main
Class BetterTokenizer

java.lang.Object
  main.BetterTokenizer

public class BetterTokenizer

extends java.lang.Object

The BetterTokenizer class takes an input stream and * parses it into "tokens", allowing the tokens to be * read one at a time. The parsing process is controlled by a table * and a number of flags that can be set to various states. The * stream tokenizer can recognize identifiers, numbers, quoted * strings, and various comment styles. *

* Each byte read from the input stream is regarded as a character * in the range '\u0000' through '\u00FF'. * The character value is used to look up five possible attributes of * the character: white space, alphabetic, * numeric, string quote, and comment character. * Each character can have zero or more of these attributes. *

* In addition, an instance has four flags. These flags indicate: *

*
• Whether line terminators are to be returned as tokens or treated * as white space that merely separates tokens. *
• Whether C-style comments are to be recognized and skipped. *
• Whether C++-style comments are to be recognized and skipped. *
• Whether the characters of identifiers are converted to lowercase. *

*

* A typical application first constructs an instance of this class, * sets up the syntax tables, and then repeatedly loops calling the * nextToken method in each iteration of the loop until * it returns the value TT_EOF. * * @author James Gosling, modified by GvonD * @version 1.21g, 03/04/99 * @see java.io.BetterTokenizer#nextToken() * @see java.io.BetterTokenizer#TT_EOF * @since JDK1.0

Field Summary

double	nval If the current token is a number, this field contains the value * of that number.
java.lang.String	sval If the current token is a word token, this field contains a * string giving the characters of the word token.
static int	TT_EOF * A constant indicating that the end of the stream has been read.
static int	TT_EOL * A constant indicating that the end of the line has been read.
static int	TT_NUMBER * A constant indicating that a number token has been read.
static int	TT_WORD * A constant indicating that a word token has been read.
int	ttype * After a call to the nextToken method, this field * contains the type of the token just read.

Constructor Summary

BetterTokenizer(java.io.InputStream is)
Creates a stream tokenizer that parses the specified input * stream.

BetterTokenizer(java.io.Reader r)
Create a tokenizer that parses the given character stream.

Method Summary

void	commentChar(int ch) * Specified that the character argument starts a single-line * comment.
void	eolIsSignificant(boolean flag) Determines whether or not ends of line are treated as tokens.
int	lineno() Return the current line number.
void	lowerCaseMode(boolean fl) Determines whether or not word token are automatically lowercased.
int	nextToken() * Parses the next token from the input stream of this tokenizer.
void	ordinaryChar(int ch) * Specifies that the character argument is "ordinary" * in this tokenizer.
void	ordinaryChars(int low, int hi) * Specifies that all characters c in the range * low <= c <= high * are "ordinary" in this tokenizer.
void	parseNumbers() * Specifies that numbers should be parsed by this tokenizer.
void	pushBack() Causes the next call to the nextToken method of this * tokenizer to return the current value in the ttype * field, and not to modify the value in the nval or * sval field.
void	quoteChar(int ch) * Specifies that matching pairs of this character delimit string * constants in this tokenizer.
void	resetSyntax() * Resets this tokenizer's syntax table so that all characters are * "ordinary." See the ordinaryChar method * for more information on a character being ordinary.
void	slashSlashComments(boolean flag) * Determines whether or not the tokenizer recognizes C++-style comments.
void	slashStarComments(boolean flag) * Determines whether or not the tokenizer recognizes C-style comments.
java.lang.String	toString() Returns the string representation of the current stream token.
void	whitespaceChars(int low, int hi) * Specifies that all characters c in the range * low <= c <= high * are white space characters.
void	wordChars(int low, int hi) * Specifies that all characters c in the range * low <= c <= high * are word constituents.

Methods inherited from class java.lang.Object

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

Field Detail

ttype

public int ttype

* After a call to the nextToken method, this field * contains the type of the token just read. For a single character * token, its value is the single character, converted to an integer. * For a quoted string token (see , its value is the quote character. * Otherwise, its value is one of the following: *

*
• TT_WORD indicates that the token is a word. *
• TT_NUMBER indicates that the token is a number. *
• TT_EOL indicates that the end of line has been read. * The field can only have this value if the * eolIsSignificant method has been called with the * argument true. *
• TT_EOF indicates that the end of the input stream * has been reached. *

* * @see java.io.BetterTokenizer#eolIsSignificant(boolean) * @see java.io.BetterTokenizer#nextToken() * @see java.io.BetterTokenizer#quoteChar(int) * @see java.io.BetterTokenizer#TT_EOF * @see java.io.BetterTokenizer#TT_EOL * @see java.io.BetterTokenizer#TT_NUMBER * @see java.io.BetterTokenizer#TT_WORD

TT_EOF

public static final int TT_EOF

* A constant indicating that the end of the stream has been read.

