5 files changed, 78 insertions, 32 deletions

diff --git a/native/jni/src/utils/byte_array_view.h b/native/jni/src/utils/byte_array_view.h
index 2c97c6d58..2b778af6f 100644
--- a/native/jni/src/utils/byte_array_view.h
+++ b/native/jni/src/utils/byte_array_view.h
@@ -42,6 +42,13 @@ class ReadOnlyByteArrayView {
         return mPtr;
     }
 
+    AK_FORCE_INLINE const ReadOnlyByteArrayView skip(const size_t n) const {
+        if (mSize <= n) {
+            return ReadOnlyByteArrayView();
+        }
+        return ReadOnlyByteArrayView(mPtr + n, mSize - n);
+    }
+
  private:
     DISALLOW_ASSIGNMENT_OPERATOR(ReadOnlyByteArrayView);
 
@@ -77,10 +84,12 @@ class ReadWriteByteArrayView {
     }
 
  private:
-    DISALLOW_ASSIGNMENT_OPERATOR(ReadWriteByteArrayView);
+    // Default copy constructor and assignment operator are used for using this class with STL
+    // containers.
 
-    uint8_t *const mPtr;
-    const size_t mSize;
+    // These members cannot be const to have the assignment operator.
+    uint8_t *mPtr;
+    size_t mSize;
 };
 
 } // namespace latinime
diff --git a/native/jni/src/utils/char_utils.cpp b/native/jni/src/utils/char_utils.cpp
index b17e0847d..3bb9055b2 100644
--- a/native/jni/src/utils/char_utils.cpp
+++ b/native/jni/src/utils/char_utils.cpp
@@ -1057,11 +1057,11 @@ static int compare_pair_capital(const void *a, const void *b) {
             - static_cast<int>((static_cast<const struct LatinCapitalSmallPair *>(b))->capital);
 }
 
-/* static */ unsigned short CharUtils::latin_tolower(const unsigned short c) {
+/* static */ int CharUtils::latin_tolower(const int c) {
     struct LatinCapitalSmallPair *p =
             static_cast<struct LatinCapitalSmallPair *>(bsearch(&c, SORTED_CHAR_MAP,
                     NELEMS(SORTED_CHAR_MAP), sizeof(SORTED_CHAR_MAP[0]), compare_pair_capital));
-    return p ? p->small : c;
+    return p ? static_cast<int>(p->small) : c;
 }
 
 /*
diff --git a/native/jni/src/utils/char_utils.h b/native/jni/src/utils/char_utils.h
index 63786502b..5e9cdd9b2 100644
--- a/native/jni/src/utils/char_utils.h
+++ b/native/jni/src/utils/char_utils.h
@@ -27,20 +27,14 @@ namespace latinime {
 
 class CharUtils {
  public:
+    static const std::vector<int> EMPTY_STRING;
+
     static AK_FORCE_INLINE bool isAsciiUpper(int c) {
         // Note: isupper(...) reports false positives for some Cyrillic characters, causing them to
         // be incorrectly lower-cased using toAsciiLower(...) rather than latin_tolower(...).
         return (c >= 'A' && c <= 'Z');
     }
 
-    static AK_FORCE_INLINE int toAsciiLower(int c) {
-        return c - 'A' + 'a';
-    }
-
-    static AK_FORCE_INLINE bool isAscii(int c) {
-        return isascii(c) != 0;
-    }
-
     static AK_FORCE_INLINE int toLowerCase(const int c) {
         if (isAsciiUpper(c)) {
             return toAsciiLower(c);
@@ -48,7 +42,7 @@ class CharUtils {
         if (isAscii(c)) {
             return c;
         }
-        return static_cast<int>(latin_tolower(static_cast<unsigned short>(c)));
+        return latin_tolower(c);
     }
 
     static AK_FORCE_INLINE int toBaseLowerCase(const int c) {
@@ -59,7 +53,6 @@ class CharUtils {
         // TODO: Do not hardcode here
         return codePoint == KEYCODE_SINGLE_QUOTE || codePoint == KEYCODE_HYPHEN_MINUS;
     }
-
     static AK_FORCE_INLINE int getCodePointCount(const int arraySize, const int *const codePoints) {
         int size = 0;
         for (; size < arraySize; ++size) {
@@ -91,9 +84,6 @@ class CharUtils {
         return codePoint >= MIN_UNICODE_CODE_POINT && codePoint <= MAX_UNICODE_CODE_POINT;
     }
 
-    static unsigned short latin_tolower(const unsigned short c);
-    static const std::vector<int> EMPTY_STRING;
-
     // Returns updated code point count. Returns 0 when the code points cannot be marked as a
     // Beginning-of-Sentence.
     static AK_FORCE_INLINE int attachBeginningOfSentenceMarker(int *const codePoints,
@@ -125,6 +115,16 @@ class CharUtils {
      */
     static const int BASE_CHARS_SIZE = 0x0500;
     static const unsigned short BASE_CHARS[BASE_CHARS_SIZE];
+
+    static AK_FORCE_INLINE bool isAscii(int c) {
+        return isascii(c) != 0;
+    }
+
+    static AK_FORCE_INLINE int toAsciiLower(int c) {
+        return c - 'A' + 'a';
+    }
+
+    static int latin_tolower(const int c);
 };
 } // namespace latinime
 #endif // LATINIME_CHAR_UTILS_H
diff --git a/native/jni/src/utils/int_array_view.h b/native/jni/src/utils/int_array_view.h
index c1ddc9812..f3a8589ca 100644
--- a/native/jni/src/utils/int_array_view.h
+++ b/native/jni/src/utils/int_array_view.h
@@ -17,8 +17,10 @@
 #ifndef LATINIME_INT_ARRAY_VIEW_H
 #define LATINIME_INT_ARRAY_VIEW_H
 
