The NuGram dynamic grammar language

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

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.

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

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]

Expressions
Comparison operators
==
!=
Logical operators
! (negation)
&& (conjunction)
|| (disjunction)

Dynamic Words
Syntax@word ( Expressions… )
Values of all expressions are concatenated
Example

Dynamic Rule References
Syntax@ref ( Expressions… )
Resulting value must start with “#” for a local rule reference
Example

Dynamic Tags
Syntax@tag ( Expressions… )
Example

Iterations
Syntax@for ( var: Expression ) Expansions…@end
Repeats the expansions for each value in the collection resulting from evaluating Expression.

Iterations
Example

Dynamic Sequences
Syntax@seqExpansions… @end
All direct expansions become part of the sequence

Dynamic sequences
Example

Dynamic Choices
Syntax@altExpansions… @end
All direct expansions become alternative choices

Dynamic Choices
Example 1

Example 2
Beware: @alt and @for may produce unexpected results
Dynamic Choices

Example 2 (cont'd)
Solution: use grouping
Dynamic Choices

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

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

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

Macros Invocations
Syntax@callIdent (Expressions…)
Arguments are comma-separated
Example@for (name : names) @call fullname (name)@end

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

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

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”;

The NuGram dynamic grammar language

by Nu Echo Inc. on Jun 16, 2010

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The NuGram dynamic grammar language — Presentation Transcript