PhpSpreadsheet\Writer\Excel5\Workbook::writeSharedStringsTable()

Complexity

Conditions	12
Paths	60

Size

Total Lines	110
Code Lines	38

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

<?php
    private function writeSharedStringsTable()
    {
        // maximum size of record data (excluding record header)
        $continue_limit = 8224;

        // initialize array of record data blocks
        $recordDatas = array();

        // start SST record data block with total number of strings, total number of unique strings
        $recordData = pack("VV", $this->stringTotal, $this->stringUnique);

        // loop through all (unique) strings in shared strings table
        foreach (array_keys($this->stringTable) as $string) {
            // here $string is a BIFF8 encoded string

            // length = character count
            $headerinfo = unpack("vlength/Cencoding", $string);

            // currently, this is always 1 = uncompressed
            $encoding = $headerinfo["encoding"];

            // initialize finished writing current $string
            $finished = false;

            while ($finished === false) {
                // normally, there will be only one cycle, but if string cannot immediately be written as is
                // there will be need for more than one cylcle, if string longer than one record data block, there
                // may be need for even more cycles

                if (strlen($recordData) + strlen($string) <= $continue_limit) {
                    // then we can write the string (or remainder of string) without any problems
                    $recordData .= $string;

                    if (strlen($recordData) + strlen($string) == $continue_limit) {
                        // we close the record data block, and initialize a new one
                        $recordDatas[] = $recordData;
                        $recordData = '';
                    }

                    // we are finished writing this string
                    $finished = true;
                } else {
                    // special treatment writing the string (or remainder of the string)
                    // If the string is very long it may need to be written in more than one CONTINUE record.

                    // check how many bytes more there is room for in the current record
                    $space_remaining = $continue_limit - strlen($recordData);

                    // minimum space needed
                    // uncompressed: 2 byte string length length field + 1 byte option flags + 2 byte character
                    // compressed:   2 byte string length length field + 1 byte option flags + 1 byte character
                    $min_space_needed = ($encoding == 1) ? 5 : 4;

                    // We have two cases
                    // 1. space remaining is less than minimum space needed
                    //        here we must waste the space remaining and move to next record data block
                    // 2. space remaining is greater than or equal to minimum space needed
                    //        here we write as much as we can in the current block, then move to next record data block

                    // 1. space remaining is less than minimum space needed
                    if ($space_remaining < $min_space_needed) {
                        // we close the block, store the block data
                        $recordDatas[] = $recordData;

                        // and start new record data block where we start writing the string
                        $recordData = '';

                    // 2. space remaining is greater than or equal to minimum space needed
                    } else {
                        // initialize effective remaining space, for Unicode strings this may need to be reduced by 1, see below
                        $effective_space_remaining = $space_remaining;

                        // for uncompressed strings, sometimes effective space remaining is reduced by 1
                        if ($encoding == 1 && (strlen($string) - $space_remaining) % 2 == 1) {
                            --$effective_space_remaining;
                        }

                        // one block fininshed, store the block data
                        $recordData .= substr($string, 0, $effective_space_remaining);

                        $string = substr($string, $effective_space_remaining); // for next cycle in while loop
                        $recordDatas[] = $recordData;

                        // start new record data block with the repeated option flags
                        $recordData = pack('C', $encoding);
                    }
                }
            }
        }

        // Store the last record data block unless it is empty
        // if there was no need for any continue records, this will be the for SST record data block itself
        if (strlen($recordData) > 0) {
            $recordDatas[] = $recordData;
        }

        // combine into one chunk with all the blocks SST, CONTINUE,...
        $chunk = '';
        foreach ($recordDatas as $i => $recordData) {
            // first block should have the SST record header, remaing should have CONTINUE header
            $record = ($i == 0) ? 0x00FC : 0x003C;

            $header = pack("vv", $record, strlen($recordData));
            $data = $header . $recordData;

            $chunk .= $this->writeData($data);
        }

        return $chunk;
    }