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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.text;
/**
* Formats any parenthesis expression.
* In addition to the obvious this can also operate in "two column mode",
* wherein each chunk that will be formatted on a separate line may optionally
* contain a prefix marked by a start and end tab sign which will be printed in a left column of the given fixed size.
* The prefix itself is not formatted but will be cut if too long.
*
* @author bratseth
*/
public class ExpressionFormatter {
private static final int indentUnit = 2;
/** The size of the first column, or 0 if none */
private final int firstColumnLength;
/**
* The desired size of the second column (or the entire line if no first column),
* or 0 to split into multiple lines as much as possible.
* Setting this collects larger chunks to one line across markup
* but will not split too long lines that have no markup.
*/
private final int secondColumnLength;
private ExpressionFormatter(int firstColumnLength, int secondColumnLength) {
this.firstColumnLength = firstColumnLength;
this.secondColumnLength = secondColumnLength;
}
public String format(String parenthesisExpression) {
StringBuilder b = new StringBuilder();
format(parenthesisExpression, 0, b);
while (b.length() > 0 && Character.isWhitespace(b.charAt(b.length() - 1)))
b.setLength(b.length() - 1);
return b.toString();
}
private void format(String expression, int indent, StringBuilder b) {
if (expression.isEmpty()) return;
expression = appendFirstColumn(expression, b);
Markup next = Markup.next(expression);
appendIndent( ! next.isClose() || next.position() > 0 ? indent : indent - 2, b);
int endOfBalancedChunk = endOfBalancedChunk(expression, Math.max(0, secondColumnLength - indent));
if (next.isEmpty()) {
b.append(expression);
}
else if (endOfBalancedChunk > 0) {
b.append(expression, 0, endOfBalancedChunk + 1).append("\n");
format(expression.substring(endOfBalancedChunk + 1), indent, b);
}
else if (next.isComma()) {
b.append(expression, 0, next.position() + 1).append("\n");
format(expression.substring(next.position() + 1), indent, b);
}
else {
if ( next.isClose() && next.position() > 0) { // content before end parenthesis: content, newline, then end parenthesis
b.append(expression, 0, next.position()).append("\n");
appendFirstColumn(")", b);
appendIndent(indent - 2, b);
b.append(")\n");
}
else {
b.append(expression, 0, next.position() + 1).append("\n");
}
format(expression.substring(next.position() + 1), indent + (next.isOpen() ? indentUnit : -indentUnit), b);
}
}
/** Returns the position of the end of a balanced chunk of at most the given size, or 0 if there is no such chunk */
private int endOfBalancedChunk(String expression, int maxSize) {
int chunkSize = 0;
int i = 0;
int nesting = 0;
while (i < maxSize && i < expression.length()) {
if (expression.charAt(i) == '\t') return chunkSize;
if (expression.charAt(i) == '(') nesting++;
if (expression.charAt(i) == ')') nesting--;
if (nesting < 0) return chunkSize;
if (nesting == 0 && ( expression.charAt(i)==')' || expression.charAt(i)==','))
chunkSize = i;
i++;
}
return chunkSize;
}
private String appendFirstColumn(String expression, StringBuilder b) {
if (firstColumnLength == 0) return expression;
while (expression.charAt(0) == ' ')
expression = expression.substring(1);
if (expression.charAt(0) == '\t') {
int tab2 = expression.indexOf('\t', 1);
if (tab2 >= 0) {
String firstColumn = expression.substring(1, tab2);
b.append(asSize(firstColumnLength, firstColumn)).append(" ");
return expression.substring(tab2 + 1);
}
}
appendIndent(firstColumnLength + 1, b);
return expression;
}
private void appendIndent(int indent, StringBuilder b) {
b.append(" ".repeat(Math.max(0, indent)));
}
private String asSize(int size, String s) {
if (s.length() > size)
return s.substring(0, size);
else
return s + " ".repeat(size - s.length());
}
/** Convenience method creating a formatter and using it to format the given expression */
public static String on(String parenthesisExpression) {
return new ExpressionFormatter(0, 80).format(parenthesisExpression);
}
public static ExpressionFormatter withLineLength(int maxLineLength) {
return new ExpressionFormatter(0, maxLineLength);
}
public static ExpressionFormatter inTwoColumnMode(int firstColumnSize, int secondColumnSize) {
return new ExpressionFormatter(firstColumnSize, secondColumnSize);
}
/** Contains the next position of each kind of markup, or Integer.MAX_VALUE if not present */
private static class Markup {
final int open, close, comma;
private Markup(int open, int close, int comma) {
this.open = open;
this.close = close;
this.comma = comma;
}
int position() {
return Math.min(Math.min(open, close), comma);
}
boolean isOpen() {
return open < close && open < comma;
}
boolean isClose() {
return close < open && close < comma;
}
boolean isComma() {
return comma < open && comma < close;
}
boolean isEmpty() {
return open == Integer.MAX_VALUE && close == Integer.MAX_VALUE && comma == Integer.MAX_VALUE;
}
static Markup next(String expression) {
int nextOpen = expression.indexOf('(');
int nextClose = expression.indexOf(')');
int nextComma = expression.indexOf(',');
if (nextOpen < 0)
nextOpen = Integer.MAX_VALUE;
if (nextClose < 0)
nextClose = Integer.MAX_VALUE;
if (nextComma < 0)
nextComma = Integer.MAX_VALUE;
return new Markup(nextOpen, nextClose, nextComma);
}
}
}
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