Temporary copy of original CSVLexer for performance comparison.
git-svn-id: https://svn.apache.org/repos/asf/commons/proper/csv/trunk@1303901 13f79535-47bb-0310-9956-ffa450edef68
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Sebastian Bazley
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.csv;
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import java.io.IOException;
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import static org.apache.commons.csv.Token.Type.*;
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class CSVLexer1 extends Lexer {
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private final StringBuilder wsBuf = new StringBuilder();
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// ctor needs to be public so can be called dynamically by PerformanceTest class
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public CSVLexer1(CSVFormat format, ExtendedBufferedReader in) {
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super(format, in);
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}
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/**
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* Returns the next token.
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* <p/>
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* A token corresponds to a term, a record change or an end-of-file indicator.
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*
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* @param tkn an existing Token object to reuse. The caller is responsible to initialize the Token.
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* @return the next token found
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* @throws java.io.IOException on stream access error
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*/
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@Override
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Token nextToken(Token tkn) throws IOException {
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wsBuf.setLength(0); // reuse
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// get the last read char (required for empty line detection)
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int lastChar = in.readAgain();
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// read the next char and set eol
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/* note: unfortunately isEndOfLine may consumes a character silently.
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* this has no effect outside of the method. so a simple workaround
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* is to call 'readAgain' on the stream...
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*/
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int c = in.read();
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boolean eol = isEndOfLine(c);
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c = in.readAgain();
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// empty line detection: eol AND (last char was EOL or beginning)
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if (format.isEmptyLinesIgnored()) {
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while (eol
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&& (lastChar == '\n' || lastChar == '\r' || lastChar == ExtendedBufferedReader.UNDEFINED)
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&& !isEndOfFile(lastChar)) {
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// go on char ahead ...
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lastChar = c;
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c = in.read();
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eol = isEndOfLine(c);
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c = in.readAgain();
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// reached end of file without any content (empty line at the end)
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if (isEndOfFile(c)) {
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tkn.type = EOF;
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return tkn;
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}
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}
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}
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// did we reach eof during the last iteration already ? EOF
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if (isEndOfFile(lastChar) || (lastChar != format.getDelimiter() && isEndOfFile(c))) {
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tkn.type = EOF;
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return tkn;
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}
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// important: make sure a new char gets consumed in each iteration
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while (!tkn.isReady && tkn.type != EOF) {
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// ignore whitespaces at beginning of a token
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if (format.isLeadingSpacesIgnored()) {
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while (isWhitespace(c) && !eol) {
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wsBuf.append((char) c);
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c = in.read();
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eol = isEndOfLine(c);
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}
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}
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// ok, start of token reached: comment, encapsulated, or token
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if (c == format.getCommentStart()) {
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// ignore everything till end of line and continue (incr linecount)
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in.readLine();
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tkn = nextToken(tkn.reset());
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} else if (c == format.getDelimiter()) {
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// empty token return TOKEN("")
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tkn.type = TOKEN;
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tkn.isReady = true;
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} else if (eol) {
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// empty token return EORECORD("")
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//noop: tkn.content.append("");
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tkn.type = EORECORD;
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tkn.isReady = true;
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} else if (c == format.getEncapsulator()) {
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// consume encapsulated token
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encapsulatedTokenLexer(tkn, c);
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} else if (isEndOfFile(c)) {
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// end of file return EOF()
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//noop: tkn.content.append("");
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tkn.type = EOF;
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tkn.isReady = true;
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} else {
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// next token must be a simple token
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// add removed blanks when not ignoring whitespace chars...
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if (!format.isLeadingSpacesIgnored()) {
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tkn.content.append(wsBuf);
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}
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simpleTokenLexer(tkn, c);
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}
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}
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return tkn;
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}
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/**
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* A simple token lexer
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* <p/>
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* Simple token are tokens which are not surrounded by encapsulators.
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* A simple token might contain escaped delimiters (as \, or \;). The
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* token is finished when one of the following conditions become true:
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* <ul>
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* <li>end of line has been reached (EORECORD)</li>
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* <li>end of stream has been reached (EOF)</li>
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* <li>an unescaped delimiter has been reached (TOKEN)</li>
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* </ul>
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*
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* @param tkn the current token
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* @param c the current character
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* @return the filled token
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* @throws IOException on stream access error
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*/
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private Token simpleTokenLexer(Token tkn, int c) throws IOException {
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while (true) {
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if (isEndOfLine(c)) {
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// end of record
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tkn.type = EORECORD;
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tkn.isReady = true;
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break;
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} else if (isEndOfFile(c)) {
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// end of file
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tkn.type = EOF;
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tkn.isReady = true;
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break;
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} else if (c == format.getDelimiter()) {
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// end of token
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tkn.type = TOKEN;
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tkn.isReady = true;
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break;
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} else if (c == format.getEscape()) {
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tkn.content.append((char) readEscape(c));
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} else {
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tkn.content.append((char) c);
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}
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c = in.read();
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}
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if (format.isTrailingSpacesIgnored()) {
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trimTrailingSpaces(tkn.content);
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}
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return tkn;
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}
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/**
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* An encapsulated token lexer
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* <p/>
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* Encapsulated tokens are surrounded by the given encapsulating-string.
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* The encapsulator itself might be included in the token using a
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* doubling syntax (as "", '') or using escaping (as in \", \').
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* Whitespaces before and after an encapsulated token are ignored.
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*
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* @param tkn the current token
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* @param c the current character
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* @return a valid token object
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* @throws IOException on invalid state
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*/
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private Token encapsulatedTokenLexer(Token tkn, int c) throws IOException {
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// save current line
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int startLineNumber = getLineNumber();
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// ignore the given delimiter
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// assert c == delimiter;
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while (true) {
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c = in.read();
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if (c == format.getEscape()) {
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tkn.content.append((char) readEscape(c));
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} else if (c == format.getEncapsulator()) {
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if (in.lookAhead() == format.getEncapsulator()) {
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// double or escaped encapsulator -> add single encapsulator to token
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c = in.read();
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tkn.content.append((char) c);
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} else {
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// token finish mark (encapsulator) reached: ignore whitespace till delimiter
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while (true) {
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c = in.read();
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if (c == format.getDelimiter()) {
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tkn.type = TOKEN;
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tkn.isReady = true;
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return tkn;
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} else if (isEndOfFile(c)) {
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tkn.type = EOF;
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tkn.isReady = true;
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return tkn;
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} else if (isEndOfLine(c)) {
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// ok eo token reached
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tkn.type = EORECORD;
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tkn.isReady = true;
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return tkn;
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} else if (!isWhitespace(c)) {
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// error invalid char between token and next delimiter
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throw new IOException("(line " + getLineNumber() + ") invalid char between encapsulated token and delimiter");
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}
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}
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}
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} else if (isEndOfFile(c)) {
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// error condition (end of file before end of token)
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throw new IOException("(startline " + startLineNumber + ") EOF reached before encapsulated token finished");
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} else {
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// consume character
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tkn.content.append((char) c);
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}
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}
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}
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}
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