mirror of
https://github.com/mermaid-js/mermaid.git
synced 2025-11-04 12:54:08 +01:00
64 lines
1.5 KiB
Markdown
64 lines
1.5 KiB
Markdown
<p align="center">
|
|
<img src="https://raw.githubusercontent.com/mermaid-js/mermaid/develop/docs/public/favicon.svg" height="150">
|
|
|
|
</p>
|
|
<h1 align="center">
|
|
Mermaid Parser
|
|
</h1>
|
|
|
|
<p align="center">
|
|
Mermaid parser package
|
|
<p>
|
|
|
|
[](https://www.npmjs.com/package/@mermaid-js/parser)
|
|
|
|
## How the package works
|
|
|
|
The package exports a `parse` function that has two parameters:
|
|
|
|
```ts
|
|
declare function parse<T extends DiagramAST>(
|
|
diagramType: keyof typeof initializers,
|
|
text: string
|
|
): T;
|
|
```
|
|
|
|
## How does a Langium-based parser work?
|
|
|
|
```mermaid
|
|
sequenceDiagram
|
|
actor Package
|
|
participant Module
|
|
participant TokenBuilder
|
|
participant Lexer
|
|
participant Parser
|
|
participant ValueConverter
|
|
|
|
|
|
Package ->> Module: Create services
|
|
Module ->> TokenBuilder: Override or/and<br>reorder rules
|
|
TokenBuilder ->> Lexer: Read the string and transform<br>it into a token stream
|
|
Lexer ->> Parser: Parse token<br>stream into AST
|
|
Parser ->> ValueConverter: Clean/modify tokenized<br>rules returned value
|
|
ValueConverter -->> Package: Return AST
|
|
```
|
|
|
|
- When to override `TokenBuilder`?
|
|
|
|
- To override keyword rules.
|
|
- To override terminal rules that need a custom function.
|
|
- To manually reorder the list of rules.
|
|
|
|
- When to override `Lexer`?
|
|
|
|
- To modify input before tokenizing.
|
|
- To insert/modify tokens that cannot or have not been parsed.
|
|
|
|
- When to override `LangiumParser`?
|
|
|
|
- To insert or modify attributes that can't be parsed.
|
|
|
|
- When to override `ValueConverter`?
|
|
|
|
- To modify the returned value from the parser.
|