change(web): remove duplicate correction-search path filtering 🚂

web/src/engine/predictive-text/worker-thread/src/main/correction/distance-modeler.ts

@@ -8,6 +8,7 @@ import { ExecutionTimer, STANDARD_TIME_BETWEEN_DEFERS } from './execution-timer.
 import { QUEUE_NODE_COMPARATOR, SearchQuotientSpur } from './search-quotient-spur.js';
 import { PathResult } from './search-quotient-node.js';
 import { subsetByChar, subsetByInterval, mergeSubset, TransformSubset } from '../transform-subsets.js';
+import TransformUtils from '../transformUtils.js';
 
 import Distribution = LexicalModelTypes.Distribution;
 import LexiconTraversal = LexicalModelTypes.LexiconTraversal;
@@ -33,6 +34,13 @@ enum TimedTaskTypes {
   CORRECTING = 2
 }
 
+enum PathEdge {
+  ROOT = 'root',
+  INSERTION = 'insertion',
+  DELETION = 'deletion',
+  SUBSTITUTION = 'substitution'
+}
+
 /**
  * This type models a partially-processed subset of Transforms to be processed
  * as a batch due to sharing similar properties.
@@ -136,9 +144,15 @@ export class SearchNode {
    */
   readonly spaceId: number;
 
+  /**
+   * Notes the edit operation used for the most recent edge in the node's
+   * represented search path.
+   */
+  private readonly lastEdgeType: PathEdge;
+
   constructor(rootTraversal: LexiconTraversal, spaceId: number, toKey?: (arg0: string) => string);
-  constructor(node: SearchNode, spaceId?: number);
-  constructor(param1: LexiconTraversal | SearchNode, spaceId?: number, toKey?: ((arg0: string) => string)) {
+  constructor(node: SearchNode, spaceId?: number, edgeType?: PathEdge);
+  constructor(param1: LexiconTraversal | SearchNode, spaceId?: number, param2?: PathEdge | ((arg0: string) => string)) {
     if(param1 instanceof SearchNode) {
       const priorNode = param1;
 
@@ -149,6 +163,8 @@ export class SearchNode {
       this.priorInput = priorNode.priorInput.slice(0);
       this.matchedTraversals = priorNode.matchedTraversals.slice();
 
+      this.lastEdgeType = param2 as PathEdge;
+
       // Do NOT copy over _inputCost; this is a helper-constructor for methods
       // building new nodes... which will have a different cost.
       delete this._inputCost;
@@ -160,8 +176,10 @@ export class SearchNode {
       this.calculation = new ClassicalDistanceCalculation();
       this.matchedTraversals = [param1];
       this.priorInput = [];
+      const toKey = param2 as ((arg0: string) => string);
       this.toKey = toKey || (x => x);
       this.spaceId = spaceId;
+      this.lastEdgeType = PathEdge.ROOT;
     }
   }
 
@@ -250,12 +268,28 @@ export class SearchNode {
       throw new Error("Invalid state:  will not take new input while still processing Transform subset");
     }
 
+    // Do not create insertion nodes after an empty transform; only before.
+    // "Before" and "after" are identical for empty transforms - why duplicate?
+    //
+    // Also, do not create insertion nodes directly after deletions; that's
+    // essentially a substitution.  We'll have an equivalent edge already built
+    // with higher-accuracy modeling.
+    //
+    // Following previous insertions is fine, as is following a proper
+    // match/substitution.
+    if(this.priorInput.length > 0) {
+      const priorInput = this.priorInput[this.priorInput.length - 1].sample;
+      if(TransformUtils.isEmpty(priorInput) || this.lastEdgeType == PathEdge.DELETION) {
+        return [];
+      }
+    }
+
     let edges: SearchNode[] = [];
 
     for(let lexicalChild of this.currentTraversal.children()) {
       let childCalc = this.calculation.addMatchChar(lexicalChild.char);
 
