Top Description Methods
org.apache.derby.impl.sql.compile

pack-priv Interface CharStream

Known Direct Implementers
org.apache.derby.impl.sql.compile.UCode_CharStream
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

Modifier and TypeMethod and Description
public void
backup(int amount)

Backs up the input stream by amount steps.

public char
BeginToken()

Returns the next character that marks the beginning of the next token.

public 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.

public int
getBeginColumn()

Returns the column number of the first character for current token (being matched after the last call to BeginTOken).

public int
getBeginLine()

Returns the line number of the first character for current token (being matched after the last call to BeginTOken).

public int
getBeginOffset()

public int
getColumn()
Deprecated

Returns the column position of the character last read.

public int
getEndColumn()

Returns the column number of the last character for current token (being matched after the last call to BeginTOken).

public int
getEndLine()

Returns the line number of the last character for current token (being matched after the last call to BeginTOken).

public int
getEndOffset()

public String
GetImage()

Returns a string made up of characters from the marked token beginning to the current buffer position.

public int
getLine()
Deprecated

Returns the line number of the character last read.

public char[]
GetSuffix(int len)

Returns an array of characters that make up the suffix of length 'len' for the currently matched token.

public char
readChar()

Returns the next character from the selected input.

public void
ReInit(Reader dstream, int startline, int startcolumn, int buffersize)

public void
ReInit(Reader dstream, int startline, int startcolumn)

public void
ReInit(InputStream dstream, int startline, int startcolumn, int buffersize)

public void
ReInit(InputStream dstream, int startline, int startcolumn)

Method Detail

backupback to summary
public void backup(int amount)

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.

BeginTokenback to summary
public char BeginToken() throws IOException

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.

Doneback to summary
public 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. Again, the body of this function can be just empty and it will not affect the lexer's operation.

getBeginColumnback to summary
public int getBeginColumn()

Returns the column number of the first character for current token (being matched after the last call to BeginTOken).

getBeginLineback to summary
public int getBeginLine()

Returns the line number of the first character for current token (being matched after the last call to BeginTOken).

getBeginOffsetback to summary
public int getBeginOffset()
getColumnback to summary
public int getColumn()

Deprecated

Returns the column position of the character last read.

Annotations
@Deprecated
See Also
getEndColumn
getEndColumnback to summary
public int getEndColumn()

Returns the column number of the last character for current token (being matched after the last call to BeginTOken).

getEndLineback to summary
public int getEndLine()

Returns the line number of the last character for current token (being matched after the last call to BeginTOken).

getEndOffsetback to summary
public int getEndOffset()
GetImageback to summary
public String GetImage()

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.

getLineback to summary
public int getLine()

Deprecated

Returns the line number of the character last read.

Annotations
@Deprecated
See Also
getEndLine
GetSuffixback to summary
public char[] GetSuffix(int len)

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(); }

readCharback to summary
public char readChar() throws IOException

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.

ReInitback to summary
public void ReInit(Reader dstream, int startline, int startcolumn, int buffersize)
ReInitback to summary
public void ReInit(Reader dstream, int startline, int startcolumn)
ReInitback to summary
public void ReInit(InputStream dstream, int startline, int startcolumn, int buffersize)
ReInitback to summary
public void ReInit(InputStream dstream, int startline, int startcolumn)