extended-embedded-languages

Adds syntax highlighting to C++, Javascript, Python and YAML for strings containing source code. Many different languages can be embedded.

This Visual Studio Code extension enables syntax highlighting within strings that contain source code. For example, a Python script might have strings containing SQL or HTML or Bash. This plugin will add syntax highlighting, and additionally code folding and language-specific editor features within those strings.

This is similar to how you can select syntax highlighting within Markdown documents using a language specifier (e.g. ```py) or switch between HTML, Javascript, and CSS in the same HTML document.

Features

This plugin extends the syntax highlighting of several host languages in order to highlight embedded sub-languages within strings.

You need to specify which language you are using within the string. How this is done depends on the host language (see below). Once that is done you can see and edit the embedded language just like you are editing a standalone file using that language. For example if you are editing SQL within a C++ document, the VSCode "Toggle Line Comment" command will prefix lines with -- not //. Code folding will use the natural structure of the embedded language block too - collapsing <tags> in an XML string, or { braces in a C string

Host Language - C++

C++ uses raw strings to specify the language.

A raw string in C++ looks like

auto s = R"foo( ...text )foo";

Between the " and ( an arbitrary token can be placed which we use here to specify the language. This token needs to exist at the end of the string as well:

Host language - Javascript

Javascript template strings delimited by backticks (e.g. `...text...`) can be multiline. This extension supports two different ways to specify the language in a multiline template string.

As an inline comment before the beginning of the string:

const s = /*lang_id*/ `
code goes here
`;

Or as a tagged template, this style expects there to be a function with the name of the language which can process the string (see the tagged template documentation for examples and for an identity template which just returns the input string)

const s = lang_id`
code goes here
`;

Host language - Python

Python multiline strings do not have custom terminators the way C++, Perl or other languages do. As such, we rely on leading comments to identify a language. This comment must be immediately after the ''' or """ which starts a multiline string

Host language - YAML

YAML has block strings that begin with a | or > and continue based on the indentation level of a block of text. Following the start indicator you can put a comment (this is a YAML comment) which indicates the language

Embedded Languages

The available embedded languages are listed in this table. The "ID" column is the IDs you can use in host languages like C++ and YAML where you can specify an ID in the host language. The "Comment" column is for host languages like Python which have no way to indicate the embedded language type directly, and shows what the first characters of the embedded language string needs to be to signal which language you are using.

[^1]: JSON does not support comments, so there is no way to indicate a string is a JSON document within the string.

Developer Notes

See CONTRIBUTING.md for adding new languages

Requirements

Known Issues

Release Notes

1.0.0

Initial release of Extended Embedded Languages