gnu.text

Class Lexer

public class Lexer extends 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.

Constructor Summary
	Lexer(LineBufferedReader port)
	Lexer(LineBufferedReader port, SourceMessages messages)

Method Summary
boolean	checkErrors(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(String msg)
void	eofError(String message, int startLine, int startColumn)
void	error(char severity, String filename, int line, int column, String message)
void	error(char severity, String message)
void	error(String message)
void	fatal(String message)
int	getColumnNumber()
SourceError	getErrors()
int	getLineNumber()
SourceMessages	getMessages()
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)
void	skip()
protected void	skip_quick()
void	tokenBufferAppend(int ch) Append one character to tokenBuffer, resizing it if need be.
void	unread(int ch)
protected void	unread()
protected void	unread_quick()

Field Detail

interactive

protected boolean interactive

nesting

protected int nesting

port

protected LineBufferedReader port

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

checkErrors

public boolean checkErrors(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)

checkNext

public boolean checkNext(char ch)

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.

clearErrors

public void clearErrors()

close

public void close()

eofError

public void eofError(String msg)

eofError

public void eofError(String message, int startLine, int startColumn)

error

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

error

public void error(char severity, String message)

error

public void error(String message)

fatal

public void fatal(String message)

getColumnNumber

public int getColumnNumber()

getErrors

public SourceError getErrors()

getLineNumber

public int getLineNumber()

getMessages

public SourceMessages getMessages()

getName

public String getName()

getPort

public final LineBufferedReader getPort()

isInteractive

public boolean isInteractive()

mark

public void mark()

Start tentative parsing. Must be followed by a reset.

peek

public int peek()

popNesting

public void popNesting(char save)

Exit a nested expression, reversing pushNesting

Parameters: save Saved values return by prior pushNesting

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.

read

public int read()

read

public int read(char[] buf, int offset, int length)

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

readOptionalExponent

public int readOptionalExponent()

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.