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hugowetterberg/ical-RFC-2445-4.1.php

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Revisions

  1. hugowetterberg revised this gist Oct 6, 2022. 1 changed file with 21 additions and 10 deletions.
    31 changes: 21 additions & 10 deletions output.txt
    View file
    Original file line number Diff line number Diff line change
    @@ -1,18 +1,29 @@
    DESCRIPTION:<p>Lines of text SHOULD NOT be longer than 75 octets, (och h
    r på den) excluding the line break. Long content lines SHOULD be split in
    o a multiple line representations using a line "folding" technique.</p> Th
    t is, a long line can be split between any two characters by inserting a C
    LF immediately followed by a single linear white space character (i.e., SP
    CE, <b>US-ASCII</b> decimal 32 or HTAB, US-ASCII decimal 9). Any sequence
    f CRLF followed immediately by a single linear white space character is ig
    ored (i.e., removed) when processing the content type.
    DESCRIPTION:Lines of text SHOULD NOT be longer than 75 octets, (och hör
    å den) excluding the line break. Long content lines SHOULD be split into
    multiple line representations using a line "folding" technique. That is,
    long line can be split between any two characters by inserting a CRLF imm
    diately followed by a single linear white space character (i.e., SPACE, US
    ASCII decimal 32 or HTAB, US-ASCII decimal 9). Any sequence of CRLF follow
    d immediately by a single linear white space character is ignored (i.e., r
    moved) when processing the content type.

    Tests
    Line 0: 72 octets
    Line 0: 73 octets
    Line 1: 75 octets
    Line 2: 75 octets
    Line 3: 75 octets
    Line 4: 75 octets
    Line 5: 75 octets
    Line 6: 75 octets
    Line 7: 55 octets
    Line 7: 41 octets

    Alt desc output:
    X-ALT-DESC:<p>Lines of text SHOULD NOT be longer than 75 octets, (och hö
    på den) excluding the line break. Long content lines SHOULD be split int
    a multiple line representations using a line "folding" technique.</p> Tha
    is, a long line can be split between any two characters by inserting a CR
    F immediately followed by a single linear white space character (i.e., SPA
    E, <b>US-ASCII</b> decimal 32 or HTAB, US-ASCII decimal 9). Any sequence o
    CRLF followed immediately by a single linear white space character is ign
    red (i.e., removed) when processing the content type.

  2. hugowetterberg revised this gist Oct 6, 2022. 2 changed files with 53 additions and 48 deletions.
    65 changes: 35 additions & 30 deletions ical-RFC-2445-4.1.php
    View file
    Original file line number Diff line number Diff line change
    @@ -10,46 +10,51 @@
    is ignored (i.e., removed) when processing the content type.
    TEXT;

    function ical_split($preamble, $value) {
    $value = trim($value);
    $value = strip_tags($value);
    $value = preg_replace('/\n+/', ' ', $value);
    $value = preg_replace('/\s{2,}/', ' ', $value);

    $preamble_len = strlen($preamble);

    $lines = array();
    while (strlen($value)>(75-$preamble_len)) {
    $space = (75-$preamble_len);
    $mbcc = $space;
    while ($mbcc) {
    $line = mb_substr($value, 0, $mbcc);
    $oct = strlen($line);
    if ($oct > $space) {
    $mbcc -= $oct-$space;
    }
    else {
    /**
    * Apply folding compliant with RFC 5545
    * See https://www.rfc-editor.org/rfc/rfc5545#section-3.1
    *
    * @param string $preamble The property name, e.g. DESCRIPTION
    * @param string $value The value for the property, e.g. a very long string
    * @param bool $strip_tags Strip HTML tags from the value
    *
    * @return string Returns the folded string without the property name
    */
    function ical_split($preamble, $value, $strip_tags=true)
    {
    $value = trim($value);
    $value = preg_replace('/[\r\n]+/', ' ', $value);
    $value = preg_replace('/\s{2,}/', ' ', $value);

    if ($strip_tags) {
    $value = strip_tags($value);
    }

    $value = $preamble . ':' . $value;
    $offset = 0;
    $chunkSize = 75;
    $lines = [];
    while ($line = mb_strcut($value, $offset, $chunkSize - 1)) {
    $lines[] = $line;
    $preamble_len = 1; // Still take the tab into account
    $value = mb_substr($value, $mbcc);
    break;
    }
    $offset += $chunkSize;
    }
    }
    if (!empty($value)) {
    $lines[] = $value;
    }

    return join($lines, "\n\t");
    return substr(join("\r\n\t", $lines), strlen($preamble) + 1);
    }

    $split = ical_split('DESCRIPTION:', $desc);
    print 'DESCRIPTION:' . $split;

    // Test results
    $lines = preg_split('/\n/', 'DESCRIPTION:' . $split);
    $lines = preg_split('/\r\n/', 'DESCRIPTION:' . $split);

    print "\n\nTests\n";
    foreach ($lines as $i => $line) {
    print "Line {$i}: " . strlen($line) . " octets\n";
    }
    }

    print "\nAlt desc output:\n";

