emmetio / py-emmet

Emmet abbreviation parser and expander, implemented in Python

Emmet — the essential toolkit for web-developers

This is the official Python port of original Emmet code base written in JavaScript: https://github.com/emmetio/emmet

Emmet is a web-developer’s toolkit for boosting HTML & CSS code writing.

With Emmet, you can type expressions (abbreviations) similar to CSS selectors and convert them into code fragment with a single keystroke. For example, this abbreviation:

ul#nav>li.item$*4>a{Item $}

...can be expanded into:

<ul id="nav">
    <li class="item1"><a href="">Item 1</a></li>
    <li class="item2"><a href="">Item 2</a></li>
    <li class="item3"><a href="">Item 3</a></li>
    <li class="item4"><a href="">Item 4</a></li>
</ul>

Features

• Familiar syntax: as a web-developer, you already know how to use Emmet. Abbreviation syntax is similar to CSS Selectors with shortcuts for id, class, custom attributes, element nesting and so on.
• Dynamic snippets: unlike default editor snippets, Emmet abbreviations are dynamic and parsed as-you-type. No need to predefine them for each project, just type MyComponent>custom-element to convert any word into a tag.
• CSS properties shortcuts: Emmet provides special syntax for CSS properties with embedded values. For example, bd1-s#f.5 will be exampled to border: 1px solid rgba(255, 255, 255, 0.5).
• Available for most popular syntaxes: use single abbreviation to produce code for most popular syntaxes like HAML, Pug, JSX, SCSS, SASS etc.

Read more about Emmet features

Installation

You can install Emmet as a regular pip module:

pip install py-emmet

Usage

To expand abbreviation, pass it to expand function of emmet module:

import emmet

print(emmet.expand('p>a')) # <p><a href=""></a></p>

By default, Emmet expands markup abbreviation, e.g. abbreviation used for producing nested elements with attributes (like HTML, XML, HAML etc.). If you want to expand stylesheet abbreviation, you should pass it as a type property of second argument:

import emmet

print(emmet.expand('p10', { 'type': 'stylesheet' })) # padding: 10px

A stylesheet abbreviation has slightly different syntax compared to markup one: it doesn’t support nesting and attributes but allows embedded values in element name.

Alternatively, Emmet supports syntaxes with predefined snippets and options:

import emmet

print(emmet.expand('p10', { 'syntax': 'css' })) # padding: 10px;
print(emmet.expand('p10', { 'syntax': 'stylus' })) # padding 10px

Predefined syntaxes already have type attribute which describes whether given abbreviation is markup or stylesheet, but if you want to use it with your custom syntax name, you should provide type config option as well (default is markup):

import emmet

print(emmet.expand('p10', {
    'syntax': 'my-custom-syntax',
    'type': 'stylesheet',
    'options': {
        'stylesheet.between': '__',
        'stylesheet.after': '',
    }
})) # padding__10px

You can pass options property as well to shape-up final output or enable/disable various features. See emmet/config.py for more info and available options.

Extracting abbreviations from text

A common workflow with Emmet is to type abbreviation somewhere in source code and then expand it with editor action. To support such workflow, abbreviations must be properly extracted from source code:

import emmet

source = 'Hello world ul.tabs>li'
data = emmet.extract(source, 22) # { abbreviation: 'ul.tabs>li' }

print(emmet.expand(data.abbreviation)) # <ul class="tabs"><li></li></ul>

The extract function accepts source code (most likely, current line) and character location in source from which abbreviation search should be started. The abbreviation is searched in backward direction: the location pointer is moved backward until it finds abbreviation bound. Returned result is an object with abbreviation property and start and end properties which describe location of extracted abbreviation in given source.

Most current editors automatically insert closing quote or bracket for (, [ and { characters so when user types abbreviation that uses attributes or text, it will end with the following state (| is caret location):

ul>li[title="Foo|"]

E.g. caret location is not at the end of abbreviation and must be moved a few characters ahead. The extract function is able to handle such cases with lookAhead option (enabled by default). This this option enabled, extract method automatically detects auto-inserted characters and adjusts location, which will be available as end property of the returned result:

import emmet

source = 'a div[title] b'
loc = 11 # right after "title" word

# `lookAhead` is enabled by default
print(emmet.extract(source, loc)) # { abbreviation: 'div[title]', start: 2, end: 12 }
print(emmet.extract(source, loc, { 'lookAhead': false })) # { abbreviation: 'title', start: 6, end: 11 }

By default, extract tries to detect markup abbreviations (see above). stylesheet abbreviations has slightly different syntax so in order to extract abbreviations for stylesheet syntaxes like CSS, you should pass type: 'stylesheet' option:

import emmet

source = 'a{b}'
loc = 3 # right after "b"

print(emmet.extract(source, loc)); # { abbreviation: 'a{b}', start: 0, end: 4 }


# Stylesheet abbreviations does not have `{text}` syntax
print(emmet.extract(source, loc, { 'type': 'stylesheet' })); # { abbreviation: 'b', start: 2, end: 3 }

Extract abbreviation with custom prefix

Lots of developers uses React (or similar) library for writing UI code which mixes JS and XML (JSX) in the same source code. Since any Latin word can be used as Emmet abbreviation, writing JSX code with Emmet becomes pain since it will interfere with native editor snippets and distract user with false positive abbreviation matches for variable names, methods etc.:

var div // `div` is a valid abbreviation, Emmet may transform it to `<div></div>`

A possible solution for this problem it to use prefix for abbreviation: abbreviation can be successfully extracted only if its preceded with given prefix.

import emmet

source1 = '() => div'
source2 = '() => <div'

emmet.extract(source1, len(source1)) # Finds `div` abbreviation
emmet.extract(source2, len(source2)) # Finds `div` abbreviation too

emmet.extract(source1, len(source1), { 'prefix': '<' }) # No match, `div` abbreviation is not preceded with `<` prefix
emmet.extract(source2, len(source2), { 'prefix': '<' }) # Finds `div` since it preceded with `<` prefix

With prefix option, you can customize your experience with Emmet in any common syntax (HTML, CSS and so on) if user is distracted too much with Emmet completions for any typed word. A prefix may contain multiple character but the last one must be a character which is not part of Emmet abbreviation. Good candidates are <, &, → (emoji or Unicode symbol) and so on.

py-emmet's Issues

Change placement of id and class attributes in expanded output

Is it possible to change where the id and class attributes are placed in expanded tags output?

For example, in the default output, the class and id attributes are always placed at the end and in the order provided.

a.hello#world => <a href="" class="hello" id="world"></a>
a#world.hello => <a href="" id="world" class="hello"></a>

Would it be possible to change this default behaviour so that class is always first, id is always second and any other attributes follow those?

Desired output:

a.hello#world => <a class="hello" id="world" href=""></a>
a#world.hello => <a class="hello" id="world" href=""></a>

I've taken a look over the Emmet.sublime-settings file and the config options and none of those seem relevant.

I can get similar results by using the config snippet below, however, this always adds the attributes even if not present in the abbreviation. It also requires me to add multiple tags to the config if I want to do this for others.

{
    "config": {
        "html": {
            "snippets": {
                "a": "a[class id href]",
               // "other tags here..."
            }
        },
    },
}

// with this config set...
a             => <a class="" id="" href=""></a>
a.hello#world => <a class="hello" id="world" href=""></a>
a#world.hello => <a class="hello" id="world" href=""></a>