closingCount == 0) {
                            break;
                        }
                        --closingCount;
                    } else if (c == ')') {
                        ++closingCount;
                    }
                }

                if (start >= 0) {
                    // If an opening brace was found
                    // search for a closing bracket.
                    int end = i;
                    for (int openingCount = 0; end < sb.length(); ++end) {
                        char c = sb.charAt(end);
                        if (c == '(') {
                            ++openingCount;
                        } else if (c == ')') {
                            if (openingCount == 0) {
                                break;
                            }
                            --openingCount;
                        }
                    }
                    String alternative = random.getBoolean() ? sb.substring(start + 1, i)
                            : sb.substring(i + 1, end);
                    sb.replace(start, end + 1, alternative);
                    i = start + alternative.length();
                    break;
                }
                String alternative = random.getBoolean() ? sb.substring(0, i) : sb.substring(i + 1);
                sb.replace(0, sb.length() + 1, alternative);
                break;
            }
        }
    }
    return sb.toString();
}

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