nom.tam.fits.utilities.FitsHeaderCardParser Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of nom-tam-fits Show documentation
Show all versions of nom-tam-fits Show documentation
Java library for reading and writing FITS files. FITS, the Flexible Image Transport System, is the format commonly used in the archiving and transport of astronomical data.
package nom.tam.fits.utilities;
/*
* #%L
* nom.tam FITS library
* %%
* Copyright (C) 1996 - 2015 nom-tam-fits
* %%
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
* #L%
*/
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import nom.tam.util.AsciiFuncs;
/**
* A helper utility class to parse header cards for there value (especially
* strings) and comments.
*
* @author Richard van Nieuwenhoven
*/
public final class FitsHeaderCardParser {
/**
* value comment pair of the header card.
*/
public static class ParsedValue {
/**
* the comment specified with the value.
*/
private String comment;
/**
* was the value quoted?
*/
private final boolean isString;
/**
* the value of the card. (trimmed)
*/
private String value = null;
public ParsedValue() {
isString = false;
}
public ParsedValue(String value, String comment) {
isString = true;
this.value = value;
this.comment = comment;
}
/**
* @return the comment of the card.
*/
public String getComment() {
return this.comment;
}
/**
* @return the value of the card.
*/
public String getValue() {
return this.value;
}
/**
* @return true if the value was quoted.
*/
public boolean isString() {
return this.isString;
}
}
/**
* pattern to match FITS keywords, specially to parse hirarchical keywords.
*/
private static final Pattern KEYWORD_PATTERN = Pattern.compile("([A-Z|a-z|0-9|_|-]+)([ |\\.]*=?)");
/**
* pattern to match a quoted string where 2 quotes are used to escape a
* single quote inside the string. Attention this patern ist optimized as
* specified in http://www.perlmonks.org/?node_id=607740
*/
private static final Pattern STRING_PATTERN = Pattern.compile("'((?:[^']+(?=')|'')*)'(?!')");
/**
* delete the start and trailing quote from the sting and replace all
* (escaped)double quotes with a single quote. Then trim the trailing
* blanks.
*
* @param quotedString
* the string to un-quote.
* @return the unquoted string
*/
private static String deleteQuotes(String quotedString) {
int indexOfQuote = quotedString.indexOf('\'');
if (indexOfQuote < 0) {
int newLength = quotedString.length();
while (newLength > 0 && AsciiFuncs.isWhitespace(quotedString.charAt(newLength - 1))) {
newLength--;
}
return quotedString.substring(0, newLength);
} else {
int lastIndexOfQuote = 0;
StringBuffer sb = new StringBuffer(quotedString.length());
while (indexOfQuote >= 0) {
sb.append(quotedString, lastIndexOfQuote, indexOfQuote);
lastIndexOfQuote = indexOfQuote + 1;
indexOfQuote = quotedString.indexOf('\'', lastIndexOfQuote + 1);
}
sb.append(quotedString, lastIndexOfQuote, quotedString.length());
int newLength = sb.length();
while (newLength > 0 && AsciiFuncs.isWhitespace(sb.charAt(newLength - 1))) {
newLength--;
}
sb.setLength(newLength);
return sb.toString();
}
}
/**
* get the not empty comment string from the end of the card. start scanning
* from the end of the value.
*
* @param stringCard
* the string representing the card
* @param startPosition
* the start point for the scan
* @return the not empty comment or null if no comment was found.
*/
private static String extractComment(String stringCard, int startPosition) {
int startOfComment = stringCard.indexOf('/', startPosition) + 1;
if (startOfComment > 0 && stringCard.length() > startOfComment) {
return stringCard.substring(startOfComment).trim();
}
return null;
}
/**
* parse a fits keyword from a card and return it as a dot separated list.
*
* @param card
* the card to parse.
* @return dot separated key list
*/
public static String parseCardKey(String card) {
int indexOfEquals = card.indexOf('=');
StringBuilder builder = new StringBuilder();
Matcher kewordMatcher = FitsHeaderCardParser.KEYWORD_PATTERN.matcher(card);
while (kewordMatcher.find() && kewordMatcher.start() < indexOfEquals) {
if (builder.length() != 0) {
builder.append('.');
}
builder.append(kewordMatcher.group(1).toUpperCase(Locale.US));
if (kewordMatcher.group(2).endsWith("=")) {
break;
}
}
return builder.toString();
}
/**
* Parse the card for a value and comment. Quoted string values are unquoted
* and the {@link ParsedValue#isString} specifies if the value was a quoted
* string. non quoted values are trimmed.
*
* @param card
* the card to parse.
* @return a parsed card or null if no value could be detected.
*/
public static ParsedValue parseCardValue(String card) {
ParsedValue value = parseStringValue(card);
if (value == null) {
// ok no string lets check for an equals.
int indexOfEquals = card.indexOf('=');
if (indexOfEquals > 0) {
// its no string so the value goes max till the comment
value = new ParsedValue();
int endOfValue = card.length() - 1;
int startOfComment = card.indexOf('/', indexOfEquals);
if (startOfComment > 0) {
endOfValue = startOfComment - 1;
value.comment = extractComment(card, startOfComment);
}
value.value = card.substring(indexOfEquals + 1, endOfValue + 1).trim();
}
}
return value;
}
/**
* lets see if there is a quoted sting in the card.
*
* @param card
* the card string to parse.
* @return the parsed value with the unquoted string or null if no quoted
* string was found.
*/
private static ParsedValue parseStringValue(String card) {
int indexOfQuote = card.indexOf('\'');
if (indexOfQuote >= 0) {
Matcher matcher = FitsHeaderCardParser.STRING_PATTERN.matcher(card);
if (matcher.find(indexOfQuote)) {
if (card.lastIndexOf('/', matcher.start()) < 0) {
return new ParsedValue(deleteQuotes(matcher.group(1)), extractComment(card, matcher.end()));
}
}
}
return null;
}
/**
* utility class will not be instantiated.
*/
private FitsHeaderCardParser() {
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy