Add a new API to add words to the recognition dictionary on runtime. Be aware that new words can't be added while a recognition is in progress. You should add new words before start a recognition process.

The API expect an array of tuples of String with the form: (word: 'HELLO', phones: 'HH EH L OW'). The first component is the word in plain English. The second is the pronunciation phones as appear in the cmudict (more here: http://www.speech.cs.cmu.edu/tools/lextool.html) In the future the second component should be calculated

Author: Bruno Berisso

Sphinx/share/pocketsphinx/model/en-us/basic-lm/6844.dic

@@ -0,0 +1,3 @@
+FORWARD	F AO R W ER D
+GO	G OW
+TEN	T EH N

Sphinx/share/pocketsphinx/model/en-us/basic-lm/6844.lm

@@ -0,0 +1,35 @@
+Language model created by QuickLM on Mon Jan 23 09:11:27 EST 2017
+Copyright (c) 1996-2010 Carnegie Mellon University and Alexander I. Rudnicky
+
+The model is in standard ARPA format, designed by Doug Paul while he was at MITRE.
+
+The code that was used to produce this language model is available in Open Source.
+Please visit http://www.speech.cs.cmu.edu/tools/ for more information
+
+The (fixed) discount mass is 0.5. The backoffs are computed using the ratio method.
+This model based on a corpus of 1 sentences and 5 words
+
+\data\
+ngram 1=5
+ngram 2=4
+ngram 3=3
+
+\1-grams:
+-1.0000 </s> -0.3010
+-1.0000 <s> -0.2553
+-1.0000 FORWARD -0.2553
+-1.0000 GO -0.2553
+-1.0000 TEN -0.2553
+
+\2-grams:
+-0.3010 <s> GO 0.0000
+-0.3010 FORWARD TEN 0.0000
+-0.3010 GO FORWARD 0.0000
+-0.3010 TEN </s> -0.3010
+
+\3-grams:
+-0.3010 <s> GO FORWARD
+-0.3010 FORWARD TEN </s>
+-0.3010 GO FORWARD TEN
+
+\end\

TLSphinx/Decoder.swift

@@ -239,4 +239,16 @@ public final class Decoder {
         engine.stop()
         engine = nil
     }
+
+    public func add(words:Array<(word: String, phones: String)>) throws {
+
+        guard engine == nil || !engine.isRunning else {
+            throw DecodeErrors.CantAddWordsWhileDecodeingSpeech
+        }
+
+        for (word,phones) in words {
+            let update = words.last?.word == word ? STrue32 : SFalse32
+            ps_add_word(psDecoder, word, phones, update)
+        }
+    }
 }

TLSphinxTests/Basic.swift

@@ -90,47 +90,61 @@ class BasicTests: XCTestCase {
             expectation.fulfill()
         }
 
-        if let modelPath = getModelPath() {
-            
-            let hmm = (modelPath as NSString).appendingPathComponent("en-us")
-            let lm = (modelPath as NSString).appendingPathComponent("en-us.lm.dmp")
-            let dict = (modelPath as NSString).appendingPathComponent("cmudict-en-us.dict")
-            
-            if let config = Config(args: ("-hmm", hmm), ("-lm", lm), ("-dict", dict)) {
-                if let decoder = Decoder(config:config) {
-                    
-                    let audioFile = (modelPath as NSString).appendingPathComponent("goforward.raw")
-                    let expectation = self.expectation(description: "Decode finish")
-                    
-                    decoder.decodeSpeechAtPath(audioFile) {
-                        
-                        if let hyp = $0 {
-                            
-                            print("Text: \(hyp.text) - Score: \(hyp.score)")
-                            XCTAssert(hyp.text == "go forward ten meters", "Pass")
-                            
-                        } else {
-                            XCTFail("Fail to decode audio")
-                        }
-                        
-                        expectation.fulfill()
+        waitForExpectations(timeout: NSTimeIntervalSince1970)
+    }
+
+    func testAddWordToLenguageModel() {
+
+        guard let modelPath = getModelPath() else {
+            XCTFail("Can't access pocketsphinx model. Bundle root: \(Bundle.main)")
+            return
+        }
+
+        let basicModelPath = (modelPath.appendingPathComponent("basic-lm") as NSString)
+        let hmm = modelPath.appendingPathComponent("en-us")
+        let lm = basicModelPath.appendingPathComponent("6844.lm")
+        let dict = basicModelPath.appendingPathComponent("6844.dic")
+
+        guard let config = Config(args: ("-hmm", hmm), ("-lm", lm), ("-dict", dict)) else {
+            XCTFail("Can't run test without a valid config")
+            return
+        }
+
+        guard let decoder = Decoder(config:config) else {
+            XCTFail("Can't run test without a decoder")
+            return
+        }
+
+        let audioFile = modelPath.appendingPathComponent("goforward.raw")
+        let expectation = self.expectation(description: "Decode finish")
+
+        try! decoder.decodeSpeech(atPath: audioFile) { [unowned decoder] in
+
+            if let hyp = $0 {
+
+                print("Text: \(hyp.text) - Score: \(hyp.score)")
+                XCTAssert(hyp.text == "GO FORWARD TEN", "Pass")
+
+                try! decoder.add(words:[("METERS","M IY T ER Z")])
+
+                try! decoder.decodeSpeech(atPath: audioFile) {
+                    if let hyp = $0 {
+
+                        print("Text: \(hyp.text) - Score: \(hyp.score)")
+                        XCTAssert(hyp.text == "GO FORWARD TEN METERS", "Pass")
+                    } else {
+                        XCTFail("Fail to decode audio")
                     }
-                    
-                    waitForExpectations(timeout: NSTimeIntervalSince1970, handler: { (_) -> Void in
-                        
-                    })
-                    
-                } else {
-                    XCTFail("Can't run test without a decoder")
+
+                    expectation.fulfill()
                 }
-                
+
             } else {
-                XCTFail("Can't run test without a valid config")
+                XCTFail("Fail to decode audio")
+                expectation.fulfill()
             }
-            
-        } else {
-            XCTFail("Can't access pocketsphinx model. Bundle root: \(Bundle.main)")
         }
-        
+
+        waitForExpectations(timeout: NSTimeIntervalSince1970)
     }
 }