/rust-sformat-dynamic

Dynamic string formatting for Rust

Primary LanguageRust

sformat-dynamic

Dynamic string formatting for Rust.

This crate tries to mimic the std::fmt syntax as closely as possible. One notable differentiation thus far is that the dynamic string format only supports named parameters like {name}, and not positional parameters like {}.

Always use the compile-time format! macro if you can. There are some situations where you might need a dynamic string formatting engine, for example if you need a lightweight library way for users to specify their own formats in a config file or something similar. Again, using dynamic string formatting is far less secure than using the compile-time format! macro, so always prefer that!

This is still a WIP, so use at your own risk!

Examples

See ./sformat-dynamic/examples for more examples.

// Note: This example requires the "derive" feature.
use sformat_dynamic::{compile, derive::Context};

#[derive(Context)]
struct ContextImpl {
  value: usize
}

let context = ContextImpl { value: 99 };
let format = compile("Value is {value:+010}").unwrap();
let formatted = format.format_str(&context).unwrap();

assert_eq!(formatted, "Value is +000000099");

You can also use a HashMap when specifying the context, although it is significantly more verbose.

use sformat_dynamic::{compile, TypedValue};
use std::collections::HashMap;

let context = HashMap::from([
    ("name", TypedValue::Str("Ferris"))
]);
let format = compile("Hello {name: >16}!").unwrap();
let formatted = format.format_str(&context).unwrap();

assert_eq!(formatted, "Hello           Ferris!")

Feature Parity

Consult the str::fmt documentation for what these features actually mean.

Feature Implemented Future Plan to Implement
Named Argument {name} ✅ N/A
Positional Argument {} ❌ ❌
Fill / Alignment < , ^ , > ✅ N/A
Sign Flag + ✅ N/A
Alternate Form Flag # ❌ 🤔
Zero Flag 0 ✅ N/A
Precision - Fixed .N ✅ N/A
Precision - Arg .N$ ❌ ❌
Precision - Astrix .* ❌ ❌

Derive Types

A table of types that can be derived using sformat-dynamic-derive.

Type Implemented Future Plan to Implement
&T : Debug ❌ ✅
&T : Display ❌ ✅
&str ✅ ✅
isize ✅ N/A
i64 ✅ N/A
i32 ✅ N/A
i16 ✅ N/A
i8 ✅ N/A
usize ✅ N/A
u64 ✅ N/A
u32 ✅ N/A
u16 ✅ N/A
u8 ✅ N/A
f64 ✅ N/A
f32 ✅ N/A
bool ✅ N/A

License

Licensed under either of

at your option.