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Only handle top-level expressions #6

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Only handle top-level expressions #6

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aaf83fa
use estree-walker for faster traversal
Rich-Harris Sep 19, 2016
531e183
only wrap top-level function expressions
Rich-Harris Sep 19, 2016
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25 changes: 14 additions & 11 deletions lib/index.js
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Original file line number Diff line number Diff line change
@@ -1,21 +1,24 @@
'use strict'

var acorn = require('acorn')
var walk = require('walk-ast')
var walk = require('estree-walker').walk
var MagicString = require('magic-string')

function optimizeJs (jsString, opts) {
opts = opts || {}
var ast = acorn.parse(jsString)
var magicString = new MagicString(jsString)

function walkIt (node) {
if (node.type === 'FunctionExpression') {
handleFunctionExpression(node)
function walkIt (node, parentNode) {
if (/Function/.test(node.type)) {
if (node.type === 'FunctionExpression') {
handleFunctionExpression(node, parentNode)
}
this.skip() // don't descend any further
}
}

function handleFunctionExpression (node) {
function handleFunctionExpression (node, parentNode) {
var prePreChar = jsString.charAt(node.start - 2)
var preChar = jsString.charAt(node.start - 1)
var postChar = jsString.charAt(node.end)
Expand All @@ -24,12 +27,12 @@ function optimizeJs (jsString, opts) {
// assuming this node is an argument to a function, return true if it itself
// is already padded with parentheses
function isPaddedArgument (node) {
var idx = node.parentNode.arguments.indexOf(node)
var idx = parentNode.arguments.indexOf(node)
if (idx === 0) { // first arg
if (prePreChar === '(' && preChar === '(' && postChar === ')') { // already padded
return true
}
} else if (idx === node.parentNode.arguments.length - 1) { // last arg
} else if (idx === parentNode.arguments.length - 1) { // last arg
if (preChar === '(' && postChar === ')' && postPostChar === ')') { // already padded
return true
}
Expand All @@ -41,19 +44,19 @@ function optimizeJs (jsString, opts) {
return false
}

if (node.parentNode && node.parentNode.type === 'CallExpression') {
if (parentNode && parentNode.type === 'CallExpression') {
// this function is getting called itself or
// it is getting passed in to another call expression
// the else statement is strictly never hit, but I think the code is easier to read this way
/* istanbul ignore else */
if (node.parentNode.arguments.length && node.parentNode.arguments.indexOf(node) !== -1) {
if (parentNode.arguments.length && parentNode.arguments.indexOf(node) !== -1) {
// function passed in to another function. these are almost _always_ executed, e.g.
// UMD bundles, Browserify bundles, Node-style errbacks, Promise then()s and catch()s, etc.
if (!isPaddedArgument(node)) { // don't double-pad
magicString = magicString.insertLeft(node.start, '(')
.insertRight(node.end, ')')
}
} else if (node.parentNode.callee === node) {
} else if (parentNode.callee === node) {
// this function is getting immediately invoked, e.g. function(){}()
if (preChar !== '(') {
magicString.insertLeft(node.start, '(')
Expand All @@ -63,7 +66,7 @@ function optimizeJs (jsString, opts) {
}
}

walk(ast, walkIt)
walk(ast, { enter: walkIt })
var out = magicString.toString()
if (opts.sourceMap) {
out += '\n//# sourceMappingURL=' + magicString.generateMap().toUrl()
Expand Down
2 changes: 1 addition & 1 deletion package.json
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Original file line number Diff line number Diff line change
Expand Up @@ -23,8 +23,8 @@
"dependencies": {
"acorn": "^3.3.0",
"concat-stream": "^1.5.1",
"estree-walker": "^0.2.1",
"magic-string": "^0.16.0",
"walk-ast": "^0.0.2",
"yargs": "^4.8.1"
},
"devDependencies": {
Expand Down