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diff --git a/tools/node_modules/eslint/node_modules/acorn/README.md b/tools/node_modules/eslint/node_modules/acorn/README.md new file mode 100644 index 0000000000..ab2c12ea51 --- /dev/null +++ b/tools/node_modules/eslint/node_modules/acorn/README.md @@ -0,0 +1,452 @@ +# Acorn + +[](https://travis-ci.org/ternjs/acorn) +[](https://www.npmjs.com/package/acorn) +[](https://cdnjs.com/libraries/acorn) +[Author funding status: ](https://marijnhaverbeke.nl/fund/) + +A tiny, fast JavaScript parser, written completely in JavaScript. + +## Community + +Acorn is open source software released under an +[MIT license](https://github.com/ternjs/acorn/blob/master/LICENSE). + +You are welcome to +[report bugs](https://github.com/ternjs/acorn/issues) or create pull +requests on [github](https://github.com/ternjs/acorn). For questions +and discussion, please use the +[Tern discussion forum](https://discuss.ternjs.net). + +## Installation + +The easiest way to install acorn is with [`npm`][npm]. + +[npm]: https://www.npmjs.com/ + +```sh +npm install acorn +``` + +Alternately, download the source. + +```sh +git clone https://github.com/ternjs/acorn.git +``` + +## Components + +When run in a CommonJS (node.js) or AMD environment, exported values +appear in the interfaces exposed by the individual files, as usual. +When loaded in the browser (Acorn works in any JS-enabled browser more +recent than IE5) without any kind of module management, a single +global object `acorn` will be defined, and all the exported properties +will be added to that. + +### Main parser + +This is implemented in `dist/acorn.js`, and is what you get when you +`require("acorn")` in node.js. + +**parse**`(input, options)` is used to parse a JavaScript program. +The `input` parameter is a string, `options` can be undefined or 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][estree]. + +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 character offset at which the +error occurred, and a `loc` object that contains a `{line, column}` +object referring to that same position. + +[estree]: https://github.com/estree/estree + +- **ecmaVersion**: Indicates the ECMAScript version to parse. Must be + either 3, 5, 6 (2015), 7 (2016), 8 (2017), or 9 (2018, partial + support). This influences support for strict mode, the set of + reserved words, and support for new syntax features. Default is 7. + + **NOTE**: Only 'stage 4' (finalized) ECMAScript features are being + implemented by Acorn. + +- **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. + +- **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. + +- **allowHashBang**: When this is enabled (off by default), if the + code starts with the characters `#!` (as in a shellscript), the + first line will be treated as a comment. + +- **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][range] `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. + +[range]: https://bugzilla.mozilla.org/show_bug.cgi?id=745678 + +**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. + +**getLineInfo**`(input, offset)` can be used to get a `{line, +column}` object for a given program string and character offset. + +**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. + +#### Note on using with [Escodegen][escodegen] + +Escodegen supports generating comments from AST, attached in +Esprima-specific format. In order to simulate same format in +Acorn, consider following example: + +```javascript +var comments = [], tokens = []; + +var ast = acorn.parse('var x = 42; // answer', { + // collect ranges for each node + ranges: true, + // collect comments in Esprima's format + onComment: comments, + // collect token ranges + onToken: tokens +}); + +// attach comments using collected information +escodegen.attachComments(ast, comments, tokens); + +// generate code +console.log(escodegen.generate(ast, {comment: true})); +// > 'var x = 42; // answer' +``` + +[escodegen]: https://github.com/estools/escodegen + +### dist/acorn_loose.js ### + +This file implements an error-tolerant parser. It exposes a single +function. The loose parser is accessible in node.js via `require("acorn/dist/acorn_loose")`. + +**parse_dammit**`(input, options)` takes the same arguments and +returns the same syntax tree as the `parse` function in `acorn.js`, +but never raises an error, and will do its best to parse syntactically +invalid code in as meaningful a way as it can. It'll insert identifier +nodes with name `"✖"` as placeholders in places where it can't make +sense of the input. Depends on `acorn.js`, because it uses the same +tokenizer. + +### dist/walk.js ### + +Implements an abstract syntax tree walker. Will store its interface in +`acorn.walk` when loaded without a module system. + +**simple**`(node, visitors, base, state)` does a 'simple' walk over +a tree. `node` should be the AST node to walk, and `visitors` an +object with properties whose names correspond to node types in the +[ESTree spec][estree]. The properties should contain functions +that will be called with the node object and, if applicable the state +at that point. The last two arguments are optional. `base` is a walker +algorithm, and `state` is a start state. The default walker will +simply visit all statements and expressions and not produce a +meaningful state. (An example of a use of state is to track scope at +each point in the tree.) + +```js +const acorn = require("acorn") +const walk = require("acorn/dist/walk") + +walk.simple(acorn.parse("let x = 10"), { + Literal(node) { + console.log(`Found a literal: ${node.value}`) + } +}) +``` + +**ancestor**`(node, visitors, base, state)` does a 'simple' walk over +a tree, building up an array of ancestor nodes (including the current node) +and passing the array to the callbacks as a third parameter. + +```js +const acorn = require("acorn") +const walk = require("acorn/dist/walk") + +walk.ancestor(acorn.parse("foo('hi')"), { + Literal(_, ancestors) { + console.log("This literal's ancestors are:", + ancestors.map(n => n.type)) + } +}) +``` + +**recursive**`(node, state, functions, base)` does a 'recursive' +walk, where the walker functions are responsible for continuing the +walk on the child nodes of their target node. `state` is the start +state, and `functions` should contain an object that maps node types +to walker functions. Such functions are called with `(node, state, c)` +arguments, and can cause the walk to continue on a sub-node by calling +the `c` argument on it with `(node, state)` arguments. The optional +`base` argument provides the fallback walker functions for node types +that aren't handled in the `functions` object. If not given, the +default walkers will be used. + +**make**`(functions, base)` builds a new walker object by using the +walker functions in `functions` and filling in the missing ones by +taking defaults from `base`. + +**full**`(node, callback, base, state)` does a 'full' +walk over a tree, calling the callback with the arguments (node, state, type) +for each node + +**fullAncestor**`(node, callback, base, state)` does a 'full' walk over +a tree, building up an array of ancestor nodes (including the current node) +and passing the array to the callbacks as a third parameter. + +```js +const acorn = require("acorn") +const walk = require("acorn/dist/walk") + +walk.full(acorn.parse("1 + 1"), node => { + console.log(`There's a ${node.type} node at ${node.ch}`) +}) +``` + +**findNodeAt**`(node, start, end, test, base, state)` tries to +locate a node in a tree at the given start and/or end offsets, which +satisfies the predicate `test`. `start` and `end` can be either `null` +(as wildcard) or a number. `test` may be a string (indicating a node +type) or a function that takes `(nodeType, node)` arguments and +returns a boolean indicating whether this node is interesting. `base` +and `state` are optional, and can be used to specify a custom walker. +Nodes are tested from inner to outer, so if two nodes match the +boundaries, the inner one will be preferred. + +**findNodeAround**`(node, pos, test, base, state)` is a lot like +`findNodeAt`, but will match any node that exists 'around' (spanning) +the given position. + +**findNodeAfter**`(node, pos, test, base, state)` is similar to +`findNodeAround`, but will match all nodes *after* the given position +(testing outer nodes before inner nodes). + +## 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`: Sets the ECMAScript version + to parse. Default is version 7. + +- `--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. + +- `--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. + +## Build system + +Acorn is written in ECMAScript 6, as a set of small modules, in the +project's `src` directory, and compiled down to bigger ECMAScript 3 +files in `dist` using [Browserify](http://browserify.org) and +[Babel](http://babeljs.io/). If you are already using Babel, you can +consider including the modules directly. + +The command-line test runner (`npm test`) uses the ES6 modules. The +browser-based test page (`test/index.html`) uses the compiled modules. +The `bin/build-acorn.js` script builds the latter from the former. + +If you are working on Acorn, you'll probably want to try the code out +directly, without an intermediate build step. In your scripts, you can +register the Babel require shim like this: + + require("babel-core/register") + +That will allow you to directly `require` the ES6 modules. + +## Plugins + +Acorn is designed support allow plugins which, within reasonable +bounds, redefine the way the parser works. Plugins can add new token +types and new tokenizer contexts (if necessary), and extend methods in +the parser object. This is not a clean, elegant API—using it requires +an understanding of Acorn's internals, and plugins are likely to break +whenever those internals are significantly changed. But still, it is +_possible_, in this way, to create parsers for JavaScript dialects +without forking all of Acorn. And in principle it is even possible to +combine such plugins, so that if you have, for example, a plugin for +parsing types and a plugin for parsing JSX-style XML literals, you +could load them both and parse code with both JSX tags and types. + +A plugin should register itself by adding a property to +`acorn.plugins`, which holds a function. Calling `acorn.parse`, a +`plugins` option can be passed, holding an object mapping plugin names +to configuration values (or just `true` for plugins that don't take +options). After the parser object has been created, the initialization +functions for the chosen plugins are called with `(parser, +configValue)` arguments. They are expected to use the `parser.extend` +method to extend parser methods. For example, the `readToken` method +could be extended like this: + +```javascript +parser.extend("readToken", function(nextMethod) { + return function(code) { + console.log("Reading a token!") + return nextMethod.call(this, code) + } +}) +``` + +The `nextMethod` argument passed to `extend`'s second argument is the +previous value of this method, and should usually be called through to +whenever the extended method does not handle the call itself. + +Similarly, the loose parser allows plugins to register themselves via +`acorn.pluginsLoose`. The extension mechanism is the same as for the +normal parser: + +```javascript +looseParser.extend("readToken", function(nextMethod) { + return function() { + console.log("Reading a token in the loose parser!") + return nextMethod.call(this) + } +}) +``` + +### Existing plugins + + - [`acorn-jsx`](https://github.com/RReverser/acorn-jsx): Parse [Facebook JSX syntax extensions](https://github.com/facebook/jsx) + - [`acorn-es7-plugin`](https://github.com/MatAtBread/acorn-es7-plugin/): Parse [async/await syntax proposal](https://github.com/tc39/ecmascript-asyncawait) + - [`acorn-object-spread`](https://github.com/UXtemple/acorn-object-spread): Parse [object spread syntax proposal](https://github.com/sebmarkbage/ecmascript-rest-spread) + - [`acorn-es7`](https://www.npmjs.com/package/acorn-es7): Parse [decorator syntax proposal](https://github.com/wycats/javascript-decorators) + - [`acorn-objj`](https://www.npmjs.com/package/acorn-objj): [Objective-J](http://www.cappuccino-project.org/learn/objective-j.html) language parser built as Acorn plugin + - [`acorn-object-rest-spread`](https://github.com/victor-homyakov/acorn-object-rest-spread) Parse [Object Rest/Spread Properties proposal](https://github.com/tc39/proposal-object-rest-spread), works with latest Acorn version (5.0.3) + - [`acorn-static-class-property-initializer`](https://github.com/victor-homyakov/acorn-static-class-property-initializer) Partial support for static class properties from [ES Class Fields & Static Properties Proposal](https://github.com/tc39/proposal-class-public-fields) to support static property initializers in [React components written as ES6+ classes](https://babeljs.io/blog/2015/06/07/react-on-es6-plus) + |