Details the extensions to W3C's SRGS ABNF format for dynamic grammars supported by the NuGram Platform.

1. The NuGramDynamic Grammar Language Supported by NuGram 2.2 June 16th, 2010

2. Background Extension to W3C’s SRGS ABNF format Supported by a complete development environment –NuGram IDE Dynamic grammars are deployable on NuGram Server Copyright © 2010 Nu Echo Inc.

3. Expressions Constants null, false, true StringsEx: “abc”, “John Smith”, “05/30/2010” NumbersEx: 10, 325.64 Variables Must be a legal Java identifier Top-level variables are provided by the instantiation context Copyright © 2010 Nu Echo Inc.

4. Expressions Properties Syntax: obj.propertyName Property name must be a valid Java identifier Method calls Syntax: obj.methodName(arguments…) Arguments are comma-separate Array elements Syntax: obj[indexValue] Copyright © 2010 Nu Echo Inc.

5. Expressions Comparison operators == != Logical operators ! (negation) && (conjunction) || (disjunction) Copyright © 2010 Nu Echo Inc.

6. Dynamic Words Syntax@word ( Expressions… ) Values of all expressions are concatenated Example Copyright © 2010 Nu Echo Inc.

7. Dynamic Rule References Syntax@ref ( Expressions… ) Values of all expressions are concatenated Resulting value must start with “#” for a local rule reference Example Copyright © 2010 Nu Echo Inc.

8. Dynamic Tags Syntax@tag ( Expressions… ) Values of all expressions are concatenated Example Copyright © 2010 Nu Echo Inc.

9. Iterations Syntax@for ( var: Expression ) Expansions…@end Repeats the expansions for each value in the collection resulting from evaluating Expression. Copyright © 2010 Nu Echo Inc.

10. Iterations Example Copyright © 2010 Nu Echo Inc.

11. Dynamic Sequences Syntax@seqExpansions… @end All direct expansions become part of the sequence Copyright © 2010 Nu Echo Inc.

12. Dynamic sequences Example Copyright © 2010 Nu Echo Inc.

13. Dynamic Choices Syntax@altExpansions… @end All direct expansions become alternative choices Copyright © 2010 Nu Echo Inc.

14. Dynamic Choices Example 1 Copyright © 2010 Nu Echo Inc.

15. Example 2 Beware: @alt and @for may produce unexpected results Dynamic Choices Copyright © 2010 Nu Echo Inc.

16. Example 2 (cont'd) Solution: use grouping Dynamic Choices Copyright © 2010 Nu Echo Inc.

17. Local Variable Definitions Syntax@varIdent = Expression :Expansions… @end Ident is visible for the Expansions Multiple variables can be declared at once Example@varfirstname = name.firstname,lastname = name.lastname : ( [@wordlastname] [@wordfirstname] @wordlastname )@end Copyright © 2010 Nu Echo Inc.

18. Conditionals Syntax@if ( Expression )Expansions… @elseif ( Expression )Expansions… @elseExpansions… @end A single branch of the conditional is executed @elseifand @else branches are optional There can be more than one @elseif, but a single @else Copyright © 2010 Nu Echo Inc.

19. Macros Definitions Syntax@defineIdent (Parameters):Expansions… @end Parameters are comma-separated identifiers Can only appear as a top-level form Example@define fullname (name) : [@word name.firstname] @word name.lastname@end Copyright © 2010 Nu Echo Inc.

20. Macros Invocations Syntax@callIdent (Expressions…) Arguments are comma-separated Example@for (name : names) @call fullname (name)@end Copyright © 2010 Nu Echo Inc.

21. Dynamic Rules Syntax@ruleExpression = Expansions… @end All direct expansions become alternative choices Especially useful inside a top-level @for Example@for (typeSet : addresses.getStreetTypes())@rule typeSet.getUniqueId() =@call streetTypes(typeSet)@end@end Copyright © 2010 Nu Echo Inc.

22. Dynamic Headers Syntaxmode @stringExpression;root @stringExpression;language @stringExpression;lexicon @stringExpression;meta “string” is @stringExpression;tag-format @stringExpression; Expression must evaluate to a string Useful for engine-specific headers Copyright © 2010 Nu Echo Inc.

23. Conditional Headers Syntax Add a @when clause at the end of the header form Examplelexicon <mylexicon.xml> @when engine == “osr”;tag-format <swi-semantics/1.0> @when engine == “osr”;meta “com.nuecho.generation.omit-tags” is “true” @when engine != “osr”; Copyright © 2010 Nu Echo Inc.