File indexing completed on 2024-04-28 15:30:55

 /*
     SPDX-FileCopyrightText: 2022 Waqar Ahmed <waqar.17a@gmail.com>
 
     SPDX-License-Identifier: LGPL-2.0-or-later
 */
 #include "kateindentdetecter.h"
 
 KateIndentDetecter::KateIndentDetecter(KTextEditor::DocumentPrivate *doc)
     : m_doc(doc)
 {
 }
 
 struct SpacesDiffResult {
     int spacesDiff = 0;
     bool looksLikeAlignment = false;
 };
 
 static SpacesDiffResult spacesDiff(const QString &a, int aLength, const QString &b, int bLength)
 {
     SpacesDiffResult result;
     result.spacesDiff = 0;
     result.looksLikeAlignment = false;
 
     // This can go both ways (e.g.):
     //  - a: "\t"
     //  - b: "\t    "
     //  => This should count 1 tab and 4 spaces
 
     int i = 0;
 
     for (i = 0; i < aLength && i < bLength; i++) {
         const auto aCharCode = a.at(i);
         const auto bCharCode = b.at(i);
 
         if (aCharCode != bCharCode) {
             break;
         }
     }
 
     int aSpacesCnt = 0;
     int aTabsCount = 0;
     for (int j = i; j < aLength; j++) {
         const auto aCharCode = a.at(j);
         if (aCharCode == QLatin1Char(' ')) {
             aSpacesCnt++;
         } else {
             aTabsCount++;
         }
     }
 
     int bSpacesCnt = 0;
     int bTabsCount = 0;
     for (int j = i; j < bLength; j++) {
         const auto bCharCode = b.at(j);
         if (bCharCode == QLatin1Char(' ')) {
             bSpacesCnt++;
         } else {
             bTabsCount++;
         }
     }
 
     if (aSpacesCnt > 0 && aTabsCount > 0) {
         return result;
     }
     if (bSpacesCnt > 0 && bTabsCount > 0) {
         return result;
     }
 
     const auto tabsDiff = std::abs(aTabsCount - bTabsCount);
     const auto spacesDiff = std::abs(aSpacesCnt - bSpacesCnt);
 
     if (tabsDiff == 0) {
         // check if the indentation difference might be caused by alignment reasons
         // sometime folks like to align their code, but this should not be used as a hint
         result.spacesDiff = spacesDiff;
 
         if (spacesDiff > 0 && 0 <= bSpacesCnt - 1 && bSpacesCnt - 1 < a.length() && bSpacesCnt < b.length()) {
             if (b.at(bSpacesCnt) != QLatin1Char(' ') && a.at(bSpacesCnt - 1) == QLatin1Char(' ')) {
                 if (a.at(a.length() - 1) == QLatin1Char(',')) {
                     // This looks like an alignment desire: e.g.
                     // const a = b + c,
                     //       d = b - c;
                     result.looksLikeAlignment = true;
                 }
             }
         }
         return result;
     }
     if (spacesDiff % tabsDiff == 0) {
         result.spacesDiff = spacesDiff / tabsDiff;
         return result;
     }
     return result;
 }
 
 KateIndentDetecter::Result KateIndentDetecter::detect(int defaultTabSize, bool defaultInsertSpaces)
 {
     // Look at most at the first 10k lines
     const int linesCount = std::min(m_doc->lines(), 10000);
 
     int linesIndentedWithTabsCount = 0; // number of lines that contain at least one tab in indentation
     int linesIndentedWithSpacesCount = 0; // number of lines that contain only spaces in indentation
 
