diff options
Diffstat (limited to 'alarm/node_modules/acorn-walk/README.md')
-rw-r--r-- | alarm/node_modules/acorn-walk/README.md | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/alarm/node_modules/acorn-walk/README.md b/alarm/node_modules/acorn-walk/README.md new file mode 100644 index 0000000..e192bac --- /dev/null +++ b/alarm/node_modules/acorn-walk/README.md @@ -0,0 +1,126 @@ +# Acorn AST walker + +An abstract syntax tree walker for the +[ESTree](https://github.com/estree/estree) format. + +## Community + +Acorn is open source software released under an +[MIT license](https://github.com/acornjs/acorn/blob/master/acorn-walk/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-walk +``` + +Alternately, you can download the source and build acorn yourself: + +```sh +git clone https://github.com/acornjs/acorn.git +cd acorn +npm install +``` + +## Interface + +An algorithm for recursing through a syntax tree is stored as an +object, with a property for each tree node type holding a function +that will recurse through such a node. There are several ways to run +such a walker. + +**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](https://github.com/estree/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-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-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-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). |