java.lang.Object
- org.vedantatree.expressionoasis.grammar.DefaultXMLGrammar

All Implemented Interfaces:

Grammar
```
public class DefaultXMLGrammar
extends Object
implements Grammar
```
This is the default XML based grammar implementation. It read the production rules from a XML file, and populate its rule sets. Use of XML makes it highly customizable without making any change to code. TODO Can we remove operators array and use precedence map keys? DefaultXMLGrammar can be loosely coupled with Compiler, i.e. can be picked from configuration.

Since:

3.1

Field Summary

Fields
Modifier and Type	Field	Description
`static String`	`ALLOWED_PATTERN`	This is the constant name for allowed pattern tag in XML
`static String`	`APPROACHABLE_PATTERN`	This is the constant name for approachable pattern tag in XML
`static String`	`BRACKET`	This is the constant name for bracket tag in XML
`static String`	`BRACKETS`	This is the constant name for brackets tag in XML
`static String`	`DELIMITER`	This is the constant name for delimiter tag in XML
`static String`	`DELIMITERS`	This is the constant name for delimiters tag in XML
`String`	`FILE_PATH`	File path for grammar configuration.
`static String`	`FUNCTIONS`	This is the constant name for functions tag in XML
`static String`	`IGNORE_BLANK`	This is the constant name for ignore blank tag in XML
`static String`	`LEFT`	This is the constant name for left tag in XML
`static String`	`NAME`	This is the constant name for name tag in XML
`static String`	`OPERATOR`	This is the constant name for operator tag in XML
`static String`	`PRECEDENCE`	This is the constant name for precedence tag in XML
`static String`	`PRODUCTION_RULE`	This is the constant name for production rule tag in XML
`static String`	`PRODUCTION_RULES`	This is the constant name for production rules tag in XML
`static String`	`RIGHT`	This is the constant name for right tag in XML
`static String`	`TRUE`	This is the constant name for true tag in XML
`static String`	`UNARY_OPERATORS`	This is the constant name for unary operators tag in XML

Constructor Summary

Constructors
Constructor Description

DefaultXMLGrammar()
Constructs the grammar

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`addFunction(String functionName)`	Adds a function name to the grammar.
`String`	`getOppositeBracket(String bracket)`	Returns the opposite bracket for the given bracket.
`int`	`getPrecedenceOrder(String operator, boolean isUnary)`	Gets the precedence order of the given operator
`int`	`getPrecedenceOrder(ExpressionToken operator, boolean isUnary)`	Gets the precedence order of the given operator
`boolean`	`isAllowed(String token)`	Checks whether the token is allowed or not.
`boolean`	`isApproachable(String token)`	Checks whether the given token is approachable using any of the pattern or not.
`boolean`	`isBinaryOperator(String token)`	Checks whether the given token is a binary operator or not.
`boolean`	`isBinaryOperator(ExpressionToken token)`	Checks whether the given token is a binary operator or not.
`boolean`	`isBracket(String token)`	Check whether the given token is a bracket or not.
`boolean`	`isBracket(ExpressionToken token)`	Check whether the given token is a bracket or not.
`boolean`	`isDelimiter(String token)`	Checks whether the token is a delimiter or not.
`boolean`	`isDelimiter(ExpressionToken token)`	Checks whether the token is a delimiter or not.
`boolean`	`isFunction(String token)`	Checks whether the token is an function or not.
`boolean`	`isFunction(ExpressionToken token)`	Checks whether the token is an function or not.
`boolean`	`isIgnoreBlank()`	Checks whether to ignore the blanks in expression or not.
`boolean`	`isLeftBracket(String token)`	Checks whether the token is a left bracket or not.
`boolean`	`isLeftBracket(ExpressionToken token)`	Checks whether the token is a left bracket or not.
`boolean`	`isOperator(String token)`	Checks whether the given token is an operator or not.
`boolean`	`isOperator(ExpressionToken token)`	Checks whether the given token is an operator or not.
`boolean`	`isRightBracket(String token)`	Checks whether the token is a right bracket or not.
`boolean`	`isRightBracket(ExpressionToken token)`	Checks whether the token is a right bracket or not.
`boolean`	`isUnary(String operator)`	Checks whether the given operator is a unary operator or not.
`boolean`	`isUnary(ExpressionToken operator)`	Checks whether the given operator is a unary operator or not.
`static void`	`main(String[] args)`	Runs the test for grammar.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - FILE_PATH
```
public final String FILE_PATH
```
    File path for grammar configuration.
  - PRODUCTION_RULES
```
public static final String PRODUCTION_RULES
```
    This is the constant name for production rules tag in XML
    
    See Also:
    
    Constant Field Values
  - UNARY_OPERATORS
```
public static final String UNARY_OPERATORS
```
    This is the constant name for unary operators tag in XML
    
    See Also:
    
    Constant Field Values
  - FUNCTIONS
```
public static final String FUNCTIONS
```
    This is the constant name for functions tag in XML
    
