Crate interpolator

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Runtime implementation of format!.

std::fmt compatible formatting

All options but the fill character for alignment is supported (due to rust-lang/rfcs#3394).

Though the non Display traits need to be enabled through features.

use interpolator::{format, Formattable};

let formatted = format(
    "{value:+05}", // could be dynamic
    &[("value", Formattable::display(&12))].into_iter().collect(),
)?;

assert_eq!(formatted, format!("{:+05}", 12));

i iter format

The feature iter enables an additional format trait i, it allows to format a list of values with a format string and an optional join expression.

The syntax is {list:i(the format string, '{}' is the array element)(the join)}, an empty join can also be omitted {list:i({})}. If join is omitted the format string {} can be omitted as well {list:i}.

Should you need to use ) inside your format string or join, you can add # similar to rust’s raw string (i.e. #(({}))#).

It is also possible to only iterate a sub-slice specified through a range before the format string, i.e. {list:i1..4}. For open ranges range bounds can also be omitted. To index from the end, you can use negative range bounds.

It is also possible to index a single value by only specifying an isize {list:i1}.

A Formattable implementing iter is created using Formattable::iter:

// HashMap macro
use collection_literals::hash;
use interpolator::{format, Formattable};
// Needs to be a slice of references because `Formattable::display` expects a
// reference
let items = [&"hello", &"hi", &"hey"].map(Formattable::display);
let items = Formattable::iter(&items);
let format_str = "Greetings: {items:i..-1(`{}`)(, )} and `{items:i-1}`";
assert_eq!(
    format(format_str, &hash!("items" => items))?,
    "Greetings: `hello`, `hi` and `hey`"
);

See format and write for details.

Features

By default only Display is supported, the rest of the formatting traits can be enabled through the following features.

  • debug enables ?, x? and X? trait specifiers
  • number enables x, X, b, o, e and E trait specifiers
  • pointer enables p trait specifiers
  • iter enables i trait specifier

Structs

  • Formattable
    Utility struct holding references to the trait implementation of a value to enable runtime verification and execution of them

Enums

Functions