package com.bizosys.hsearch.loader.csv;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/**
* Splits a line to cells
*/
public class CsvParser {
private final char separator;
private final char quotechar;
private final char escape;
private final boolean strictQuotes;
private String pending;
private boolean inField = false;
private final boolean ignoreLeadingWhiteSpace;
/**
* The default separator to use if none is supplied to the constructor.
*/
public static final char DEFAULT_SEPARATOR = ',';
public static final int INITIAL_READ_SIZE = 128;
/**
* The default quote character to use if none is supplied to the
* constructor.
*/
public static final char DEFAULT_QUOTE_CHARACTER = '"';
/**
* The default escape character to use if none is supplied to the
* constructor.
*/
public static final char DEFAULT_ESCAPE_CHARACTER = '\\';
/**
* The default strict quote behavior to use if none is supplied to the
* constructor
*/
public static final boolean DEFAULT_STRICT_QUOTES = false;
/**
* The default leading whitespace behavior to use if none is supplied to the
* constructor
*/
public static final boolean DEFAULT_IGNORE_LEADING_WHITESPACE = true;
/**
* This is the "null" character - if a value is set to this then it is ignored.
* I.E. if the quote character is set to null then there is no quote character.
*/
public static final char NULL_CHARACTER = '\0';
/**
* Constructs CSVParser using a comma for the separator.
*/
public CsvParser() {
this(DEFAULT_SEPARATOR, DEFAULT_QUOTE_CHARACTER, DEFAULT_ESCAPE_CHARACTER);
}
/**
* Constructs CSVParser with supplied separator.
*
* @param separator the delimiter to use for separating entries.
*/
public CsvParser(char separator) {
this(separator, DEFAULT_QUOTE_CHARACTER, DEFAULT_ESCAPE_CHARACTER);
}
/**
* Constructs CSVParser with supplied separator and quote char.
*
* @param separator the delimiter to use for separating entries
* @param quotechar the character to use for quoted elements
*/
public CsvParser(char separator, char quotechar) {
this(separator, quotechar, DEFAULT_ESCAPE_CHARACTER);
}
/**
* Constructs CSVReader with supplied separator and quote char.
*
* @param separator the delimiter to use for separating entries
* @param quotechar the character to use for quoted elements
* @param escape the character to use for escaping a separator or quote
*/
public CsvParser(char separator, char quotechar, char escape) {
this(separator, quotechar, escape, DEFAULT_STRICT_QUOTES);
}
/**
* Constructs CSVReader with supplied separator and quote char.
* Allows setting the "strict quotes" flag
*
* @param separator the delimiter to use for separating entries
* @param quotechar the character to use for quoted elements
* @param escape the character to use for escaping a separator or quote
* @param strictQuotes if true, characters outside the quotes are ignored
*/
public CsvParser(char separator, char quotechar, char escape, boolean strictQuotes) {
this(separator, quotechar, escape, strictQuotes, DEFAULT_IGNORE_LEADING_WHITESPACE);
}
/**
* Constructs CSVReader with supplied separator and quote char.
* Allows setting the "strict quotes" and "ignore leading whitespace" flags
*
* @param separator the delimiter to use for separating entries
* @param quotechar the character to use for quoted elements
* @param escape the character to use for escaping a separator or quote
* @param strictQuotes if true, characters outside the quotes are ignored
* @param ignoreLeadingWhiteSpace if true, white space in front of a quote in a field is ignored
*/
public CsvParser(char separator, char quotechar, char escape, boolean strictQuotes, boolean ignoreLeadingWhiteSpace) {
if (anyCharactersAreTheSame(separator, quotechar, escape)) {
throw new UnsupportedOperationException("The separator, quote, and escape characters must be different!");
}
if (separator == NULL_CHARACTER) {
throw new UnsupportedOperationException("The separator character must be defined!");
}
this.separator = separator;
this.quotechar = quotechar;
this.escape = escape;
this.strictQuotes = strictQuotes;
this.ignoreLeadingWhiteSpace = ignoreLeadingWhiteSpace;
}
private boolean anyCharactersAreTheSame(char separator, char quotechar, char escape) {
return isSameCharacter(separator, quotechar) || isSameCharacter(separator, escape) || isSameCharacter(quotechar, escape);
}
private boolean isSameCharacter(char c1, char c2) {
return c1 != NULL_CHARACTER && c1 == c2;
}
/**
* @return true if something was left over from last call(s)
*/
public boolean isPending() {
return pending != null;
}
public String[] parseLineMulti(String nextLine) throws IOException {
return parseLine(nextLine, true);
}
public String[] parseLine(String nextLine) throws IOException {
return parseLine(nextLine, false);
}
/**
* Parses an incoming String and returns an array of elements.
