+
−/*
+
− * This Source Code Form is subject to the terms of the Mozilla Public
+
− * License, v. 2.0.  If a copy of the MPL was not distributed with this
+
− * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
− *
+
− * Copyright 1997 - July 2008 CWI, August 2008 - 2019 MonetDB B.V.
+
− */
+
−
+
−package nl.cwi.monetdb.mcl.parser;
+
−
+
−/**
+
− * The TupleLineParser extracts the values from a given tuple.  The
+
− * number of values that are expected are known upfront to speed up
+
− * allocation and validation.
+
− *
+
− * @author Fabian Groffen
+
− */
+
−public class TupleLineParser extends MCLParser {
+
−	/**
+
−	 * Constructs a TupleLineParser which expects columncount columns.
+
−	 *
+
−	 * @param columncount the number of columns in the to be parsed string
+
−	 */
+
−	public TupleLineParser(int columncount) {
+
−		super(columncount);
+
−	}
+
−
+
−	/**
+
−	 * Parses the given String source as tuple line.  If source cannot
+
−	 * be parsed, a ParseException is thrown.  The columncount argument
+
−	 * is used for allocation of the returned array.  While this seems
+
−	 * illogical, the caller should know this size, since the
+
−	 * StartOfHeader contains this information.
+
−	 *
+
−	 * @param source a String which should be parsed
+
−	 * @return 0, as there is no 'type' of TupleLine
+
−	 * @throws MCLParseException if an error occurs during parsing
+
−	 */
+
−	@Override
+
−	public int parse(String source) throws MCLParseException {
+
−		final int len = source.length();
+
−		// first detect whether this is a single value line (=) or a
+
−		// real tuple ([)
+
−		if (len >= 1 && source.charAt(0) == '=') {
+
−			if (values.length != 1)
+
−				throw new MCLParseException(values.length +
+
−						" columns expected, but only single value found");
+
−
+
−			// return the whole string but without the leading =
+
−			values[0] = source.substring(1);
+
−
+
−			// reset colnr
+
−			reset();
+
−			return 0;
+
−		}
+
−
+
−		if (!source.startsWith("["))
+
−			throw new MCLParseException("Expected a data row starting with [");
+
−
+
−		// It is a tuple. Extract separate fields by examining the string data char for char
+
−		final char[] chrLine = source.toCharArray();	// convert whole string to char[] to avoid overhead of source.charAt(i) calls TODO: measure the overhead
+
−		boolean inString = false, escaped = false, fieldHasEscape = false;
+
−		final StringBuilder uesc = new StringBuilder(128);	// used for building field string value when an escape is present in the field value
+
−		int column = 0, cursor = 2;
+
−		for (int i = 2; i < len; i++) {
+
−			switch(chrLine[i]) {
+
−				case '\\':
+
−					escaped = !escaped;
+
−					fieldHasEscape = true;
+
−					break;
+
−				case '"':
+
−					/**
+
−					 * If all strings are wrapped between two quotes, a \" can
+
−					 * never exist outside a string. Thus if we believe that we
+
−					 * are not within a string, we can safely assume we're about
+
−					 * to enter a string if we find a quote.
+
−					 * If we are in a string we should stop being in a string if
+
−					 * we find a quote which is not prefixed by a \, for that
+
−					 * would be an escaped quote. However, a nasty situation can
+
−					 * occur where the string is like "test \\" as obvious, a
+
−					 * test for a \ in front of a " doesn't hold here for all
+
−					 * cases. Because "test \\\"" can exist as well, we need to
+
−					 * know if a quote is prefixed by an escaping slash or not.