    See Also:
    
    Constant Field Values
  - DELIMITERS
```
public static final String DELIMITERS
```
    This is the constant name for delimiters tag in XML
    
    See Also:
    
    Constant Field Values
  - BRACKETS
```
public static final String BRACKETS
```
    This is the constant name for brackets tag in XML
    
    See Also:
    
    Constant Field Values
  - IGNORE_BLANK
```
public static final String IGNORE_BLANK
```
    This is the constant name for ignore blank tag in XML
    
    See Also:
    
    Constant Field Values
  - TRUE
```
public static final String TRUE
```
    This is the constant name for true tag in XML
    
    See Also:
    
    Constant Field Values
  - NAME
```
public static final String NAME
```
    This is the constant name for name tag in XML
    
    See Also:
    
    Constant Field Values
  - BRACKET
```
public static final String BRACKET
```
    This is the constant name for bracket tag in XML
    
    See Also:
    
    Constant Field Values
  - LEFT
```
public static final String LEFT
```
    This is the constant name for left tag in XML
    
    See Also:
    
    Constant Field Values
  - RIGHT
```
public static final String RIGHT
```
    This is the constant name for right tag in XML
    
    See Also:
    
    Constant Field Values
  - OPERATOR
```
public static final String OPERATOR
```
    This is the constant name for operator tag in XML
    
    See Also:
    
    Constant Field Values
  - PRECEDENCE
```
public static final String PRECEDENCE
```
    This is the constant name for precedence tag in XML
    
    See Also:
    
    Constant Field Values
  - DELIMITER
```
public static final String DELIMITER
```
    This is the constant name for delimiter tag in XML
    
    See Also:
    
    Constant Field Values
  - PRODUCTION_RULE
```
public static final String PRODUCTION_RULE
```
    This is the constant name for production rule tag in XML
    
    See Also:
    
    Constant Field Values
  - APPROACHABLE_PATTERN
```
public static final String APPROACHABLE_PATTERN
```
    This is the constant name for approachable pattern tag in XML
    
    See Also:
    
    Constant Field Values
  - ALLOWED_PATTERN
```
public static final String ALLOWED_PATTERN
```
    This is the constant name for allowed pattern tag in XML
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - DefaultXMLGrammar
```
public DefaultXMLGrammar()
```
    Constructs the grammar
- Method Detail
  - isDelimiter
```
public boolean isDelimiter(ExpressionToken token)
```
    Checks whether the token is a delimiter or not.
    
    Specified by:
    
    isDelimiter in interface Grammar
    
    Parameters:
    
    token - the token
    
    Returns:
    
    true if the token is delimiter false otherwise.
  - isDelimiter
```
public boolean isDelimiter(String token)
```
    Checks whether the token is a delimiter or not.
    
    Specified by:
    
    isDelimiter in interface Grammar
    
    Parameters:
    
    token - the token
    
    Returns:
    
    true if the token is delimiter false otherwise.
  - isApproachable
```
public boolean isApproachable(String token)
```
    Checks whether the given token is approachable using any of the pattern or not. Given token can be partially or fully constructed token during parsing process. Parser generally calls this method to check whether the current token can be combined with next character of expression to form some meaningful token or not. If not, then it utilize the existing collected characters as one token, otherwise it keep collecting characters.
    
    Specified by:
    
    isApproachable in interface Grammar
    
    Parameters:
    
    token - the token, partially or full constructed, to check whether it can approach to any expression token pattern or not.
    
    Returns:
    
    true if the token pattern is approachable false otherwise.
  - isAllowed
```
public boolean isAllowed(String token)
```
    Checks whether the token is allowed or not. A token is fully constructed token. Parser generally calls this method to check whether the current token is a valid token as per the production rules or not.
    
    Specified by:
    
    isAllowed in interface Grammar
    
    Parameters:
    
    token - the token which is to be checked for its validity
    
    Returns:
    
    true if the token is allowed false otherwise.
  - isIgnoreBlank
```
public boolean isIgnoreBlank()
```
    Checks whether to ignore the blanks in expression or not. It tells the parser whether to exclude the extra blanks while parsing or not.
    
    Specified by:
    
    isIgnoreBlank in interface Grammar
    
    Returns:
    
    true if parser wants to exclude the blanks false otherwise.
  - isOperator
```
public boolean isOperator(ExpressionToken token)
```
    Checks whether the given token is an operator or not.
    
    Specified by:
    
    isOperator in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token is an operator false otherwise
  - isOperator
```
public boolean isOperator(String token)
```
    Checks whether the given token is an operator or not.
    
    Specified by:
    
    isOperator in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token is an operator false otherwise
  - isBinaryOperator
```
public boolean isBinaryOperator(ExpressionToken token)
```
    Checks whether the given token is a binary operator or not.
    
    Specified by:
    
    isBinaryOperator in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token is a binary operator false otherwise
  - isBinaryOperator
```
public boolean isBinaryOperator(String token)
```
    Checks whether the given token is a binary operator or not.
    
