forked from benjamn/ast-types
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scope.js
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scope.js
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var assert = require("assert");
var types = require("./types");
var Type = types.Type;
var namedTypes = types.namedTypes;
var Node = namedTypes.Node;
var isArray = types.builtInTypes.array;
var hasOwn = Object.prototype.hasOwnProperty;
function Scope(path, parentScope) {
assert.ok(this instanceof Scope);
assert.ok(path instanceof require("./node-path"));
ScopeType.assert(path.value);
var depth;
if (parentScope) {
assert.ok(parentScope instanceof Scope);
depth = parentScope.depth + 1;
} else {
parentScope = null;
depth = 0;
}
Object.defineProperties(this, {
path: { value: path },
node: { value: path.value },
isGlobal: { value: !parentScope, enumerable: true },
depth: { value: depth },
parent: { value: parentScope },
bindings: { value: {} }
});
}
var scopeTypes = [
// Program nodes introduce global scopes.
namedTypes.Program,
// Function is the supertype of FunctionExpression,
// FunctionDeclaration, ArrowExpression, etc.
namedTypes.Function,
// In case you didn't know, the caught parameter shadows any variable
// of the same name in an outer scope.
namedTypes.CatchClause
];
var ScopeType = Type.or.apply(Type, scopeTypes);
Scope.isEstablishedBy = function(node) {
return ScopeType.check(node);
};
var Sp = Scope.prototype;
// Will be overridden after an instance lazily calls scanScope.
Sp.didScan = false;
Sp.declares = function(name) {
this.scan();
return hasOwn.call(this.bindings, name);
};
Sp.scan = function(force) {
if (force || !this.didScan) {
for (var name in this.bindings) {
// Empty out this.bindings, just in cases.
delete this.bindings[name];
}
scanScope(this.path, this.bindings);
this.didScan = true;
}
};
Sp.getBindings = function () {
this.scan();
return this.bindings;
};
function scanScope(path, bindings) {
var node = path.value;
ScopeType.assert(node);
if (namedTypes.CatchClause.check(node)) {
// A catch clause establishes a new scope but the only variable
// bound in that scope is the catch parameter. Any other
// declarations create bindings in the outer scope.
addPattern(path.get("param"), bindings);
} else {
recursiveScanScope(path, bindings);
}
}
function recursiveScanScope(path, bindings) {
var node = path.value;
if (isArray.check(node)) {
path.each(function(childPath) {
recursiveScanChild(childPath, bindings);
});
} else if (namedTypes.Function.check(node)) {
path.get("params").each(function(paramPath) {
addPattern(paramPath, bindings);
});
recursiveScanChild(path.get("body"), bindings);
} else if (namedTypes.VariableDeclarator.check(node)) {
addPattern(path.get("id"), bindings);
recursiveScanChild(path.get("init"), bindings);
} else if (namedTypes.ImportSpecifier &&
namedTypes.ImportSpecifier.check(node)) {
addPattern(
node.name ? path.get("name") : path.get("id"),
bindings
);
} else if (namedTypes.ModuleDeclaration &&
namedTypes.ModuleDeclaration.check(node)) {
addPattern(path.get("id"), bindings);
} else if (Node.check(node)) {
types.eachField(node, function(name, child) {
var childPath = path.get(name);
assert.strictEqual(childPath.value, child);
recursiveScanChild(childPath, bindings);
});
}
}
function recursiveScanChild(path, bindings) {
var node = path.value;
if (namedTypes.FunctionDeclaration.check(node)) {
addPattern(path.get("id"), bindings);
} else if (namedTypes.ClassDeclaration &&
namedTypes.ClassDeclaration.check(node)) {
addPattern(path.get("id"), bindings);
} else if (Scope.isEstablishedBy(node)) {
if (namedTypes.CatchClause.check(node)) {
var catchParamName = node.param.name;
var hadBinding = hasOwn.call(bindings, catchParamName);
// Any declarations that occur inside the catch body that do
// not have the same name as the catch parameter should count
// as bindings in the outer scope.
recursiveScanScope(path.get("body"), bindings);
// If a new binding matching the catch parameter name was
// created while scanning the catch body, ignore it because it
// actually refers to the catch parameter and not the outer
// scope that we're currently scanning.
if (!hadBinding) {
delete bindings[catchParamName];
}
}
} else {
recursiveScanScope(path, bindings);
}
}
function addPattern(patternPath, bindings) {
var pattern = patternPath.value;
namedTypes.Pattern.assert(pattern);
if (namedTypes.Identifier.check(pattern)) {
if (hasOwn.call(bindings, pattern.name)) {
bindings[pattern.name].push(patternPath);
} else {
bindings[pattern.name] = [patternPath];
}
} else if (namedTypes.SpreadElement &&
namedTypes.SpreadElement.check(pattern)) {
addPattern(patternPath.get("argument"), bindings);
}
}
Sp.lookup = function(name) {
for (var scope = this; scope; scope = scope.parent)
if (scope.declares(name))
break;
return scope;
};
Sp.getGlobalScope = function() {
var scope = this;
while (!scope.isGlobal)
scope = scope.parent;
return scope;
};
module.exports = Scope;