+
−					 */
+
−					if (!inString) {
+
−						inString = true;
+
−					} else if (!escaped) {
+
−						inString = false;
+
−					}
+
−					// reset escaped flag
+
−					escaped = false;
+
−					break;
+
−				case '\t':		// potential field separator found
+
−					if (!inString &&
+
−						((chrLine[i - 1] == ',') ||		// found field separator: ,\t
+
−						 ((i + 1 == len - 1) && chrLine[++i] == ']'))) // found last field: \t]
+
−					{
+
−						// extract the field value as a string, without the potential escape codes
+
−						final int endpos = i - 2;	// minus the tab and the comma or ]
+
−						if (chrLine[cursor] == '"' &&
+
−						    chrLine[endpos] == '"')	// field is surrounded by double quotes, so a string with possible escape codes
+
−						{
+
−							if (fieldHasEscape) {
+
−								// reuse the StringBuilder by cleaning it
+
−								uesc.delete(0, uesc.length());
+
−								// prevent capacity increasements
+
−								uesc.ensureCapacity(endpos - (cursor + 1));
+
−								// parse the field value (excluding the double quotes) and convert it to a string without any escape characters
+
−								for (int pos = cursor + 1; pos < endpos; pos++) {
+
−									char chr = chrLine[pos];
+
−									if (chr == '\\' && pos + 1 < endpos) {
+
−										// we detected an escape
+
−										// escapedStr and GDKstrFromStr in gdk_atoms.c only
+
−										// support \\ \f \n \r \t \" and \377
+
−										pos++;
+
−										chr = chrLine[pos];
+
−										switch (chr) {
+
−											case '\\':
+
−												uesc.append('\\');
+
−												break;
+
−											case 'f':
+
−												uesc.append('\f');
+
−												break;
+
−											case 'n':
+
−												uesc.append('\n');
+
−												break;
+
−											case 'r':
+
−												uesc.append('\r');
+
−												break;
+
−											case 't':
+
−												uesc.append('\t');
+
−												break;
+
−											case '"':
+
−												uesc.append('"');
+
−												break;
+
−											case '0': case '1': case '2': case '3':
+
−												// this could be an octal number, let's check it out
+
−												if (pos + 2 < endpos) {
+
−													char chr2 = chrLine[pos + 1];
+
−													char chr3 = chrLine[pos + 2];
+
−													if (chr2 >= '0' && chr2 <= '7' && chr3 >= '0' && chr3 <= '7') {
+
−														// we got an octal number between \000 and \377
+
−														try {
+
−															uesc.append((char)(Integer.parseInt("" + chr + chr2 + chr3, 8)));
+
−															pos += 2;
+
−														} catch (NumberFormatException e) {
+
−															// hmmm, this point should never be reached actually...
+
−															throw new AssertionError("Flow error, should never try to parse non-number");
+
−														}
+
−													} else {
+
−														// do default action if number seems not to be an octal number
+
−														uesc.append(chr);
+
−													}
+
−												} else {
+
−													// do default action if number seems not to be an octal number
+
−													uesc.append(chr);
+
−												}
+
−												break;
+
−											default:
+
−												// this is wrong usage of escape, just ignore the \-escape and print the char
+
−												uesc.append(chr);
+
−												break;
+
−										}
+
−									} else {
+
−										uesc.append(chr);
+
−									}
+
−								}
+
−								// put the unescaped string in the right place
+
−								values[column] = uesc.toString();
+
−							} else {
+
−								// the field is a string surrounded by double quotes and without escape chars
+
−								cursor++;
+
−								String fieldVal = new String(chrLine, cursor, endpos - cursor);
+
−								// if (fieldVal.contains("\\")) {
+
−								//	throw new MCLParseException("Invalid parsing: detected a \\ in double quoted string: " + fieldVal);
+
−								// }
+
−								values[column] = fieldVal;
+
−							}
+
−						} else if (((i - 1 - cursor) == 4) && source.indexOf("NULL", cursor) == cursor) {
+
−							// the field contains NULL, so no value
+
−							values[column] = null;
+
−						} else {
+
−							// the field is a string NOT surrounded by double quotes and thus without escape chars
+
−							String fieldVal = new String(chrLine, cursor, i - 1 - cursor);
+
−							// if (fieldVal.contains("\\")) {
+
−							//	throw new MCLParseException("Invalid parsing: detected a \\ in unquoted string: " + fieldVal);
+
−							// }
+
−							values[column] = fieldVal;
+
−						}
+
−						cursor = i + 1;
+
−						fieldHasEscape = false;		// reset for next field scan
+
−						column++;
+
−					}
+
−					// reset escaped flag
+
−					escaped = false;
+
−					break;
+
−				default:
+
−					escaped = false;
+
−					break;
+
−			} // end of switch()
+
−		} // end of for()
+
−
+
−		// check if this result is of the size we expected it to be
+
−		if (column != values.length)
+
−			throw new MCLParseException("illegal result length: " + column + "\nlast read: " + (column > 0 ? values[column - 1] : "<none>"));
+
−
+
−		// reset colnr
+
−		reset();
+
−		return 0;
+
−	}
+
−}