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java.lang.Object | +----java.io.StreamTokenizer
StreamTokenizer 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:
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.
nval
sval
TT_EOF
TT_EOL
TT_NUMBER
TT_WORD
ttype
nextToken method, this field
contains the type of the token just read.
StreamTokenizer(InputStream)
StreamTokenizer(Reader)
commentChar(int)
eolIsSignificant(boolean)
lineno()
lowerCaseMode(boolean)
nextToken()
ordinaryChar(int)
ordinaryChars(int, int)
low <= c <= high
are "ordinary" in this tokenizer.
parseNumbers()
pushBack()
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.
quoteChar(int)
resetSyntax()
ordinaryChar method
for more information on a character being ordinary.
slashSlashComments(boolean)
slashStarComments(boolean)
toString()
whitespaceChars(int, int)
low <= c <= high
are white space characters.
wordChars(int, int)
low <= c <= high
are word constituents.
ttype
public int ttype
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.
TT_EOF
public static final int TT_EOF
TT_EOL
public static final int TT_EOL
TT_NUMBER
public static final int TT_NUMBER
TT_WORD
public static final int TT_WORD
sval
public String sval
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.
nval
public double nval
ttype field is TT_NUMBER.
StreamTokenizer
public StreamTokenizer(InputStream is)
Reader r = new BufferedReader(new InputStreamReader(is)); StreamTokenizer st = new StreamTokenizer(r);
'A' through 'Z',
'a' through 'z', and
'\u00A0' through '\u00FF' are
considered to be alphabetic.
'\u0000' through
'\u0020' are considered to be white space.
'/' is a comment character.
'\'' and double quote '"'
are string quote characters.
StreamTokenizer
public StreamTokenizer(Reader r)
resetSyntax
public void resetSyntax()
ordinaryChar method
for more information on a character being ordinary.
wordChars
public void wordChars(int low,
int hi)
low <= c <= high
are word constituents. A word token consists of a word constituent
followed by zero or more word constituents or number constituents.
whitespaceChars
public void whitespaceChars(int low,
int hi)
low <= c <= high
are white space characters. White space characters serve only to
separate tokens in the input stream.
ordinaryChars
public void ordinaryChars(int low,
int hi)
low <= c <= high
are "ordinary" in this tokenizer. See the
ordinaryChar method for more information on a
character being ordinary.
ordinaryChar
public void ordinaryChar(int ch)
ttype field to the
character value.
commentChar
public void commentChar(int ch)
quoteChar
public void quoteChar(int ch)
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.
parseNumbers
public void parseNumbers()
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.
eolIsSignificant
public void eolIsSignificant(boolean flag)
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.
true indicates that end-of-line characters
are separate tokens; false indicates that
end-of-line characters are white space.
slashStarComments
public void slashStarComments(boolean flag)
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.
true indicates to recognize and ignore
C-style comments.
slashSlashComments
public void slashSlashComments(boolean flag)
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.
true indicates to recognize and ignore
C++-style comments.
lowerCaseMode
public void lowerCaseMode(boolean fl)
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.
true indicates that all word tokens should
be lowercased.
nextToken
public int nextToken() throws IOException
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.
ttype field.
pushBack
public void pushBack()
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.
lineno
public int lineno()
toString
public String toString()
ttype, nval, and sval
fields.
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