Smart punctuation

SmartPunctuationExtension replaces straight quotes, apostrophes, dash runs, and three-dot ellipses while rendering. It leaves the source Markdown unchanged.

Install

This extension is bundled with alto/markdown.

composer require alto/markdown

Configure

<?php

use Alto\Markdown\Extension\SmartPunctuation\SmartPunctuationExtension;
use Alto\Markdown\Markdown;

$markdown = Markdown::github()->with(new SmartPunctuationExtension());

Markdown

"Hello," she said... It's ready -- really --- now.

HTML

<p>“Hello,” she said… It’s ready – really — now.</p>

Options

Pass a SmartPunctuationPolicy to replace the four quote characters:

<?php

use Alto\Markdown\Extension\SmartPunctuation\SmartPunctuationPolicy;

$markdown = Markdown::commonmark()->with(new SmartPunctuationExtension(
    new SmartPunctuationPolicy(
        doubleQuoteOpener: '« ',
        doubleQuoteCloser: ' »',
        singleQuoteOpener: '‹ ',
        singleQuoteCloser: ' ›',
    ),
));

Each replacement must be a non-empty valid UTF-8 string. Ellipses and dash replacement rules are fixed: ... becomes …, -- becomes an en dash, and --- becomes an em dash. Longer runs are decomposed deterministically into em and en dashes.

Security

Every replacement is validated as non-empty UTF-8 and emitted as text. The extension does not enable raw HTML or access external resources.

Behavior

Quote direction is selected from the surrounding characters. Apostrophes inside words use the configured single-quote closer. Code spans and escaped punctuation stay literal. Punctuation inside raw HTML is not replaced; the active HTML policy still decides whether that HTML is escaped, removed, or emitted. Replacements also apply inside rich inline content and GFM table cells.