-      let searchChild = new SearchNode(this);
+      let searchChild = new SearchNode(this, this.spaceId, PathEdge.INSERTION);
       searchChild.calculation = childCalc;
       searchChild.priorInput = this.priorInput;
       searchChild.matchedTraversals.push(lexicalChild.traversal());
@@ -367,7 +401,7 @@ export class SearchNode {
 
       keySet.add(char);
 
-      const node = new SearchNode(this);
+      const node = new SearchNode(this, this.spaceId, this.lastEdgeType);
       node.calculation = calculation;
       node.partialEdge.subsetSubindex++;
       // Append the newly-processed char to the subset's `insert` string.
@@ -415,7 +449,7 @@ export class SearchNode {
       // `insert` string.
       childSubset.insert += SENTINEL_CODE_UNIT;
 
-      const node = new SearchNode(this);
+      const node = new SearchNode(this, this.spaceId, this.lastEdgeType);
       node.calculation = childCalc;
       node.matchedTraversals.push(childTraversal);
       node.partialEdge.subsetSubindex++;
@@ -464,7 +498,7 @@ export class SearchNode {
           continue;
         }
 
-        const node = new SearchNode(this, edgeId);
+        const node = new SearchNode(this, edgeId, isSubstitution ? PathEdge.SUBSTITUTION : PathEdge.DELETION);
         node.calculation = edgeCalc;
         node.partialEdge = {
           doSubsetMatching: isSubstitution,
@@ -514,31 +548,6 @@ export class SearchNode {
     return this.setupSubsetProcessing(dist, true, edgeId);
   }
 
-  /**
-   * A key uniquely identifying identical search path nodes.  Replacement of a keystroke's
-   * text in a manner that results in identical path to a different keystroke should result
-   * in both path nodes sharing the same pathKey value.
-   *
-   * This mostly matters after re-use of a SearchSpace when a token is extended; children of
-   * completed paths are possible, and so children can be re-built in such a case.
-   */
-  get pathKey(): string {
-    // Note:  deleteLefts apply before inserts, so order them that way.
-    let inputString = this.priorInput.map((value) => '-' + value.sample.deleteLeft + '+' + value.sample.insert).join('');
-    const partialEdge = this.partialEdge;
-    // Make sure the subset progress contributes to the key!
-    if(partialEdge) {
-      const subset = partialEdge.transformSubset;
-      // We need a copy of at least one insert string in the subset here.  Without that, all subsets
-      // at the same level of the search, against the same match, look identical - not cool!
-      inputString += `-${subset.entries[0].sample.deleteLeft}+<${subset.key},${partialEdge.subsetSubindex},${subset.entries[0].sample.insert}>`;
-    }
-    let matchString =  this.calculation.matchSequence.join('');
-
-    // TODO:  might should also track diagonalWidth.
-    return inputString + ' @@ ' + matchString;
-  }
-
   /**
    * A key uniquely identifying identical match sequences.  Reaching the same net result
    * by different paths should result in identical `resultKey` values.

web/src/engine/predictive-text/worker-thread/src/main/correction/search-quotient-spur.ts

@@ -52,16 +52,6 @@ export class SearchQuotientSpur implements SearchQuotientNode {
    */
   public returnedValues?: {[resultKey: string]: SearchNode} = {}; // TODO:  make it private again!
 
-  /**
-   * Acts as a Map that prevents duplicating a correction-search path if reached
-   * more than once.
-   */
-  protected get processedEdgeSet(): {[pathKey: string]: boolean} {
-    return this._processedEdgeSet;
-  }
-
-  private _processedEdgeSet?: {[pathKey: string]: boolean} = {};
-
   /**
    * Provides a heuristic for the base cost at each depth if the best
    * individual input were taken at that level.
@@ -245,7 +235,7 @@ export class SearchQuotientSpur implements SearchQuotientNode {
 
       const result = this.parentPath.handleNextNode();
 
