Add spellcheck and word suggestion to the prediction service

third_party/prediction/suggest/core/suggest.cpp

Index: third_party/prediction/suggest/core/suggest.cpp
diff --git a/third_party/prediction/suggest/core/suggest.cpp b/third_party/prediction/suggest/core/suggest.cpp
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index 0000000000000000000000000000000000000000..98f5ca4d29a0bc1235ac8b402cb0b12222fbe86f
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+++ b/third_party/prediction/suggest/core/suggest.cpp
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+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "third_party/prediction/suggest/core/suggest.h"
+#include "third_party/prediction/suggest/core/dicnode/dic_node.h"
+#include "third_party/prediction/suggest/core/dicnode/dic_node_priority_queue.h"
+#include "third_party/prediction/suggest/core/dicnode/dic_node_vector.h"
+#include "third_party/prediction/suggest/core/dictionary/dictionary.h"
+#include "third_party/prediction/suggest/core/dictionary/digraph_utils.h"
+#include "third_party/prediction/suggest/core/layout/proximity_info.h"
+#include "third_party/prediction/suggest/core/policy/dictionary_structure_with_buffer_policy.h"
+#include "third_party/prediction/suggest/core/policy/traversal.h"
+#include "third_party/prediction/suggest/core/policy/weighting.h"
+#include "third_party/prediction/suggest/core/result/suggestions_output_utils.h"
+#include "third_party/prediction/suggest/core/session/dic_traverse_session.h"
+
+namespace latinime {
+
+// Initialization of class constants.
+const int Suggest::MIN_CONTINUOUS_SUGGESTION_INPUT_SIZE = 2;
+
+/**
+ * Returns a set of suggestions for the given input touch points. The
+ *commitPoint argument indicates
+ * whether to prematurely commit the suggested words up to the given point for
+ *sentence-level
+ * suggestion.
+ *
+ * Note: Currently does not support concurrent calls across threads. Continuous
+ *suggestion is
+ * automatically activated for sequential calls that share the same starting
+ *input.
+ * TODO: Stop detecting continuous suggestion. Start using traverseSession
+ *instead.
+ */
+void Suggest::getSuggestions(
+    ProximityInfo* pInfo,
+    void* traverseSession,
+    int* inputXs,
+    int* inputYs,
+    int* times,
+    int* pointerIds,
+    int* inputCodePoints,
+    int inputSize,
+    const float languageWeight,
+    SuggestionResults* const outSuggestionResults) const {
+  PROF_OPEN;
+  PROF_START(0);
+  const float maxSpatialDistance = TRAVERSAL->getMaxSpatialDistance();
+  DicTraverseSession* tSession =
+      static_cast<DicTraverseSession*>(traverseSession);
+  tSession->setupForGetSuggestions(
+      pInfo, inputCodePoints, inputSize, inputXs, inputYs, times, pointerIds,
+      maxSpatialDistance, TRAVERSAL->getMaxPointerCount());
+  // TODO: Add the way to evaluate cache
+
+  initializeSearch(tSession);
+  PROF_END(0);
+  PROF_START(1);
+
+  // keep expanding search dicNodes until all have terminated.
+  while (tSession->getDicTraverseCache()->activeSize() > 0) {
+    expandCurrentDicNodes(tSession);
+    tSession->getDicTraverseCache()->advanceActiveDicNodes();
+    tSession->getDicTraverseCache()->advanceInputIndex(inputSize);
+  }
+  PROF_END(1);
+  PROF_START(2);
+  SuggestionsOutputUtils::outputSuggestions(SCORING, tSession, languageWeight,
+                                            outSuggestionResults);
+  PROF_END(2);
+  PROF_CLOSE;
+}
+
+/**
+ * Initializes the search at the root of the lexicon trie. Note that when
+ * possible the search will
+ * continue suggestion from where it left off during the last call.
+ */
+void Suggest::initializeSearch(DicTraverseSession* traverseSession) const {
+  if (!traverseSession->getProximityInfoState(0)->isUsed()) {
+    return;
+  }
+
+  if (traverseSession->getInputSize() > MIN_CONTINUOUS_SUGGESTION_INPUT_SIZE &&
+      traverseSession->isContinuousSuggestionPossible()) {
+    // Continue suggestion
+    traverseSession->getDicTraverseCache()->continueSearch();
+  } else {
+    // Restart recognition at the root.
