Add spellcheck and word suggestion to the prediction service

third_party/android_prediction/suggest/core/result/suggestions_output_utils.cpp

Index: third_party/android_prediction/suggest/core/result/suggestions_output_utils.cpp
diff --git a/third_party/android_prediction/suggest/core/result/suggestions_output_utils.cpp b/third_party/android_prediction/suggest/core/result/suggestions_output_utils.cpp
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index 0000000000000000000000000000000000000000..727bcbf21502652eb8d0cb3eaa690b21891c61f7
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+++ b/third_party/android_prediction/suggest/core/result/suggestions_output_utils.cpp
@@ -0,0 +1,229 @@
+/*
+ * Copyright (C) 2013 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/android_prediction/suggest/core/result/suggestions_output_utils.h"
+
+#include <algorithm>
+#include <vector>
+
+#include "third_party/android_prediction/suggest/core/dicnode/dic_node.h"
+#include "third_party/android_prediction/suggest/core/dicnode/dic_node_utils.h"
+#include "third_party/android_prediction/suggest/core/dictionary/binary_dictionary_shortcut_iterator.h"
+#include "third_party/android_prediction/suggest/core/dictionary/error_type_utils.h"
+#include "third_party/android_prediction/suggest/core/policy/scoring.h"
+#include "third_party/android_prediction/suggest/core/result/suggestion_results.h"
+#include "third_party/android_prediction/suggest/core/session/dic_traverse_session.h"
+#include "third_party/android_prediction/suggest/core/suggest_options.h"
+
+namespace latinime {
+
+const int SuggestionsOutputUtils::MIN_LEN_FOR_MULTI_WORD_AUTOCORRECT = 16;
+
+/* static */ void SuggestionsOutputUtils::outputSuggestions(
+        const Scoring *const scoringPolicy, DicTraverseSession *traverseSession,
+        const float languageWeight, SuggestionResults *const outSuggestionResults) {
+#if DEBUG_EVALUATE_MOST_PROBABLE_STRING
+    const int terminalSize = 0;
+#else
+    const int terminalSize = traverseSession->getDicTraverseCache()->terminalSize();
+#endif
+    std::vector<DicNode> terminals(terminalSize);
+    for (int index = terminalSize - 1; index >= 0; --index) {
+        traverseSession->getDicTraverseCache()->popTerminal(&terminals[index]);
+    }
+    // Compute a language weight when an invalid language weight is passed.
+    // NOT_A_LANGUAGE_WEIGHT (-1) is assumed as an invalid language weight.
+    const float languageWeightToOutputSuggestions = (languageWeight < 0.0f) ?
+            scoringPolicy->getAdjustedLanguageWeight(
+                    traverseSession, terminals.data(), terminalSize) : languageWeight;
+    outSuggestionResults->setLanguageWeight(languageWeightToOutputSuggestions);
+    // Force autocorrection for obvious long multi-word suggestions when the top suggestion is
+    // a long multiple words suggestion.
+    // TODO: Implement a smarter auto-commit method for handling multi-word suggestions.
+    const bool forceCommitMultiWords = scoringPolicy->autoCorrectsToMultiWordSuggestionIfTop()
+            && (traverseSession->getInputSize() >= MIN_LEN_FOR_MULTI_WORD_AUTOCORRECT
+                    && !terminals.empty() && terminals.front().hasMultipleWords());
+    // TODO: have partial commit work even with multiple pointers.
+    const bool outputSecondWordFirstLetterInputIndex =
+            traverseSession->isOnlyOnePointerUsed(0 /* pointerId */);
+    const bool boostExactMatches = traverseSession->getDictionaryStructurePolicy()->
+            getHeaderStructurePolicy()->shouldBoostExactMatches();
+
+    // Output suggestion results here
+    for (auto &terminalDicNode : terminals) {
+        outputSuggestionsOfDicNode(scoringPolicy, traverseSession, &terminalDicNode,
+                languageWeightToOutputSuggestions, boostExactMatches, forceCommitMultiWords,
+                outputSecondWordFirstLetterInputIndex, outSuggestionResults);
+    }
+    scoringPolicy->getMostProbableString(traverseSession, languageWeightToOutputSuggestions,
+            outSuggestionResults);
+}
+
+/* static */ void SuggestionsOutputUtils::outputSuggestionsOfDicNode(
+        const Scoring *const scoringPolicy, DicTraverseSession *traverseSession,
+        const DicNode *const terminalDicNode, const float languageWeight,
+        const bool boostExactMatches, const bool forceCommitMultiWords,
+        const bool outputSecondWordFirstLetterInputIndex,
+        SuggestionResults *const outSuggestionResults) {
+    if (DEBUG_GEO_FULL) {
+        terminalDicNode->dump("OUT:");
+    }
+    const float doubleLetterCost =
+            scoringPolicy->getDoubleLetterDemotionDistanceCost(terminalDicNode);
+    const float compoundDistance = terminalDicNode->getCompoundDistance(languageWeight)
+            + doubleLetterCost;
+    const bool isPossiblyOffensiveWord =
+            traverseSession->getDictionaryStructurePolicy()->getProbability(
+                    terminalDicNode->getProbability(), NOT_A_PROBABILITY) <= 0;
+    const bool isExactMatch =
+            ErrorTypeUtils::isExactMatch(terminalDicNode->getContainedErrorTypes());
+    const bool isExactMatchWithIntentionalOmission =
+            ErrorTypeUtils::isExactMatchWithIntentionalOmission(
+                    terminalDicNode->getContainedErrorTypes());
+    const bool isFirstCharUppercase = terminalDicNode->isFirstCharUppercase();
+    // Heuristic: We exclude probability=0 first-char-uppercase words from exact match.
