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With inspiration from other libraries
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.math3.geometry;
import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;
import java.util.Locale;
import org.apache.commons.math3.util.CompositeFormat;
import org.apache.commons.math3.exception.MathParseException;
/**
* Formats a vector in components list format "{x; y; ...}".
* The prefix and suffix "{" and "}" and the separator "; " can be replaced by
* any user-defined strings. The number format for components can be configured.
* White space is ignored at parse time, even if it is in the prefix, suffix
* or separator specifications. So even if the default separator does include a space
* character that is used at format time, both input string "{1;1;1}" and
* " { 1 ; 1 ; 1 } " will be parsed without error and the same vector will be
* returned. In the second case, however, the parse position after parsing will be
* just after the closing curly brace, i.e. just before the trailing space.
* Note: using "," as a separator may interfere with the grouping separator
* of the default {@link NumberFormat} for the current locale. Thus it is advised
* to use a {@link NumberFormat} instance with disabled grouping in such a case.
*
* @param Type of the space.
* @since 3.0
*/
public abstract class VectorFormat {
/** The default prefix: "{". */
public static final String DEFAULT_PREFIX = "{";
/** The default suffix: "}". */
public static final String DEFAULT_SUFFIX = "}";
/** The default separator: ", ". */
public static final String DEFAULT_SEPARATOR = "; ";
/** Prefix. */
private final String prefix;
/** Suffix. */
private final String suffix;
/** Separator. */
private final String separator;
/** Trimmed prefix. */
private final String trimmedPrefix;
/** Trimmed suffix. */
private final String trimmedSuffix;
/** Trimmed separator. */
private final String trimmedSeparator;
/** The format used for components. */
private final NumberFormat format;
/**
* Create an instance with default settings.
* The instance uses the default prefix, suffix and separator:
* "{", "}", and "; " and the default number format for components.
*/
protected VectorFormat() {
this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR,
CompositeFormat.getDefaultNumberFormat());
}
/**
* Create an instance with a custom number format for components.
* @param format the custom format for components.
*/
protected VectorFormat(final NumberFormat format) {
this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR, format);
}
/**
* Create an instance with custom prefix, suffix and separator.
* @param prefix prefix to use instead of the default "{"
* @param suffix suffix to use instead of the default "}"
* @param separator separator to use instead of the default "; "
*/
protected VectorFormat(final String prefix, final String suffix,
final String separator) {
this(prefix, suffix, separator, CompositeFormat.getDefaultNumberFormat());
}
/**
* Create an instance with custom prefix, suffix, separator and format
* for components.
* @param prefix prefix to use instead of the default "{"
* @param suffix suffix to use instead of the default "}"
* @param separator separator to use instead of the default "; "
* @param format the custom format for components.
*/
protected VectorFormat(final String prefix, final String suffix,
final String separator, final NumberFormat format) {
this.prefix = prefix;
this.suffix = suffix;
this.separator = separator;
trimmedPrefix = prefix.trim();
trimmedSuffix = suffix.trim();
trimmedSeparator = separator.trim();
this.format = format;
}
/**
* Get the set of locales for which point/vector formats are available.
* This is the same set as the {@link NumberFormat} set.
* @return available point/vector format locales.
*/
public static Locale[] getAvailableLocales() {
return NumberFormat.getAvailableLocales();
}
/**
* Get the format prefix.
* @return format prefix.
*/
public String getPrefix() {
return prefix;
}
/**
* Get the format suffix.
* @return format suffix.
*/
public String getSuffix() {
return suffix;
}
/**
* Get the format separator between components.
* @return format separator.
*/
public String getSeparator() {
return separator;
}
/**
* Get the components format.
* @return components format.
*/
public NumberFormat getFormat() {
return format;
}
/**
* Formats a {@link Vector} object to produce a string.
* @param vector the object to format.
* @return a formatted string.
*/
public String format(Vector vector) {
return format(vector, new StringBuffer(), new FieldPosition(0)).toString();
}
/**
* Formats a {@link Vector} object to produce a string.
* @param vector the object to format.
* @param toAppendTo where the text is to be appended
* @param pos On input: an alignment field, if desired. On output: the
* offsets of the alignment field
* @return the value passed in as toAppendTo.
*/
public abstract StringBuffer format(Vector vector,
StringBuffer toAppendTo, FieldPosition pos);
/**
* Formats the coordinates of a {@link Vector} to produce a string.
* @param toAppendTo where the text is to be appended
* @param pos On input: an alignment field, if desired. On output: the
* offsets of the alignment field
* @param coordinates coordinates of the object to format.
* @return the value passed in as toAppendTo.
*/
protected StringBuffer format(StringBuffer toAppendTo, FieldPosition pos,
double ... coordinates) {
pos.setBeginIndex(0);
pos.setEndIndex(0);
// format prefix
toAppendTo.append(prefix);
// format components
for (int i = 0; i < coordinates.length; ++i) {
if (i > 0) {
toAppendTo.append(separator);
}
CompositeFormat.formatDouble(coordinates[i], format, toAppendTo, pos);
}
// format suffix
toAppendTo.append(suffix);
return toAppendTo;
}
/**
* Parses a string to produce a {@link Vector} object.
* @param source the string to parse
* @return the parsed {@link Vector} object.
* @throws MathParseException if the beginning of the specified string
* cannot be parsed.
*/
public abstract Vector parse(String source) throws MathParseException;
/**
* Parses a string to produce a {@link Vector} object.
* @param source the string to parse
* @param pos input/output parsing parameter.
* @return the parsed {@link Vector} object.
*/
public abstract Vector parse(String source, ParsePosition pos);
/**
* Parses a string to produce an array of coordinates.
* @param dimension dimension of the space
* @param source the string to parse
* @param pos input/output parsing parameter.
* @return coordinates array.
*/
protected double[] parseCoordinates(int dimension, String source, ParsePosition pos) {
int initialIndex = pos.getIndex();
double[] coordinates = new double[dimension];
// parse prefix
CompositeFormat.parseAndIgnoreWhitespace(source, pos);
if (!CompositeFormat.parseFixedstring(source, trimmedPrefix, pos)) {
return null;
}
for (int i = 0; i < dimension; ++i) {
// skip whitespace
CompositeFormat.parseAndIgnoreWhitespace(source, pos);
// parse separator
if (i > 0 && !CompositeFormat.parseFixedstring(source, trimmedSeparator, pos)) {
return null;
}
// skip whitespace
CompositeFormat.parseAndIgnoreWhitespace(source, pos);
// parse coordinate
Number c = CompositeFormat.parseNumber(source, format, pos);
if (c == null) {
// invalid coordinate
// set index back to initial, error index should already be set
pos.setIndex(initialIndex);
return null;
}
// store coordinate
coordinates[i] = c.doubleValue();
}
// parse suffix
CompositeFormat.parseAndIgnoreWhitespace(source, pos);
if (!CompositeFormat.parseFixedstring(source, trimmedSuffix, pos)) {
return null;
}
return coordinates;
}
}