ZhuyinTable: throughly QStringView-enable

Nothing in the implementation of ZhuyinTable needs QList, or
QString. This is all very basic parsing. So use QStringView. Now all
operations are free of dynamic memory allocations.

Saves ~2.7KiB (0.9%) in text size on optimized AMD64 Linux GCC 9.1
builds.

Change-Id: Iefa38980b52ede17a0c11f752653616d1944911a
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

4 files changed, 83 insertions, 100 deletions

diff --git a/src/plugins/tcime/3rdparty/tcime/zhuyindictionary.cpp b/src/plugins/tcime/3rdparty/tcime/zhuyindictionary.cpp
index 1cf303c1..6bcc08a1 100644
--- a/src/plugins/tcime/3rdparty/tcime/zhuyindictionary.cpp
+++ b/src/plugins/tcime/3rdparty/tcime/zhuyindictionary.cpp
@@ -32,8 +32,8 @@ ZhuyinDictionary::ZhuyinDictionary() :
 QStringList ZhuyinDictionary::getWords(const QString &input) const
 {
     // Look up the syllables index; return empty string for invalid syllables.
-    QStringList pair = ZhuyinTable::stripTones(input);
-    int syllablesIndex = !pair.isEmpty() ? ZhuyinTable::getSyllablesIndex(pair[0]) : -1;
+    auto strippedTones = ZhuyinTable::stripTones(input);
+    int syllablesIndex = strippedTones.ok ? ZhuyinTable::getSyllablesIndex(strippedTones.pair[0]) : -1;
     if (syllablesIndex < 0 || syllablesIndex >= dictionary().size())
         return QStringList();
 
@@ -44,7 +44,7 @@ QStringList ZhuyinDictionary::getWords(const QString &input) const
         return QStringList();
 
     // Counts of words for each tone are stored in the array beginning.
-    int tone = ZhuyinTable::getTones(pair[1].at(0));
+    int tone = ZhuyinTable::getTones(strippedTones.pair[1].at(0));
     int length = (int) data[tone].unicode();
     if (length == 0)
         return QStringList();
diff --git a/src/plugins/tcime/3rdparty/tcime/zhuyintable.cpp b/src/plugins/tcime/3rdparty/tcime/zhuyintable.cpp
index 7dc62f37..2f3da2ab 100644
--- a/src/plugins/tcime/3rdparty/tcime/zhuyintable.cpp
+++ b/src/plugins/tcime/3rdparty/tcime/zhuyintable.cpp
@@ -20,41 +20,51 @@
  */
 
 #include "zhuyintable.h"
-#include <QStringList>
+
+#include <QStringView>
 
 using namespace tcime;
 
-const int ZhuyinTable::INITIALS_SIZE = 22;
-const QList<QChar> ZhuyinTable::yiEndingFinals = QList<QChar>()
-        << QChar(0x311a) << QChar(0x311b) << QChar(0x311d) << QChar(0x311e) << QChar(0x3120) << QChar(0x3121) << QChar(0x3122)
-        << QChar(0x3123) << QChar(0x3124) << QChar(0x3125);
-const QList<QChar> ZhuyinTable::wuEndingFinals = QList<QChar>()
-        << QChar(0x311a) << QChar(0x311b) << QChar(0x311e) << QChar(0x311f) << QChar(0x3122) << QChar(0x3123) << QChar(0x3124)
-        << QChar(0x3125);
-const QList<QChar> ZhuyinTable::yuEndingFinals = QList<QChar>()
-        << QChar(0x311d) << QChar(0x3122) << QChar(0x3123) << QChar(0x3125);
-const int ZhuyinTable::YI_FINALS_INDEX = 14;
-const int ZhuyinTable::WU_FINALS_INDEX = 25;
-const int ZhuyinTable::YU_FINALS_INDEX = 34;
-const QChar ZhuyinTable::YI_FINALS(0x3127);
-const QChar ZhuyinTable::WU_FINALS(0x3128);
-const QChar ZhuyinTable::YU_FINALS (0x3129);
-const QList<QChar> ZhuyinTable::tones = QList<QChar>()
-        << ZhuyinTable::DEFAULT_TONE << QChar(0x02d9) << QChar(0x02ca) << QChar(0x02c7) << QChar(0x02cb);
+// All Chinese characters are mapped into a zhuyin table as described in
+// http://en.wikipedia.org/wiki/Zhuyin_table.
+const int INITIALS_SIZE = 22;
+
+// Finals that can be appended after 'ㄧ' (yi), 'ㄨ' (wu), or 'ㄩ' (yu).
+static Q_CONSTEXPR char16_t yiEndingFinals[] =
+        u"\x311a\x311b\x311d\x311e\x3120\x3121\x3122\x3123\x3124\x3125";
+static Q_CONSTEXPR char16_t wuEndingFinals[] =
+        u"\x311a\x311b\x311e\x311f\x3122\x3123\x3124\x3125";
+static Q_CONSTEXPR char16_t yuEndingFinals[] =
+        u"\x311d\x3122\x3123\x3125";
+
+// 'ㄧ' (yi) finals start from position 14 and are followed by 'ㄨ' (wu)
+// finals, and 'ㄩ' (yu) finals follow after 'ㄨ' (wu) finals.
+const int YI_FINALS_INDEX = 14;
+const int WU_FINALS_INDEX = 25;
+const int YU_FINALS_INDEX = 34;
+
+// 'ㄧ' (yi), 'ㄨ' (wu) , and 'ㄩ' (yu) finals.
+const QChar YI_FINALS(0x3127);
+const QChar WU_FINALS(0x3128);
+const QChar YU_FINALS (0x3129);
+
 const QChar ZhuyinTable::DEFAULT_TONE = QLatin1Char(' ');
 
