Package nl.rrd.wool.expressions

Class ExpressionParser

java.lang.Object

nl.rrd.wool.expressions.ExpressionParser

public class ExpressionParser
extends Object

An expression parser can read Expressions from text input. After construction, you can read expressions with readExpression(). If you construct the parser with a LineColumnNumberReader, then you can rewind the input after each call of readExpression(), regardless of whether it returns a token or null or a parse error. Rewinding can be useful if an expression is embedded inside other text input.

Field Summary

Fields

Modifier and Type	Field	Description
static Token.Type[][]	PRECEDENCE

Constructor Summary

Constructors

Constructor	Description
ExpressionParser(Reader reader)
ExpressionParser(String input)
ExpressionParser(Tokenizer tokenizer)
ExpressionParser(LineColumnNumberReader reader)

Method Summary

Modifier and Type	Method	Description
void	close()	Closes the parser and the input reader.
int	getColNum()	Returns the current column number.
ExpressionParserConfig	getConfig()
int	getLineNum()	Returns the current line number.
Expression	readExpression()	Tries to read the next expression.
Expression	readOperand()	Tries to read an operand.
void	rewind()	Rewinds the LineColumnNumberReader so it is reset to the same position as before the last call of readExpression().
void	setConfig(ExpressionParserConfig config)

Methods inherited from class java.lang.Object

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

Field Detail

PRECEDENCE

public static final Token.Type[][] PRECEDENCE

Constructor Detail

ExpressionParser

public ExpressionParser(String input)

ExpressionParser

public ExpressionParser(Reader reader)

ExpressionParser

public ExpressionParser(LineColumnNumberReader reader)

ExpressionParser

public ExpressionParser(Tokenizer tokenizer)

Method Detail

close

public void close()
           throws IOException

Closes the parser and the input reader.

Throws:

IOException - if the reader can't be closed

getConfig

public ExpressionParserConfig getConfig()

setConfig

public void setConfig(ExpressionParserConfig config)

readExpression

public Expression readExpression()
                          throws LineNumberParseException,
                                 IOException

Tries to read the next expression. If the end of input is reached, this method returns null.

Returns:

the expression or null

Throws:

LineNumberParseException - if a parse error occurs

IOException - if a reading error occurs

readOperand

public Expression readOperand()
                       throws LineNumberParseException,
                              IOException

Tries to read an operand. That is an expression with any operators. If the end of input is reached, this method returns null.

Returns:

the operand or null

Throws:

LineNumberParseException - if a parse error occurs

IOException - if a reading error occurs

getLineNum

public int getLineNum()

Returns the current line number.

Returns:

the current line number

getColNum

public int getColNum()

Returns the current column number.

Returns:

the current column number

rewind

public void rewind()
            throws IOException

Rewinds the LineColumnNumberReader so it is reset to the same position as before the last call of readExpression().

Throws:

IOException - if an I/O error occurs