[−][src]Crate rslint_parser

Extremely fast, lossless, and error tolerant JavaScript Parser.

The parser uses an abstraction over non-whitespace tokens. This allows us to losslessly or lossly parse code without requiring explicit handling of whitespace. The parser yields events, not an AST, the events are resolved into untyped syntax nodes, which can then be casted into a typed AST.

The parser is able to produce a valid AST from any source code. Erroneous productions are wrapped into ERROR syntax nodes, the original source code is completely represented in the final syntax nodes.

You probably do not want to use the parser struct, unless you want to parse fragments of Js source code or make your own productions. Instead use functions such as parse_text and parse_text_lossy which offer abstracted versions for parsing.

Notable features of the parser are:

Extremely fast parsing and lexing through the extremely fast rslint_lexer.
Ability to do Lossy or Lossless parsing on demand without explicit whitespace handling.
Customizable, able to parse any fragments of JS code at your discretion.
Completely error tolerant, able to produce an AST from any source code.
Zero cost for converting untyped nodes to a typed AST.
Ability to go from AST to SyntaxNodes to SyntaxTokens to source code and back very easily with nearly zero cost.
Very easy tree traversal through SyntaxNode.
Descriptive errors with multiple labels and notes.
Very cheap cloning, cloning an ast node or syntax node is the cost of adding a reference to an Rc.
Cheap incremental reparsing of changed text.

The crate further includes utilities such as:

ANSI syntax highlighting of nodes (through util) or text through rslint_lexer.
Rich utility functions for syntax nodes through SyntaxNodeExt.

It is inspired by the rust analyzer parser but adapted for JavaScript.

Syntax Nodes vs AST Nodes

The crate relies on a concept of untyped SyntaxNodes vs typed AstNodes. Syntax nodes represent the syntax tree in an untyped way. They represent a location in an immutable tree with two pointers. The syntax tree is composed of SyntaxNodes and SyntaxTokens in a nested tree structure. Each node can have parents, siblings, children, descendants, etc.

AstNodes represent a typed version of a syntax node. They have the same exact representation as syntax nodes therefore a conversion between either has zero runtime cost. Every piece of data of an ast node is optional, this is due to the fact that the parser is completely error tolerant.

Each representation has its advantages:

SyntaxNodes

Very simple traversing of the syntax tree through functions on them.
Easily able to convert to underlying text, range, or tokens.
Contain all whitespace bound to the underlying production (in the case of lossless parsing).
Can be easily converted into its typed representation with zero cost.
Can be turned into a pretty representation with fmt debug.

AST Nodes

Easy access to properties of the underlying production.
Zero cost conversion to a syntax node.

In conclusion, the use of both representations means we are not constrained to acting through typed nodes. Which makes traversal hard and you often have to resort to autogenerated visitor patterns. AST nodes are simply a way to easily access subproperties of a syntax node.event;

Re-exports

pub use crate::ast::AstNode;

pub use crate::ast::AstToken;

pub use crate::util::SyntaxNodeExt;

pub use crate::util::SyntaxTokenExt;

Modules

ast	AST definitions for converting untyped syntax nodes into typed AST nodes.
syntax	The Js syntax itself and parser functions.
util	Extra utlities for untyped syntax nodes, syntax tokens, and AST nodes.

Macros

T	Utility macro for creating a SyntaxKind through simple macro syntax
match_ast	Matches a `SyntaxNode` against an `ast` type.
op	A simple macro for making assign, binop, or unary operators
token_set	Utility macro for making a new token set

Structs

BigInt	A big signed integer type.
CompletedMarker	A structure signifying a completed node
ErrorBuilder	A builder for generating codespan diagnostics
GreenNode	Internal node in the immutable tree. It has other nodes and tokens as children.
JsLanguage
LosslessTreeSink	Structure for converting events to a syntax tree representation, while preserving whitespace.
LossyTreeSink	Structure to convert events to a lossy syntax tree which does not preserve whitespace.
Marker	A structure signifying the start of parsing of a syntax tree node
Parse	A utility struct for managing the result of a parser job
Parser	An extremely fast, error tolerant, completely lossless JavaScript parser
ParserState	State kept by the parser while parsing. It is required for things such as strict mode or async functions
SmolStr	A `SmolStr` is a string type that has the following properties:
SyntaxText
SyntaxTreeBuilder	Simple wrapper around a rslint_rowan `GreenNodeBuilder`
TextRange	A range in text, represented as a pair of `TextSize`.
TextSize	A measure of text length. Also, equivalently, an index into text.
Token	Abstracted token for `TokenSource`
TokenSet	A bit-set of `SyntaxKind`s
TokenSource	The source of tokens for the parser

Enums

Direction
Event	Events emitted by the Parser, these events are later made into a syntax tree with `process` into TreeSink.
JsNum
NodeOrToken
StrictMode
SyntaxKind	The kind of syntax node, e.g. `IDENT`, `FUNCTION_KW`, or `FOR_STMT`.
WalkEvent	`WalkEvent` describes tree walking process.

Traits

TreeSink

An abstraction for syntax tree implementations

Functions

parse_expr	Losslessly Parse text into an expression `Parse` which can then be turned into an untyped root `SyntaxNode`. Or turned into a typed `Expr` with `tree`.
parse_module	Same as `parse_text` but configures the parser to parse an ECMAScript module instead of a script
parse_module_lossy	Same as `parse_text_lossy` but configures the parser to parse an ECMAScript module instead of a Script
parse_text	Parse text into a `Parse` which can then be turned into an untyped root `SyntaxNode`. Or turned into a typed `Script` with `tree`.
parse_text_lossy	Lossly parse text into a `Parse` which can then be turned into an untyped root `SyntaxNode`. Or turned into a typed `Script` with `tree`.
process	Generate the syntax tree with the control of events.
tokenize	Run the rslint_lexer lexer to turn source code into tokens and errors produced by the lexer

Type Definitions

ParserError	The type of error emitted by the parser, this includes warnings, notes, and errors. It also includes labels and possibly notes
SyntaxElement
SyntaxElementChildren
SyntaxNode
SyntaxNodeChildren
SyntaxToken