+#include <algorithm>
+#include <array>
 #include <cstdint>
-#include <cstdlib>
+#include <cstring>
 #include <vector>
 
 #include "defines.h"
@@ -56,14 +58,14 @@ class IntArrayView {
     explicit IntArrayView(const std::vector<int> &vector)
             : mPtr(vector.data()), mSize(vector.size()) {}
 
-    template <int N>
-    AK_FORCE_INLINE static IntArrayView fromFixedSizeArray(const int (&array)[N]) {
-        return IntArrayView(array, N);
+    template <size_t N>
+    AK_FORCE_INLINE static IntArrayView fromArray(const std::array<int, N> &array) {
+        return IntArrayView(array.data(), array.size());
     }
 
-    // Returns a view that points one int object. Does not take ownership of the given object.
-    AK_FORCE_INLINE static IntArrayView fromObject(const int *const object) {
-        return IntArrayView(object, 1);
+    // Returns a view that points one int object.
+    AK_FORCE_INLINE static IntArrayView singleElementView(const int *const ptr) {
+        return IntArrayView(ptr, 1);
     }
 
     AK_FORCE_INLINE int operator[](const size_t index) const {
@@ -91,6 +93,42 @@ class IntArrayView {
         return mPtr + mSize;
     }
 
+    AK_FORCE_INLINE bool contains(const int value) const {
+        return std::find(begin(), end(), value) != end();
+    }
+
+    // Returns the view whose size is smaller than or equal to the given count.
+    AK_FORCE_INLINE const IntArrayView limit(const size_t maxSize) const {
+        return IntArrayView(mPtr, std::min(maxSize, mSize));
+    }
+
+    AK_FORCE_INLINE const IntArrayView skip(const size_t n) const {
+        if (mSize <= n) {
+            return IntArrayView();
+        }
+        return IntArrayView(mPtr + n, mSize - n);
+    }
+
+    template <size_t N>
+    void copyToArray(std::array<int, N> *const buffer, const size_t offset) const {
+        ASSERT(mSize + offset <= N);
+        memmove(buffer->data() + offset, mPtr, sizeof(int) * mSize);
+    }
+
+    AK_FORCE_INLINE int firstOrDefault(const int defaultValue) const {
+        if (empty()) {
+            return defaultValue;
+        }
+        return mPtr[0];
+    }
+
+    AK_FORCE_INLINE int lastOrDefault(const int defaultValue) const {
+        if (empty()) {
+            return defaultValue;
+        }
+        return mPtr[mSize - 1];
+    }
+
  private:
     DISALLOW_ASSIGNMENT_OPERATOR(IntArrayView);
 
@@ -100,6 +138,9 @@ class IntArrayView {
 
 using WordIdArrayView = IntArrayView;
 using PtNodePosArrayView = IntArrayView;
+using CodePointArrayView = IntArrayView;
+template <size_t size>
+using WordIdArray = std::array<int, size>;
 
 } // namespace latinime
 #endif // LATINIME_MEMORY_VIEW_H
diff --git a/native/jni/src/utils/jni_data_utils.h b/native/jni/src/utils/jni_data_utils.h
index cb82d3c3b..235a03bba 100644
--- a/native/jni/src/utils/jni_data_utils.h
+++ b/native/jni/src/utils/jni_data_utils.h
@@ -97,17 +97,13 @@ class JniDataUtils {
     }
 
     static PrevWordsInfo constructPrevWordsInfo(JNIEnv *env, jobjectArray prevWordCodePointArrays,
-            jbooleanArray isBeginningOfSentenceArray) {
+            jbooleanArray isBeginningOfSentenceArray, const size_t prevWordCount) {
         int prevWordCodePoints[MAX_PREV_WORD_COUNT_FOR_N_GRAM][MAX_WORD_LENGTH];
         int prevWordCodePointCount[MAX_PREV_WORD_COUNT_FOR_N_GRAM];
         bool isBeginningOfSentence[MAX_PREV_WORD_COUNT_FOR_N_GRAM];
-        jsize prevWordsCount = env->GetArrayLength(prevWordCodePointArrays);
-        for (size_t i = 0; i < NELEMS(prevWordCodePoints); ++i) {
+        for (size_t i = 0; i < prevWordCount; ++i) {
             prevWordCodePointCount[i] = 0;
             isBeginningOfSentence[i] = false;
-            if (prevWordsCount <= static_cast<int>(i)) {
-                continue;
-            }
             jintArray prevWord = (jintArray)env->GetObjectArrayElement(prevWordCodePointArrays, i);
             if (!prevWord) {
                 continue;
@@ -124,7 +120,7 @@ class JniDataUtils {
             isBeginningOfSentence[i] = isBeginningOfSentenceBoolean == JNI_TRUE;
         }
         return PrevWordsInfo(prevWordCodePoints, prevWordCodePointCount, isBeginningOfSentence,
-                MAX_PREV_WORD_COUNT_FOR_N_GRAM);
+                prevWordCount);
     }
 
     static void putBooleanToArray(JNIEnv *env, jbooleanArray array, const int index,