diff --git a/README.md b/README.md index 81488e77f2..f44bacfa8b 100644 --- a/README.md +++ b/README.md @@ -1,122 +1,205 @@ # Acorn -[acorn]: http://marijnhaverbeke.nl/acorn/ -[range]: https://bugzilla.mozilla.org/show_bug.cgi?id=745678 - A tiny, fast JavaScript parser, written completely in JavaScript. -## Invoking +## Installation -Acorn can be invoked in several ways. +The easiest way to install acorn is with [`npm`][npm]. -- From a Node script. -- From the command line. -- From a browser script. - -### Node script - -To use acorn from a [Node](http://nodejs.org) script, install acorn as a package as usual using npm: +[npm]: http://npmjs.org ```sh npm install acorn ``` -Alternately, download the source and link to that: +Alternately, download the source. ```sh git clone https://github.com/marijnh/acorn.git -cd acorn -npm link -cd /path/to/project -npm link acorn ``` -Now you can `require` acorn in your node scripts. The main entrypoint to acorn is the `parse` function, which returns an object with the AST nodes: +## Components -```javascript -var fs = require('fs'), - acorn = require('acorn'); +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 without any kind of module management, a +single global object `acorn` will be defined, and all the exported +properties will be added to that. -try -{ - var code = fs.readFileSync(pathToFile, "utf8"), - ast = acorn.parse(code); -} -catch(e) -{ - console.error(e.message); - process.exit(1); -} -``` +### acorn.js -### Command line +This file contains the actual parser (and is what you get when you +`require("acorn")` in node.js). -To use acorn from the command line, use the `acorn` binary, which is installed when you use npm to install or link the acorn package. Alternately, you can execute `bin/acorn` directly. The syntax is as follows: +**`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 +[Mozilla Parser API][mozapi]. -```text -acorn [options] file +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. -Parses and outputs the AST in JSON format. +[mozapi]: https://developer.mozilla.org/en-US/docs/SpiderMonkey/Parser_API -Options: ---ecma3|--ecma5 Sets the ECMAScript version to parse. Default is version 5. ---strictSemicolons Prevents the parser from doing automatic semicolon insertion. - Statements that do not end in semicolons will generate an error. ---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. ---compact No whitespace is used in the AST output. ---silent Do not output the AST, just return the exit status. ---help Print this usage information and quit. -``` +- **`ecmaVersion`**: Indicates the ECMAScript version to parse. Must be + either 3 or 5. This influences support for strict mode, the set of + reserved words, and support for getters and setter. Default is 5. -### Browser script +- **`strictSemicolons`**: If `true`, prevents the parser from doing + automatic semicolon insertion, and statements that do not end with + a semicolon will generate an error. Defaults to `false`. -To use acorn in the browser, load `acorn.js` with a ` -``` +- **`forbidReserved`**: If `true`, using a reserved word will generate + an error. Defaults to `false`. -Acorn is compatible with [AMD](https://github.com/amdjs/amdjs-api/wiki/AMD), so you may also use loaders like [require.js](http://www.requirejs.org) to load acorn in the browser. +- **`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`. -Once acorn is loaded, you may use acorn within your own scripts by calling `acorn.parse` as illustrated in the Node example above. +- **`onComment`**: If a function is passed for this option, whenever a + comment is encountered the function will be called with the + following parameters: -## Options + - `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. -The optional second parameter to the `parse` function is an options object. Acorn supports a number of options that control its behavior and its output. + When the `locations` options is on, the `{line, column}` locations + of the comment’s start and end are passed as two additional + parameters. -- **ecmaVersion**: Indicates the ECMAScript version to parse. Must be either 3 or 5. This influences support for strict mode, the set of reserved words, and support for getters and setter. *Default*: 5 +- **`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`. -- **strictSemicolons**: If `true`, prevents the parser from doing automatic semicolon insertion, and statements that do not end with a semicolon will generate an error. *Default*: `false` +- **`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. -- **allowTrailingCommas**: If `false`, the parser will not allow trailing commas in array and object literals. +- **`sourceFile`**: When the `locations` option is `true`, you can pass + this option to add a `sourceFile` 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. -- **forbidReserved**: If `true`, using a reserved word will generate an error. *Default*: `false` +- **`directSourceFile`**: Like `sourceFile`, but the property will be + added directly to the nodes, rather than to a `loc` object. -- **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*: `false` +[range]: https://bugzilla.mozilla.org/show_bug.cgi?id=745678 -- **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. +**`getLineInfo`**`(input, offset)` can be used to get a `{line, +column}` object for a given program string and character offset. - When the `locations` options is on, the `{line, column}` locations of the comment’s start and end are passed as two additional parameters. *Default*: `null` +**`tokenize`**`(input, options)` exports a primitive interface to +Acorn's tokenizer. The function takes an input string and options +similar to `parse` (though only some options are meaningful here), and +returns a function that can be called repeatedly to read a single +token, and returns a `{start, end, type, value}` object (with added +`startLoc` and `endLoc` properties when the `locations` option is +enabled). This object will be reused (updated) for each token, so you +can't count on it staying stable. -- **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`. *Default*: `false` +**`tokTypes`** holds an object mapping names to the token type objects +that end up in the `type` properties of tokens. -- **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. *Default*: `null` +### acorn_loose.js ### -- **sourceFile**: When the `locations` option is `true`, you can pass this option to add a "sourceFile" 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. *Default*: `null` +This file implements an error-tolerant parser. It exposes a single +function. -- **directSourceFile**: Like the `sourceFile` option, but adds a "sourceFile" attribute directly to every node, whether or not `locations` is `true`. *Default*: `null` +**`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. -## Errors +### util/walk.js ### -When an error occurs, acorn throws a `SyntaxError` with the following attributes: +Implements an abstract syntax tree walker. Will store its interface in +`acorn.walk` when used without a module system. -- **message**: A descriptive message of the error. The error message will end with `(line:column)`, where `line` is the one-based line number on which the error occurred, and `column` is the zero-based column within that line. -- **pos**: The zero-based character position at which the error occurred. -- **loc**: An object in the form `{line:N, column:N}`, where `line` is the one-based line number on which the error occurred, and `column` is the zero-based column number within that line. -- **raisedAt**: The zero-based character position the parser had reached at the point where the error occurred. +**`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 +[Mozilla Parser API][mozapi]. 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 it to track scope at +each point in the tree.) + +**`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`. + +**`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` end `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`: Sets the ECMAScript version to parse. Default is + version 5. + +- `--strictSemicolons`: Prevents the parser from doing automatic + semicolon insertion. Statements that do not end in semicolons will + generate an error. + +- `--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. + +- `--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. diff --git a/index.html b/index.html index c2892ecf92..18d4291ef6 100644 --- a/index.html +++ b/index.html @@ -59,9 +59,9 @@ end] array with the same numbers, set the ranges option to passing the tree produced by parsing the first file as 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.

    program: null,

When location is on, you can pass this to record the source +of an existing parse tree.

    program: null,

When locations is on, you can pass this to record the source file in every node's loc object.

    sourceFile: null,

This value, if given, is stored in every node, whether -location is on or off.

    directSourceFile: null
+locations is on or off.
                                         
    directSourceFile: null
   };
 
   function setOptions(opts) {