Expressions

Expressions can be a lone literal like "A string." or a more complicated calculation or comparison. While expressions often evaluate to strings for output in writs, they can also be mathematical equations and comparisons for branching logic.

Literals

Oxiplate supports many of the same literals Rust itself does:

• String (e.g., "This is a string.")
• Boolean (i.e., true or false)
• Integer (e.g., 19)
• Float (e.g., 1.9e1)
• Binary (e.g., 0b10011)
• Octal (e.g., 0o23)
• Hexadecimal (e.g., 0x13)
• Underscore number separators (e.g., 1_000_000)

Variables, fields, and functions

Oxiplate accesses variables, fields, and functions similarly to Rust:

{{ foo }}
{{ foo.bar }}
{{ foo.hello() }}

All data available to templates is stored in the struct that referenced the template, or within the template itself. Local variables override those set for the template. Therefore, self. is neither needed nor allowed; it will be implied when a local variable of the same name doesn't exist.

Filters

Filters modify expressions that precede them:

{{ "foo" | upper }}

FOO

Behind the scenes, filters are functions in the filters_for_oxiplate module at the root of your crate that are passed the result of the expression as the first argument. Additional arguments can be passed to the filter directly:

{{ "hello world" | replace("hello", "goodbye") }}

goodbye world

Cow prefix for more efficient string conversion

Expressions and filters can be prefixed with the cow prefix (>) to convert string-like values into ::oxiplate_traits::CowStr which filters can use to retrieve the generated Cow<str> via CowStr::cow_str(). This conversion happens more efficiently than using Display and the cow prefix helps template writers avoid fragile boilerplate.

{{ >"hello world" | >replace(>19, >89) | shorten(19) }}

Operators

Unless otherwise specified, the operators behave the same as they do in Rust.

Math:

• +
• -
• *
• /
• %

Comparison:

• ==
• !=
• >
• <
• >=
• <=

Logic:

• ||
• &&

Other:

• ~: Concatenate the left and right sides into a single string.