gnu.text
Class Lexer

java.lang.Object
  java.io.Reader
      gnu.text.Lexer

All Implemented Interfaces:

java.io.Closeable, java.lang.Readable

Direct Known Subclasses:

Lexer, LispReader, XQParser, XslTranslator

public class Lexer
extends java.io.Reader

Framework for implementing lexical scanners and parsers.

Field Summary

protected boolean	interactive
protected int	nesting
protected LineBufferedReader	port
char[]	tokenBuffer For building tokens of various kinds.
int	tokenBufferLength The number of chars of tokenBuffer that are used.

Fields inherited from class java.io.Reader

lock

Constructor Summary

Lexer(LineBufferedReader port)

Lexer(LineBufferedReader port, SourceMessages messages)

Method Summary

boolean	checkErrors(java.io.PrintWriter out, int max) Returns true if any error were seen.
boolean	checkNext(char ch) Check if the next character matches a given character.
void	clearErrors()
void	close()
void	eofError(java.lang.String msg)
void	eofError(java.lang.String message, int startLine, int startColumn)
void	error(char severity, java.lang.String message)
void	error(char severity, java.lang.String filename, int line, int column, java.lang.String message)
void	error(java.lang.String message)
void	fatal(java.lang.String message)
int	getColumnNumber()
SourceError	getErrors()
int	getLineNumber()
SourceMessages	getMessages()
java.lang.String	getName()
LineBufferedReader	getPort()
boolean	isInteractive()
void	mark() Start tentative parsing.
int	peek()
void	popNesting(char save) Exit a nested expression, reversing pushNesting
char	pushNesting(char promptChar) Enter a nested expression.
int	read()
int	read(char[] buf, int offset, int length)
static long	readDigitsInBuffer(LineBufferedReader port, int radix) Read digits, up to the first non-digit or the buffer limit
int	readOptionalExponent() Read an optional signed integer.
void	reset() Stop tentative parsing.
boolean	seenErrors()
void	setInteractive(boolean v)
void	setMessages(SourceMessages messages)
protected void	skip_quick()
void	skip()
void	tokenBufferAppend(int ch) Append one character to tokenBuffer, resizing it if need be.
protected void	unread_quick()
protected void	unread()
void	unread(int ch)

Methods inherited from class java.io.Reader

mark, markSupported, read, read, ready, skip

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

port

protected LineBufferedReader port

interactive

protected boolean interactive

nesting

protected int nesting

tokenBuffer

public char[] tokenBuffer

For building tokens of various kinds.

tokenBufferLength

public int tokenBufferLength

The number of chars of tokenBuffer that are used.

Constructor Detail

Lexer

public Lexer(LineBufferedReader port)

Lexer

public Lexer(LineBufferedReader port,
             SourceMessages messages)

Method Detail

pushNesting

public char pushNesting(char promptChar)

Enter a nested expression. This is used in interactive mode to control whether to continue past end of line, depending on whether the expression is incomplete.

Parameters:

promptChar - Used in prompt string to indicate type of nesting.

Returns:

The previous value of promptChar, to be passed to popNesting.

popNesting

public void popNesting(char save)

Exit a nested expression, reversing pushNesting

Parameters:

save - Saved values return by prior pushNesting

getPort

public final LineBufferedReader getPort()

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.io.Closeable

Specified by:

close in class java.io.Reader

Throws:

java.io.IOException

read

public int read()
         throws java.io.IOException

Overrides:

read in class java.io.Reader

Throws:

java.io.IOException

read

public int read(char[] buf,
                int offset,
                int length)
         throws java.io.IOException

Specified by:

read in class java.io.Reader

Throws:

java.io.IOException

unread

public void unread(int ch)
            throws java.io.IOException

Throws:

java.io.IOException

peek

public int peek()
         throws java.io.IOException

Throws:

java.io.IOException

skip

public void skip()
          throws java.io.IOException

Throws:

java.io.IOException

unread

protected void unread()
               throws java.io.IOException

Throws:

java.io.IOException

unread_quick

protected void unread_quick()
                     throws java.io.IOException

Throws:

java.io.IOException

checkNext

public boolean checkNext(char ch)
                  throws java.io.IOException

Check if the next character matches a given character.

Parameters:

ch - The character to match against.

Returns:

if the character read matches On a match, the position is advanced following that character.

Throws:

java.io.IOException

skip_quick

protected void skip_quick()
                   throws java.io.IOException

Throws:

java.io.IOException

getMessages

public SourceMessages getMessages()

setMessages

public void setMessages(SourceMessages messages)

checkErrors

public boolean checkErrors(java.io.PrintWriter out,
                           int max)

Returns true if any error were seen. Prints and clears the errors.

Parameters:

out - where to write the error message to

max - maximum number of messages to print (can be 0)

getErrors

public SourceError getErrors()

seenErrors

public boolean seenErrors()

clearErrors

public void clearErrors()

error

public void error(char severity,
                  java.lang.String filename,
                  int line,
                  int column,
                  java.lang.String message)

error

public void error(char severity,
                  java.lang.String message)

error

public void error(java.lang.String message)

fatal

public void fatal(java.lang.String message)
           throws SyntaxException

Throws:

SyntaxException

eofError

public void eofError(java.lang.String msg)
              throws SyntaxException

Throws:

SyntaxException

eofError

public void eofError(java.lang.String message,
                     int startLine,
                     int startColumn)
              throws SyntaxException

Throws:

SyntaxException

readOptionalExponent

public int readOptionalExponent()
                         throws java.io.IOException

Read an optional signed integer. If there is no integer in the input stream, return 1. For excessively large exponents, return Integer.MIN_VALUE or Integer.MAX_VALUE.

Throws:

java.io.IOException

readDigitsInBuffer

public static long readDigitsInBuffer(LineBufferedReader port,
                                      int radix)

Read digits, up to the first non-digit or the buffer limit

Returns:

the digits seen as a non-negative long, or -1 on overflow

getName

public java.lang.String getName()

getLineNumber

public int getLineNumber()

getColumnNumber

public int getColumnNumber()

isInteractive

public boolean isInteractive()

setInteractive

public void setInteractive(boolean v)

tokenBufferAppend

public void tokenBufferAppend(int ch)

Append one character to tokenBuffer, resizing it if need be.

mark

public void mark()
          throws java.io.IOException

Start tentative parsing. Must be followed by a reset.

Throws:

java.io.IOException

reset

public void reset()
           throws java.io.IOException

Stop tentative parsing. Return to position where we called mark.

Overrides:

reset in class java.io.Reader

Throws:

java.io.IOException