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MySQL JDBC Type 4 driver
/*
Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
The MySQL Connector/J is licensed under the terms of the GPLv2
, like most MySQL Connectors.
There are special exceptions to the terms and conditions of the GPLv2 as it is applied to
this software, see the FOSS License Exception
.
This program is free software; you can redistribute it and/or modify it under the terms
of the GNU General Public License as published by the Free Software Foundation; version 2
of the License.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this
program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth
Floor, Boston, MA 02110-1301 USA
*/
package com.mysql.jdbc;
/**
* EscapeTokenizer breaks up an SQL statement into SQL and escape code parts.
*/
public class EscapeTokenizer {
private static final char CHR_ESCAPE = '\\';
private static final char CHR_SGL_QUOTE = '\'';
private static final char CHR_DBL_QUOTE = '"';
private static final char CHR_LF = '\n';
private static final char CHR_CR = '\r';
private static final char CHR_COMMENT = '-';
private static final char CHR_BEGIN_TOKEN = '{';
private static final char CHR_END_TOKEN = '}';
private static final char CHR_VARIABLE = '@';
private String source = null;
private int sourceLength = 0;
private int pos = 0;
private boolean emittingEscapeCode = false;
private boolean sawVariableUse = false;
private int bracesLevel = 0;
private boolean inQuotes = false;
private char quoteChar = 0;
/**
* Creates a new EscapeTokenizer object.
*
* @param source
* the string to tokenize
*/
public EscapeTokenizer(String source) {
this.source = source;
this.sourceLength = source.length();
this.pos = 0;
}
/**
* Does this tokenizer have more tokens available?
*
* @return if this tokenizer has more tokens available
*/
public synchronized boolean hasMoreTokens() {
return (this.pos < this.sourceLength);
}
/**
* Returns the next token
*
* @return the next token.
*/
public synchronized String nextToken() {
StringBuilder tokenBuf = new StringBuilder();
boolean backslashEscape = false;
if (this.emittingEscapeCode) {
// Previous token ended at the beginning of an escape code, so this token must start with '{'
tokenBuf.append("{");
this.emittingEscapeCode = false;
}
for (; this.pos < this.sourceLength; this.pos++) {
char c = this.source.charAt(this.pos);
// process escape char: (\)
if (c == CHR_ESCAPE) {
tokenBuf.append(c);
backslashEscape = !backslashEscape;
continue;
}
// process quotes: ('|")
if ((c == CHR_SGL_QUOTE || c == CHR_DBL_QUOTE) && !backslashEscape) {
tokenBuf.append(c);
if (this.inQuotes) {
if (c == this.quoteChar) {
// look ahead for doubled quote
if ((this.pos + 1 < this.sourceLength) && (this.source.charAt(this.pos + 1) == this.quoteChar)) {
tokenBuf.append(c);
this.pos++; // consume following char '\'' or '"'
} else {
this.inQuotes = false;
}
}
} else {
this.inQuotes = true;
this.quoteChar = c;
}
continue;
}
// process new line: (\n|\r)
if ((c == CHR_LF) || (c == CHR_CR)) {
tokenBuf.append(c);
backslashEscape = false;
continue;
}
if (!this.inQuotes && !backslashEscape) {
// process comments: (--)
if (c == CHR_COMMENT) {
tokenBuf.append(c);
// look ahead for double hyphen
if ((this.pos + 1 < this.sourceLength) && (this.source.charAt(this.pos + 1) == CHR_COMMENT)) {
// consume following chars until new line or end of string
while (++this.pos < this.sourceLength && c != CHR_LF && c != CHR_CR) {
c = this.source.charAt(this.pos);
tokenBuf.append(c);
}
this.pos--;
}
continue;
}
// process begin token: ({)
if (c == CHR_BEGIN_TOKEN) {
this.bracesLevel++;
if (this.bracesLevel == 1) {
this.emittingEscapeCode = true;
this.pos++; // consume char '{' before returning
return tokenBuf.toString();
}
tokenBuf.append(c);
continue;
}
// process end token: (})
if (c == CHR_END_TOKEN) {
tokenBuf.append(c);
this.bracesLevel--;
if (this.bracesLevel == 0) {
this.pos++; // consume char '}' before returning
return tokenBuf.toString();
}
continue;
}
// detect variable usage: (@)
if (c == CHR_VARIABLE) {
this.sawVariableUse = true;
}
}
tokenBuf.append(c);
backslashEscape = false;
}
return tokenBuf.toString();
}
/**
* Returns true if a variable reference was found. Note that this information isn't accurate until finishing to
* process all tokens from source String. It also can't be used as per token basis.
*
* @return true if a variable reference was found.
*/
boolean sawVariableUse() {
return this.sawVariableUse;
}
}