org.glassfish.grizzly.http.server.util.StringParser Maven / Gradle / Ivy
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/*
* Copyright (c) 2010, 2020 Oracle and/or its affiliates. All rights reserved.
* Copyright 2004 The Apache Software Foundation
*
* Licensed 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.glassfish.grizzly.http.server.util;
/**
* Utility class for string parsing that is higher performance than StringParser for simple delimited text cases.
* Parsing is performed by setting the string, and then using the findXxxx() and skipXxxx()
* families of methods to remember significant offsets. To retrieve the parsed substrings, call the
* extract() method with the appropriate saved offset values.
*
* @author Craig R. McClanahan
* @version $Revision: 1.3 $ $Date: 2007/06/18 14:17:08 $
*/
public final class StringParser {
// ----------------------------------------------------------- Constructors
/**
* Construct a string parser with no preset string to be parsed.
*/
public StringParser() {
this(null);
}
/**
* Construct a string parser that is initialized to parse the specified string.
*
* @param string The string to be parsed
*/
public StringParser(String string) {
super();
setString(string);
}
// ----------------------------------------------------- Instance Variables
/**
* The characters of the current string, as a character array. Stored when the string is first specified to speed up
* access to characters being compared during parsing.
*/
private char chars[] = null;
/**
* The zero-relative index of the current point at which we are positioned within the string being parsed.
* NOTE: the value of this index can be one larger than the index of the last character of the string
* (i.e. equal to the string length) if you parse off the end of the string. This value is useful for extracting
* substrings that include the end of the string.
*/
private int index = 0;
/**
* The length of the String we are currently parsing. Stored when the string is first specified to avoid repeated
* recalculations.
*/
private int length = 0;
/**
* The String we are currently parsing.
*/
private String string = null;
// ------------------------------------------------------------- Properties
/**
* Return the zero-relative index of our current parsing position within the string being parsed.
*/
public int getIndex() {
return this.index;
}
/**
* Return the length of the string we are parsing.
*/
public int getLength() {
return this.length;
}
/**
* Return the String we are currently parsing.
*/
public String getString() {
return this.string;
}
/**
* Set the String we are currently parsing. The parser state is also reset to begin at the start of this string.
*
* @param string The string to be parsed.
*/
public void setString(String string) {
this.string = string;
if (string != null) {
this.length = string.length();
chars = this.string.toCharArray();
} else {
this.length = 0;
chars = new char[0];
}
reset();
}
// --------------------------------------------------------- Public Methods
/**
* Advance the current parsing position by one, if we are not already past the end of the string.
*/
public void advance() {
if (index < length) {
index++;
}
}
/**
* Extract and return a substring that starts at the specified position, and extends to the end of the string being
* parsed. If this is not possible, a zero-length string is returned.
*
* @param start Starting index, zero relative, inclusive
*/
public String extract(int start) {
if (start < 0 || start >= length) {
return "";
} else {
return string.substring(start);
}
}
/**
* Extract and return a substring that starts at the specified position, and ends at the character before the specified
* position. If this is not possible, a zero-length string is returned.
*
* @param start Starting index, zero relative, inclusive
* @param end Ending index, zero relative, exclusive
*/
public String extract(int start, int end) {
if (start < 0 || start >= end || end > length) {
return "";
} else {
return string.substring(start, end);
}
}
/**
* Return the index of the next occurrence of the specified character, or the index of the character after the last
* position of the string if no more occurrences of this character are found. The current parsing position is updated to
* the returned value.
*
* @param ch Character to be found
*/
public int findChar(char ch) {
while (index < length && ch != chars[index]) {
index++;
}
return index;
}
/**
* Return the index of the next occurrence of a non-whitespace character, or the index of the character after the last
* position of the string if no more non-whitespace characters are found. The current parsing position is updated to the
* returned value.
*/
public int findText() {
while (index < length && isWhite(chars[index])) {
index++;
}
return index;
}
/**
* Return the index of the next occurrence of a whitespace character, or the index of the character after the last
* position of the string if no more whitespace characters are found. The current parsing position is updated to the
* returned value.
*/
public int findWhite() {
while (index < length && !isWhite(chars[index])) {
index++;
}
return index;
}
/**
* Reset the current state of the parser to the beginning of the current string being parsed.
*/
public void reset() {
index = 0;
}
/**
* Advance the current parsing position while it is pointing at the specified character, or until it moves past the end
* of the string. Return the final value.
*
* @param ch Character to be skipped
*/
public int skipChar(char ch) {
while (index < length && ch == chars[index]) {
index++;
}
return index;
}
/**
* Advance the current parsing position while it is pointing at a non-whitespace character, or until it moves past the
* end of the string. Return the final value.
*/
public int skipText() {
while (index < length && !isWhite(chars[index])) {
index++;
}
return index;
}
/**
* Advance the current parsing position while it is pointing at a whitespace character, or until it moves past the end
* of the string. Return the final value.
*/
public int skipWhite() {
while (index < length && isWhite(chars[index])) {
index++;
}
return index;
}
// ------------------------------------------------------ Protected Methods
/**
* Is the specified character considered to be whitespace?
*
* @param ch Character to be checked
*/
protected boolean isWhite(char ch) {
if (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n') {
return true;
} else {
return false;
}
}
}
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