-int ZhuyinTable::getInitials(const QChar &initials)
+// Default tone and four tone symbols: '˙', 'ˊ', 'ˇ', and 'ˋ'.
+static Q_CONSTEXPR char16_t tones[] = u" \x02d9\x02ca\x02c7\x02cb";
+
+int ZhuyinTable::getInitials(QChar initials)
 {
     // Calculate the index by its distance to the first initials 'ㄅ' (b).
     int index = initials.unicode() - 0x3105 + 1;
-    if (index >= ZhuyinTable::INITIALS_SIZE)
+    if (index >= INITIALS_SIZE)
         // Syllables starting with finals can still be valid.
         return 0;
 
     return (index >= 0) ? index : -1;
 }
 
-int ZhuyinTable::getFinals(const QString &finals)
+int ZhuyinTable::getFinals(QStringView finals)
 {
     if (finals.length() == 0)
         // Syllables ending with no finals can still be valid.
@@ -72,7 +82,7 @@ int ZhuyinTable::getFinals(const QString &finals)
         return index;
 
     // Check 'ㄧ' (yi), 'ㄨ' (wu) , and 'ㄩ' (yu) group finals.
-    QList<QChar> endingFinals;
+    QStringView endingFinals;
     if (firstFinal == YI_FINALS) {
         index = YI_FINALS_INDEX;
         endingFinals = yiEndingFinals;
@@ -96,7 +106,7 @@ int ZhuyinTable::getFinals(const QString &finals)
     return -1;
 }
 
-int ZhuyinTable::getSyllablesIndex(const QString &syllables)
+int ZhuyinTable::getSyllablesIndex(QStringView syllables)
 {
     if (syllables.isEmpty())
         return -1;
@@ -113,48 +123,50 @@ int ZhuyinTable::getSyllablesIndex(const QString &syllables)
     return (finals * INITIALS_SIZE + initials);
 }
 
-int ZhuyinTable::getTones(const QChar &c)
+int ZhuyinTable::getTones(QChar c)
 {
-    for (int i = 0; i < tones.size(); ++i) {
-        if (tones[i] == c)
-            return i;
-    }
+    const qsizetype i = QStringView(tones).indexOf(c);
+    if (i >= 0)
+        return int(i);
     // Treat all other characters as the default tone with the index 0.
     return 0;
 }
 
 int ZhuyinTable::getTonesCount()
 {
-    return tones.size();
+    return int(QStringView(tones).size());
 }
 
-bool ZhuyinTable::isTone(const QChar &c)
+bool ZhuyinTable::isTone(QChar c)
 {
-    for (int i = 0; i < tones.size(); ++i) {
-        if (tones[i] == c)
-            return true;
-    }
-    return false;
+    return QStringView(tones).contains(c);
 }
 
-bool ZhuyinTable::isYiWuYuFinals(const QChar &c)
+bool ZhuyinTable::isYiWuYuFinals(QChar c)
 {
     return c == YI_FINALS || c == WU_FINALS || c == YU_FINALS;
 }
 
-QStringList ZhuyinTable::stripTones(const QString &input)
+auto ZhuyinTable::stripTones(QStringView input) -> StripTonesResult
 {
-    const int last = input.length() - 1;
-    if (last < 0)
-        return QStringList();
+    StripTonesResult result;
+    result.ok = false;
+    if (input.isEmpty())
+        return result;
 
-    QChar tone = input.at(last);
+    const QChar tone = input.back();
     if (isTone(tone)) {
-        QString syllables = input.left(last);
-        if (syllables.length() <= 0)
-            return QStringList();
-        return QStringList() << syllables << QString(tone);
+        QStringView syllables = input.chopped(1);
+        if (!syllables.isEmpty()) {
+            result.pair[0] = syllables;
+            result.pair[1] = input.right(1);
+            result.ok = true;
+        }
+    } else {
+        // Treat the tone-less input as the default tone (tone-0).
+        result.pair[0] = input;
+        result.pair[1] = QStringView(&DEFAULT_TONE, 1);
+        result.ok = true;
     }
-    // Treat the tone-less input as the default tone (tone-0).
-    return QStringList() << input << QString(DEFAULT_TONE);
+    return result;
 }
diff --git a/src/plugins/tcime/3rdparty/tcime/zhuyintable.h b/src/plugins/tcime/3rdparty/tcime/zhuyintable.h
index 8512574e..57e9d36c 100644
--- a/src/plugins/tcime/3rdparty/tcime/zhuyintable.h
+++ b/src/plugins/tcime/3rdparty/tcime/zhuyintable.h
@@ -22,53 +22,24 @@
 #ifndef ZHUYINTABLE_H
 #define ZHUYINTABLE_H
 
