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template: overrides/main.html
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# Code blocks

Code blocks and examples are an essential part of technical project
documentation. Material for MkDocs provides different ways to set up syntax
highlighting for code blocks, either during build time using [Pygments] or
during runtime using a JavaScript syntax highlighter.

  [Pygments]: https://pygments.org

## Configuration

This configuration enables syntax highlighting on code blocks and inline code 
blocks, and allows to include source code directly from other files. Add the 
following lines to `mkdocs.yml`:

``` yaml
markdown_extensions:
  - pymdownx.highlight
  - pymdownx.inlinehilite
  - pymdownx.superfences
  - pymdownx.snippets
```

The following sections discuss how to use different syntax highlighting features
with [Pygments], the recommended highlighter, so they don't apply when using a
JavaScript syntax highlighter.

See additional configuration options:

- [Highlight]
- [InlineHilite]
- [SuperFences]
- [Snippets]

  [Highlight]: ../setup/extensions/python-markdown-extensions.md#highlight
  [InlineHilite]: ../setup/extensions/python-markdown-extensions.md#inlinehilite
  [SuperFences]: ../setup/extensions/python-markdown-extensions.md#superfences
  [Snippets]: ../setup/extensions/python-markdown-extensions.md#snippets

### Code annotations

[:octicons-tag-24: 8.0.0][Code annotations support] ·
:octicons-unlock-24: Feature flag ·
:octicons-beaker-24: Experimental

Code annotations offer a comfortable and friendly way to attach arbitrary
content to specific sections of code blocks by adding numeric markers in block
and inline comments in the language of the code block. Add the following to
`mkdocs.yml` to enable them globally:

``` yaml
theme:
  features:
    - content.code.annotate # (1)
```

1.  :man_raising_hand: I'm a code annotation! I can contain `code`, __formatted
    text__, images, ... basically anything that can be expressed in Markdown.

??? info "Enabling code annotations for a specific code block"

    If you don't want to enable code annotations globally, because you don't
    like the automatic inlining behavior, you can enable them for a specific
    code block by using a slightly different syntax based on the
    [Attribute Lists] extension:

    ```` yaml
    ``` { .yaml .annotate }
    # Code block content
    ```
    ````

    Note that the language shortcode which has to come first must now also be 
    prefixed by a `.`.

  [Code annotations support]: https://github.com/squidfunk/mkdocs-material/releases/tag/8.0.0
  [Attribute Lists]: ../setup/extensions/python-markdown.md#attribute-lists

## Usage

Code blocks must be enclosed with two separate lines containing three backticks.
To add syntax highlighting to those blocks, add the language shortcode directly
after the opening block. See the [list of available lexers] to find the
shortcode for a given language.

_Example_:

```` markdown
``` py
import tensorflow as tf
```
````

_Result_:

``` py
import tensorflow as tf
```

  [list of available lexers]: https://pygments.org/docs/lexers/

### Adding a title

[:octicons-tag-24: 7.3.6][Title support] ·
:octicons-beaker-24: Experimental

In order to provide additional context, a custom title can be added to a code
block by using the `title="<custom title>"` option directly after the shortcode,
e.g. to display the name of a file:

_Example_:

```` markdown
``` py title="bubble_sort.py"
def bubble_sort(items):
    for i in range(len(items)):
        for j in range(len(items) - 1 - i):
            if items[j] > items[j + 1]:
                items[j], items[j + 1] = items[j + 1], items[j]
```
````

_Result_:

``` py title="bubble_sort.py"
def bubble_sort(items):
    for i in range(len(items)):
        for j in range(len(items) - 1 - i):
            if items[j] > items[j + 1]:
                items[j], items[j + 1] = items[j + 1], items[j]
```

  [Title support]: https://github.com/squidfunk/mkdocs-material/releases/tag/7.3.6

### Adding annotations

Code annotations can be placed anywhere in a code block where a comment for the
language of the block can be placed, e.g. for JavaScript in `#!js // ...` and
`#!js /* ... */`, for YAML in `#!yaml # ...`, etc.[^1]

  [^1]:
    Code annotations require syntax highlighting with [Pygments] – they're
    currently not compatible with JavaScript syntax highlighters, or languages
    that do not have comments in their grammar. However, we're actively working
    on supporting alternate ways of defining code annotations, allowing to
    always place code annotations at the end of lines.

_Example_:

```` markdown
``` yaml
theme:
  features:
    - content.code.annotate # (1)
```

1.  :man_raising_hand: I'm a code annotation! I can contain `code`, __formatted
    text__, images, ... basically anything that can be expressed in Markdown.
````

_Result_:

``` yaml
theme:
  features:
    - content.code.annotate # (1)
```

1.  :man_raising_hand: I'm a code annotation! I can contain `code`, __formatted
    text__, images, ... basically anything that can be expressed in Markdown.

### Adding line numbers

Line numbers can be added to a code block by using the `linenums="<start>"`
option directly after the shortcode, whereas `<start>` represents the starting
line number. A code block can start from a line number other than `1`, which
allows to split large code blocks for readability.

