parser

Documentation

Overview

Package parser implements a parser for JavaScript.

import (
    "github.com/kubeshark/otto/parser"
)

Parse and return an AST

filename := "" // A filename is optional
src := `
    // Sample xyzzy example
    (function(){
        if (3.14159 > 0) {
            console.log("Hello, World.");
            return;
        }

        var xyzzy = NaN;
        console.log("Nothing happens.");
        return xyzzy;
    })();
`

// Parse some JavaScript, yielding a *ast.Program and/or an ErrorList
program, err := parser.ParseFile(nil, filename, src, 0)

Warning

The parser and AST interfaces are still works-in-progress (particularly where node types are concerned) and may change in the future.

Index

• func ParseFile(fileSet *file.FileSet, filename string, src interface{}, mode Mode) (*ast.Program, error)
• func ParseFileWithSourceMap(fileSet *file.FileSet, filename string, ...) (*ast.Program, error)
• func ParseFunction(parameterList, body string) (*ast.FunctionLiteral, error)
• func ReadSource(filename string, src interface{}) ([]byte, error)
• func ReadSourceMap(filename string, src interface{}) (*sourcemap.Consumer, error)
• func TransformRegExp(pattern string) (string, error)
• type Error
  • func (e Error) Error() string
• type ErrorList
  • func (el *ErrorList) Add(position file.Position, msg string)
  • func (el *ErrorList) Err() error
  • func (el *ErrorList) Error() string
  • func (el *ErrorList) Len() int
  • func (el *ErrorList) Less(i, j int) bool
  • func (el *ErrorList) Reset()
  • func (el *ErrorList) Sort()
  • func (el *ErrorList) Swap(i, j int)
• type Mode
• type Parser
  • func NewParser(filename, src string) Parser

Functions

func ParseFile

func ParseFile(fileSet *file.FileSet, filename string, src interface{}, mode Mode) (*ast.Program, error)

ParseFile parses the source code of a single JavaScript/ECMAScript source file and returns the corresponding ast.Program node.

If fileSet == nil, ParseFile parses source without a FileSet. If fileSet != nil, ParseFile first adds filename and src to fileSet.

The filename argument is optional and is used for labelling errors, etc.

src may be a string, a byte slice, a bytes.Buffer, or an io.Reader, but it MUST always be in UTF-8.

// Parse some JavaScript, yielding a *ast.Program and/or an ErrorList
program, err := parser.ParseFile(nil, "", `if (abc > 1) {}`, 0)

func ParseFileWithSourceMap

func ParseFileWithSourceMap(fileSet *file.FileSet, filename string, javascriptSource, sourcemapSource interface{}, mode Mode) (*ast.Program, error)

ParseFileWithSourceMap parses the sourcemap returning the resulting Program.

func ParseFunction

func ParseFunction(parameterList, body string) (*ast.FunctionLiteral, error)

ParseFunction parses a given parameter list and body as a function and returns the corresponding ast.FunctionLiteral node.

The parameter list, if any, should be a comma-separated list of identifiers.

func ReadSource

func ReadSource(filename string, src interface{}) ([]byte, error)

ReadSource reads code from src if not nil, otherwise reads from filename.

func ReadSourceMap

func ReadSourceMap(filename string, src interface{}) (*sourcemap.Consumer, error)

ReadSourceMap reads the source map from src if not nil, otherwise is a noop.

func TransformRegExp

func TransformRegExp(pattern string) (string, error)

TransformRegExp transforms a JavaScript pattern into a Go "regexp" pattern.

re2 (Go) cannot do backtracking, so the presence of a lookahead (?=) (?!) or backreference (\1, \2, ...) will cause an error.

re2 (Go) has a different definition for \s: [\t\n\f\r ]. The JavaScript definition, on the other hand, also includes \v, Unicode "Separator, Space", etc.

If the pattern is invalid (not valid even in JavaScript), then this function returns the empty string and an error.

If the pattern is valid, but incompatible (contains a lookahead or backreference), then this function returns the transformation (a non-empty string) AND an error.

Types

type Error

type Error struct {
	Position file.Position
	Message  string
}

An Error represents a parsing error. It includes the position where the error occurred and a message/description.

func (Error) Error

func (e Error) Error() string

type ErrorList

type ErrorList []*Error //nolint: errname

ErrorList is a list of *Errors.

func (*ErrorList) Add

func (el *ErrorList) Add(position file.Position, msg string)

Add adds an Error with given position and message to an ErrorList.

func (*ErrorList) Err

func (el *ErrorList) Err() error

Err returns an error equivalent to this ErrorList. If the list is empty, Err returns nil.

func (*ErrorList) Error

func (el *ErrorList) Error() string

Error implements the Error interface.

func (*ErrorList) Len

func (el *ErrorList) Len() int

Len implement sort.Interface.

func (*ErrorList) Less

func (el *ErrorList) Less(i, j int) bool

Less implement sort.Interface.

func (*ErrorList) Reset

func (el *ErrorList) Reset()

Reset resets an ErrorList to no errors.

func (*ErrorList) Sort

func (el *ErrorList) Sort()

Sort sorts el.

func (*ErrorList) Swap

func (el *ErrorList) Swap(i, j int)

Swap implement sort.Interface.

type Mode

type Mode uint

A Mode value is a set of flags (or 0). They control optional parser functionality.

const (
	// IgnoreRegExpErrors ignores RegExp compatibility errors (allow backtracking).
	IgnoreRegExpErrors Mode = 1 << iota

	// StoreComments stores the comments from source to the comments map.
	StoreComments
)

type Parser

type Parser interface {
	Scan() (tkn token.Token, literal string, idx file.Idx)
}

Parser is implemented by types which can parse JavaScript Code.

func NewParser

func NewParser(filename, src string) Parser

NewParser returns a new Parser.