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§2.22 Class StreamTokenizer
public class java.io.StreamTokenizer
extends java.lang.Object (I-§1.12)
{
// Fields
public double nval; §2.22.1
public String sval; §2.22.2
public int ttype; §2.22.3
// possible values for the ttype field
public final static int TT_EOF; §2.22.4
public final static int TT_EOL; §2.22.5
public final static int TT_NUMBER; §2.22.6
public final static int TT_WORD; §2.22.7
// Constructors
public StreamTokenizer(InputStream I); §2.22.8
// Methods
public void commentChar(int ch); §2.22.9
public void eolIsSignificant(boolean flag); §2.22.10
public int lineno(); §2.22.11
public void lowerCaseMode(boolean fl); §2.22.12
public int nextToken(); §2.22.13
public void ordinaryChar(int ch); §2.22.14
public void ordinaryChars(int low, int hi); §2.22.15
public void parseNumbers(); §2.22.16
public void pushBack(); §2.22.17
public void quoteChar(int ch); §2.22.18
public void resetSyntax(); §2.22.19
public void whitespaceChars(int low, int hi); §2.22.20
public void slashStarComments(boolean flag); §2.22.21
public String toString(); §2.22.22
public void whitespaceChars(int low, int hi); §2.22.23
public void wordChars(int low, int hi); §2.22.24
}
The 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: whitespace, 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 (I-§2.22.13) in each iteration of the
loop until it returns the value TT_EOF (I-§2.22.4).
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
(I-§2.22.3) is TT_NUMBER (I-§2.22.6).
sval
public 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 when the value of the ttype field
(I-§2.22.3) is TT_WORD (I-§2.22.7). The current token is a quoted string
token when the value of the ttype field is a quote character (see I-§2.22.18).
ttype
public int ttype
- After a call to the nextToken method (I-§2.22.13), 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
I-§2.22.18), its value is the quote character. Otherwise, its value is one of
the following:
TT_EOF
public final static int TT_EOF = -1
- A constant indicating that the end of the stream has been read.
TT_EOL
public final static int TT_EOL = '\n'
- A constant indicating that the end of line has been read.
TT_NUMBER
public final static int TT_NUMBER = -2
- A constant indicating that a number has been read.
TT_WORD
public final static int TT_WORD = -3
- A constant indicating that a token has been read.
StreamTokenizer
public StreamTokenizer(InputStream I)
- Creates a stream tokenizer that parses the specified input stream. The
stream tokenizer is initialized to the following default state:
- Parameters:
I
-
the input stream
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.
- Parameters:
ch
-
the character
eolIsSignificant
public void eolIsSignificant(boolean flag)
- If the flag argument is true, this tokenizer treats end of lines as tokens; the
nextToken method (I-§2.22.13) returns TT_EOL (I-§2.22.5) and also sets the
ttype field (I-§2.22.3) 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 whitespace and serve
only to separate tokens.
- Parameters:
flag
-
true indicates that end-of-line characters are separate tokens; false
indicates that end-of-line characters are whitespace
lineno
public int lineno()
- Returns:
- the current line number of this stream tokenizer
lowerCaseMode
public void lowerCaseMode(boolean fl)
- If the flag argument is true, then the value in the sval field is lowercased
whenever a word token is returned (the ttype field (I-§2.22.3) has the value
TT_WORD (I-§2.22.7)) by the nextToken method (I-§2.22.13) of this tokenizer.
- If the flag argument is false, then the sval field is not modified.
- Parameters:
fl
-
true indicates that all word tokens should be lowercased
nextToken
public int nextToken()
throws IOException
- Parses the next token from the input stream of this tokenizer. The type of
the next token is returned in the ttype field (I-§2.22.3). Additional information about the token may be in the nval field (I-§2.22.1) or the sval field
(I-§2.22.2) of this tokenizer.
- Returns:
- The value of the ttype field (I-§2.22.3).
- Throws
- IOException (I-§2.29)
- If an I/O error occurs.
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, whitespace, 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 (I-§2.22.3) to the character value.
- Parameters:
ch
-
the character
ordinaryChars
public void ordinaryChars(int low, int hi)
- Specifies that all characters c in the range are "ordinary" in
this tokenizer. See the ordinaryChar method (I-§2.22.14) for more information on a character being ordinary.
- Parameters:
low
-
the low end of the range
hi
-
the high end of the range
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
- has the "numeric" attribute.
- When the parser encounters a word token that has the format of a double
precision floating point number, it treates the token as a number rather
than a word, by setting the the ttype field (I-§2.22.3) to the value
TT_NUMBER (I-§2.22.6) and putting the numeric value of the token into
the nval field (I-§2.22.1).
pushBack
public void pushBack()
- Causes the next call to the nextToken method (I-§2.22.13) of this tokenizer
to return the current value in the ttype field (I-§2.22.3), and not to modify
the value in the nval (I-§2.22.1) or sval (I-§2.22.2) field.
quoteChar
public void quoteChar(int ch)
- Specifies that matching pairs of this character delimit string constants in
this tokenizer.
- When the nextToken method (I-§2.22.13) encounters a string constant, the
ttype field (I-§2.22.3) field is set to the string delimiter and the sval field
(I-§2.22.2) 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.
- Parameters:
ch
-
the character
resetSyntax
public void resetSyntax()
- Resets this tokenizer's syntax table so that all characters are "ordinary."
See the ordinaryChar method (I-§2.22.14) for more information on a character being ordinary.
slashSlashComments
public void slashSlashComments(boolean flag)
- 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.
- Parameters:
flag
-
true indicates to recognize and ignore C++ style comments
slashStarComments
public void slashStarComments(boolean flag)
- 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.
- Parameters:
flag
-
true indicates to recognize and ignore C style comments
toString
public String toString()
- Returns the string representation of the current stream token.
- Returns:
- a string representation of the token specified by the ttype (I-§2.22.3),
nval (I-§2.22.1), and sval (I-§2.22.2) fields.
- Overrides:
- toString in class Object (I-§1.12.9).
whitespaceChars
public void whitespaceChars(int low, int hi)
- Specifies that all characters c in the range are whitespace
character. Whitepsace characters serve only to separate tokens in the input
stream.
- Parameters:
low
-
the low end of the range
hi
-
the high end of the range
wordChars
public void wordChars(int low, int hi)
- Specifies that all characters c in the range are word constituents. A word token consists of a word constitutent followed by zero or
more word constituents or number constituents.
- Parameters:
low
-
the low end of the range
hi
-
the high end of the range
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Java API Document (HTML generated by dkramer on April 22, 1996)
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