Permalink
278 lines (211 sloc)
10.3 KB
Name already in use
A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
codeql-action/node_modules/acorn/README.md
Go to fileThis commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
# Acorn | |
A tiny, fast JavaScript parser written in JavaScript. | |
## Community | |
Acorn is open source software released under an | |
[MIT license](https://github.com/acornjs/acorn/blob/master/acorn/LICENSE). | |
You are welcome to | |
[report bugs](https://github.com/acornjs/acorn/issues) or create pull | |
requests on [github](https://github.com/acornjs/acorn). For questions | |
and discussion, please use the | |
[Tern discussion forum](https://discuss.ternjs.net). | |
## Installation | |
The easiest way to install acorn is from [`npm`](https://www.npmjs.com/): | |
```sh | |
npm install acorn | |
``` | |
Alternately, you can download the source and build acorn yourself: | |
```sh | |
git clone https://github.com/acornjs/acorn.git | |
cd acorn | |
npm install | |
``` | |
## Interface | |
**parse**`(input, options)` is the main interface to the library. The | |
`input` parameter is a string, `options` must be an object setting | |
some of the options listed below. The return value will be an abstract | |
syntax tree object as specified by the [ESTree | |
spec](https://github.com/estree/estree). | |
```javascript | |
let acorn = require("acorn"); | |
console.log(acorn.parse("1 + 1", {ecmaVersion: 2020})); | |
``` | |
When encountering a syntax error, the parser will raise a | |
`SyntaxError` object with a meaningful message. The error object will | |
have a `pos` property that indicates the string offset at which the | |
error occurred, and a `loc` object that contains a `{line, column}` | |
object referring to that same position. | |
Options are provided by in a second argument, which should be an | |
object containing any of these fields (only `ecmaVersion` is | |
required): | |
- **ecmaVersion**: Indicates the ECMAScript version to parse. Must be | |
either 3, 5, 6 (or 2015), 7 (2016), 8 (2017), 9 (2018), 10 (2019), | |
11 (2020), 12 (2021), 13 (2022), 14 (2023), or `"latest"` (the | |
latest the library supports). This influences support for strict | |
mode, the set of reserved words, and support for new syntax | |
features. | |
**NOTE**: Only 'stage 4' (finalized) ECMAScript features are being | |
implemented by Acorn. Other proposed new features must be | |
implemented through plugins. | |
- **sourceType**: Indicate the mode the code should be parsed in. Can be | |
either `"script"` or `"module"`. This influences global strict mode | |
and parsing of `import` and `export` declarations. | |
**NOTE**: If set to `"module"`, then static `import` / `export` syntax | |
will be valid, even if `ecmaVersion` is less than 6. | |
- **onInsertedSemicolon**: If given a callback, that callback will be | |
called whenever a missing semicolon is inserted by the parser. The | |
callback will be given the character offset of the point where the | |
semicolon is inserted as argument, and if `locations` is on, also a | |
`{line, column}` object representing this position. | |
- **onTrailingComma**: Like `onInsertedSemicolon`, but for trailing | |
commas. | |
- **allowReserved**: If `false`, using a reserved word will generate | |
an error. Defaults to `true` for `ecmaVersion` 3, `false` for higher | |
versions. When given the value `"never"`, reserved words and | |
keywords can also not be used as property names (as in Internet | |
Explorer's old parser). | |
- **allowReturnOutsideFunction**: By default, a return statement at | |
the top level raises an error. Set this to `true` to accept such | |
code. | |
- **allowImportExportEverywhere**: By default, `import` and `export` | |
declarations can only appear at a program's top level. Setting this | |
option to `true` allows them anywhere where a statement is allowed, | |
and also allows `import.meta` expressions to appear in scripts | |
(when `sourceType` is not `"module"`). | |
- **allowAwaitOutsideFunction**: If `false`, `await` expressions can | |
only appear inside `async` functions. Defaults to `true` in modules | |
for `ecmaVersion` 2022 and later, `false` for lower versions. | |
Setting this option to `true` allows to have top-level `await` | |
expressions. They are still not allowed in non-`async` functions, | |
though. | |
- **allowSuperOutsideMethod**: By default, `super` outside a method | |
raises an error. Set this to `true` to accept such code. | |
- **allowHashBang**: When this is enabled, if the code starts with the | |
characters `#!` (as in a shellscript), the first line will be | |
treated as a comment. Defaults to true when `ecmaVersion` >= 2023. | |
- **checkPrivateFields**: By default, the parser will verify that | |
private properties are only used in places where they are valid and | |
have been declared. Set this to false to turn such checks off. | |
- **locations**: When `true`, each node has a `loc` object attached | |
with `start` and `end` subobjects, each of which contains the | |
one-based line and zero-based column numbers in `{line, column}` | |
form. Default is `false`. | |
- **onToken**: If a function is passed for this option, each found | |
token will be passed in same format as tokens returned from | |
`tokenizer().getToken()`. | |
If array is passed, each found token is pushed to it. | |
Note that you are not allowed to call the parser from the | |
callback—that will corrupt its internal state. | |
- **onComment**: If a function is passed for this option, whenever a | |
comment is encountered the function will be called with the | |
following parameters: | |
