| org.apache.derby.impl.sql.compile.CharStream
All known Subclasses: org.apache.derby.impl.sql.compile.UCode_CharStream,
| CharStream | | public interface CharStream (Code) | | 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.
|
| Method Summary | |
| char | BeginToken()
Returns the next character that marks the beginning of the next token. | | void | Done()
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. | | String | GetImage()
Returns a string made up of characters from the marked token beginning
to the current buffer position. | | char[] | GetSuffix(int len)
Returns an array of characters that make up the suffix of length 'len' for
the currently matched token. | | 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)
| | void | backup(int amount)
Backs up the input stream by amount steps. | | int | getBeginColumn()
Returns the column number of the first character for current token (being
matched after the last call to BeginTOken). | | int | getBeginLine()
Returns the line number of the first character for current token (being
matched after the last call to BeginTOken). | | abstract int | getBeginOffset()
| | int | getColumn()
Returns the column position of the character last read. | | int | getEndColumn()
Returns the column number of the last character for current token (being
matched after the last call to BeginTOken). | | int | getEndLine()
Returns the line number of the last character for current token (being
matched after the last call to BeginTOken). | | abstract int | getEndOffset()
| | int | getLine()
Returns the line number of the character last read. | | char | readChar()
Returns the next character from the selected input. |
| BeginToken | | char BeginToken() throws java.io.IOException(Code) | | 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.
|
| Done | | void Done()(Code) | | 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.
|
| GetImage | | String GetImage()(Code) | | 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.
|
| GetSuffix | | char[] GetSuffix(int len)(Code) | | 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();
}
|
| ReInit | | abstract void ReInit(java.io.Reader dstream, int startline, int startcolumn, int buffersize)(Code) | | |
| backup | | void backup(int amount)(Code) | | 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.
|
| getBeginColumn | | int getBeginColumn()(Code) | | Returns the column number of the first character for current token (being
matched after the last call to BeginTOken).
|
| getBeginLine | | int getBeginLine()(Code) | | Returns the line number of the first character for current token (being
matched after the last call to BeginTOken).
|
| getBeginOffset | | abstract int getBeginOffset()(Code) | | |
| getEndColumn | | int getEndColumn()(Code) | | Returns the column number of the last character for current token (being
matched after the last call to BeginTOken).
|
| getEndLine | | int getEndLine()(Code) | | Returns the line number of the last character for current token (being
matched after the last call to BeginTOken).
|
| getEndOffset | | abstract int getEndOffset()(Code) | | |
| readChar | | char readChar() throws java.io.IOException(Code) | | 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.
|
|
|