+    // (e.g. "AMD" and "and")
+    const bool isSafeExactMatch = isExactMatch
+            && !(isPossiblyOffensiveWord && isFirstCharUppercase);
+    const int outputTypeFlags =
+            (isPossiblyOffensiveWord ? Dictionary::KIND_FLAG_POSSIBLY_OFFENSIVE : 0)
+            | ((isSafeExactMatch && boostExactMatches) ? Dictionary::KIND_FLAG_EXACT_MATCH : 0)
+            | (isExactMatchWithIntentionalOmission ?
+                    Dictionary::KIND_FLAG_EXACT_MATCH_WITH_INTENTIONAL_OMISSION : 0);
+
+    // Entries that are blacklisted or do not represent a word should not be output.
+    const bool isValidWord = !terminalDicNode->isBlacklistedOrNotAWord();
+    // When we have to block offensive words, non-exact matched offensive words should not be
+    // output.
+    const bool blockOffensiveWords = traverseSession->getSuggestOptions()->blockOffensiveWords();
+    const bool isBlockedOffensiveWord = blockOffensiveWords && isPossiblyOffensiveWord
+            && !isSafeExactMatch;
+
+    // Increase output score of top typing suggestion to ensure autocorrection.
+    // TODO: Better integration with java side autocorrection logic.
+    const int finalScore = scoringPolicy->calculateFinalScore(
+            compoundDistance, traverseSession->getInputSize(),
+            terminalDicNode->getContainedErrorTypes(),
+            (forceCommitMultiWords && terminalDicNode->hasMultipleWords()),
+            boostExactMatches);
+
+    // Don't output invalid or blocked offensive words. However, we still need to submit their
+    // shortcuts if any.
+    if (isValidWord && !isBlockedOffensiveWord) {
+        int codePoints[MAX_WORD_LENGTH];
+        terminalDicNode->outputResult(codePoints);
+        const int indexToPartialCommit = outputSecondWordFirstLetterInputIndex ?
+                terminalDicNode->getSecondWordFirstInputIndex(
+                        traverseSession->getProximityInfoState(0)) :
+                NOT_AN_INDEX;
+        outSuggestionResults->addSuggestion(codePoints,
+                terminalDicNode->getTotalNodeCodePointCount(),
+                finalScore, Dictionary::KIND_CORRECTION | outputTypeFlags,
+                indexToPartialCommit, computeFirstWordConfidence(terminalDicNode));
+    }
+
+    // Output shortcuts.
+    // Shortcut is not supported for multiple words suggestions.
+    // TODO: Check shortcuts during traversal for multiple words suggestions.
+    if (!terminalDicNode->hasMultipleWords()) {
+        BinaryDictionaryShortcutIterator shortcutIt(
+                traverseSession->getDictionaryStructurePolicy()->getShortcutsStructurePolicy(),
+                traverseSession->getDictionaryStructurePolicy()
+                        ->getShortcutPositionOfPtNode(terminalDicNode->getPtNodePos()));
+        const bool sameAsTyped = scoringPolicy->sameAsTyped(traverseSession, terminalDicNode);
+        outputShortcuts(&shortcutIt, finalScore, sameAsTyped, outSuggestionResults);
+    }
+}
+
+/* static */ int SuggestionsOutputUtils::computeFirstWordConfidence(
+        const DicNode *const terminalDicNode) {
+    // Get the number of spaces in the first suggestion
+    const int spaceCount = terminalDicNode->getTotalNodeSpaceCount();
+    // Get the number of characters in the first suggestion
+    const int length = terminalDicNode->getTotalNodeCodePointCount();
+    // Get the distance for the first word of the suggestion
+    const float distance = terminalDicNode->getNormalizedCompoundDistanceAfterFirstWord();
+
+    // Arbitrarily, we give a score whose useful values range from 0 to 1,000,000.
