Leon template library (#766)

* leon: first implementation

* Update crates/leon/src/values.rs

Co-authored-by: Jiahao XU <Jiahao_XU@outlook.com>

* Workaround orphan rules to make API more intuitive

* Fmt

* Clippy

* Use CoW

* Use cow for items too

* Test that const construction works

* leon: Initial attempt at O(n) parser

* leon: finish parser (except escapes)

* leon: Improve ergonomics of compile-time templates

* Document helpers

* leon: Docs tweaks

* leon: Use macro to minimise parser tests

* leon: add escapes to parser

* leon: test escapes preceding keys

* leon: add multibyte tests

* leon: test escapes following keys

* Format

* Debug

* leon: Don't actually need to keep track of the key

* leon: Parse to vec first

* leon: there's actually no need for string cows

* leon: reorganise and redo macro now that there's no coww

* Well that was silly

* leon: Adjust text end when pushing

* leon: catch unbalanced keys

* Add error tests

* leon: Catch unfinished escape

* Comment out debugging

* leon: fuzz

* Clippy

* leon: Box parse error

* leon: &dyn instead of impl

* Can't impl FromStr, so rename to parse

* Add Vec<> to values

* leon: Add benches for ways to supply values

* leon: Add bench comparing to std and tt

* Fix fuzz

* Fmt

* Split ParseError and RenderError

* Make miette optional

* Remove RenderError lifetime

* Simplify ParseError type schema

* Write concrete Values types instead of generics

* Add license files

* Reduce criterion deps

* Make default a cow

* Add a CLI leon tool

* Fix tests

* Clippy

* Disable cli by default

* Avoid failing the build when cli is off

* Add to ci

* Update crates/leon/src/main.rs

Co-authored-by: Jiahao XU <Jiahao_XU@outlook.com>

* Update crates/leon/Cargo.toml

Co-authored-by: Jiahao XU <Jiahao_XU@outlook.com>

* Bump version

* Error not transparent

* Diagnostic can do forwarding

* Simplify error type

* Expand doc examples

* Generic Values for Hash and BTree maps

* One more borrowed

* Forward implementations

* More generics

* Add has_keys

* Lock stdout in leon tool

* No more debug comments in parser

* Even more generics

* Macros to reduce bench duplication

* Further simplify error

* Fix leon main

* Stable support

* Clippy

---------

Co-authored-by: Jiahao XU <Jiahao_XU@outlook.com>

crates/leon/Cargo.toml

@@ -0,0 +1,33 @@
+[package]
+name = "leon"
+description = "Dead-simple string templating"
+repository = "https://github.com/cargo-bins/cargo-binstall"
+documentation = "https://docs.rs/leon"
+version = "0.0.1"
+rust-version = "1.61.0"
+authors = ["Félix Saparelli <felix@passcod.name>"]
+edition = "2021"
+license = "Apache-2.0 OR MIT"
+
+[dependencies]
+clap = { version = "4.1.4", features = ["derive"], optional = true }
+miette = { version = "5.5.0", default-features = false, optional = true }
+thiserror = "1.0.38"
+
+[features]
+default = ["miette"]
+cli = ["dep:clap", "miette?/fancy-no-backtrace"]
+miette = ["dep:miette"]
+
+[dev-dependencies]
+criterion = { version = "0.4.0", default-features = false, features = ["cargo_bench_support"] }
+serde = { version = "1.0.152", features = ["derive"] }
+tinytemplate = "1.2.1"
+
+[[bench]]
+name = "values"
+harness = false
+
+[[bench]]
+name = "others"
+harness = false