org.opensourcephysics.ejs.control.value
Class ParserSuryono

java.lang.Object
  extended by org.opensourcephysics.ejs.control.value.ParserSuryono

public final class ParserSuryono
extends java.lang.Object

The class Parser is a mathematical expression parser.

Example of code that uses this class:

 Parser parser = new Parser(1);    // creates parser with one variable
 parser.defineVariable(0,"x");     // lets the variable be 'x'
 parser.define("Math.sin(x)/x");        // defines function: sin(x)/x
 parser.parse();                   // parses the function

 IMPORTANT: Notice that my variables start at 0 in this version


 // calculates: sin(x)/x with x = -5.0 .. +5.0 in 20 steps
 // and prints the result to standard output.

 double result;
 for (i=-10; i <= 10; i++) {
   parser.setVariable(0,(double)i/2.0f);
   result = parser.evaluate();
   System.out.println(result);
 }
 


Field Summary
static int CODE_DAMAGED
          Code damaged.
static int COMMA_EXPECTED
          Comma expected.
static int EXPRESSION_EXPECTED
          Expression expected.
static int INVALID_OPERAND
          Invalid operand.
static int INVALID_OPERATOR
          Invalid operator.
static int NO_ERROR
          No error.
static int NO_FUNC_DEFINITION
          No function definition to parse.
static int OPERATOR_EXPECTED
          Operator expected.
static int PAREN_EXPECTED
          Parentheses expected.
static int PAREN_NOT_MATCH
          Parenthesis mismatch.
static int REF_NAME_EXPECTED
          Referenced name could not be found.
static int STACK_OVERFLOW
          Stack overflow.
static int SYNTAX_ERROR
          Syntax error.
static int TOO_MANY_CONSTS
          Too many constants.
static int UNCOMPILED_FUNCTION
          Attempt to evaluate an uncompiled function.
static int UNKNOWN_IDENTIFIER
          Unknown identifier.
 
Constructor Summary
ParserSuryono(int variablecount)
          The constructor of Parser.
 
Method Summary
 void define(java.lang.String definition)
          Defines a function.
 void defineVariable(int index, java.lang.String name)
          Sets the variable names.
 double evaluate()
          Evaluates compiled function.
 int getErrorCode()
          Gets error code of last operation.
 int getErrorPosition()
          Gets error position.
 java.lang.String getErrorString()
          Gets error string/message of last operation.
static java.lang.String[] getVariableList(java.lang.String _expression)
          Gets an expression and returns a String[] of the variables the expression will need.
static java.util.Vector<java.lang.String> getVariableList(java.lang.String _expression, java.util.Vector<java.lang.String> varlist)
          Gets an expression and a Vector of declared variables and updates the Vector with extra variables the expression will need.
static boolean isKeyword(java.lang.String token)
          Wether a given token is a reserved word
 void parse()
          Parses defined function.
 void setVariable(int index, double value)
          Sets the variable value.
static java.lang.String toErrorString(int errorcode)
          Converts error code to error string.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

NO_ERROR

public static final int NO_ERROR
No error.

See Also:
Constant Field Values

SYNTAX_ERROR

public static final int SYNTAX_ERROR
Syntax error.

See Also:
Constant Field Values

PAREN_EXPECTED

public static final int PAREN_EXPECTED
Parentheses expected.

See Also:
Constant Field Values

UNCOMPILED_FUNCTION

public static final int UNCOMPILED_FUNCTION
Attempt to evaluate an uncompiled function.

See Also:
Constant Field Values

EXPRESSION_EXPECTED

public static final int EXPRESSION_EXPECTED
Expression expected.

See Also:
Constant Field Values

UNKNOWN_IDENTIFIER

public static final int UNKNOWN_IDENTIFIER
Unknown identifier.

See Also:
Constant Field Values

OPERATOR_EXPECTED

public static final int OPERATOR_EXPECTED
Operator expected.

See Also:
Constant Field Values

PAREN_NOT_MATCH

public static final int PAREN_NOT_MATCH
Parenthesis mismatch.

See Also:
Constant Field Values

CODE_DAMAGED

public static final int CODE_DAMAGED
Code damaged.

See Also:
Constant Field Values

STACK_OVERFLOW

public static final int STACK_OVERFLOW
Stack overflow.

See Also:
Constant Field Values

TOO_MANY_CONSTS

public static final int TOO_MANY_CONSTS
Too many constants.

See Also:
Constant Field Values

COMMA_EXPECTED

public static final int COMMA_EXPECTED
Comma expected.

See Also:
Constant Field Values

INVALID_OPERAND

public static final int INVALID_OPERAND
Invalid operand.

See Also:
Constant Field Values

INVALID_OPERATOR

public static final int INVALID_OPERATOR
Invalid operator.

See Also:
Constant Field Values

NO_FUNC_DEFINITION

public static final int NO_FUNC_DEFINITION
No function definition to parse.

See Also:
Constant Field Values

REF_NAME_EXPECTED

public static final int REF_NAME_EXPECTED
Referenced name could not be found.

See Also:
Constant Field Values
Constructor Detail

ParserSuryono

public ParserSuryono(int variablecount)
The constructor of Parser.

Parameters:
variablecount - the number of variables
Method Detail

isKeyword

public static boolean isKeyword(java.lang.String token)
Wether a given token is a reserved word

Parameters:
token -
Returns:

getVariableList

public static java.lang.String[] getVariableList(java.lang.String _expression)
Gets an expression and returns a String[] of the variables the expression will need. This can be used to decide beforehand how many variables a new parser should have.


getVariableList

public static java.util.Vector<java.lang.String> getVariableList(java.lang.String _expression,
                                                                 java.util.Vector<java.lang.String> varlist)
Gets an expression and a Vector of declared variables and updates the Vector with extra variables the expression will need. This can be used to decide beforehand how many variables a new parser should have.

Returns:
the same Vector updated

defineVariable

public void defineVariable(int index,
                           java.lang.String name)
Sets the variable names.

Parameters:
index - the variable index (one based)
name - the variable name

setVariable

public void setVariable(int index,
                        double value)
Sets the variable value. The variable is accessed by index.

Parameters:
index - the variable index (one based)
value - the variable value

define

public void define(java.lang.String definition)
Defines a function. Current postfix code becomes invalid.

Parameters:
definition - the function definition

parse

public void parse()
Parses defined function.


evaluate

public double evaluate()
Evaluates compiled function.

Returns:
the result of the function

getErrorCode

public int getErrorCode()
Gets error code of last operation.

Returns:
the error code

getErrorString

public java.lang.String getErrorString()
Gets error string/message of last operation.

Returns:
the error string

getErrorPosition

public int getErrorPosition()
Gets error position. Valid only if error code != NO_ERROR

Returns:
error position (one based)

toErrorString

public static java.lang.String toErrorString(int errorcode)
Converts error code to error string.

Returns:
the error string