    Specified by:
    
    isBinaryOperator in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token is a binary operator false otherwise
  - addFunction
```
public void addFunction(String functionName)
```
    Adds a function name to the grammar. TODO: should probably look up function precedence from grammar config file rather than hard coding it to 13.
    
    Specified by:
    
    addFunction in interface Grammar
    
    Parameters:
    
    name - name of the function to add
  - isFunction
```
public boolean isFunction(ExpressionToken token)
```
    Checks whether the token is an function or not.
    
    Specified by:
    
    isFunction in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token is an function false otherwise
  - isFunction
```
public boolean isFunction(String token)
```
    Checks whether the token is an function or not.
    
    Specified by:
    
    isFunction in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token is an function false otherwise
  - isUnary
```
public boolean isUnary(ExpressionToken operator)
```
    Checks whether the given operator is a unary operator or not.
    
    Specified by:
    
    isUnary in interface Grammar
    
    Parameters:
    
    operator - the operator to check
    
    Returns:
    
    true if the operator is used as unary operator false otherwise.
  - isUnary
```
public boolean isUnary(String operator)
```
    Checks whether the given operator is a unary operator or not.
    
    Specified by:
    
    isUnary in interface Grammar
    
    Parameters:
    
    operator - the operator to check
    
    Returns:
    
    true if the operator is used as unary operator false otherwise.
  - isLeftBracket
```
public boolean isLeftBracket(ExpressionToken token)
```
    Checks whether the token is a left bracket or not.
    
    Specified by:
    
    isLeftBracket in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token can be used as left bracket false otherwise.
  - isLeftBracket
```
public boolean isLeftBracket(String token)
```
    Checks whether the token is a left bracket or not.
    
    Specified by:
    
    isLeftBracket in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token can be used as left bracket false otherwise.
  - isRightBracket
```
public boolean isRightBracket(ExpressionToken token)
```
    Checks whether the token is a right bracket or not.
    
    Specified by:
    
    isRightBracket in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token can be used as right bracket false otherwise.
  - isRightBracket
```
public boolean isRightBracket(String token)
```
    Checks whether the token is a right bracket or not.
    
    Specified by:
    
    isRightBracket in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token can be used as right bracket false otherwise.
  - isBracket
```
public boolean isBracket(ExpressionToken token)
```
    Check whether the given token is a bracket or not.
    
    Specified by:
    
    isBracket in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token is a bracket false otherwise
  - isBracket
```
public boolean isBracket(String token)
```
    Check whether the given token is a bracket or not.
    
    Specified by:
    
    isBracket in interface Grammar
    
    Parameters:
    
    token - the token to check
    
    Returns:
    
    true if the token is a bracket false otherwise
  - getOppositeBracket
```
public String getOppositeBracket(String bracket)
```
    Returns the opposite bracket for the given bracket.
    
    Specified by:
    
    getOppositeBracket in interface Grammar
    
    Parameters:
    
    bracket - the bracket for which we need to find the opposite bracket
    
    Returns:
    
    the opposite part of bracket w.r.t given bracket
  - getPrecedenceOrder
```
public int getPrecedenceOrder(ExpressionToken operator,
                              boolean isUnary)
```
    Gets the precedence order of the given operator
    
    Specified by:
    
    getPrecedenceOrder in interface Grammar
    
    Parameters:
    
    operator - the operator to check for precedence
    
    isUnary - true if the operator is unary, as an operator can behave either as unary or as binary
    
    Returns:
    
    the precedence order of the operator
  - getPrecedenceOrder
```
public int getPrecedenceOrder(String operator,
                              boolean isUnary)
```
    Gets the precedence order of the given operator
    
    Specified by:
    
    getPrecedenceOrder in interface Grammar
    
    Parameters:
    
    operator - the operator to check for precedence
    
    isUnary - true if the operator is unary, as an operator can behave either as unary or as binary
    
    Returns:
    
    the precedence order of the operator
  - main
```
public static void main(String[] args)
```
    Runs the test for grammar.

Class DefaultXMLGrammar

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

FILE_PATH

PRODUCTION_RULES

UNARY_OPERATORS

FUNCTIONS

DELIMITERS

BRACKETS

IGNORE_BLANK

TRUE

NAME

BRACKET

LEFT

RIGHT

OPERATOR

PRECEDENCE

DELIMITER

PRODUCTION_RULE

APPROACHABLE_PATTERN

ALLOWED_PATTERN

Constructor Detail

DefaultXMLGrammar

Method Detail

isDelimiter

isDelimiter

isApproachable

isAllowed

isIgnoreBlank

isOperator

isOperator

isBinaryOperator

isBinaryOperator

addFunction

isFunction

isFunction

isUnary

isUnary

isLeftBracket

isLeftBracket

isRightBracket

isRightBracket

isBracket

isBracket

getOppositeBracket

getPrecedenceOrder

getPrecedenceOrder

main