See Also:

Constant Field Values

TT_EOL

public static final int TT_EOL

* A constant indicating that the end of the line has been read.

See Also:

Constant Field Values

TT_NUMBER

public static final int TT_NUMBER

* A constant indicating that a number token has been read.

See Also:

Constant Field Values

TT_WORD

public static final int TT_WORD

* A constant indicating that a word token has been read.

See Also:

Constant Field Values

sval

public java.lang.String sval

If the current token is a word token, this field contains a * string giving the characters of the word token. When the current * token is a quoted string token, this field contains the body of * the string. *

* The current token is a word when the value of the * ttype field is TT_WORD. The current token is * a quoted string token when the value of the ttype field is * a quote character. * * @see java.io.BetterTokenizer#quoteChar(int) * @see java.io.BetterTokenizer#TT_WORD * @see java.io.BetterTokenizer#ttype * @since JDK1.0

nval

public double nval

If the current token is a number, this field contains the value * of that number. The current token is a number when the value of * the ttype field is TT_NUMBER. * * @see java.io.BetterTokenizer#TT_NUMBER * @see java.io.BetterTokenizer#ttype

Constructor Detail

BetterTokenizer

public BetterTokenizer(java.io.InputStream is)

Creates a stream tokenizer that parses the specified input * stream. The stream tokenizer is initialized to the following * default state: *

*
• All byte values 'A' through 'Z', * 'a' through 'z', and * '\u00A0' through '\u00FF' are * considered to be alphabetic. *
• All byte values '\u0000' through * '\u0020' are considered to be white space. *
• '/' is a comment character. *
• Single quote '\'' and double quote '"' * are string quote characters. *
• Numbers are parsed. *
• Ends of lines are treated as white space, not as separate tokens. *
• C-style and C++-style comments are not recognized. *

* * @deprecated As of JDK version 1.1, the preferred way to tokenize an * input stream is to convert it into a character stream, for example: *

*

	 *   Reader r = new BufferedReader(new InputStreamReader(is));
	 *   BetterTokenizer st = new BetterTokenizer(r);
	 * 

* * @param is an input stream. * @see java.io.BufferedReader * @see java.io.InputStreamReader * @see java.io.BetterTokenizer#BetterTokenizer(java.io.Reader)

BetterTokenizer

public BetterTokenizer(java.io.Reader r)

Create a tokenizer that parses the given character stream. * @since JDK1.1

Method Detail

resetSyntax

public void resetSyntax()

* Resets this tokenizer's syntax table so that all characters are * "ordinary." See the ordinaryChar method * for more information on a character being ordinary. * * @see java.io.BetterTokenizer#ordinaryChar(int)

wordChars

public void wordChars(int low,
                      int hi)

* Specifies that all characters c in the range * low <= c <= high * are word constituents. A word token consists of a word constituent * followed by zero or more word constituents or number constituents. * * @param low the low end of the range. * @param hi the high end of the range.

whitespaceChars

public void whitespaceChars(int low,
                            int hi)

* Specifies that all characters c in the range * low <= c <= high * are white space characters. White space characters serve only to * separate tokens in the input stream. * * @param low the low end of the range. * @param hi the high end of the range.

ordinaryChars

public void ordinaryChars(int low,
                          int hi)

* Specifies that all characters c in the range * low <= c <= high * are "ordinary" in this tokenizer. See the * ordinaryChar method for more information on a * character being ordinary. * * @param low the low end of the range. * @param hi the high end of the range. * @see java.io.BetterTokenizer#ordinaryChar(int)

ordinaryChar

public void ordinaryChar(int ch)

* Specifies that the character argument is "ordinary" * in this tokenizer. It removes any special significance the * character has as a comment character, word component, string * delimiter, white space, or number character. When such a character * is encountered by the parser, the parser treates it as a * single-character token and sets ttype field to the * character value. * * @param ch the character. * @see java.io.BetterTokenizer#ttype

commentChar

public void commentChar(int ch)

* Specified that the character argument starts a single-line * comment. All characters from the comment character to the end of * the line are ignored by this stream tokenizer. * * @param ch the character.

quoteChar

public void quoteChar(int ch)

* Specifies that matching pairs of this character delimit string * constants in this tokenizer. *

* When the nextToken method encounters a string * constant, the ttype field is set to the string * delimiter and the sval field is set to the body of * the string. *

