org.moremotion.evaluator
Interface SymbolResolver

All Known Implementing Classes:

MMSymbolResolver

public interface SymbolResolver

Defines an interface to provide the data types and the values of the symbols. The objects of the classes that implement this interface can be introduced to Expression class to say that call My Symbol MScriptResolver for the symbols existing in the expression.

Example:

 import org.moremotion.evaluator.SymbolResolver;

 public class MySymbolResolver implements org.moremotion.evaluator.SymbolResolver {

   int age = 0;
   boolean retired = false;
   String name = "John Coombes";

   public MySymbolResolver() {
   }

   public double getNumberValue(String symbol) throws Exception {
     if (symbol.equals("AGE")) return age;
     return 0;
   }

   public boolean getBoolValue(String symbol) throws Exception {
     if (symbol.equals("RETIRED")) return retired;
     return false;
   }

   public String getStringValue(String symbol) throws Exception {
     if (symbol.equals("NAME")) return name;
     return "";
   }

   public int getType(String symbol) throws Exception {
     if (symbol.equals("AGE")) return DT_NUMBER;
     if (symbol.equals("RETIRED")) return DT_BOOL;
     return DT_STRING;
   }

   public String getValue(String symbol) throws Exception {
     if (symbol.equals("AGE")) return "" + age;
     if (symbol.equals("RETIRED")) return "" + retired;
     if (symbol.equals("NAME")) return name;
     return "";
   }

   public void setValue(String symbol, String value) throws Exception {
   }

 }
 

Usage Example

 MySymbolResolver msr = new MySymbolResolver();
 Expression expr = new Expression("A + (B / 3) - 2", msr);
 String result = expr.eval();
 

Version:

$Id: SymbolResolver.java 51 2008-03-10 11:46:54Z erkan $

Field Summary

static byte	DT_BOOL
static byte	DT_NUMBER
static byte	DT_STRING

Method Summary

boolean	getBoolValue(java.lang.String symbol) Returns the value of the given symbol as boolean.
double	getNumberValue(java.lang.String symbol) Returns the value of the given symbol as double.
java.lang.String	getStringValue(java.lang.String symbol) Returns the value of the given symbol as String.
int	getType(java.lang.String symbol) Returns the type of the given symbol.
java.lang.String	getValue(java.lang.String symbol) Returns the value of the given symbol as String.
void	setValue(java.lang.String symbol, java.lang.String value) Although this method takes place in this interface it will not be called by Expression class.

Field Detail

DT_STRING

public static final byte DT_STRING

See Also:

Constant Field Values

DT_NUMBER

public static final byte DT_NUMBER

See Also:

Constant Field Values

DT_BOOL

public static final byte DT_BOOL

See Also:

Constant Field Values

Method Detail

getType

public int getType(java.lang.String symbol)
            throws EvaluationException

Returns the type of the given symbol. The types can be DT_STRING, DT_BOOL or DT_NUMBER

Throws:

EvaluationException

getValue

public java.lang.String getValue(java.lang.String symbol)
                          throws EvaluationException

Returns the value of the given symbol as String. This method will be called when type of the symbol is undefined.

Throws:

EvaluationException

getStringValue

public java.lang.String getStringValue(java.lang.String symbol)
                                throws EvaluationException

Returns the value of the given symbol as String. This method will be called when type of the symbol is String.

Throws:

EvaluationException

getNumberValue

public double getNumberValue(java.lang.String symbol)
                      throws EvaluationException

Returns the value of the given symbol as double. This method will be called when type of the symbol is either int or double.

Throws:

EvaluationException

getBoolValue

public boolean getBoolValue(java.lang.String symbol)
                     throws EvaluationException

Returns the value of the given symbol as boolean. This method will be called when type of the symbol is boolean.

Throws:

EvaluationException

setValue

public void setValue(java.lang.String symbol,
                     java.lang.String value)
              throws EvaluationException

Although this method takes place in this interface it will not be called by Expression class.

Throws:

EvaluationException