_Example_:

```` markdown
``` py linenums="1"
def bubble_sort(items):
    for i in range(len(items)):
        for j in range(len(items) - 1 - i):
            if items[j] > items[j + 1]:
                items[j], items[j + 1] = items[j + 1], items[j]
```
````

_Result_:

``` py linenums="1"
def bubble_sort(items):
    for i in range(len(items)):
        for j in range(len(items) - 1 - i):
            if items[j] > items[j + 1]:
                items[j], items[j + 1] = items[j + 1], items[j]
```

### Highlighting specific lines

Specific lines can be highlighted by passing the line numbers to the `hl_lines`
argument placed right after the language shortcode. Note that line counts start
at `1`, regardless of the starting line number specified as part of
[`linenums`][Adding line numbers].

=== "Line numbers"

    _Example_:

    ```` markdown 
    ``` py hl_lines="2 3"
    def bubble_sort(items):
        for i in range(len(items)):
            for j in range(len(items) - 1 - i):
                if items[j] > items[j + 1]:
                    items[j], items[j + 1] = items[j + 1], items[j]
    ```
    ````

    _Result_:

    ``` py linenums="1" hl_lines="2 3"
    def bubble_sort(items):
        for i in range(len(items)):
            for j in range(len(items) - 1 - i):
                if items[j] > items[j + 1]:
                    items[j], items[j + 1] = items[j + 1], items[j]
    ```

=== "Line number ranges"

    _Example_:

    ```` markdown
    ``` py hl_lines="2-5"
    def bubble_sort(items):
        for i in range(len(items)):
            for j in range(len(items) - 1 - i):
                if items[j] > items[j + 1]:
                    items[j], items[j + 1] = items[j + 1], items[j]
    ```
    ````

    _Result_:

    ``` py linenums="1" hl_lines="2-5"
    def bubble_sort(items):
        for i in range(len(items)):
            for j in range(len(items) - 1 - i):
                if items[j] > items[j + 1]:
                    items[j], items[j + 1] = items[j + 1], items[j]
    ```

  [Adding line numbers]: #adding-line-numbers

### Highlighting inline code blocks

When [InlineHilite] is enabled, syntax highlighting can be applied to inline
code blocks by prefixing them with a shebang, i.e. `#!`, directly followed by
the corresponding [language shortcode][list of available lexers].

_Example_:

``` markdown
The `#!python range()` function is used to generate a sequence of numbers.
```

_Result_:

The `#!python range()` function is used to generate a sequence of numbers.

### Embedding external files

When [Snippets] is enabled, content from other files (including source files)
can be embedded by using the [`--8<--` notation][Snippets notation] directly
from within a code block:

_Example_:

```` markdown
``` title=".browserslistrc"
--8<--​ ".browserslistrc"
```
````

_Result_:

``` title=".browserslistrc"
last 4 years
```

  [Snippets notation]: https://facelessuser.github.io/pymdown-extensions/extensions/snippets/#snippets-notation

## Customization

### Custom syntax theme

If [Pygments] is used, Material for MkDocs provides the [styles for code blocks]
[colors], which are built with a custom and well-balanced palette that works
equally well for both [color schemes]:

- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-number-color) " } `--md-code-hl-number-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-special-color) " } `--md-code-hl-special-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-function-color) " } `--md-code-hl-function-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-constant-color) " } `--md-code-hl-constant-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-keyword-color) " } `--md-code-hl-keyword-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-string-color) " } `--md-code-hl-string-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-name-color) " } `--md-code-hl-name-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-operator-color) " } `--md-code-hl-operator-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-punctuation-color) " } `--md-code-hl-punctuation-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-comment-color) " } `--md-code-hl-comment-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-generic-color) " } `--md-code-hl-generic-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-variable-color) " } `--md-code-hl-variable-color`

Code block foreground, background and line highlight colors are defined via:

- :material-checkbox-blank-circle:{ style="color: var(--md-code-fg-color) " } `--md-code-fg-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-bg-color) " } `--md-code-bg-color`
- :material-checkbox-blank-circle:{ style="color: var(--md-code-hl-color) " } `--md-code-hl-color`

Let's say you want to change the color of `#!js "strings"`. While there are
several [types of string tokens], they use the same color. You can assign
a new color by using an [additional style sheet]:

=== ":octicons-file-code-16: docs/stylesheets/extra.css"

    ``` css
    :root > * {
      --md-code-hl-string-color: #0FF1CE;
    }
    ```

=== ":octicons-file-code-16: mkdocs.yml"

    ``` yaml
    extra_css:
      - stylesheets/extra.css
    ```

If you want to tweak a specific type of string, e.g. ``#!js `backticks` ``, you
can lookup the specific CSS class name in the [syntax theme definition], and
override it as part of your [additional style sheet]:

=== ":octicons-file-code-16: docs/stylesheets/extra.css"

    ``` css
    .highlight .sb {
      color: #0FF1CE;
    }
    ```

=== ":octicons-file-code-16: mkdocs.yml"

    ``` yaml
    extra_css:
      - stylesheets/extra.css
    ```

  [colors]: https://github.com/squidfunk/mkdocs-material/blob/master/src/assets/stylesheets/main/_colors.scss
  [color schemes]: ../setup/changing-the-colors.md#color-scheme
  [types of string tokens]: https://pygments.org/docs/tokens/#literals
  [additional style sheet]: ../customization.md#additional-css
  [syntax theme definition]: https://github.com/squidfunk/mkdocs-material/blob/master/src/assets/stylesheets/main/extensions/pymdownx/_highlight.scss