Package net.sourceforge.nrl.parser.ast

The fully resolved abstract syntax tree (AST) representation of the constraint language.

See:
Description

Interface Summary

IDeclaration	A declaration is either a rule declaration or a fragment declaration, as defined by the sub-interfaces.
IModelFileReference
IModelReference	A reference to a model element, consisting of several steps along element and attribute names.
IMultipleContextDeclaration	Any declaration that takes multiple contexts, with parameter names.
INRLAstNode	Basic interface for all NRL constructs.
INRLAstVisitor	A very simple visitor interface for straight-forward recursive descent traversals of the AST.
IOperatorFileReference	A reference to an operator file, by file name
IRuleDeclaration	A generic rule declaration.
IRuleFile	IRuleFile is the top level interface - it contains the entire, fully resolved AST of a rule file.
IRuleSetDeclaration	A rule set is a named collection of rules, with an optional precondition attached to the execution of the rules.
ISingleContextDeclaration	A SingleContextDeclaration is a declaration with a unique context, for example a rule.
IVariable	A variable reference.

Class Summary

ActionVisitorDispatcher	An extension of the basic dispatching AST visitor class that adds action language support.
ConstraintVisitorDispatcher	A default implementation of the INRLAstVisitor interface that dispatches calls to the visitor method to a client-supplied INRLConstraintDetailVisitor.
NRLDataType	Representation of NRL primitive types.
Variable	A default implementation of the variable reference interface.

Enum Summary

NRLDataType.Type

Enumeration of basic type names

Package net.sourceforge.nrl.parser.ast Description

The fully resolved abstract syntax tree (AST) representation of the constraint language. The interfaces in this package specify what a fully resolved representation of a rule file looks like.

The package specifies no implementation. In order to obtain an AST instance, use a concrete implementation, for example using the public classes in the 'antlr' subpackage.

The main interface here is IRuleFile. In order to get to a fully resolved implementation of this class, a number of steps have to be performed:

• An NRL file has to be parsed, into an AST representation that is specific to a parser, for example an ANTLR AST.
• The textual cross-references in the parsed AST, for example references to properties, have to be resolved into proper object cross-references in the AST. This means that when we come across a "property application", we can directly look up the referenced property instead of retrieving its name and performing a look-up.
• An underlying model has to be loaded, and the AST has to be resolved against it. After this step, it is possible to navigate from element references within rules directly to model elements.
• Additional static semantic checks are performed.

If any of the above steps fail, the AST is unsafe and has to be discarded. For this reason, during all of the above steps, SyntaxError and SemanticError entries are collected.