org.scijava.parse.eval

Class AbstractEvaluator

java.lang.Object

org.scijava.parse.eval.AbstractEvaluator

All Implemented Interfaces:

Evaluator

Direct Known Subclasses:

AbstractStackEvaluator

public abstract class AbstractEvaluator
extends Object
implements Evaluator

Base class for Evaluator implementations.

Author:

Curtis Rueden

Constructor Summary

Constructors

Constructor and Description
AbstractEvaluator()
AbstractEvaluator(ExpressionParser parser)

Method Summary

Methods

Modifier and Type	Method and Description
Object	evaluate(String expression) Evaluates the given infix expression, returning the result.
Object	evaluate(SyntaxTree syntaxTree) Evaluates the given syntax tree, returning the result.
Object	get(Variable v) Gets the value of the given variable.
ExpressionParser	getParser() Gets the parser used when evaluating expressions.
boolean	isStrict() Gets whether the evaluator is operating in strict mode.
void	set(Variable v, Object value) Sets the value of the given variable.
void	setAll(Map<? extends String,? extends Object> map) Assigns variables en masse.
void	setStrict(boolean strict) Sets whether the evaluator is operating in strict mode.
Object	value(Object token) Gets the value of the given token.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.scijava.parse.eval.Evaluator

evaluate

Constructor Detail

AbstractEvaluator

public AbstractEvaluator()

AbstractEvaluator

public AbstractEvaluator(ExpressionParser parser)

Method Detail

getParser

public ExpressionParser getParser()

Description copied from interface: Evaluator

Gets the parser used when evaluating expressions.

Specified by:

getParser in interface Evaluator

isStrict

public boolean isStrict()

Description copied from interface: Evaluator

Gets whether the evaluator is operating in strict mode.

Specified by:

isStrict in interface Evaluator

See Also:

Evaluator.setStrict(boolean)

setStrict

public void setStrict(boolean strict)

Description copied from interface: Evaluator

Sets whether the evaluator is operating in strict mode. Evaluators operate in strict mode by default.

When evaluating strictly, usage of an unassigned variable token in a place where its value is needed will generate an IllegalArgumentException with an "Unknown variable" message; in non-strict mode, such a variable will instead be resolved to an object of type Unresolved with the same name as the original variable.

In cases such as assignment, this may be sufficient to complete the evaluation; for example, the expression foo=bar will complete successfully in non-strict mode, with the variable foo containing an object of type Unresolved and token value "bar". But in cases where the unresolved value is needed as an input for additional operations, the evaluation may still ultimately fail of the operation in question is not defined for unresolved values. For example, the DefaultEvaluator will fail with an "Unsupported binary operator" exception when given the expression foo+bar, since foo and bar are unresolved variables, and the + operator cannot handle such objects.

Specified by:

setStrict in interface Evaluator

evaluate

public Object evaluate(SyntaxTree syntaxTree)

Description copied from interface: Evaluator

Evaluates the given syntax tree, returning the result.

Specified by:

evaluate in interface Evaluator

evaluate

public Object evaluate(String expression)

Description copied from interface: Evaluator

Evaluates the given infix expression, returning the result.

Specified by:

evaluate in interface Evaluator

value

public Object value(Object token)

Description copied from interface: Evaluator

Gets the value of the given token. For variables, returns the value of the variable, throwing an exception if the variable is not set. For literals, returns the token itself.

Specified by:

value in interface Evaluator

get

public Object get(Variable v)

Description copied from interface: Evaluator

Gets the value of the given variable.

Specified by:

get in interface Evaluator

set

public void set(Variable v,
       Object value)

Description copied from interface: Evaluator

Sets the value of the given variable.

Specified by:

set in interface Evaluator

setAll

public void setAll(Map<? extends String,? extends Object> map)

Description copied from interface: Evaluator

Assigns variables en masse.

Specified by:

setAll in interface Evaluator