magelang 0.1.0

A lexer/parser generator for a growing number of languages

Mage: Text Analysis Made Easy

Mage is tool for performing text analysis. It does so by generating a lexer, parser and parse tree for you. Whether it is a piece of programming code or some tabular data in a fringe format, Mage has got you covered!

• 🚀 Full support for Python typings. Avoid runtime errors while building your language!
• ➕ Add your own languages through the use of a powerful template engine!

👀 Mage is written in itself. Check out the generated code of our Python generator!

Here is the status of the various languages supported by Mage:

Python

Name	Description	Status
CST	Create a parse tree from a grammar	✅
AST	Create an AST that is derived from a CST	⏳
Lexer	Create a fully functioning lexer from a grammar	⏳
Parser	Create a fully functioning parser from a grammmar	⏳

Installation

$ pip3 install --user -U magelang

Usage

mage generate <filename>

Generate a parser for the given grammar in a language that you specify.

Example

mage generate foo.mage python --prefix foo --out-dir src/foolang

mage test <filename..>

🚧 This command is under construction.

Run all tests inside the documentation of the given grammar.

Grammar

pub <name> = <expr>

Define a new node or token that must be parsed according the given expression.

You can use both inline rules and other node rules inside expr. When referring to another node, that node will become a field in the node that referred to it. Nodes that have no fields are converted to a special token type that is more efficient to represent.

pub var_decl = 'var' name:ident '=' type_expr

<name> = <expr>

Define a new inline rule that can be used inside other rules.

As the name suggests, this type of rule is merely syntactic sugar and gets inlined whenever it is referred to inside another rule.

digits = [0-9]+

extern <name>

Defines a new parsing rule that is defined somewhere else, possibly in a different language.

extern token <name>

Defines a new lexing rule that is defined somewhere else, possibly in a different language.

pub token <name> = <expr>

Like pub <name> = <expr> but forces the rule to be a token.

Mage will show an error when the rule could not be converted to a token rule. This usually means that the rule references another rule that is pub.

pub token float_expression
  = digits? '.' digits

expr1 expr2

First parse expr1 and continue to parse expr2 immediately after it.

pub two_column_csv_line
  = text ',' text '\n'

expr1 | expr2

First try to parse expr1. If that fails, try to parse expr2. If none of the expressions matched, the parser fails.

pub declaration
  = function_declaration
  | let_declaration
  | const_declaration

expr?

Parse or skip the given expression, depending on whether the expression can be parsed.

pub singleton_or_pair
  = value (',' value)?

expr*

Parse the given expression as much as possible.

skip = (multiline_comment | whitespace)*

expr+

Parse the given expression one or more times.

For example, in Python, there must always be at least one statement in the body of a class or function:

body = stmt+

\expr

Escape an expression by making it hidden. The expression will be parsed, but not be visible in the resulting CST/AST.

expr{n,m}

Parse the expression at least n times and at most m times.

unicode_char = 'U+' hex_digit{4,4}

Contributing

Run the following command in a terminal to link the mage command to your checkout:

pip3 install -e '.[dev]'

License

This code is generously licensed under the MIT license.