public class ProcessTreeTokeniser
extends java.lang.Object
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
.
StreamTokenizer.nextToken()
,
StreamTokenizer.TT_EOF
Modifier and Type | Field and Description |
---|---|
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 and Description |
---|
ProcessTreeTokeniser(java.io.InputStream is)
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)); StreamTokenizer st = new StreamTokenizer(r); |
ProcessTreeTokeniser(java.io.Reader r)
Create a tokenizer that parses the given character stream.
|
Modifier and Type | Method and Description |
---|---|
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 and the
line number it occurs on.
|
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. |
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, 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.
The initial value of this field is -4.
StreamTokenizer.eolIsSignificant(boolean)
,
StreamTokenizer.nextToken()
,
StreamTokenizer.quoteChar(int)
,
StreamTokenizer.TT_EOF
,
StreamTokenizer.TT_EOL
,
StreamTokenizer.TT_NUMBER
,
StreamTokenizer.TT_WORD
public static final int TT_EOF
public static final int TT_EOL
public static final int TT_NUMBER
public static final int TT_WORD
public java.lang.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.
The initial value of this field is null.
StreamTokenizer.quoteChar(int)
,
StreamTokenizer.TT_WORD
,
StreamTokenizer.ttype
public double nval
ttype
field is TT_NUMBER
.
The initial value of this field is 0.0.
StreamTokenizer.TT_NUMBER
,
StreamTokenizer.ttype
@Deprecated public ProcessTreeTokeniser(java.io.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.
is
- an input stream.BufferedReader
,
InputStreamReader
,
StreamTokenizer.StreamTokenizer(java.io.Reader)
public ProcessTreeTokeniser(java.io.Reader r)
r
- a Reader object providing the input stream.public void resetSyntax()
ordinaryChar
method for more information
on a character being ordinary.StreamTokenizer.ordinaryChar(int)
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.low
- the low end of the range.hi
- the high end of the range.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.
Any other attribute settings for the characters in the specified range are cleared.
low
- the low end of the range.hi
- the high end of the range.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.low
- the low end of the range.hi
- the high end of the range.StreamTokenizer.ordinaryChar(int)
public void ordinaryChar(int ch)
ttype
field
to the character value.
Making a line terminator character "ordinary" may interfere with the
ability of a StreamTokenizer
to count lines. The
lineno
method may no longer reflect the presence of such
terminator characters in its line count.
ch
- the character.StreamTokenizer.ttype
public void commentChar(int ch)
Any other attribute settings for the specified character are cleared.
ch
- the character.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.
Any other attribute settings for the specified character are cleared.
ch
- the character.StreamTokenizer.nextToken()
,
StreamTokenizer.sval
,
StreamTokenizer.ttype
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 ttype
field to the value
TT_NUMBER
and putting the numeric value of the token into
the nval
field.
StreamTokenizer.nval
,
StreamTokenizer.TT_NUMBER
,
StreamTokenizer.ttype
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.
flag
- true
indicates that end-of-line characters are
separate tokens; false
indicates that end-of-line
characters are white space.StreamTokenizer.nextToken()
,
StreamTokenizer.ttype
,
StreamTokenizer.TT_EOL
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.
flag
- true
indicates to recognize and ignore C-style
comments.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.
flag
- true
indicates to recognize and ignore C++-style
comments.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.
fl
- true
indicates that all word tokens should be
lowercased.StreamTokenizer.nextToken()
,
StreamTokenizer.ttype
,
StreamTokenizer.TT_WORD
public int nextToken() throws java.io.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.java.io.IOException
- if an I/O error occurs.StreamTokenizer.nval
,
StreamTokenizer.sval
,
StreamTokenizer.ttype
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.StreamTokenizer.nextToken()
,
StreamTokenizer.nval
,
StreamTokenizer.sval
,
StreamTokenizer.ttype
public int lineno()
public java.lang.String toString()
The precise string returned is unspecified, although the following example can be considered typical:
Token['a'], line 10
toString
in class java.lang.Object
StreamTokenizer.nval
,
StreamTokenizer.sval
,
StreamTokenizer.ttype