gistfile1.java

    /**
     * Shifts all tiles to the left, merging consecutive tiles as necessary.
     */
    public void moveLeft() {
        if (mIsGameOver) {
            return;
        }

        final int oldScore = mCurrentScore;
        boolean moved = false;

        final List<Tile> currentStreak = new ArrayList<>();
        final List<Tile> shiftTiles = new ArrayList<>();
        final List<Tile> mergeTiles = new ArrayList<>();
        for (int row = 0; row < mNumRows; row++) {
            currentStreak.clear();
            shiftTiles.clear();
            mergeTiles.clear();
            for (int col = 0; col < mNumCols; col++) {
                final Tile currentTile = mGrid[row][col];
                if (currentTile != null) {
                    if (isConsecutiveTile(currentStreak, currentTile)) {
                        // Then the current tile matches the last tile in
                        // the current streak.
                        currentStreak.add(currentTile);
                        if (currentStreak.size() == mMaxMergedTiles) {
                            // If the maximum streak size has been reached, then
                            // merge all of the tiles in the current streak.
                            mergeTiles.addAll(currentStreak);
                            currentStreak.clear();
                        }
                    } else {
                        // Then the current tile does not match the last tile
                        // in the current streak.
                        if (mMinMergedTiles <= currentStreak.size()) {
                            // The current streak satisfies the minimum number
                            // of tiles required, so merge the tiles.
                            mergeTiles.addAll(currentStreak);
                            currentStreak.clear();
                            currentStreak.add(currentTile);
                        } else {
                            shiftTiles.addAll(currentStreak);
                            currentStreak.clear();
                            currentStreak.add(currentTile);
                        }
                    }
                }

                if (col + 1 == mNumCols) {
                    if (mMinMergedTiles <= currentStreak.size()) {
                        // If at the edge and the streak satisfies the minimum
                        // allowed size, then merge the tiles.
                        mergeTiles.addAll(currentStreak);
                    } else {
                        // Otherwise, shift the leftover tiles.
                        shiftTiles.addAll(currentStreak);
                    }
                }

                if (!mergeTiles.isEmpty()) {
                    // TODO: merge the tiles.
                }

                if (!shiftTiles.isEmpty()) {
                    // TODO: shift the tiles.
                }
            }
        }

        if (moved) {
            for (int i = 0; i < mRules.getNumDropTiles(); i++) {
                addRandomTile();
            }
        }

        if (oldScore != mCurrentScore) {
            mListener.onScoreChanged(oldScore, mCurrentScore);
        }
        resetMoveState();
    }