README

Attribute-driven PHP lexer and parser toolkit.

Lexicon lets you define tokens with PHP enums, parse into typed AST nodes, and inspect tokens, AST shape, and generated BNF-like grammar.

$tokens = Lexer::from(MyToken::class)->scan($source);
$node = Parser::fromTokens($tokens)->parse(MyNode::class);

Features

• enum-based token definitions with PHP attributes
• matcher-backed literals, fixed tokens, keywords, symbols, trivia, unknown tokens, and EOF
• trivia preservation with Token::fullText()
• user-defined lexer modes with enter/push/pop transitions
• diagnostics for lexer and parser errors
• recursive descent parser primitives
• attribute grammar recipes: Terminal, OneOf, Between, Optional, Many, SeparatedBy, SeparatedByRequired, ListBetween, Sequence, Fold
• reusable parser extension points with parslets and #[Parse(...)]
• custom parser escape hatch with ParseableNodeInterface
• token table, AST printer, and BNF grammar printer

Install

composer require edin/lexicon

For local development:

composer install

Quick Taste

#[OneOf([
    GroupedExpressionNode::class,
    NumberNode::class,
])]
interface PrimaryExpressionNode extends ExpressionNode
{
}

#[Terminal(MathToken::Number)]
final readonly class NumberNode implements PrimaryExpressionNode
{
    public function __construct(public Token $token)
    {
    }
}

#[Fold(
    operators: [MathToken::Plus, MathToken::Minus],
    operand: TermNode::class
)]
final readonly class ExpressionNode
{
    public function __construct(
        public Token $operator,
        public Node $left,
        public Node $right
    ) {
    }
}

Generated grammar:

Start ::= AdditiveExpressionNode

AdditiveExpressionNode ::= MultiplicativeExpressionNode ((Plus | Minus) MultiplicativeExpressionNode)*
MultiplicativeExpressionNode ::= PrimaryExpressionNode ((Star | Slash) PrimaryExpressionNode)*
PrimaryExpressionNode ::= GroupedExpressionNode | NumberNode
GroupedExpressionNode ::= OpenParen AdditiveExpressionNode CloseParen
NumberNode ::= Number

Documentation

• Quick Start
• Token Attributes
• Matchers
• Modes
• Parser Primitives And Recipes
• Debugging Tokens
• Examples

Run Examples

php examples/basic-scanner.php
php examples/json-scanner.php
php examples/xml-scanner.php
php examples/math.php

Test

composer test
composer analyse

License

MIT