- `block`: `true` if the comment is a block comment, false if it | |
is a line comment. | |
- `text`: The content of the comment. | |
- `start`: Character offset of the start of the comment. | |
- `end`: Character offset of the end of the comment. | |
When the `locations` options is on, the `{line, column}` locations | |
of the comment’s start and end are passed as two additional | |
parameters. | |
If array is passed for this option, each found comment is pushed | |
to it as object in Esprima format: | |
```javascript | |
{ | |
"type": "Line" | "Block", | |
"value": "comment text", | |
"start": Number, | |
"end": Number, | |
// If `locations` option is on: | |
"loc": { | |
"start": {line: Number, column: Number} | |
"end": {line: Number, column: Number} | |
}, | |
// If `ranges` option is on: | |
"range": [Number, Number] | |
} | |
``` | |
Note that you are not allowed to call the parser from the | |
callback—that will corrupt its internal state. | |
- **ranges**: Nodes have their start and end characters offsets | |
recorded in `start` and `end` properties (directly on the node, | |
rather than the `loc` object, which holds line/column data. To also | |
add a | |
[semi-standardized](https://bugzilla.mozilla.org/show_bug.cgi?id=745678) | |
`range` property holding a `[start, end]` array with the same | |
numbers, set the `ranges` option to `true`. | |
- **program**: It is possible to parse multiple files into a single | |
AST by passing the tree produced by parsing the first file as the | |
`program` option in subsequent parses. This will add the toplevel | |
forms of the parsed file to the "Program" (top) node of an existing | |
parse tree. | |
- **sourceFile**: When the `locations` option is `true`, you can pass | |
this option to add a `source` attribute in every node’s `loc` | |
object. Note that the contents of this option are not examined or | |
processed in any way; you are free to use whatever format you | |
choose. | |
- **directSourceFile**: Like `sourceFile`, but a `sourceFile` property | |
will be added (regardless of the `location` option) directly to the | |
nodes, rather than the `loc` object. | |
- **preserveParens**: If this option is `true`, parenthesized expressions | |
are represented by (non-standard) `ParenthesizedExpression` nodes | |
that have a single `expression` property containing the expression | |
inside parentheses. | |
**parseExpressionAt**`(input, offset, options)` will parse a single | |
expression in a string, and return its AST. It will not complain if | |
there is more of the string left after the expression. | |
**tokenizer**`(input, options)` returns an object with a `getToken` | |
method that can be called repeatedly to get the next token, a `{start, | |
end, type, value}` object (with added `loc` property when the | |
`locations` option is enabled and `range` property when the `ranges` | |
option is enabled). When the token's type is `tokTypes.eof`, you | |
should stop calling the method, since it will keep returning that same | |
token forever. | |
In ES6 environment, returned result can be used as any other | |
protocol-compliant iterable: | |
```javascript | |
for (let token of acorn.tokenizer(str)) { | |
// iterate over the tokens | |
} | |
// transform code to array of tokens: | |
var tokens = [...acorn.tokenizer(str)]; | |
``` | |
**tokTypes** holds an object mapping names to the token type objects | |
that end up in the `type` properties of tokens. | |
**getLineInfo**`(input, offset)` can be used to get a `{line, | |
column}` object for a given program string and offset. | |
### The `Parser` class | |
Instances of the **`Parser`** class contain all the state and logic | |
that drives a parse. It has static methods `parse`, | |
`parseExpressionAt`, and `tokenizer` that match the top-level | |
functions by the same name. | |
When extending the parser with plugins, you need to call these methods | |
on the extended version of the class. To extend a parser with plugins, | |
you can use its static `extend` method. | |
```javascript | |
var acorn = require("acorn"); | |
var jsx = require("acorn-jsx"); | |
var JSXParser = acorn.Parser.extend(jsx()); | |
JSXParser.parse("foo(<bar/>)", {ecmaVersion: 2020}); | |
``` | |
The `extend` method takes any number of plugin values, and returns a | |
new `Parser` class that includes the extra parser logic provided by | |
the plugins. | |
## Command line interface | |
The `bin/acorn` utility can be used to parse a file from the command | |
line. It accepts as arguments its input file and the following | |
options: | |
- `--ecma3|--ecma5|--ecma6|--ecma7|--ecma8|--ecma9|--ecma10`: Sets the ECMAScript version | |
to parse. Default is version 9. | |
- `--module`: Sets the parsing mode to `"module"`. Is set to `"script"` otherwise. | |
- `--locations`: Attaches a "loc" object to each node with "start" and | |
"end" subobjects, each of which contains the one-based line and | |
zero-based column numbers in `{line, column}` form. | |
- `--allow-hash-bang`: If the code starts with the characters #! (as | |
in a shellscript), the first line will be treated as a comment. | |
- `--allow-await-outside-function`: Allows top-level `await` expressions. | |
See the `allowAwaitOutsideFunction` option for more information. | |
- `--compact`: No whitespace is used in the AST output. | |
- `--silent`: Do not output the AST, just return the exit status. | |
- `--help`: Print the usage information and quit. | |
The utility spits out the syntax tree as JSON data. | |
## Existing plugins | |
- [`acorn-jsx`](https://github.com/RReverser/acorn-jsx): Parse [Facebook JSX syntax extensions](https://github.com/facebook/jsx) |