+    traverseSession->resetCache(
+        TRAVERSAL->getMaxCacheSize(traverseSession->getInputSize()),
+        TRAVERSAL->getTerminalCacheSize());
+    // Create a new dic node here
+    DicNode rootNode;
+    DicNodeUtils::initAsRoot(traverseSession->getDictionaryStructurePolicy(),
+                             traverseSession->getPrevWordsPtNodePos(),
+                             &rootNode);
+    traverseSession->getDicTraverseCache()->copyPushActive(&rootNode);
+  }
+}
+
+/**
+ * Expands the dicNodes in the current search priority queue by advancing to the
+ * possible child
+ * nodes based on the next touch point(s) (or no touch points for lookahead)
+ */
+void Suggest::expandCurrentDicNodes(DicTraverseSession* traverseSession) const {
+  const int inputSize = traverseSession->getInputSize();
+  DicNodeVector childDicNodes(TRAVERSAL->getDefaultExpandDicNodeSize());
+  DicNode correctionDicNode;
+
+  // TODO: Find more efficient caching
+  const bool shouldDepthLevelCache =
+      TRAVERSAL->shouldDepthLevelCache(traverseSession);
+  if (shouldDepthLevelCache) {
+    traverseSession->getDicTraverseCache()->updateLastCachedInputIndex();
+  }
+  if (DEBUG_CACHE) {
+    AKLOGI("expandCurrentDicNodes depth level cache = %d, inputSize = %d",
+           shouldDepthLevelCache, inputSize);
+  }
+  while (traverseSession->getDicTraverseCache()->activeSize() > 0) {
+    DicNode dicNode;
+    traverseSession->getDicTraverseCache()->popActive(&dicNode);
+    if (dicNode.isTotalInputSizeExceedingLimit()) {
+      return;
+    }
+    childDicNodes.clear();
+    const int point0Index = dicNode.getInputIndex(0);
+    const bool canDoLookAheadCorrection =
+        TRAVERSAL->canDoLookAheadCorrection(traverseSession, &dicNode);
+    const bool isLookAheadCorrection =
+        canDoLookAheadCorrection &&
+        traverseSession->getDicTraverseCache()->isLookAheadCorrectionInputIndex(
+            static_cast<int>(point0Index));
+    const bool isCompletion = dicNode.isCompletion(inputSize);
+
+    const bool shouldNodeLevelCache =
+        TRAVERSAL->shouldNodeLevelCache(traverseSession, &dicNode);
+    if (shouldDepthLevelCache || shouldNodeLevelCache) {
+      if (DEBUG_CACHE) {
+        dicNode.dump("PUSH_CACHE");
+      }
+      traverseSession->getDicTraverseCache()->copyPushContinue(&dicNode);
+      dicNode.setCached();
+    }
+
+    if (dicNode.isInDigraph()) {
+      // Finish digraph handling if the node is in the middle of a digraph
+      // expansion.
+      processDicNodeAsDigraph(traverseSession, &dicNode);
+    } else if (isLookAheadCorrection) {
+      // The algorithm maintains a small set of "deferred" nodes that have not
+      // consumed the
+      // latest touch point yet. These are needed to apply look-ahead correction
+      // operations
+      // that require special handling of the latest touch point. For example,
+      // with insertions
+      // (e.g., "thiis" -> "this") the latest touch point should not be consumed
+      // at all.
+      processDicNodeAsTransposition(traverseSession, &dicNode);
+      processDicNodeAsInsertion(traverseSession, &dicNode);
+    } else {  // !isLookAheadCorrection
+      // Only consider typing error corrections if the normalized compound
+      // distance is
+      // below a spatial distance threshold.
+      // NOTE: the threshold may need to be updated if scoring model changes.
+      // TODO: Remove. Do not prune node here.
+      const bool allowsErrorCorrections =
+          TRAVERSAL->allowsErrorCorrections(&dicNode);
+      // Process for handling space substitution (e.g., hevis => he is)
+      if (allowsErrorCorrections &&
+          TRAVERSAL->isSpaceSubstitutionTerminal(traverseSession, &dicNode)) {
+        createNextWordDicNode(traverseSession, &dicNode,
+                              true /* spaceSubstitution */);
+      }
+
+      DicNodeUtils::getAllChildDicNodes(
+          &dicNode, traverseSession->getDictionaryStructurePolicy(),
+          &childDicNodes);
+
+      const int childDicNodesSize = childDicNodes.getSizeAndLock();
+      for (int i = 0; i < childDicNodesSize; ++i) {
+        DicNode* const childDicNode = childDicNodes[i];
+        if (isCompletion) {
+          // Handle forward lookahead when the lexicon letter exceeds the input
+          // size.
