railroad_dsl 0.1.2

A small DSL to generate syntax diagrams using [this library](https://github.com/lukaslueg/railroad).

[![Crates.io Version](https://img.shields.io/crates/v/railroad_dsl.svg)](https://crates.io/crates/railroad_dsl)[![Build Status](https://travis-ci.org/lukaslueg/railroad_dsl.svg?branch=master)](https://travis-ci.org/lukaslueg/railroad_dsl)

**[Some examples](https://htmlpreview.github.io/?https://github.com/lukaslueg/railroad_dsl/blob/master/examples/example_diagrams.html)**


* `{...}` is a horizontal stack of connected elements
* `[...]` is a vertical sequence of connected elements
* `<...>` is a choice of multiple options, exactly one of which has to be picked
* `"foobar"` is a terminal
* `'foobar'` is a non-terminal
* `` `foobar` `` is a comment
* `...?` is an optional element
* `...*...` is a repeated element
* `!` is the empty element

Quotes (and backslashes) can be escaped using backslashes.

For example:

```
{["CONSTRAINT" "name"]?,
 <["PRIMARY" "KEY" <!, "ASC", "DESC"> 'conflict-clause' <!, "AUTOINCREMENT">],
  ["NOT" "NULL" 'conflict-clause'],
  ["UNIQUE" 'conflict-clause'],
  ["CHECK" "(" 'expr' ")"],
  ["DEFAULT" <'signed-number', 'literal-value', ["(" 'expr' ")"]>],
  ["COLLATE" "collation-name"],
  'foreign-key-clause'>}
```

![diagram for constraint syntax](https://raw.githubusercontent.com/lukaslueg/railroad_dsl/master/examples/column_constraint.jpeg)