Class FastCharStream
- java.lang.Object
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- org.apache.lucene.queryparser.charstream.FastCharStream
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- All Implemented Interfaces:
CharStream
public final class FastCharStream extends Object implements CharStream
An efficient implementation of JavaCC's CharStream interface.Note that this does not do line-number counting, but instead keeps track of the character position of the token in the input, as required by Lucene's
OffsetAttribute
API.
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Constructor Summary
Constructors Constructor Description FastCharStream(Reader r)
Constructs from a Reader.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
backup(int amount)
Backs up the input stream by amount steps.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.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).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).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.char
readChar()
Returns the next character from the selected input.
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Constructor Detail
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FastCharStream
public FastCharStream(Reader r)
Constructs from a Reader.
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Method Detail
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readChar
public final char readChar() throws IOException
Description copied from 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.- Specified by:
readChar
in interfaceCharStream
- Throws:
IOException
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BeginToken
public final char BeginToken() throws IOException
Description copied from interface:CharStream
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.- Specified by:
BeginToken
in interfaceCharStream
- Throws:
IOException
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backup
public final void backup(int amount)
Description copied from interface:CharStream
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 implementation's responsibility to do this right.- Specified by:
backup
in interfaceCharStream
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GetImage
public final String GetImage()
Description copied from interface:CharStream
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.- Specified by:
GetImage
in interfaceCharStream
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GetSuffix
public final char[] GetSuffix(int len)
Description copied from interface:CharStream
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(); }
- Specified by:
GetSuffix
in interfaceCharStream
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Done
public final void Done()
Description copied from interface:CharStream
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.- Specified by:
Done
in interfaceCharStream
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getEndColumn
public final int getEndColumn()
Description copied from interface:CharStream
Returns the column number of the last character for current token (being matched after the last call to BeginTOken).- Specified by:
getEndColumn
in interfaceCharStream
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getEndLine
public final int getEndLine()
Description copied from interface:CharStream
Returns the line number of the last character for current token (being matched after the last call to BeginTOken).- Specified by:
getEndLine
in interfaceCharStream
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getBeginColumn
public final int getBeginColumn()
Description copied from interface:CharStream
Returns the column number of the first character for current token (being matched after the last call to BeginTOken).- Specified by:
getBeginColumn
in interfaceCharStream
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getBeginLine
public final int getBeginLine()
Description copied from interface:CharStream
Returns the line number of the first character for current token (being matched after the last call to BeginTOken).- Specified by:
getBeginLine
in interfaceCharStream
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