| /* |
| |
| Derby - Class org.apache.derby.impl.sql.compile.CharStream |
| |
| Licensed to the Apache Software Foundation (ASF) under one or more |
| contributor license agreements. See the NOTICE file distributed with |
| this work for additional information regarding copyright ownership. |
| The ASF licenses this file to you 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.apache.derby.impl.sql.compile; |
| |
| /** |
| * This interface describes a character stream that maintains line and |
| * column number positions of the characters. It also has the capability |
| * to backup the stream to some extent. An implementation of this |
| * interface is used in the TokenManager implementation generated by |
| * JavaCCParser. |
| * |
| * All the methods except backup can be implemented in any fashion. backup |
| * needs to be implemented correctly for the correct operation of the lexer. |
| * Rest of the methods are all used to get information like line number, |
| * column number and the String that constitutes a token and are not used |
| * by the lexer. Hence their implementation won't affect the generated lexer's |
| * operation. |
| */ |
| |
| interface CharStream { |
| |
| /** |
| * Returns the next character from the selected input. The method |
| * of selecting the input is the responsibility of the class |
| * implementing this interface. Can throw any java.io.IOException. |
| */ |
| char readChar() throws java.io.IOException; |
| |
| /** |
| * Returns the column position of the character last read. |
| * @deprecated |
| * @see #getEndColumn |
| */ |
| @Deprecated |
| int getColumn(); |
| |
| /** |
| * Returns the line number of the character last read. |
| * @deprecated |
| * @see #getEndLine |
| */ |
| @Deprecated |
| int getLine(); |
| |
| /** |
| * Returns the column number of the last character for current token (being |
| * matched after the last call to BeginTOken). |
| */ |
| int getEndColumn(); |
| |
| /** |
| * Returns the line number of the last character for current token (being |
| * matched after the last call to BeginTOken). |
| */ |
| int getEndLine(); |
| |
| /** |
| * Returns the column number of the first character for current token (being |
| * matched after the last call to BeginTOken). |
| */ |
| int getBeginColumn(); |
| |
| /** |
| * Returns the line number of the first character for current token (being |
| * matched after the last call to BeginTOken). |
| */ |
| int getBeginLine(); |
| |
| /** |
| * Backs up the input stream by amount steps. Lexer calls this method if it |
| * had already read some characters, but could not use them to match a |
| * (longer) token. So, they will be used again as the prefix of the next |
| * token and it is the implemetation's responsibility to do this right. |
| */ |
| void backup(int amount); |
| |
| /** |
| * Returns the next character that marks the beginning of the next token. |
| * All characters must remain in the buffer between two successive calls |
| * to this method to implement backup correctly. |
| */ |
| char BeginToken() throws java.io.IOException; |
| |
| /** |
| * Returns a string made up of characters from the marked token beginning |
| * to the current buffer position. Implementations have the choice of returning |
| * anything that they want to. For example, for efficiency, one might decide |
| * to just return null, which is a valid implementation. |
| */ |
| String GetImage(); |
| |
| /** |
| * Returns an array of characters that make up the suffix of length 'len' for |
| * the currently matched token. This is used to build up the matched string |
| * for use in actions in the case of MORE. A simple and inefficient |
| * implementation of this is as follows : |
| * |
| * { |
| * String t = GetImage(); |
| * return t.substring(t.length() - len, t.length()).toCharArray(); |
| * } |
| */ |
| char[] GetSuffix(int len); |
| |
| /** |
| * The lexer calls this function to indicate that it is done with the stream |
| * and hence implementations can free any resources held by this class. |
| * Again, the body of this function can be just empty and it will not |
| * affect the lexer's operation. |
| */ |
| void Done(); |
| |
| |
| // This method was added to support ability to get the input |
| // between two tokens. |
| abstract int getBeginOffset(); |
| |
| // This method was added to support ability to get the input |
| // between two tokens. |
| abstract int getEndOffset(); |
| |
| // These methods were added to support re-initialization of CharStreams |
| abstract void ReInit(java.io.Reader dstream, |
| int startline, int startcolumn, int buffersize); |
| |
| abstract void ReInit(java.io.Reader dstream, int startline, int startcolumn); |
| |
| abstract void ReInit(java.io.InputStream dstream, int startline, |
| int startcolumn, int buffersize); |
| |
| abstract void ReInit(java.io.InputStream dstream, int startline, |
| int startcolumn); |
| |
| } |