+          processDicNodeAsMatch(traverseSession, childDicNode);
+          continue;
+        }
+        if (DigraphUtils::hasDigraphForCodePoint(
+                traverseSession->getDictionaryStructurePolicy()
+                    ->getHeaderStructurePolicy(),
+                childDicNode->getNodeCodePoint())) {
+          correctionDicNode.initByCopy(childDicNode);
+          correctionDicNode.advanceDigraphIndex();
+          processDicNodeAsDigraph(traverseSession, &correctionDicNode);
+        }
+        if (TRAVERSAL->isOmission(traverseSession, &dicNode, childDicNode,
+                                  allowsErrorCorrections)) {
+          // TODO: (Gesture) Change weight between omission and substitution
+          // errors
+          // TODO: (Gesture) Terminal node should not be handled as omission
+          correctionDicNode.initByCopy(childDicNode);
+          processDicNodeAsOmission(traverseSession, &correctionDicNode);
+        }
+        const ProximityType proximityType = TRAVERSAL->getProximityType(
+            traverseSession, &dicNode, childDicNode);
+        switch (proximityType) {
+          // TODO: Consider the difference of proximityType here
+          case MATCH_CHAR:
+          case PROXIMITY_CHAR:
+            processDicNodeAsMatch(traverseSession, childDicNode);
+            break;
+          case ADDITIONAL_PROXIMITY_CHAR:
+            if (allowsErrorCorrections) {
+              processDicNodeAsAdditionalProximityChar(traverseSession, &dicNode,
+                                                      childDicNode);
+            }
+            break;
+          case SUBSTITUTION_CHAR:
+            if (allowsErrorCorrections) {
+              processDicNodeAsSubstitution(traverseSession, &dicNode,
+                                           childDicNode);
+            }
+            break;
+          case UNRELATED_CHAR:
+            // Just drop this dicNode and do nothing.
+            break;
+          default:
+            // Just drop this dicNode and do nothing.
+            break;
+        }
+      }
+
+      // Push the dicNode for look-ahead correction
+      if (allowsErrorCorrections && canDoLookAheadCorrection) {
+        traverseSession->getDicTraverseCache()->copyPushNextActive(&dicNode);
+      }
+    }
+  }
+}
+
+void Suggest::processTerminalDicNode(DicTraverseSession* traverseSession,
+                                     DicNode* dicNode) const {
+  if (dicNode->getCompoundDistance() >=
+      static_cast<float>(MAX_VALUE_FOR_WEIGHTING)) {
+    return;
+  }
+  if (!dicNode->isTerminalDicNode()) {
+    return;
+  }
+  if (dicNode->shouldBeFilteredBySafetyNetForBigram()) {
+    return;
+  }
+  if (!dicNode->hasMatchedOrProximityCodePoints()) {
+    return;
+  }
+  // Create a non-cached node here.
+  DicNode terminalDicNode(*dicNode);
+  if (TRAVERSAL->needsToTraverseAllUserInput() &&
+      dicNode->getInputIndex(0) < traverseSession->getInputSize()) {
+    Weighting::addCostAndForwardInputIndex(
+        WEIGHTING, CT_TERMINAL_INSERTION, traverseSession, 0, &terminalDicNode,
+        traverseSession->getMultiBigramMap());
+  }
+  Weighting::addCostAndForwardInputIndex(WEIGHTING, CT_TERMINAL,
+                                         traverseSession, 0, &terminalDicNode,
+                                         traverseSession->getMultiBigramMap());
+  traverseSession->getDicTraverseCache()->copyPushTerminal(&terminalDicNode);
+}
+
+/**
+ * Adds the expanded dicNode to the next search priority queue. Also creates an
+ * additional next word
+ * (by the space omission error correction) search path if input dicNode is on a
+ * terminal.
+ */
+void Suggest::processExpandedDicNode(DicTraverseSession* traverseSession,
+                                     DicNode* dicNode) const {
+  processTerminalDicNode(traverseSession, dicNode);
+  if (dicNode->getCompoundDistance() <
+      static_cast<float>(MAX_VALUE_FOR_WEIGHTING)) {
+    if (TRAVERSAL->isSpaceOmissionTerminal(traverseSession, dicNode)) {
+      createNextWordDicNode(traverseSession, dicNode,
+                            false /* spaceSubstitution */);
+    }
+    const int allowsLookAhead =
+        !(dicNode->hasMultipleWords() &&
+          dicNode->isCompletion(traverseSession->getInputSize()));
+    if (dicNode->hasChildren() && allowsLookAhead) {
+      traverseSession->getDicTraverseCache()->copyPushNextActive(dicNode);
+    }
+  }
+}
+
+void Suggest::processDicNodeAsMatch(DicTraverseSession* traverseSession,
+                                    DicNode* childDicNode) const {
+  weightChildNode(traverseSession, childDicNode);
+  processExpandedDicNode(traverseSession, childDicNode);
+}
+
+void Suggest::processDicNodeAsAdditionalProximityChar(
+    DicTraverseSession* traverseSession,
+    DicNode* dicNode,
+    DicNode* childDicNode) const {
+  // Note: Most types of corrections don't need to look up the bigram
+  // information since they do
+  // not treat the node as a terminal. There is no need to pass the bigram map
+  // in these cases.