    $split = ical_split('X-ALT-DESC:', $desc, false);
    print 'X-ALT-DESC:' . $split;
    print "\n\n";
    36 changes: 18 additions & 18 deletions output.txt
    View file
    Original file line number Diff line number Diff line change
    @@ -1,18 +1,18 @@
    DESCRIPTION:Lines of text SHOULD NOT be longer than 75 octets, (och hör p
    å den) excluding the line break. Long content lines SHOULD be split into
    a multiple line representations using a line "folding" technique. That is,
    a long line can be split between any two characters by inserting a CRLF i
    mmediately followed by a single linear white space character (i.e., SPACE,
    US-ASCII decimal 32 or HTAB, US-ASCII decimal 9). Any sequence of CRLF fo
    llowed immediately by a single linear white space character is ignored (i.
    e., removed) when processing the content type.
    Tests
    Line 0: 74 octets
    Line 1: 75 octets
    Line 2: 75 octets
    Line 3: 75 octets
    Line 4: 75 octets
    Line 5: 75 octets
    Line 6: 75 octets
    Line 7: 47 octets
    DESCRIPTION:<p>Lines of text SHOULD NOT be longer than 75 octets, (och h
    r på den) excluding the line break. Long content lines SHOULD be split in
    o a multiple line representations using a line "folding" technique.</p> Th
    t is, a long line can be split between any two characters by inserting a C
    LF immediately followed by a single linear white space character (i.e., SP
    CE, <b>US-ASCII</b> decimal 32 or HTAB, US-ASCII decimal 9). Any sequence
    f CRLF followed immediately by a single linear white space character is ig
    ored (i.e., removed) when processing the content type.

    Tests
    Line 0: 72 octets
    Line 1: 75 octets
    Line 2: 75 octets
    Line 3: 75 octets
    Line 4: 75 octets
    Line 5: 75 octets
    Line 6: 75 octets
    Line 7: 55 octets
  3. hugowetterberg created this gist Mar 19, 2009.
    55 changes: 55 additions & 0 deletions ical-RFC-2445-4.1.php
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,55 @@
    <?php
    mb_internal_encoding("UTF-8");
    $desc = <<<TEXT
    <p>Lines of text SHOULD NOT be longer than 75 octets, (och hör på den) excluding the line break. Long content lines SHOULD be split into a multiple line representations using a line "folding" technique.</p>
    That is, a long line can be split between any two characters by inserting a CRLF
    immediately followed by a single linear white space character (i.e.,
    SPACE, <b>US-ASCII</b> decimal 32 or HTAB, US-ASCII decimal 9). Any sequence
    of CRLF followed immediately by a single linear white space character
    is ignored (i.e., removed) when processing the content type.
    TEXT;

    function ical_split($preamble, $value) {
    $value = trim($value);
    $value = strip_tags($value);
    $value = preg_replace('/\n+/', ' ', $value);
    $value = preg_replace('/\s{2,}/', ' ', $value);

    $preamble_len = strlen($preamble);

    $lines = array();
    while (strlen($value)>(75-$preamble_len)) {
    $space = (75-$preamble_len);
    $mbcc = $space;
    while ($mbcc) {
    $line = mb_substr($value, 0, $mbcc);
    $oct = strlen($line);
    if ($oct > $space) {
    $mbcc -= $oct-$space;
    }
    else {
    $lines[] = $line;
    $preamble_len = 1; // Still take the tab into account
    $value = mb_substr($value, $mbcc);
    break;
    }
    }
    }
    if (!empty($value)) {
    $lines[] = $value;
    }

    return join($lines, "\n\t");
    }

    $split = ical_split('DESCRIPTION:', $desc);
    print 'DESCRIPTION:' . $split;

    // Test results
    $lines = preg_split('/\n/', 'DESCRIPTION:' . $split);

    print "\n\nTests\n";
    foreach ($lines as $i => $line) {
    print "Line {$i}: " . strlen($line) . " octets\n";
    }
    18 changes: 18 additions & 0 deletions output.txt
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,18 @@
    DESCRIPTION:Lines of text SHOULD NOT be longer than 75 octets, (och hör p
    å den) excluding the line break. Long content lines SHOULD be split into
    a multiple line representations using a line "folding" technique. That is,
    a long line can be split between any two characters by inserting a CRLF i
    mmediately followed by a single linear white space character (i.e., SPACE,
    US-ASCII decimal 32 or HTAB, US-ASCII decimal 9). Any sequence of CRLF fo
    llowed immediately by a single linear white space character is ignored (i.
    e., removed) when processing the content type.

    Tests
    Line 0: 74 octets
    Line 1: 75 octets
    Line 2: 75 octets
    Line 3: 75 octets
    Line 4: 75 octets
    Line 5: 75 octets
    Line 6: 75 octets
    Line 7: 47 octets