* If a string quote character is encountered, then a string is * recognized, consisting of all characters after (but not including) * the string quote character, up to (but not including) the next * occurrence of that same string quote character, or a line * terminator, or end of file. The usual escape sequences such as * "\n" and "\t" are recognized and * converted to single characters as the string is parsed. * * @param ch the character. * @see java.io.BetterTokenizer#nextToken() * @see java.io.BetterTokenizer#sval * @see java.io.BetterTokenizer#ttype

parseNumbers

public void parseNumbers()

* Specifies that numbers should be parsed by this tokenizer. The * syntax table of this tokenizer is modified so that each of the twelve * characters: *

* 0 1 2 3 4 5 6 7 8 9 . - *

*

* has the "numeric" attribute. *

* When the parser encounters a word token that has the format of a * double precision floating-point number, it treats the token as a * number rather than a word, by setting the the ttype * field to the value TT_NUMBER and putting the numeric * value of the token into the nval field. * * @see java.io.BetterTokenizer#nval * @see java.io.BetterTokenizer#TT_NUMBER * @see java.io.BetterTokenizer#ttype

eolIsSignificant

public void eolIsSignificant(boolean flag)

Determines whether or not ends of line are treated as tokens. * If the flag argument is true, this tokenizer treats end of lines * as tokens; the nextToken method returns * TT_EOL and also sets the ttype field to * this value when an end of line is read. *

* A line is a sequence of characters ending with either a * carriage-return character ('\r') or a newline * character ('\n'). In addition, a carriage-return * character followed immediately by a newline character is treated * as a single end-of-line token. *

* If the flag is false, end-of-line characters are * treated as white space and serve only to separate tokens. * * @param flag true indicates that end-of-line characters * are separate tokens; false indicates that * end-of-line characters are white space. * @see java.io.BetterTokenizer#nextToken() * @see java.io.BetterTokenizer#ttype * @see java.io.BetterTokenizer#TT_EOL

slashStarComments

public void slashStarComments(boolean flag)

* Determines whether or not the tokenizer recognizes C-style comments. * If the flag argument is true, this stream tokenizer * recognizes C-style comments. All text between successive * occurrences of /* and */ are discarded. *

* If the flag argument is false, then C-style comments * are not treated specially. * * @param flag true indicates to recognize and ignore * C-style comments.

slashSlashComments

public void slashSlashComments(boolean flag)

* Determines whether or not the tokenizer recognizes C++-style comments. * If the flag argument is true, this stream tokenizer * recognizes C++-style comments. Any occurrence of two consecutive * slash characters ('/') is treated as the beginning of * a comment that extends to the end of the line. *

* If the flag argument is false, then C++-style * comments are not treated specially. * * @param flag true indicates to recognize and ignore * C++-style comments.

lowerCaseMode

public void lowerCaseMode(boolean fl)

Determines whether or not word token are automatically lowercased. * If the flag argument is true, then the value in the * sval field is lowercased whenever a word token is * returned (the ttype field has the * value TT_WORD by the nextToken method * of this tokenizer. *

* If the flag argument is false, then the * sval field is not modified. * * @param fl true indicates that all word tokens should * be lowercased. * @see java.io.BetterTokenizer#nextToken() * @see java.io.BetterTokenizer#ttype * @see java.io.BetterTokenizer#TT_WORD

nextToken

public int nextToken()
              throws java.io.IOException

* Parses the next token from the input stream of this tokenizer. * The type of the next token is returned in the ttype * field. Additional information about the token may be in the * nval field or the sval field of this * tokenizer. *

* Typical clients of this * class first set up the syntax tables and then sit in a loop * calling nextToken to parse successive tokens until TT_EOF * is returned. * * @return the value of the ttype field. * @exception IOException if an I/O error occurs. * @see java.io.BetterTokenizer#nval * @see java.io.BetterTokenizer#sval * @see java.io.BetterTokenizer#ttype

Throws:

java.io.IOException

pushBack

public void pushBack()

Causes the next call to the nextToken method of this * tokenizer to return the current value in the ttype * field, and not to modify the value in the nval or * sval field. * * @see java.io.BetterTokenizer#nextToken() * @see java.io.BetterTokenizer#nval * @see java.io.BetterTokenizer#sval * @see java.io.BetterTokenizer#ttype

lineno

public int lineno()

Return the current line number. * * @return the current line number of this stream tokenizer.

toString

public java.lang.String toString()

Returns the string representation of the current stream token. * * @return a string representation of the token specified by the * ttype, nval, and sval * fields. * @see java.io.BetterTokenizer#nval * @see java.io.BetterTokenizer#sval * @see java.io.BetterTokenizer#ttype