+  Weighting::addCostAndForwardInputIndex(WEIGHTING, CT_ADDITIONAL_PROXIMITY,
+                                         traverseSession, dicNode, childDicNode,
+                                         0 /* multiBigramMap */);
+  weightChildNode(traverseSession, childDicNode);
+  processExpandedDicNode(traverseSession, childDicNode);
+}
+
+void Suggest::processDicNodeAsSubstitution(DicTraverseSession* traverseSession,
+                                           DicNode* dicNode,
+                                           DicNode* childDicNode) const {
+  Weighting::addCostAndForwardInputIndex(WEIGHTING, CT_SUBSTITUTION,
+                                         traverseSession, dicNode, childDicNode,
+                                         0 /* multiBigramMap */);
+  weightChildNode(traverseSession, childDicNode);
+  processExpandedDicNode(traverseSession, childDicNode);
+}
+
+// Process the DicNode codepoint as a digraph. This means that composite glyphs
+// like the German
+// u-umlaut is expanded to the transliteration "ue". Note that this happens in
+// parallel with
+// the normal non-digraph traversal, so both "uber" and "ueber" can be corrected
+// to "[u-umlaut]ber".
+void Suggest::processDicNodeAsDigraph(DicTraverseSession* traverseSession,
+                                      DicNode* childDicNode) const {
+  weightChildNode(traverseSession, childDicNode);
+  childDicNode->advanceDigraphIndex();
+  processExpandedDicNode(traverseSession, childDicNode);
+}
+
+/**
+ * Handle the dicNode as an omission error (e.g., ths => this). Skip the current
+ * letter and consider
+ * matches for all possible next letters. Note that just skipping the current
+ * letter without any
+ * other conditions tends to flood the search DicNodes cache with omission
+ * DicNodes. Instead, check
+ * the possible *next* letters after the omission to better limit search to
+ * plausible omissions.
+ * Note that apostrophes are handled as omissions.
+ */
+void Suggest::processDicNodeAsOmission(DicTraverseSession* traverseSession,
+                                       DicNode* dicNode) const {
+  DicNodeVector childDicNodes;
+  DicNodeUtils::getAllChildDicNodes(
+      dicNode, traverseSession->getDictionaryStructurePolicy(), &childDicNodes);
+
+  const int size = childDicNodes.getSizeAndLock();
+  for (int i = 0; i < size; i++) {
+    DicNode* const childDicNode = childDicNodes[i];
+    // Treat this word as omission
+    Weighting::addCostAndForwardInputIndex(
+        WEIGHTING, CT_OMISSION, traverseSession, dicNode, childDicNode,
+        0 /* multiBigramMap */);
+    weightChildNode(traverseSession, childDicNode);
+    if (!TRAVERSAL->isPossibleOmissionChildNode(traverseSession, dicNode,
+                                                childDicNode)) {
+      continue;
+    }
+    processExpandedDicNode(traverseSession, childDicNode);
+  }
+}
+
+/**
+ * Handle the dicNode as an insertion error (e.g., thiis => this). Skip the
+ * current touch point and
+ * consider matches for the next touch point.
+ */
+void Suggest::processDicNodeAsInsertion(DicTraverseSession* traverseSession,
+                                        DicNode* dicNode) const {
+  const int16_t pointIndex = dicNode->getInputIndex(0);
+  DicNodeVector childDicNodes;
+  DicNodeUtils::getAllChildDicNodes(
+      dicNode, traverseSession->getDictionaryStructurePolicy(), &childDicNodes);
+  const int size = childDicNodes.getSizeAndLock();
+  for (int i = 0; i < size; i++) {
+    if (traverseSession->getProximityInfoState(0)->getPrimaryCodePointAt(
+            pointIndex + 1) != childDicNodes[i]->getNodeCodePoint()) {
+      continue;
+    }
+    DicNode* const childDicNode = childDicNodes[i];
+    Weighting::addCostAndForwardInputIndex(
+        WEIGHTING, CT_INSERTION, traverseSession, dicNode, childDicNode,
+        0 /* multiBigramMap */);
+    processExpandedDicNode(traverseSession, childDicNode);
+  }
+}
+
+/**
+ * Handle the dicNode as a transposition error (e.g., thsi => this). Swap the
+ * next two touch points.
