使用preg_match_all创建chord charts

Question

我想创建一个PDF和弦图表时，有人输入歌词。将输入歌词的格式如下：

[B]Some lyrics blah blah [D]more lyrics blah
Lyrics without any chord charts blah blah
Some lyrics [C]blah blah more [E]lyrics blah

然后我想提取每个和弦的变化，这样我就可以导出并在PDF中显示它，如下所示：

B                     D
Some lyrics blah blah more lyrics blah
Lyrics without any chord charts blah blah
            C              E
Some lyrics blah blah more lyrics blah

我已经把其他的都整理好了。目前，我只需要弄清楚如何提取每个和弦之间的所有文本和和弦本身…

下面是我当前的代码：

$lyrics = '[B]Some lyrics blah blah [D]more lyrics blah
Lyrics without any chord charts blah blah
Some lyrics [C]blah blah more [E]lyrics blah';

$lyrics_html = '';
$x = 0;
$lyrics_lines = explode("\n", $lyrics);

// We've put each line into an array and now we will process each individually
foreach($lyrics_lines AS $lyrics_line) {

    $x++;
    if ($x > 1)
        $lyrics_html .= '<br />';

    // Check and see if an chords exist in this line
    preg_match_all('/\[(\w{1,3})\]/i',
    $lyrics_line,
    $out);

    if (!empty($out[0])) { // Found some chords, format it

        print_r($out);

    } else { // No chords found so just display the lyrics

        $lyrics_html .= $lyrics_line;

    }

}

echo $lyrics_html;

不用担心，下面的代码会选择和弦

preg_match_all('/\[(\w{1,3})\]/i',
    $lyrics_line,
    $out);

但是当我尝试在和弦之前和之后选择文本时，我似乎无法弄清楚……我尝试了以下几种方法：

preg_match_all('/(\w+)\[(\w{1,3})\](\w+)/i',
    $lyrics_line,
    $out);

有什么想法，我需要什么代码，以便我可以选择和弦和歌词，以便我可以格式化？

这样的结果会很好：

Array
(
    [0] => Array
        (
        [0] => [B]
        [1] => [D]
        )

    [1] => Array
        (
        [0] => Some lyrics blah bla
        [1] => more lyrics blah
        )

)

Answer 1

有趣的问题。这里有一个可能的解决方案。我使用了您已有的正则表达式，但也使用了它来查看需要多少空格来填充和弦。

<?php
define('REGEX_CHORD', '[A-G].*?');

$input = '[B]Some lyrics blah blah [D]more lyrics blah
Lyrics without any chord charts blah blah
Some lyrics [C]blah blah more [E]lyrics blah';

$lines = explode("\n", $input);
echo '<pre>';
foreach($lines as $line) {
    $chordline = '';
    $tmpline = $line;
    while(preg_match('~(.*)\[('.REGEX_CHORD.')\]~', $tmpline, $matches)) {
        // Length before the chord shows how many spaces are required.
        $chordline = str_repeat(' ', strlen($matches[1]))
                .$matches[2]
                .substr($chordline, 
                    strlen($matches[2]) + 3 + strlen($matches[1]));
        $tmpline = $matches[1];
    }
    echo $chordline."\n";
    echo preg_replace('~\[('.REGEX_CHORD.')\]~', '', $line)."\n";
}

Answer 2

我想这就是你要找的preg_match：

/(\[[A-G].*?\])/

它捕获由方括号封装的任何弦和后面的符号。它甚至可以匹配平坦、锐化和修饰，如下所示：

[B]Some lyrics blah blah [D]more lyrics blah
Lyrics without any chord charts blah blah
Some lyrics [C]blah blah more [E]lyrics blah


[Bb]Some lyrics blah blah [Dm7+9]more lyrics blah
Lyrics without any chord charts blah blah
Some lyrics [C]blah blah more [Eb]lyrics blah

请看这里的工作示例：http://regexr.com?2t408