add letters-words-prediction tries

Author: michael-spengler

README.md

@@ -30,10 +30,37 @@ console.log(trie.hasSequence("missing")) // false
 
 ```
 
+## Letters and Words Prediction Tries
+
+```ts
+
+import { LettersWordsPredictionTrie } from "https://deno.land/tries/mod-letters-and-word-prediction.ts"
+
+const lettersWordsPredictionTrie = new LettersWordsPredictionTrie()
+
+lettersWordsPredictionTrie.learn(['ether', 'eth', 'ethereum', 'super'])
+
+const brain = lettersWordsPredictionTrie.getBrain()
+
+console.log(JSON.stringify(brain, undefined, 2))
+
+
+```
+
+## PATRICIA Tries
+**P** Practical  
+**A** Algorithm  
+**T** To   
+**R** Retrieve   
+**I** Information  
+**C** Coded  
+**I** In   
+**A** Alphanumeric  
+
+In the Ethereum Blockchain pretty much everything (state trie, transaction trie, receipt trie, ...) ist stored in PATRICIA Tries. For details I can recommend [this video](https://www.youtube.com/watch?v=OxofT39TJgg).
 
-## Patricia Tries
 ### Usage Examples
-[Patricia Tries](https://de.wikipedia.org/wiki/Patricia-Trie) ...
+... Under Construction ...
 
 ## Unit Tests
 For further usage examples etc. please check the [unit tests](https://github.com/distributed-ledger-technology/tries/blob/main/src/trie.spec.ts).

mod-letters-and-word-prediction.ts

@@ -0,0 +1 @@
+export * from "./src/letters-words-prediction-trie/letters-words-prediction-trie.ts"

mod.ts

@@ -1 +1 @@
-export * from "./src/trie.ts"
+export * from "./src/trie.ts"

src/letters-words-prediction-trie/letters-words-prediction-trie.spec.ts

@@ -0,0 +1,15 @@
+
+import { assertEquals } from "https://deno.land/std@0.106.0/testing/asserts.ts"
+import { LettersWordsPredictionTrie } from "./letters-words-prediction-trie.ts"
+
+Deno.test("should build a data structure optimized for letters and words prediction", async () => {
+
+    const lettersWordsPredictionTrie = new LettersWordsPredictionTrie()
+
+    lettersWordsPredictionTrie.learn(['ether', 'eth', 'ethereum', 'super'])
+
+    const brain = lettersWordsPredictionTrie.getBrain()
+
+    assertEquals(JSON.stringify(brain).length, 575) // better assertion follows --> search / query ... 
+})
+

src/letters-words-prediction-trie/letters-words-prediction-trie.ts

@@ -0,0 +1,58 @@
+export class LettersWordsPredictionTrie {
+
+    private brain: any = {}
+
+    public learn(inputs: string[]): any {
+
+        this.freeMyBrain()
+
+        for (const input of inputs) {
+            this.addInput(input, this.brain)
+        }
+
+    }
+
+    public getBrain(): any {
+        return this.brain
+    }
+
+    private addInput(input: string, brain: any): any {
+
+        if (input.length == 0) return {}
+
+        if (this.isCharacterInBrain(input[0], brain)) {
+            this.incrementCountForCharacter(input[0], brain)
+        } else {
+            this.createNewNode(input[0], brain)
+        }
+
+        const theRestOfTheInput = input.substring(1)
+
+        if (theRestOfTheInput !== '') {
+            this.handleTheRestOfTheMessage(input[0], brain, theRestOfTheInput)
+        }
+
+        return brain
+    }
+
+    private createNewNode(character: string, brain: any): void {
+        brain[character] = { value: character, count: 1, followables: {} }
+    }
+
+    private incrementCountForCharacter(character: string, brain: any): void {
+        brain[character].count += 1
+    }
+
+    private handleTheRestOfTheMessage(character: string, brain: any, theRestOfTheMessage: string): void {
+        brain[character].followables = this.addInput(theRestOfTheMessage, brain[character].followables)
+    }
+
+    private freeMyBrain(): void {
+        this.brain = {}
+    }
+
+    private isCharacterInBrain(character: string, brain: any): boolean {
+        return (brain[character] !== undefined)
+    }
+
+}

usage-example-letters-and-word-predictions.ts

@@ -0,0 +1,9 @@
+import { LettersWordsPredictionTrie } from "https://deno.land/tries/mod-letters-and-word-prediction.ts"
+
+const lettersWordsPredictionTrie = new LettersWordsPredictionTrie()
+
+lettersWordsPredictionTrie.learn(['ether', 'eth', 'ethereum', 'super'])
+
+const brain = lettersWordsPredictionTrie.getBrain()
+
+console.log(JSON.stringify(brain, undefined, 2))