Package com.igormaznitsa.jcp.expression

Class ExpressionParser

java.lang.Object

com.igormaznitsa.jcp.expression.ExpressionParser

public final class ExpressionParser
extends java.lang.Object

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

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	ExpressionParser.ParserState	The enumeration describes inside states of the parses
static class	ExpressionParser.SpecialItem	The enumeration describes some special items which can be met in the expression

Field Summary

Fields

Modifier and Type	Field	Description
private static ExpressionParser	INSTANCE	It contains the instance for the parser, because the parser is a singletone

Constructor Summary

Constructors

Constructor	Description
ExpressionParser()

Method Summary

Modifier and Type	Method	Description
static ExpressionParser	getInstance()
private static boolean	isDelimiter(char chr)
private static boolean	isDelimiterOrOperatorChar(char chr)
private static boolean	isOperatorChar(char chr)
(package private) ExpressionItem	nextItem(java.io.PushbackReader reader, PreprocessorContext context)	Read the next item from the reader
ExpressionTree	parse(java.lang.String expressionStr, PreprocessorContext context)	To parse an expression represented as a string and get a tree
ExpressionItem	readExpression(java.io.PushbackReader reader, ExpressionTree tree, PreprocessorContext context, boolean insideBracket, boolean argument)	It reads an expression from a reader and fill a tree
private ExpressionTree	readFunction(AbstractFunction function, java.io.PushbackReader reader, PreprocessorContext context, FilePositionInfo[] includeStack, java.lang.String sources)	The auxiliary method allows to form a function and its arguments as a tree
(package private) ExpressionItem	readFunctionArgument(java.io.PushbackReader reader, ExpressionTree tree, PreprocessorContext context, FilePositionInfo[] callStack, java.lang.String source)	The auxiliary method allows to read a function argument

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

private static final ExpressionParser INSTANCE

It contains the instance for the parser, because the parser is a singletone

Constructor Detail

ExpressionParser

public ExpressionParser()

Method Detail

getInstance

public static ExpressionParser getInstance()

parse

public ExpressionTree parse(java.lang.String expressionStr,
                            PreprocessorContext context)
                     throws java.io.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

Returns:

a tree containing parsed expression

Throws:

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

readExpression

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

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:

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

readFunction

private ExpressionTree readFunction(AbstractFunction function,
                                    java.io.PushbackReader reader,
                                    PreprocessorContext context,
                                    @MustNotContainNull
                                    FilePositionInfo[] includeStack,
                                    java.lang.String sources)
                             throws java.io.IOException

The auxiliary method allows to form a function and its arguments as a tree

Parameters:

function - the function which arguments will be read from the stream, must not be null

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

context - a preprocessor context, it will be used for a user functions and variables

includeStack - the current file include stack, can be null

sources - the current source line, can be null

Returns:

an expression tree containing parsed function arguments

Throws:

java.io.IOException - it will be thrown if there is any problem to read chars

readFunctionArgument

ExpressionItem readFunctionArgument(java.io.PushbackReader reader,
                                    ExpressionTree tree,
                                    PreprocessorContext context,
                                    @MustNotContainNull
                                    FilePositionInfo[] callStack,
                                    java.lang.String source)
                             throws java.io.IOException

The auxiliary method allows to read a function argument

Parameters:

reader - a reader to be 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

callStack - the current file call stack, can be null

source - the current source line, can be null

Returns:

the last read expression item (a comma or a bracket)

Throws:

java.io.IOException - it will be thrown if there is any error during char reading from the reader

isDelimiterOrOperatorChar

private static boolean isDelimiterOrOperatorChar(char chr)

isDelimiter

private static boolean isDelimiter(char chr)

isOperatorChar

private static boolean isOperatorChar(char chr)

nextItem

ExpressionItem nextItem(java.io.PushbackReader reader,
                        PreprocessorContext context)
                 throws java.io.IOException

Read the next item from the reader

Parameters:

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

context - a preprocessor context

Returns:

a read expression item, it can be null if the end is reached

Throws:

java.io.IOException - it will be thrown if there is any error during a char reading