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Use escope's native implicit global variable search code instead of our own.

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That code was buggy when we first wrote linker; we reported the bugs and the
maintainer fixed it. Yay!
This commit is contained in:
David Glasser
2013-10-04 09:31:58 -07:00
parent 7864aa77a1
commit 6a836cca94
1 changed files with 4 additions and 73 deletions
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77
packages/js-analyze/js_analyze.js
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@@ -158,81 +158,12 @@ JSAnalyze.findAssignedGlobals = function (source) {
// But it can't pull references outward, so for our purposes it is safe to
// ignore.
var scoper = escope.analyze(parseTree, {ignoreEval: true});
var globalScope = scoper.scopes[0];
var currentScope = null;
var assignedGlobals = {};
// XXX This whole traversal is somewhat overkill. escope actually already
// calculates the implicit global variables. The following code ALMOST works,
// and doesn't even require ignoreEval:
//
// var globalScope = scoper.acquire(parseTree);
// if (globalScope.type !== 'global')
// throw new Error("Unexpected scope type " + globalScope.type);
//
// // can't use underscore because we want to have no dependencies
// for (var i = 0; i < globalScope.variables.length; ++i) {
// var variable = globalScope.variables[i];
// // Because this is the global scope, and we wrap source in a function,
// // the only variables in it should have a single implicit definition.
// if (variable.defs.length !== 1)
// throw new Error("Unexpected def length", variable.defs.length);
// if (variable.defs[0].type !== escope.Variable.ImplicitGlobalVariable)
// throw new Error("Unexpected def type", variable.defs[0].type);
// assignedGlobals[variable.name] = true;
// }
//
// Unfortunately, escope's ImplicitGlobalVariable search has several bugs.
// https://github.com/Constellation/escope/issues/17
// This may have been fixed in 1.0.0, though the syntax to use has changed:
// https://github.com/Constellation/escope/commit/6a4c33364fb1643e12285fb9daa04c015c00af63
// Traverse the tree looking for assignments to unreferenced variables.
estraverse.traverse(parseTree, {
enter: function (node, parent) {
currentScope = scoper.acquire(node) || currentScope;
// We only care about identifiers.
if (node.type !== Syntax.Identifier)
return;
// We already know this one is an assigned global.
// (Avoid using _.has here so that we have no Meteor package
// dependencies.)
if (assignedGlobals.hasOwnProperty(node.name))
return;
var ref = null;
// Find an `escope.Reference` in the current Scope whose identifier node
// is `===` to `node`. If found, this means escope determined this site
// to be a reference rather than some other identifier (like the `x` in
// `var x` or `a.x`).
for (var i = 0; i < currentScope.references.length; i++) {
if (currentScope.references[i].identifier === node) {
ref = currentScope.references[i];
break;
}
}
// If this isn't a reference at all, or it's been resolved to a local, do
// nothing.
if (!ref || ref.resolved)
return;
// OK, it's a global. But is it being assigned to? The situations where a
// global is assigned to are:
// - left-hand side of an '=' assignment
// - the `x` in `for (x in y)` (without a `var`)
// (You might think that ++, --, and the += family of operators also
// write to globals, but they can't in and of themselves conjure up
// a reference where none existed before.)
if ((parent.type === Syntax.AssignmentExpression && parent.left === node
&& parent.operator === '=')
|| (parent.type === Syntax.ForInStatement && parent.left === node)) {
assignedGlobals[node.name] = true;
}
},
leave: function (node, parent) {
currentScope = scoper.release(node) || currentScope;
}
// Underscore is not available in this package.
globalScope.implicit.variables.forEach(function (variable) {
assignedGlobals[variable.name] = true;
});
return assignedGlobals;