GrammarBuilder.Add Method (GrammarBuilder, Choices)


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Creates a new GrammarBuilder that contains a GrammarBuilder object followed by a Choices object.

Namespace:   System.Speech.Recognition
Assembly:  System.Speech (in System.Speech.dll)

public static GrammarBuilder Add(
	GrammarBuilder builder,
	Choices choices


Type: System.Speech.Recognition.GrammarBuilder

The first grammar element.

Type: System.Speech.Recognition.Choices

The second grammar element, which represents a set of alternatives.

Return Value

Type: System.Speech.Recognition.GrammarBuilder

A GrammarBuilder for the sequence of the builder element followed by the choices element.

GrammarBuilder supports implicit conversions from the following classes:

This method accepts the objects listed above for the builder parameter.

For more information, see the Implicit(Choices to GrammarBuilder) and Addition operators.


When you combine Choices and GrammarBuilder objects that contain SemanticResultValue or SemanticResultKey instances with other grammar elements, make sure you avoid creating duplicate semantic elements with the same key name or multiple semantic elements that could repeatedly modify the Value property of a SemanticValue object. The speech recognizer can throw an exception if it encounters these circumstances. For more information about building a speech recognition grammar that contains semantic information, see Using SemanticResultKey and SemanticResultValue Objects.

The following example creates a speech recognition grammar that can recognize the two phrases, "Make background color" and "Set background to color", where color is selected from a set of colors. Various types are used to build the final grammar, such as String, Choices, and GrammarBuilder objects. The explicit cast operators in the calls to the Add methods are optional.

private Grammar CreateColorGrammar()

  // Create a set of color choices.
  Choices colorChoice = new Choices(new string[] {"red", "green", "blue"});

  // Create grammar builders for the two versions of the phrase.
  GrammarBuilder makePhrase =
    GrammarBuilder.Add((GrammarBuilder)"Make background", colorChoice);
  GrammarBuilder setPhrase =
    GrammarBuilder.Add("Set background to", (GrammarBuilder)colorChoice);

  // Create a Choices for the two alternative phrases, convert the Choices
  // to a GrammarBuilder, and construct the grammar from the result.
  Choices bothChoices = new Choices(new GrammarBuilder[] {makePhrase, setPhrase});
  GrammarBuilder bothPhrases = new GrammarBuilder(bothChoices);

  Grammar grammar = new Grammar(bothPhrases);
  grammar.Name = "backgroundColor";
  return grammar;

.NET Framework
Available since 3.0
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