-      if(result.type == 'complete' && !this.processedEdgeSet[result.finalNode.pathKey]) {
+      if(result.type == 'complete') {
         this.addEdgesForNodes(result.finalNode);
       }
 
@@ -262,14 +252,6 @@ export class SearchQuotientSpur implements SearchQuotientNode {
       cost: currentNode.currentCost
     }
 
-    // Have we already processed a matching edge?  If so, skip it.
-    // We already know the previous edge is of lower cost.
-    if(this.processedEdgeSet[currentNode.pathKey]) {
-      return unmatchedResult;
-    } else {
-      this.processedEdgeSet[currentNode.pathKey] = true;
-    }
-
     // Stage 1:  filter out nodes/edges we want to prune
 
     // Forbid a raw edit-distance of greater than 2.

web/src/test/auto/headless/engine/predictive-text/worker-thread/correction-search/distance-modeler.tests.ts

@@ -341,31 +341,130 @@ describe('Correction Distance Modeler', () => {
       });
     });
 
-    // Consider adding more, deeper?
-    it('builds insertion edges based on lexicon, from root', () => {
-      const rootTraversal = testModel.traverseFromRoot();
-      assert.isNotEmpty(rootTraversal);
+    describe('buildInsertionEdges()', () => {
+      it('builds insertion edges from (empty) root', () => {
+        const rootTraversal = testModel.traverseFromRoot();
+        assert.isNotEmpty(rootTraversal);
 
-      const rootSeed = SEARCH_EDGE_SEED++;
-      const rootNode = new correction.SearchNode(rootTraversal, rootSeed);
-      assert.equal(rootNode.calculation.getHeuristicFinalCost(), 0);
+        const rootSeed = SEARCH_EDGE_SEED++;
+        const rootNode = new correction.SearchNode(rootTraversal, rootSeed);
+        assert.equal(rootNode.calculation.getHeuristicFinalCost(), 0);
 
-      const edges = rootNode.buildInsertionEdges();
-      assert.isAbove(edges.length, 0);
+        const edges = rootNode.buildInsertionEdges();
+        assert.isAbove(edges.length, 0);
 
-      let expectedChildCount = 0;
-      for(const child of rootTraversal.children()) {
-        expectedChildCount++;
+        let expectedChildCount = 0;
+        for(const child of rootTraversal.children()) {
+          expectedChildCount++;
 
-        let childEdge = edges.filter(value => lastEntry(value.calculation.matchSequence) == child.char)[0];
-        assert.isOk(childEdge);
-        assert.isEmpty(childEdge.priorInput);
-        assert.isEmpty(childEdge.calculation.inputSequence);
-        assert.isAbove(childEdge.currentCost, 0);
-        assert.equal(childEdge.spaceId, rootSeed);
-      }
+          let childEdge = edges.filter(value => lastEntry(value.calculation.matchSequence) == child.char)[0];
+          assert.isOk(childEdge);
+          assert.isEmpty(childEdge.priorInput);
+          assert.isEmpty(childEdge.calculation.inputSequence);
+          assert.isAbove(childEdge.currentCost, 0);
+          assert.equal(childEdge.spaceId, rootSeed);
+        }
 