+    // 1,000,000 will be the cutoff to auto-commit. It's fine if the number is under 0 or
+    // above 1,000,000 : under 0 just means it's very bad to commit, and above 1,000,000 means
+    // we are very confident.
+    // Expected space count is 1 ~ 5
+    static const int MIN_EXPECTED_SPACE_COUNT = 1;
+    static const int MAX_EXPECTED_SPACE_COUNT = 5;
+    // Expected length is about 4 ~ 30
+    static const int MIN_EXPECTED_LENGTH = 4;
+    static const int MAX_EXPECTED_LENGTH = 30;
+    // Expected distance is about 0.2 ~ 2.0, but consider 0.0 ~ 2.0
+    static const float MIN_EXPECTED_DISTANCE = 0.0;
+    static const float MAX_EXPECTED_DISTANCE = 2.0;
+    // This is not strict: it's where most stuff will be falling, but it's still fine if it's
+    // outside these values. We want to output a value that reflects all of these. Each factor
+    // contributes a bit.
+
+    // We need at least a space.
+    if (spaceCount < 1) return NOT_A_FIRST_WORD_CONFIDENCE;
+
+    // The smaller the edit distance, the higher the contribution. MIN_EXPECTED_DISTANCE means 0
+    // contribution, while MAX_EXPECTED_DISTANCE means full contribution according to the
+    // weight of the distance. Clamp to avoid overflows.
+    const float clampedDistance = distance < MIN_EXPECTED_DISTANCE ? MIN_EXPECTED_DISTANCE
+            : distance > MAX_EXPECTED_DISTANCE ? MAX_EXPECTED_DISTANCE : distance;
+    const int distanceContribution = DISTANCE_WEIGHT_FOR_AUTO_COMMIT
+            * (MAX_EXPECTED_DISTANCE - clampedDistance)
+            / (MAX_EXPECTED_DISTANCE - MIN_EXPECTED_DISTANCE);
+    // The larger the suggestion length, the larger the contribution. MIN_EXPECTED_LENGTH is no
+    // contribution, MAX_EXPECTED_LENGTH is full contribution according to the weight of the
+    // length. Length is guaranteed to be between 1 and 48, so we don't need to clamp.
+    const int lengthContribution = LENGTH_WEIGHT_FOR_AUTO_COMMIT
+            * (length - MIN_EXPECTED_LENGTH) / (MAX_EXPECTED_LENGTH - MIN_EXPECTED_LENGTH);
+    // The more spaces, the larger the contribution. MIN_EXPECTED_SPACE_COUNT space is no
+    // contribution, MAX_EXPECTED_SPACE_COUNT spaces is full contribution according to the
+    // weight of the space count.
+    const int spaceContribution = SPACE_COUNT_WEIGHT_FOR_AUTO_COMMIT
+            * (spaceCount - MIN_EXPECTED_SPACE_COUNT)
+            / (MAX_EXPECTED_SPACE_COUNT - MIN_EXPECTED_SPACE_COUNT);
+
+    return distanceContribution + lengthContribution + spaceContribution;
+}
+
+/* static */ void SuggestionsOutputUtils::outputShortcuts(
+        BinaryDictionaryShortcutIterator *const shortcutIt, const int finalScore,
+        const bool sameAsTyped, SuggestionResults *const outSuggestionResults) {
+    int shortcutTarget[MAX_WORD_LENGTH];
+    while (shortcutIt->hasNextShortcutTarget()) {
+        bool isWhilelist;
+        int shortcutTargetStringLength;
+        shortcutIt->nextShortcutTarget(MAX_WORD_LENGTH, shortcutTarget,
+                &shortcutTargetStringLength, &isWhilelist);
+        int shortcutScore;
+        int kind;
+        if (isWhilelist && sameAsTyped) {
+            shortcutScore = S_INT_MAX;
+            kind = Dictionary::KIND_WHITELIST;
+        } else {
+            // shortcut entry's score == its base entry's score - 1
+            shortcutScore = finalScore;
+            // Protection against int underflow
+            shortcutScore = std::max(S_INT_MIN + 1, shortcutScore) - 1;
+            kind = Dictionary::KIND_SHORTCUT;
+        }
+        outSuggestionResults->addSuggestion(shortcutTarget, shortcutTargetStringLength,
+                std::max(S_INT_MIN + 1, shortcutScore) - 1, kind, NOT_AN_INDEX,
+                NOT_A_FIRST_WORD_CONFIDENCE);
+    }
+}
+} // namespace latinime