From 8599208037ada7020a3ab8c6fc979e31a2ff934c Mon Sep 17 00:00:00 2001
From: Max McLennan <mpmclenn@indiana.edu>
Date: Sat, 26 Dec 2015 01:50:02 -0800
Subject: [PATCH] Add support for custom slot types. User can create a slot
 name literal using the syntax '{-|Name}' => '{Name}', where Name is the name
 of a slot using a custom datatype in its skill's interaction model.

---
 README.md     | 15 ++++++++++++++-
 index.js      | 21 +++++++++++++++++++--
 test/index.js | 15 +++++++++++++++
 3 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index a521e87..e7002b7 100644
--- a/README.md
+++ b/README.md
@@ -51,7 +51,7 @@ var result = utterances(template, slots, dictionary);
 
 #### slots
 
-The slots object is a simple Name:Type mapping. The type must be one of Amazon's supported slot types: LITERAL, NUMBER, DATE, TIME, DURATION
+The slots object is a simple Name:Type mapping. The type must be one of Amazon's supported slot types: LITERAL, NUMBER, DATE, TIME, DURATION. You can use custom slot types, but you cannot integrate them with the slots object here and must instead do so with an [alternate syntax](#custom-slot-types).
 
 
 #### Using a Dictionary
@@ -117,3 +117,16 @@ Number ranges can also increment in steps
 "what is your color"
 "what is your favorite color"
 ```
+
+#### Custom Slot Types <a name="custom-slot-types"></a>
+
+You may want to work with [Custom Slot Types](https://developer.amazon.com/appsandservices/solutions/alexa/alexa-skills-kit/docs/defining-the-voice-interface#The Speech Input Data) registered in your interaction model. You can use a special syntax to leave a curly-braced slot name unparsed. For example, if you have defined in your skill a `FRUIT_TYPE` with the values `Apple`, `Orange` and `Lemon` for the slot `Fruit`, you can keep `Fruit` a curly-braced literal as follows
+
+```javascript
+"{my|your} {favorite|least favorite} snack is {-|Fruit}"
+=>
+"my favorite snack is {Fruit}"
+"your favorite snack is {Fruit}"
+"my least favorite snack is {Fruit}"
+"your least favorite snack is {Fruit}"
+```
diff --git a/index.js b/index.js
index a714f03..4888873 100644
--- a/index.js
+++ b/index.js
@@ -14,6 +14,12 @@ function expandNumberRange(start, end, by) {
   return converted;
 }
 
+// Determine if a curly brace expression is a Slot name literal
+// Returns true if expression is of the form {-|Name}, false otherwise
+function isSlotLiteral(braceExpression) {
+  return braceExpression.substring(0, 3) == "{-|";
+}
+
 // Recognize shortcuts in utterance definitions and swap them out with the actual values
 function expandShortcuts(str, slots, dictionary) {
   // If the string is found in the dictionary, just provide the matching values
@@ -90,6 +96,11 @@ function generateUtterances(str, slots, dictionary, exhaustiveUtterances) {
   var placeholders=[], utterances=[], slotmap={}, slotValues=[];
   // First extract sample placeholders values from the string
   str = str.replace(/\{([^\}]+)\}/g, function(match,p1) {
+
+    if (isSlotLiteral(match)) {
+      return match;
+    }
+
     var expandedValues=[], slot, values = p1.split("|");
     // If the last of the values is a SLOT name, we need to keep the name in the utterances
     if (values && values.length && values.length>1 && slots && typeof slots[values[values.length-1]]!="undefined") {
@@ -134,14 +145,20 @@ function generateUtterances(str, slots, dictionary, exhaustiveUtterances) {
       });
       // Replace slot placeholders
       utterance = utterance.replace(/\{(.*?)\}/g,function(match,p1){ 
-        return "{"+values[slotmap[p1]]+"|"+p1+"}";
+        return (isSlotLiteral(match)) ? match : "{"+values[slotmap[p1]]+"|"+p1+"}";
       });
       utterances.push( utterance );
     });
   }
   else {
-    return [str];
+    utterances = [str];
+  }
+
+  // Convert all {-|Name} to {Name} to accomodate slot literals
+  for (var idx in utterances) {
+    utterances[idx] = utterances[idx].replace(/\{\-\|/g, "{");
   }
+
   return utterances;
 }
 
diff --git a/test/index.js b/test/index.js
index b82500f..2e905b3 100644
--- a/test/index.js
+++ b/test/index.js
@@ -108,3 +108,18 @@ test('exhaustive vs non-exhaustive expansion', function (t) {
   ]);
   t.end();
 });
+
+test('raw curly braces for custom slot types', function (t) {
+  var dictionary = {};
+  var slots = {"Artist": "CUSTOM_TYPE"};
+  var template = "{my|your} {favorite|least favorite} fruit is {-|Fruit}";
+
+  var result = utterances(template, slots, dictionary);
+  t.deepEqual(result, [
+    "my favorite fruit is {Fruit}",
+    "your favorite fruit is {Fruit}",
+    "my least favorite fruit is {Fruit}",
+    "your least favorite fruit is {Fruit}"
+  ]);
+  t.end();
+});