+ */
+void Suggest::processDicNodeAsTransposition(DicTraverseSession* traverseSession,
+                                            DicNode* dicNode) const {
+  const int16_t pointIndex = dicNode->getInputIndex(0);
+  DicNodeVector childDicNodes1;
+  DicNodeVector childDicNodes2;
+  DicNodeUtils::getAllChildDicNodes(
+      dicNode, traverseSession->getDictionaryStructurePolicy(),
+      &childDicNodes1);
+  const int childSize1 = childDicNodes1.getSizeAndLock();
+  for (int i = 0; i < childSize1; i++) {
+    const ProximityType matchedId1 =
+        traverseSession->getProximityInfoState(0)->getProximityType(
+            pointIndex + 1, childDicNodes1[i]->getNodeCodePoint(),
+            true /* checkProximityChars */);
+    if (!ProximityInfoUtils::isMatchOrProximityChar(matchedId1)) {
+      continue;
+    }
+    if (childDicNodes1[i]->hasChildren()) {
+      childDicNodes2.clear();
+      DicNodeUtils::getAllChildDicNodes(
+          childDicNodes1[i], traverseSession->getDictionaryStructurePolicy(),
+          &childDicNodes2);
+      const int childSize2 = childDicNodes2.getSizeAndLock();
+      for (int j = 0; j < childSize2; j++) {
+        DicNode* const childDicNode2 = childDicNodes2[j];
+        const ProximityType matchedId2 =
+            traverseSession->getProximityInfoState(0)->getProximityType(
+                pointIndex, childDicNode2->getNodeCodePoint(),
+                true /* checkProximityChars */);
+        if (!ProximityInfoUtils::isMatchOrProximityChar(matchedId2)) {
+          continue;
+        }
+        Weighting::addCostAndForwardInputIndex(
+            WEIGHTING, CT_TRANSPOSITION, traverseSession, childDicNodes1[i],
+            childDicNode2, 0 /* multiBigramMap */);
+        processExpandedDicNode(traverseSession, childDicNode2);
+      }
+    }
+  }
+}
+
+/**
+ * Weight child dicNode by aligning it to the key
+ */
+void Suggest::weightChildNode(DicTraverseSession* traverseSession,
+                              DicNode* dicNode) const {
+  const int inputSize = traverseSession->getInputSize();
+  if (dicNode->isCompletion(inputSize)) {
+    Weighting::addCostAndForwardInputIndex(
+        WEIGHTING, CT_COMPLETION, traverseSession, 0 /* parentDicNode */,
+        dicNode, 0 /* multiBigramMap */);
+  } else {  // completion
+    Weighting::addCostAndForwardInputIndex(WEIGHTING, CT_MATCH, traverseSession,
+                                           0 /* parentDicNode */, dicNode,
+                                           0 /* multiBigramMap */);
+  }
+}
+
+/**
+ * Creates a new dicNode that represents a space insertion at the end of the
+ * input dicNode. Also
+ * incorporates the unigram / bigram score for the ending word into the new
+ * dicNode.
+ */
+void Suggest::createNextWordDicNode(DicTraverseSession* traverseSession,
+                                    DicNode* dicNode,
+                                    const bool spaceSubstitution) const {
+  if (!TRAVERSAL->isGoodToTraverseNextWord(dicNode)) {
+    return;
+  }
+
+  // Create a non-cached node here.
+  DicNode newDicNode;
+  DicNodeUtils::initAsRootWithPreviousWord(
+      traverseSession->getDictionaryStructurePolicy(), dicNode, &newDicNode);
+  const CorrectionType correctionType = spaceSubstitution
+                                            ? CT_NEW_WORD_SPACE_SUBSTITUTION
+                                            : CT_NEW_WORD_SPACE_OMISSION;
+  Weighting::addCostAndForwardInputIndex(WEIGHTING, correctionType,
+                                         traverseSession, dicNode, &newDicNode,
+                                         traverseSession->getMultiBigramMap());
+  if (newDicNode.getCompoundDistance() <
+      static_cast<float>(MAX_VALUE_FOR_WEIGHTING)) {
+    // newDicNode is worth continuing to traverse.
+    // CAVEAT: This pruning is important for speed. Remove this when we can
+    // afford not to prune
+    // here because here is not the right place to do pruning. Pruning should
+    // take place only
+    // in DicNodePriorityQueue.
+    traverseSession->getDicTraverseCache()->copyPushNextActive(&newDicNode);
+  }
+}
+}  // namespace latinime