Crate ezno_parser

Ezno’s Parser

Contains “string to AST” parser, AST definitions, AST back to text/string form methods and hooks for traversing/visiting AST. Used in the Ezno checker.

This is more of an exercise project and doesn’t offer too much over other great Rust based JS parsers such as swc, rome and boa.

Goals:

• Keep under 15k lines of code (excluding /tests and /examples folders)
• Easy to use (see examples folder)
• Easy to read and is maintainable
• Useful for analysis and transformations
  • See expression identifiers & source positions
  • Contains visiting implementation
• Optionally extend the ecmascript language definition
  • TypeScript type annotations, interfaces and enums
  • JSX support
  • Others under feature = "extras"

Non-goals

• CSTs, close to source operations etc
• Increase code size or decrease readability for speed improvements
• Allow new syntax at that would require modifications the lexer at runtime

“Cursors”

• Allows holes in AST where a cursor exists, allows for LSP to provide suggestions here.

Notable structures

• ASTNode, a trait that all AST should implement
• FunctionBase, a abstraction for functions
• Expression
• Statements
• Operators
• TSXToken
• TSXKeyword

Re-exports

• pub use cursor::CursorId;
• pub use cursor::EmptyCursorId;
• pub use expressions::Expression;
• pub use expressions::PropertyReference;
• pub use extractor::UniversalFunctionId;
• pub use functions::FunctionBase;
• pub use functions::FunctionBased;
• pub use functions::FunctionHeader;
• pub use functions::FunctionId;
• pub use parameters::FunctionParameters;
• pub use parameters::OptionalOrWithDefaultValueParameter;
• pub use parameters::Parameter;
• pub use parameters::SpreadParameter;
• pub use statements::Statement;

Modules

• ast
  Re-exports or generator and general use
• cursor
• expressions
• extractor
• functions
• is_expression
• operators
  Contains the definitions for expressions Operators marked in spec but implemented as a variant of crate::Expression rather than a operator: OptionalChain, OptionalCall, OptionalIndex, Index, Group, Initialize, Call,
• parameters
• statements
• tsx_keywords
• type_declarations
• type_references

Structs

• Block
  A “block” of braced statements
• BlockId
  A identifier for a group of statements
• BlockLike
• BlockLikeMut
• Chain
  The current location in the AST
• Decorated
  TODO under cfg if don’t want this could just be type Decorated<T> = T;
• Decorator
• ExpressionPosition
• JSXElement
• JSXFragment
• Keyword
  A keyword
• LexSettings
• Module
• ParseError
  A error for not parsing
• ParseOutput
• ParseSettings
  Settings to customize parsing
• ParsingState
• PropertyId
• SourceId
  A identifier to some source
• Span
  A start and end. Also contains trace of original source
• StatementPosition
• ToStringSettings
  Settings for serializing ASTNodes
• ToStringSettingsAndData
• TypeDeclaration
  Similar to type reference but no unions or intersections AND includes generic constraints. Used for declaring classes, interfaces and functions
• TypeDefinitionModule
• TypeId
  A id of a syntax types
• VariableFieldInSourceCode
• VariableFieldInTypeReference
  For function type references
• VariableId
  Id given to AST that declares a variable
• VisitSettings
  Options for behavior when visiting AST. Customizable behavior is important for analysis
• Visitors
• VisitorsMut

Enums

• ArrayDestructuringField
  TODO not sure about the positions here, is potential duplication if T::OptionalExpression is none
• BlockOrSingleStatement
  For ifs and other statements
• ChainVariable
  Could borrow identifiers but most of them are smaller than a pointer so it doesn’t matter =
• FromFileError
• GenericTypeConstraint
  Represents a generic parameter. Can have default or constraint to extend a type or a key of a type
• GetSetGeneratorOrNone
• ImmutableVariableOrPropertyPart
  TODO these may go
• InterfaceMember
  This is also used for TypeReference::ObjectLiteral
• JSXAttribute
  TODO spread attributes and boolean attributes
• JSXElementChildren
• JSXNode
• JSXRoot
• MutableVariablePart
  TODO these may go
• NumberSign
• NumberStructure
  TODO BigInt TODO a mix between runtime numbers and source syntax based number https://tc39.es/ecma262/multipage/ecmascript-language-lexical-grammar.html#sec-literals-numeric-literals
• ObjectDestructuringField
• ParseErrors
• PropertyKey
  A key for a member in a class or object literal
• PropertyKeyLocation
• Quoted
  The notation of a string
• TSXKeyword
• TSXToken
  All JS Tokens with extensions including TypeScript, JSX and more
• TypeDefinitionModuleStatement
  Statements for ‘.d.ts’ files
• TypeReference
  A reference to a type
• VariableField
  A variable declaration name, used in variable declarations and function parameters. See destructuring
• VariableIdentifier
• VariableOrPropertyId
• WithComment

Traits

• ASTNode
  Defines common methods that would exist on a AST part include position in source, creation from reader and serializing to string from settings.
• ExpressionOrStatementPosition
  Classes and function functions have two variants depending whether in statement position or expression position
• IntoAST
  A trait which means that self can be pushed to a [TokenSender]
• SelfVisitable
• SelfVisitableMut
• VariableFieldTypes
  Variable field can be used in type annotations but cannot have a value
• Visitable
  For something to visitable it can visit all nested fields.
• Visitor
  A visitor over something which is hooked/is SelfVisitable with some Data
• VisitorMut
  A visitor over something which is hooked/is SelfVisitable with some Data
• VisitorMutReceiver
  These are a receiver traits of the visitor
• VisitorReceiver
  These are a receiver traits of the visitor

Functions

• html_tag_contains_literal_content
  Used for lexing
• html_tag_is_self_closing
  Used for lexing

Type Definitions

• ParseResult