-#include <QMap>
-#include <QChar>
-#include <QString>
+#include <QtCore/QStringView>
 
 namespace tcime {
-
-class ZhuyinTable
-{
-    Q_DISABLE_COPY(ZhuyinTable)
-    ZhuyinTable() {}
-
-    // All Chinese characters are mapped into a zhuyin table as described in
-    // http://en.wikipedia.org/wiki/Zhuyin_table.
-    static const int INITIALS_SIZE;
-
-    // Finals that can be appended after 'ㄧ' (yi), 'ㄨ' (wu), or 'ㄩ' (yu).
-    static const QList<QChar> yiEndingFinals;
-    static const QList<QChar> wuEndingFinals;
-    static const QList<QChar> yuEndingFinals;
-
-    // 'ㄧ' (yi) finals start from position 14 and are followed by 'ㄨ' (wu)
-    // finals, and 'ㄩ' (yu) finals follow after 'ㄨ' (wu) finals.
-    static const int YI_FINALS_INDEX;
-    static const int WU_FINALS_INDEX;
-    static const int YU_FINALS_INDEX;
-
-    // 'ㄧ' (yi), 'ㄨ' (wu) , and 'ㄩ' (yu) finals.
-    static const QChar YI_FINALS;
-    static const QChar WU_FINALS;
-    static const QChar YU_FINALS;
-
-    // Default tone and four tone symbols: '˙', 'ˊ', 'ˇ', and 'ˋ'.
-    static const QList<QChar> tones;
-
-public:
+struct ZhuyinTable {
     static const QChar DEFAULT_TONE;
-
-    static int getInitials(const QChar &initials);
-    static int getFinals(const QString &finals);
-    static int getSyllablesIndex(const QString &syllables);
-    static int getTones(const QChar &c);
+    static int getInitials(QChar initials);
+    static int getFinals(QStringView finals);
+    static int getSyllablesIndex(QStringView syllables);
+    static int getTones(QChar c);
     static int getTonesCount();
-    static bool isTone(const QChar &c);
-    static bool isYiWuYuFinals(const QChar &c);
-    static QStringList stripTones(const QString &input);
+    static bool isTone(QChar c);
+    static bool isYiWuYuFinals(QChar c);
+    struct StripTonesResult {
+        bool ok;
+        QStringView pair[2];
+    };
+    static StripTonesResult stripTones(QStringView input);
 };
-
 }
 
 #endif // ZHUYINTABLE_H
diff --git a/src/plugins/tcime/plugin/tcinputmethod.cpp b/src/plugins/tcime/plugin/tcinputmethod.cpp
index 1f5fc6e3..73a4b900 100644
--- a/src/plugins/tcime/plugin/tcinputmethod.cpp
+++ b/src/plugins/tcime/plugin/tcinputmethod.cpp
@@ -206,14 +206,14 @@ public:
                 // Tones are accepted only when there's text in composing.
                 return false;
 
-            QStringList pair = ZhuyinTable::stripTones(input);
-            if (pair.isEmpty())
+            auto strippedTones = ZhuyinTable::stripTones(input);
+            if (!strippedTones.ok)
                 // Tones cannot be composed if there's no syllables.
                 return false;
 
             // Replace the original tone with the new tone, but the default tone
             // character should not be composed into the composing text.
-            QChar tone = pair[1].at(0);
+            QChar tone = strippedTones.pair[1].at(0);
             if (c == ZhuyinTable::DEFAULT_TONE) {
                 if (tone != ZhuyinTable::DEFAULT_TONE)
                     input.remove(input.length() - 1, 1);
@@ -229,7 +229,7 @@ public:
                 input.insert(0, c);
             else
                 input.replace(0, 1, c);
-        } else if (ZhuyinTable::getFinals(QString(c)) > 0) {
+        } else if (ZhuyinTable::getFinals(QStringView(&c, 1)) > 0) {
             // Replace the finals in the decomposed of syllables and tones.
             QList<QChar> decomposed = decomposeZhuyin();
             if (ZhuyinTable::isYiWuYuFinals(c)) {
@@ -261,15 +261,15 @@ public:
     QList<QChar> decomposeZhuyin()
     {
         QList<QChar> results = {QChar::Null, QChar::Null, QChar::Null, QChar::Null};
-        QStringList pair = ZhuyinTable::stripTones(input);
-        if (!pair.isEmpty()) {
+        auto strippedTones = ZhuyinTable::stripTones(input);
+        if (strippedTones.ok) {
             // Decompose tones.
-            QChar tone = pair[1].at(0);
+            QChar tone = strippedTones.pair[1].at(0);
             if (tone != ZhuyinTable::DEFAULT_TONE)
                 results[3] = tone;
 
             // Decompose initials.
-            QString syllables = pair[0];
+            QStringView syllables = strippedTones.pair[0];
             if (ZhuyinTable::getInitials(syllables.at(0)) > 0) {
                 results[0] = syllables.at(0);
                 syllables = syllables.mid(1);