Code refactoring: Make Cell::isDateTime() reliable

src/xlsx/qtxlsx.pri

@@ -34,7 +34,8 @@ HEADERS += $$PWD/xlsxdocpropscore_p.h \
     $$PWD/xlsxrichstring.h \
     $$PWD/xlsxconditionalformatting.h \
     $$PWD/xlsxconditionalformatting_p.h \
-    $$PWD/xlsxcolor_p.h
+    $$PWD/xlsxcolor_p.h \
+    $$PWD/xlsxnumformatparser_p.h
 
 SOURCES += $$PWD/xlsxdocpropscore.cpp \
     $$PWD/xlsxdocpropsapp.cpp \
@@ -57,4 +58,5 @@ SOURCES += $$PWD/xlsxdocpropscore.cpp \
     $$PWD/xlsxcellrange.cpp \
     $$PWD/xlsxrichstring.cpp \
     $$PWD/xlsxconditionalformatting.cpp \
-    $$PWD/xlsxcolor.cpp
+    $$PWD/xlsxcolor.cpp \
+    $$PWD/xlsxnumformatparser.cpp

src/xlsx/xlsxcell.cpp

@@ -122,8 +122,10 @@ QString Cell::formula() const
 bool Cell::isDateTime() const
 {
     Q_D(const Cell);
-    if (d->dataType == Numeric && d->format.isValid() && d->format.isDateTimeFormat())
+    if (d->dataType == Numeric && d->value.toDouble() >=0
+            && d->format.isValid() && d->format.isDateTimeFormat()) {
         return true;
+    }
     return false;
 }
 

src/xlsx/xlsxformat.cpp

@@ -25,8 +25,8 @@
 #include "xlsxformat.h"
 #include "xlsxformat_p.h"
 #include "xlsxcolor_p.h"
+#include "xlsxnumformatparser_p.h"
 #include <QDataStream>
-#include <QRegularExpression>
 #include <QDebug>
 
 QT_BEGIN_NAMESPACE_XLSX
@@ -266,16 +266,16 @@ bool Format::isDateTimeFormat() const
     if (hasProperty(FormatPrivate::P_NumFmt_FormatCode)) {
         //Custom numFmt, so
         //Gauss from the number string
-        QString formatCode = numberFormat();
-        formatCode.remove(QRegularExpression(QStringLiteral("\\[(Green|White|Blue|Magenta|Yellow|Cyan|Red)\\]")));
-        if (formatCode.contains(QRegularExpression(QStringLiteral("[dmhys]"))))
-            return true;
+        return NumFormatParser::isDateTime(numberFormat());
     } else if (hasProperty(FormatPrivate::P_NumFmt_Id)){
         //Non-custom numFmt
         int idx = numberFormatIndex();
 
         //Is built-in date time number id?
-        if ((idx >= 15 && idx <= 22) || (idx >= 45 && idx <= 47))
+        if ((idx >= 14 && idx <= 22) || (idx >= 45 && idx <= 47))
+            return true;
+
+        if ((idx >= 27 && idx <= 36) || (idx >= 50 && idx <= 58)) //Used in CHS\CHT\JPN\KOR
             return true;
     }
 

src/xlsx/xlsxnumformatparser.cpp

@@ -0,0 +1,94 @@
+/****************************************************************************
+** Copyright (c) 2013 Debao Zhang <hello@debao.me>
+** All right reserved.
+**
+** Permission is hereby granted, free of charge, to any person obtaining
+** a copy of this software and associated documentation files (the
+** "Software"), to deal in the Software without restriction, including
+** without limitation the rights to use, copy, modify, merge, publish,
+** distribute, sublicense, and/or sell copies of the Software, and to
+** permit persons to whom the Software is furnished to do so, subject to
+** the following conditions:
+**
+** The above copyright notice and this permission notice shall be
+** included in all copies or substantial portions of the Software.
+**
+** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+** NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+** LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+** OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+** WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+**
+****************************************************************************/
+#include "xlsxnumformatparser_p.h"
+
+#include <QString>
+
+namespace QXlsx {
+
+bool NumFormatParser::isDateTime(const QString &formatCode)
+{
+    for (int i = 0; i < formatCode.length(); ++i) {
+        const QChar &c = formatCode[i];
+
+        switch (c.unicode()) {
+        case '[':
+            // [h], [m], [s] are valid format for time
+            if (i < formatCode.length()-2 && formatCode[i+2] == QLatin1Char(']')) {
+                const QChar cc = formatCode[i+1].toLower();
+                if (cc == QLatin1Char('h') || cc == QLatin1Char('m') || cc == QLatin1Char('s'))
+                    return true;
+                i+=2;
+                break;
+            } else {
+                // condition or color: don't care, ignore
+                while (i < formatCode.length() && formatCode[i] != QLatin1Char(']'))
+                    ++i;
+                break;
+            }
+
+        // quoted plain text block: don't care, ignore
+        case '"':
+            while (i < formatCode.length()-1 && formatCode[++i] != QLatin1Char('"'))
+                ;
+            break;
+
+        // escaped char: don't care, ignore
+        case '\\':
+            if (i < formatCode.length() - 1)
+                ++i;
+            break;
+
+        // date/time can only be positive number,
+        // so only the first section of the format make sense.
+        case ';':
+            return false;
+            break;
+
+        // days
+        case 'D':
+        case 'd':
+        // years
+        case 'Y':
+        case 'y':
+        // hours
+        case 'H':
+        case 'h':
+        // seconds
+        case 'S':
+        case 's':
+        // minutes or months, depending on context
+        case 'M':
+        case 'm':
+            return true;
+
+        default:
+            break;
+        }
+    }
+    return false;
+}
+
+} // namespace QXlsx

src/xlsx/xlsxnumformatparser_p.h

@@ -0,0 +1,51 @@
+/****************************************************************************
+** Copyright (c) 2013 Debao Zhang <hello@debao.me>
+** All right reserved.
+**
+** Permission is hereby granted, free of charge, to any person obtaining
+** a copy of this software and associated documentation files (the
+** "Software"), to deal in the Software without restriction, including
+** without limitation the rights to use, copy, modify, merge, publish,
+** distribute, sublicense, and/or sell copies of the Software, and to
+** permit persons to whom the Software is furnished to do so, subject to
+** the following conditions:
+**
+** The above copyright notice and this permission notice shall be
+** included in all copies or substantial portions of the Software.
+**
+** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+** NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+** LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+** OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+** WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+**
+****************************************************************************/
+#ifndef QXLSX_NUMFORMATPARSER_H
+#define QXLSX_NUMFORMATPARSER_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt Xlsx API.  It exists for the convenience
+// of the Qt Xlsx.  This header file may change from
+// version to version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "xlsxglobal.h"
+
+namespace QXlsx {
+
+class NumFormatParser
+{
+public:
+    static bool isDateTime(const QString &formatCode);
+};
+
+} // namespace QXlsx
+
+#endif // QXLSX_NUMFORMATPARSER_H