com.igormaznitsa.jcp.expression

Class ExpressionParser

java.lang.Object

com.igormaznitsa.jcp.expression.ExpressionParser

public final class ExpressionParser
extends Object

This class is a parser allows to parse an expression and make a tree as the output

Author:

Igor Maznitsa (igor.maznitsa@igormaznitsa.com)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ExpressionParser.SpecialItem The enumeration describes some special items which can be met in the expression

Constructor Summary

Constructors

Constructor and Description
ExpressionParser()

Method Summary

Modifier and Type	Method and Description
static ExpressionParser	getInstance()
ExpressionTree	parse(String expressionStr, PreprocessorContext context) To parse an expression represented as a string and get a tree
ExpressionItem	readExpression(PushbackReader reader, ExpressionTree tree, PreprocessorContext context, boolean insideBracket, boolean argument) It reads an expression from a reader and fill a tree

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionParser

public ExpressionParser()

Method Detail

getInstance

public static ExpressionParser getInstance()

parse

public ExpressionTree parse(String expressionStr,
                            PreprocessorContext context)
                     throws IOException

To parse an expression represented as a string and get a tree

Parameters:

expressionStr - the expression string to be parsed, must not be null

context - a preprocessor context to be used to get variable values, it can be null

Returns:

a tree containing parsed expression

Throws:

IOException - it will be thrown if there is a problem to read the expression string

readExpression

public ExpressionItem readExpression(PushbackReader reader,
                                     ExpressionTree tree,
                                     PreprocessorContext context,
                                     boolean insideBracket,
                                     boolean argument)
                              throws IOException

It reads an expression from a reader and fill a tree

Parameters:

reader - the reader to be used as the character source, must not be null

tree - the result tree to be filled by read items, must not be null

context - a preprocessor context to be used for variables, it can be null

insideBracket - the flag shows that the expression can be ended by a bracket

argument - the flag shows that the expression can be ended by a comma

Returns:

the last read expression item (a comma or a bracket for instance), it can be null

Throws:

IOException - it will be thrown if there is a problem in reading from the reader