SML

SML is a simple markup language. It is designed to convert human readable information into Rust data-structures. The focus is on simplicity, usability and hands-on control (no magic). The format looks this,

text hobbit: name: "Frodo Baggins" age: "98" friends: hobbit: name: "Bilbo Baggins" age: "176" hobbit: name: "Samwise Gamgee" age: "66"

State of Progress

Small was created for processing schemas and loading config files, where its better to manually specify conversion types. This becomes overly verbose when used for serializing and deserializing structs and enums, where data-structures tend to be nested within each other. The goal is to reduce this verbosity by using procedural macros, but no deadlines are set for this.

Data Format Rules

  1. Indentation has meaning and is 4 spaces, relative to the top key.

  2. All values must be double quoted.

  3. Every key/value combination must be nested in a key. For example rust hobbit: "Frodo" by itself is invalid. It can be written: rust hobbit: name: "Frodo" The motivation behind this is for the data format to distinguish clearly between whole data structures, which are headed by a key only, and parts of a data structure which are either key/value pairs, representing fields or variants, or other data-structures, which again are headed by a key only.

  4. Separation of lines has meaning.

  5. Keys may not include :.

  6. Double quotes in values must be escaped using \".

  7. Everything after the second double quote is ignored (and can be used for commenting).

  8. Empty lines or lines with whitespace only are ignored.

Basic Organization

text --------------------------from_str()---------------------------- | | | --------path()-------- | | | | | | | FromSmall trait | | | | --from_small()-- | -----to_ref()---- --from_str()--- | | | | | | | | | | | v v v | | v | v | | ---------- ------------ --------- ---------- | Hobbit | | SmallRef |-ref into->| Small | | String | ---------- ------------ --------- ---------- ^ ^ | ^ | | | | ------------ to_small()----------------- --to_string()-- ToSmall trait

Example 1: From Small-formatted String to Your Data-structure.

The following two examples should cover 90 percent of use cases. data-structure.

```rust use small::{Small, FromSmall, SmallError};

[derive(Debug)]

struct Hobbit { name: String, age: u32, friends: Vec, bicycle: Option, }

impl FromSmall for Hobbit { fn from_small(s: SmallRef) -> Result { Ok(Self { name: String::path(&s, "hobbit::name")?, age: u32::path(&s, "hobbit::age")?, friends: Vec::::path(&s, "hobbit::friends::hobbit")?, bicycle: Option::::path(&s, "hobbit::bicycle")?, }) } }

fn main() { let s = r#" hobbit: name: "Frodo Baggins" age: "98" friends: hobbit: name: "Bilbo Baggins" age: "176" hobbit: name: "Samwise Gamgee" age: "66""#;

let frodo = Hobbit::from_str_debug(s);

} ```

Most standard-library types are implemented for FromSmall. To custom convert strings from Small values to your data-type, use from_val(s: &SmallRef, key_path: &str) which returns a Vec of Strings or from_unique_val(s: &SmallRef, key_path: &str) which provides a single String value. These can then be used in the FromSmall implementation for your data-structure.

Example 2: From Your Data-structure to a Small-formatted String.

To convert from a data-structure to a string,

```rust use sml::{Small, ToSmall, SmallError};

[derive(Debug)]

struct Hobbit { name: String, age: u32, friends: Vec, bicycle: Option, }

impl ToSmall for Hobbit { fn tosmall(&self, key: &str) -> Result { Small::join("hobbit", &vec!( self.name.tosmall("name")?,
self.age.tosmall("age")?,
self.friends.tosmall("friends")?,
self.bicycle.to_small("bicycle")?, )) } }

println!("{}", frodo::key("hobbit"));

// hobbit: // name: "Frodo Baggins" // age: "98" // friends: // hobbit: // name: "Bilbo Baggins" // age: "176" // hobbit: // name: "Samwise Gamgee" // age: "66" ```