phplrt/phplrt

# Introduction

PHP Language Recognition Tool (phplrt) - it is a set of libraries for the
development of the so-called «frontend» programming languages.
After writing a grammar describing the syntax of your language, you get an
[abstract syntax tree](https://en.wikipedia.org/wiki/Abstract_syntax_tree).

The tool is divided into two components - a component for development, the
so-called [compiler-compiler](https://en.wikipedia.org/wiki/Compiler-compiler)
(or compiler generator) and a runtime component used for parsing after the 
development of the language itself.

For brevity, your `composer.json` file may contain lines similar to the following:

```json
{
    "require": {
        "phplrt/runtime": "^3.2"
    },
    "require-dev": {
        "phplrt/phplrt": "^3.2"
    }
}
```

However, it should be noted that, although this is a valid, but not mandatory
option. Each library can be used separately, and the components interact
directly with each other using interfaces (using «contract» 
components). For example, you might well use completely custom lexer, and use
the `phplrt` as a parser only, like this:

```json
{
    "require": {
        "phplrt/parser": "^3.2",
        "custom/lexer": "*"
    }
}
```

## Components

Now let's move on to the components themselves and a description of what they
are responsible for.

### Source

As the name implies, the component is responsible for minimal abstraction
over the source code. The minimum capabilities of the source interface is
to read data and obtain auxiliary information, such as the name of the file
from which the source was created and the identification hash of the
source code.

To install the component, use the command `composer require phplrt/source`.

### Position

The position component provides the ability to process information about the
position in the source code: offset in bytes, line and column. And also work
with intervals: Start and end positions in the source.

To install the component, use the command `composer require phplrt/position`.

### Exception

The exception component provides advanced error and error message manipulation
capabilities, allowing their internal information containing PHP data to be
delegated to an external language.

To install the component, use the command `composer require phplrt/exception`.

### Lexer

The lexer component provides the ability to group a sequence of characters
according to some criteria, forming so-called tokens (or lexemes) from the
source code.

To install the component, use the command `composer require phplrt/lexer`.

### Buffer

The buffer component provides a set of classes with the ability to convert
a list of tokens from a lexer to an iterator with the ability to loop back
to a specific token.

Each driver from the package contains its own features and can both store
the entire data set in memory, as well as a certain segment.

To install the component, use the command `composer require phplrt/buffer`.

### Parser

The parser component allows you to parse grammar rules and check user data
for compliance with these rules.

As it is parsed, the parser can also build an abstract syntax tree for
later use by the user.

To install the component, use the command `composer require phplrt/parser`.

### Visitor

The visitor component allows you to traverse each node of the abstract
syntax tree by applying a set of rules generated by the user to it,
such as replacing nodes, changing values, copying, and so on.

To install the component, use the command `composer require phplrt/visitor`.