com.github.tnakamot.jscdg.json.token.StringLocation Maven / Gradle / Ivy
/*
* Copyright (C) 2020 Takashi Nakamoto .
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see
* This basically has three properties, position, line and column.
* Position and column are counted based on Unicode code units, which
* means that a surrogate pair uses two positions (columns).
*
*
* Position starts from zero, while line and column start from one.
*
*
* A line is considered to be terminated by any one of a line feed
* ('\n'), a carriage return ('\r'), or a carriage return followed
* immediately by a linefeed.
*
*
* Assume this text:
*
*
* abc\ndef\r\nghi\rjkl\n\rmn
*
*
*
* Then, the position, line and column of each character are as
* shown below.
*
*
* - 'a': position = 0, line = 1, column = 1
* - 'b': position = 1, line = 1, column = 2
* - 'c': position = 2, line = 1, column = 3
* - \n : position = 3, line = 1, column = 4
* - 'd': position = 4, line = 2, column = 1
* - 'e': position = 5, line = 2, column = 2
* - 'f': position = 6, line = 2, column = 3
* - \r : position = 7, line = 2, column = 4
* - \n : position = 8, line = 2, column = 5
* - 'g': position = 9, line = 3, column = 1
* - 'h': position = 10, line = 3, column = 2
* - 'i': position = 11, line = 3, column = 3
* - \r : position = 12, line = 3, column = 4
* - 'j': position = 13, line = 4, column = 1
* - 'k': position = 14, line = 4, column = 2
* - 'l': position = 15, line = 4, column = 3
* - \n : position = 16, line = 4, column = 4
* - \r : position = 17, line = 5, column = 1
* - 'm': position = 18, line = 6, column = 1
* - 'n': position = 19, line = 6, column = 2
*
*
*
* Instances of this class are immutable.
*/
public class StringLocation {
private final StringLocation previous;
private final int position;
private final int line;
private final int column;
private StringLocation(StringLocation previous, int position, int line, int column) {
this.previous = previous;
this.position = position;
this.line = line;
this.column = column;
if (position < 0) {
throw new IllegalArgumentException("position must be zero or positive");
}
if (line < 1) {
throw new IllegalArgumentException("line must be positive");
}
if (column < 1) {
throw new IllegalArgumentException("column must be positive");
}
}
/**
* @return position in a certain {@link String} starting from zero
*/
public int position() {
return position;
}
/**
* @return line number in a certain {@link String} starting from one.
*/
public int line() {
return line;
}
/**
* @return column number in a certain {@link String} starting from one.
*/
public int column() {
return column;
}
/**
* @return an instance of {@link StringLocation} which represents the
* beginning of a {@link String}
*/
public static StringLocation begin() {
return new StringLocation(null,0, 1, 1);
}
/**
* @return the instance of {@link StringLocation} which represents
* the previous location of this instance.
*/
public StringLocation previous() {
return previous;
}
/**
* @param newline true if the next character is a new line
* @return an instance of {@link StringLocation} which represents
* the next location of this instance.
*/
public StringLocation next(boolean newline) {
if (newline) {
return new StringLocation(this, position + 1, line + 1, 1);
} else {
return new StringLocation(this, position + 1, line, column + 1);
}
}
}