-      assert.equal(edges.length, expectedChildCount);
+        assert.equal(edges.length, expectedChildCount);
+      });
+
+      it('builds insertion edges directly after prior insertion', () => {
+        const rootTraversal = testModel.traverseFromRoot();
+        assert.isNotEmpty(rootTraversal);
+
+        const rootSeed = SEARCH_EDGE_SEED++;
+        const rootNode = new correction.SearchNode(rootTraversal, rootSeed);
+        assert.equal(rootNode.calculation.getHeuristicFinalCost(), 0);
+
+        const edges = rootNode.buildInsertionEdges();
+        assert.isAbove(edges.length, 0);
+
+        const firstChild = edges[0];
+        const childEdges = firstChild.buildInsertionEdges();
+
+        let expectedChildCount = 0;
+        for(const child of firstChild.currentTraversal.children()) {
+          expectedChildCount++;
+
+          let childEdge = edges.filter(value => lastEntry(value.calculation.matchSequence) == child.char)[0];
+          assert.isOk(childEdge);
+          assert.isEmpty(childEdge.priorInput);
+          assert.isEmpty(childEdge.calculation.inputSequence);
+          assert.isAbove(childEdge.currentCost, 0);
+          assert.equal(childEdge.spaceId, rootSeed);
+        }
+
+        assert.equal(childEdges.length, expectedChildCount);
+      });
+
+      it('does not build insertion edges after a deletion', () => {
+        const rootTraversal = testModel.traverseFromRoot();
+        assert.isNotEmpty(rootTraversal);
+
+        const rootSeed = SEARCH_EDGE_SEED++;
+        const rootNode = new correction.SearchNode(rootTraversal, rootSeed);
+        assert.equal(rootNode.calculation.getHeuristicFinalCost(), 0);
+
+        const edges = rootNode.buildDeletionEdges([{
+          sample: { insert: 'd', deleteLeft: 0 },
+          p: 1
+        }], SEARCH_EDGE_SEED++).flatMap(n => n.processSubsetEdge());
+        assert.isAbove(edges.length, 0);
+        const firstChild = edges[0];
+
+        const insertEdgesAfterDelete = firstChild.buildInsertionEdges();
+        assert.equal(insertEdgesAfterDelete.length, 0);
+      });
+
+      it('does not build insertion edges after receiving an empty transform as input', () => {
+        const rootTraversal = testModel.traverseFromRoot();
+        assert.isNotEmpty(rootTraversal);
+
+        const rootSeed = SEARCH_EDGE_SEED++;
+        const rootNode = new correction.SearchNode(rootTraversal, rootSeed);
+        assert.equal(rootNode.calculation.getHeuristicFinalCost(), 0);
+
+        const edges = rootNode.buildSubstitutionEdges([{
+          // intentionally empty!
+          sample: { insert: '', deleteLeft: 0 },
+          p: 1
+        }], SEARCH_EDGE_SEED++).flatMap(n => n.processSubsetEdge());
+        assert.isAbove(edges.length, 0);
+        const firstChild = edges[0];
+        const insertsAfterEmpty = firstChild.buildInsertionEdges();
+
+        assert.equal(insertsAfterEmpty.length, 0);
+      });
+
+      it('builds insertion edges after a substitution', () => {
+        const rootTraversal = testModel.traverseFromRoot();
+        assert.isNotEmpty(rootTraversal);
+
+        const rootSeed = SEARCH_EDGE_SEED++;
+        const rootNode = new correction.SearchNode(rootTraversal, rootSeed);
+        assert.equal(rootNode.calculation.getHeuristicFinalCost(), 0);
+
+        const subSeed = SEARCH_EDGE_SEED++;
+        const edges = rootNode.buildSubstitutionEdges([{
+          sample: { insert: 't', deleteLeft: 0 },
+          p: 1
+        }], subSeed).flatMap(n => n.processSubsetEdge());
+        assert.isAbove(edges.length, 0);
+        const firstChild = edges[0];
+        const insertsAfterInput = firstChild.buildInsertionEdges();
+
+        let expectedChildCount = 0;
+        for(const child of firstChild.currentTraversal.children()) {
+          expectedChildCount++;
+
+          let childEdge = edges.filter(value => lastEntry(value.calculation.matchSequence) == child.char)[0];
+          assert.isOk(childEdge);
+          assert.equal(childEdge.priorInput.length, 1);
+          assert.equal(childEdge.spaceId, subSeed);
+        }
+
+        assert.equal(insertsAfterInput.length, expectedChildCount);
+      });
     });
 
     describe('buildDeletionEdges @ token root', () => {