Package org.evrete.api

Interface ExpressionResolver

public interface ExpressionResolver

An interface with a set of basic methods that are necessary for parsing string expressions.

Method Summary

Modifier and Type	Method	Description
Evaluator	buildExpression(String expression, NamedType.Resolver resolver)	This method parses a string argument and returns an Evaluator if possible.
FieldReference	resolve(String arg, NamedType.Resolver resolver)	This method takes a string as an argument and builds a FieldReference if possible.
default FieldReference[]	resolve(NamedType.Resolver resolver, String... strings)

Method Details

resolve

FieldReference resolve(String arg,
 NamedType.Resolver resolver)

This method takes a string as an argument and builds a FieldReference if possible.

For example, if the argument is "$c.category.id", the implementation might do the following:

1. Use the supplied resolver to identify which NamedType this expression refers to (let's say it's a Customer fact, named "$c")
2. Use the resolved NamedType to parse the remaining part of the argument, "category.id", by the means provided by the Type interface.

Parameters:

arg - a String to parse

resolver - a mapping function between fact name and full NamedType

Returns:

returns FieldReference instance or throws an IllegalArgumentException

Throws:

IllegalArgumentException - if the argument can not be resolved

resolve

default FieldReference[] resolve(NamedType.Resolver resolver,
 String... strings)

buildExpression

Evaluator buildExpression(String expression,
 NamedType.Resolver resolver)
                   throws CompilationException

This method parses a string argument and returns an Evaluator if possible.

Parameters:

expression - - a String condition expression to parse

resolver - a mapping function between fact name and NamedType

Returns:

returns an Evaluator instance or throws an exception

Throws:

CompilationException - if the argument can not be compiled

IllegalArgumentException - if the expression can not be resolved

See Also:

• resolve(String, NamedType.Resolver)