Package com.ezylang.evalex

Class Expression

java.lang.Object

com.ezylang.evalex.Expression

public class Expression
extends java.lang.Object

Main class that allow creating, parsing, passing parameters and evaluating an expression string.

See Also:

EvalEx Homepage

Constructor Summary

Constructors

Constructor	Description
Expression(Expression expression)	Creates a copy with the same expression string, configuration and syntax tree from an existing expression.
Expression(java.lang.String expressionString)	Creates a new expression with the default configuration.
Expression(java.lang.String expressionString, ExpressionConfiguration configuration)	Creates a new expression with a custom configuration.

Method Summary

Modifier and Type	Method	Description
Expression	and(java.lang.String variable, java.lang.Object value)	Adds a variable value to the expression data storage.
EvaluationValue	convertDoubleValue(double value)	Converts a double value to an EvaluationValue by considering the configured MathContext.
EvaluationValue	convertValue(java.lang.Object value)	Converts an object value to an EvaluationValue by considering the configuration EvaluationValue(Object, ExpressionConfiguration).
Expression	copy()	Return a copy of the expression using the copy constructor Expression(com.ezylang.evalex.Expression).
ASTNode	createExpressionNode(java.lang.String expression)	Create an AST representation for an expression string.
EvaluationValue	evaluate()	Evaluates the expression by parsing it (if not done before) and the evaluating it.
EvaluationValue	evaluateSubtree(ASTNode startNode)	Evaluates only a subtree of the abstract syntax tree.
ASTNode	getAbstractSyntaxTree()	Returns the root ode of the parsed abstract syntax tree.
java.util.List<ASTNode>	getAllASTNodes()	Returns the list of all nodes of the abstract syntax tree.
java.util.Set<java.lang.String>	getUndefinedVariables()	Returns all variables that are used in the expression, but have no value assigned.
java.util.Set<java.lang.String>	getUsedVariables()	Returns all variables that are used i the expression, excluding the constants like e.g.
void	validate()	Validates the expression by parsing it and throwing an exception, if the parser fails.
Expression	with(java.lang.String variable, java.lang.Object value)	Adds a variable value to the expression data storage.
Expression	withValues(java.util.Map<java.lang.String,?> values)	Adds all variables values defined in the map with their name (key) and value to the data storage.If a value with the same name already exists, it is overridden.

Methods inherited from class java.lang.Object

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

Constructor Detail

Expression

public Expression(java.lang.String expressionString)

Creates a new expression with the default configuration. The expression is not parsed until it is first evaluated or validated.

Parameters:

expressionString - A string holding an expression.

Expression

public Expression(java.lang.String expressionString,
                  ExpressionConfiguration configuration)

Creates a new expression with a custom configuration. The expression is not parsed until it is first evaluated or validated.

Parameters:

expressionString - A string holding an expression.

Expression

public Expression(Expression expression)
           throws ParseException

Creates a copy with the same expression string, configuration and syntax tree from an existing expression. The existing expression will be parsed to populate the syntax tree.

Parameters:

expression - An existing expression.

Throws:

ParseException - If there were problems while parsing the existing expression.

Method Detail

evaluate

public EvaluationValue evaluate()
                         throws EvaluationException,
                                ParseException

Evaluates the expression by parsing it (if not done before) and the evaluating it.

Returns:

The evaluation result value.

Throws:

EvaluationException - If there were problems while evaluating the expression.

ParseException - If there were problems while parsing the expression.

evaluateSubtree

public EvaluationValue evaluateSubtree(ASTNode startNode)
                                throws EvaluationException

Evaluates only a subtree of the abstract syntax tree.

Parameters:

startNode - The ASTNode to start evaluation from.

Returns:

The evaluation result value.

Throws:

EvaluationException - If there were problems while evaluating the expression.

getAbstractSyntaxTree

public ASTNode getAbstractSyntaxTree()
                              throws ParseException

Returns the root ode of the parsed abstract syntax tree.

Returns:

The abstract syntax tree root node.

Throws:

ParseException - If there were problems while parsing the expression.

validate

public void validate()
              throws ParseException

Validates the expression by parsing it and throwing an exception, if the parser fails.

Throws:

ParseException - If there were problems while parsing the expression.

with

public Expression with(java.lang.String variable,
                       java.lang.Object value)

Adds a variable value to the expression data storage. If a value with the same name already exists, it is overridden. The data type will be determined by examining the passed value object. An exception is thrown, if he found data type is not supported.

Parameters:

variable - The variable name.

value - The variable value.

Returns:

The Expression instance, to allow chaining of methods.

and

public Expression and(java.lang.String variable,
                      java.lang.Object value)

Adds a variable value to the expression data storage. If a value with the same name already exists, it is overridden. The data type will be determined by examining the passed value object. An exception is thrown, if he found data type is not supported.

Parameters:

variable - The variable name.

value - The variable value.

Returns:

The Expression instance, to allow chaining of methods.

withValues

public Expression withValues(java.util.Map<java.lang.String,?> values)

Adds all variables values defined in the map with their name (key) and value to the data storage.If a value with the same name already exists, it is overridden. The data type will be determined by examining the passed value object. An exception is thrown, if he found data type is not supported.

Parameters:

values - A map with variable values.

Returns:

The Expression instance, to allow chaining of methods.

copy

public Expression copy()
                throws ParseException

Return a copy of the expression using the copy constructor Expression(com.ezylang.evalex.Expression).

Returns:

The copied Expression instance.

Throws:

ParseException - If there were problems while parsing the existing expression.

createExpressionNode

public ASTNode createExpressionNode(java.lang.String expression)
                             throws ParseException

Create an AST representation for an expression string. The node can then be used as a sub-expression. Subexpressions are not cached.

Parameters:

expression - The expression string.

Returns:

The root node of the expression AST representation.

Throws:

ParseException - On any parsing error.

convertDoubleValue

public EvaluationValue convertDoubleValue(double value)

Converts a double value to an EvaluationValue by considering the configured MathContext.

Parameters:

value - The double value to covert.

Returns:

An EvaluationValue of type EvaluationValue.DataType.NUMBER.

convertValue

public EvaluationValue convertValue(java.lang.Object value)

Converts an object value to an EvaluationValue by considering the configuration EvaluationValue(Object, ExpressionConfiguration).

Parameters:

value - The object value to covert.

Returns:

An EvaluationValue of the detected type and value.

getAllASTNodes

public java.util.List<ASTNode> getAllASTNodes()
                                       throws ParseException

Returns the list of all nodes of the abstract syntax tree.

Returns:

The list of all nodes in the parsed expression.

Throws:

ParseException - If there were problems while parsing the expression.

getUsedVariables

public java.util.Set<java.lang.String> getUsedVariables()
                                                 throws ParseException

Returns all variables that are used i the expression, excluding the constants like e.g. PI or TRUE and FALSE.

Returns:

All used variables excluding constants.

Throws:

ParseException - If there were problems while parsing the expression.

getUndefinedVariables

public java.util.Set<java.lang.String> getUndefinedVariables()
                                                      throws ParseException

Returns all variables that are used in the expression, but have no value assigned.

Returns:

All variables that have no value assigned.

Throws:

ParseException - If there were problems while parsing the expression.