     QString previousLineText; // content of latest line that contained non-whitespace chars
     int previousLineIndentation = 0; // index at which latest line contained the first non-whitespace char
 
     constexpr int ALLOWED_TAB_SIZE_GUESSES[7] = {2, 4, 6, 8, 3, 5, 7}; // prefer even guesses for `tabSize`, limit to [2, 8].
     constexpr int MAX_ALLOWED_TAB_SIZE_GUESS = 8; // max(ALLOWED_TAB_SIZE_GUESSES) = 8
 
     int spacesDiffCount[] = {0, 0, 0, 0, 0, 0, 0, 0, 0}; // `tabSize` scores
     SpacesDiffResult tmp;
 
     for (int lineNumber = 0; lineNumber < linesCount; lineNumber++) {
         const QString currentLineText = m_doc->line(lineNumber);
         const int currentLineLength = currentLineText.length();
 
         bool currentLineHasContent = false; // does `currentLineText` contain non-whitespace chars
         int currentLineIndentation = 0; // index at which `currentLineText` contains the first non-whitespace char
         int currentLineSpacesCount = 0; // count of spaces found in `currentLineText` indentation
         int currentLineTabsCount = 0; // count of tabs found in `currentLineText` indentation
         for (int j = 0, lenJ = currentLineLength; j < lenJ; j++) {
             const auto charCode = currentLineText.at(j);
 
             if (charCode == QLatin1Char('\t')) {
                 currentLineTabsCount++;
             } else if (charCode == QLatin1Char(' ')) {
                 currentLineSpacesCount++;
             } else {
                 // Hit non whitespace character on this line
                 currentLineHasContent = true;
                 currentLineIndentation = j;
                 break;
             }
         }
 
         // Ignore empty or only whitespace lines
         if (!currentLineHasContent) {
             continue;
         }
 
         if (currentLineTabsCount > 0) {
             linesIndentedWithTabsCount++;
         } else if (currentLineSpacesCount > 1) {
             linesIndentedWithSpacesCount++;
         }
 
         tmp = spacesDiff(previousLineText, previousLineIndentation, currentLineText, currentLineIndentation);
 
         if (tmp.looksLikeAlignment) {
             // if defaultInsertSpaces === true && the spaces count == tabSize, we may want to count it as valid indentation
             //
             // - item1
             //   - item2
             //
             // otherwise skip this line entirely
             //
             // const a = 1,
             //       b = 2;
 
             if (!(defaultInsertSpaces && defaultTabSize == tmp.spacesDiff)) {
                 continue;
             }
         }
 
         const int currentSpacesDiff = tmp.spacesDiff;
         if (currentSpacesDiff <= MAX_ALLOWED_TAB_SIZE_GUESS) {
             spacesDiffCount[currentSpacesDiff]++;
         }
 
         previousLineText = currentLineText;
         previousLineIndentation = currentLineIndentation;
     }
 
     bool insertSpaces = defaultInsertSpaces;
     if (linesIndentedWithTabsCount != linesIndentedWithSpacesCount) {
         insertSpaces = (linesIndentedWithTabsCount < linesIndentedWithSpacesCount);
     }
 
     int tabSize = defaultTabSize;
 
     // Guess tabSize only if inserting spaces...
     if (insertSpaces) {
         int tabSizeScore = 0;
         for (int i = 0; i < 7; ++i) {
             int possibleTabSize = ALLOWED_TAB_SIZE_GUESSES[i];
             const int possibleTabSizeScore = spacesDiffCount[possibleTabSize];
             if (possibleTabSizeScore > tabSizeScore) {
                 tabSizeScore = possibleTabSizeScore;
                 tabSize = possibleTabSize;
             }
         }
 
         // Let a tabSize of 2 win even if it is not the maximum
         // (only in case 4 was guessed)
         if (tabSize == 4 && spacesDiffCount[4] > 0 && spacesDiffCount[2] > 0 && spacesDiffCount[2] >= spacesDiffCount[4] / 2) {
             tabSize = 2;
         }
 
         // If no indent detected, check if the file is 1 space indented
         if (tabSizeScore == 0) {
             const auto it = std::max_element(spacesDiffCount, spacesDiffCount + 9);
             const auto maxIdx = std::distance(spacesDiffCount, it);
             if (maxIdx == 1) {
                 tabSize = 1;
             }
         }
     }
 
     return {tabSize, insertSpaces};
 }