*
* @param nextLine the string to parse
* @param multi
* @return the comma-tokenized list of elements, or null if nextLine is null
* @throws IOException if bad things happen during the read
*/
private String[] parseLine(String nextLine, boolean multi) throws IOException {
if (!multi && pending != null) {
pending = null;
}
if (nextLine == null) {
if (pending != null) {
String s = pending;
pending = null;
return new String[]{s};
} else {
return null;
}
}
List<String> tokensOnThisLine = new ArrayList<String>();
StringBuilder sb = new StringBuilder(INITIAL_READ_SIZE);
boolean inQuotes = false;
if (pending != null) {
sb.append(pending);
pending = null;
inQuotes = true;
}
for (int i = 0; i < nextLine.length(); i++) {
char c = nextLine.charAt(i);
if (c == this.escape) {
if (isNextCharacterEscapable(nextLine, inQuotes || inField, i)) {
sb.append(nextLine.charAt(i + 1));
i++;
}
} else if (c == quotechar) {
if (isNextCharacterEscapedQuote(nextLine, inQuotes || inField, i)) {
sb.append(nextLine.charAt(i + 1));
i++;
} else {
//inQuotes = !inQuotes;
// the tricky case of an embedded quote in the middle: a,bc"d"ef,g
if (!strictQuotes) {
if (i > 2 //not on the beginning of the line
&& nextLine.charAt(i - 1) != this.separator //not at the beginning of an escape sequence
&& nextLine.length() > (i + 1) &&
nextLine.charAt(i + 1) != this.separator //not at the end of an escape sequence
) {
if (ignoreLeadingWhiteSpace && sb.length() > 0 && isAllWhiteSpace(sb)) {
sb.setLength(0); //discard white space leading up to quote
} else {
sb.append(c);
//continue;
}
}
}
inQuotes = !inQuotes;
}
inField = !inField;
} else if (c == separator && !inQuotes) {
tokensOnThisLine.add(sb.toString());
sb.setLength(0); // start work on next token
inField = false;
} else {
if (!strictQuotes || inQuotes) {
sb.append(c);
inField = true;
}
}
}
// line is done - check status
if (inQuotes) {
if (multi) {
// continuing a quoted section, re-append newline
sb.append("\n");
pending = sb.toString();
sb = null; // this partial content is not to be added to field list yet
} else {
throw new IOException("Un-terminated quoted field at end of CSV line");
}
}
if (sb != null) {
tokensOnThisLine.add(sb.toString());
}
return tokensOnThisLine.toArray(new String[tokensOnThisLine.size()]);
}
/**
* precondition: the current character is a quote or an escape
*
* @param nextLine the current line
* @param inQuotes true if the current context is quoted
* @param i current index in line
* @return true if the following character is a quote
*/
private boolean isNextCharacterEscapedQuote(String nextLine, boolean inQuotes, int i) {
return inQuotes // we are in quotes, therefore there can be escaped quotes in here.
&& nextLine.length() > (i + 1) // there is indeed another character to check.
&& nextLine.charAt(i + 1) == quotechar;
}
/**
* precondition: the current character is an escape
*
* @param nextLine the current line
* @param inQuotes true if the current context is quoted
* @param i current index in line
* @return true if the following character is a quote
*/
protected boolean isNextCharacterEscapable(String nextLine, boolean inQuotes, int i) {
return inQuotes // we are in quotes, therefore there can be escaped quotes in here.
&& nextLine.length() > (i + 1) // there is indeed another character to check.
&& (nextLine.charAt(i + 1) == quotechar || nextLine.charAt(i + 1) == this.escape);
}
/**
* precondition: sb.length() > 0
*
* @param sb A sequence of characters to examine
* @return true if every character in the sequence is whitespace
*/
protected boolean isAllWhiteSpace(CharSequence sb) {
boolean result = true;
for (int i = 0; i < sb.length(); i++) {
char c = sb.charAt(i);
if (!Character.isWhitespace(c)) {
return false;
}
}
return result;
}
}