var hasOwn = Object.prototype.hasOwnProperty;
module.exports = function (fork) {
var types = fork.use(require("./types"));
var Type = types.Type;
var namedTypes = types.namedTypes;
var Node = namedTypes.Node;
var Expression = namedTypes.Expression;
var isArray = types.builtInTypes.array;
var b = types.builders;
function Scope(path, parentScope) {
if (!(this instanceof Scope)) {
throw new Error("Scope constructor cannot be invoked without 'new'");
}
if (!(path instanceof fork.use(require("./node-path")))) {
throw new Error("");
}
ScopeType.assert(path.value);
var depth;
if (parentScope) {
if (!(parentScope instanceof Scope)) {
throw new Error("");
}
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: {} },
types: { 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.declaresType = function(name) {
this.scan();
return hasOwn.call(this.types, name);
};
Sp.declareTemporary = function(prefix) {
if (prefix) {
if (!/^[a-z$_]/i.test(prefix)) {
throw new Error("");
}
} else {
prefix = "t$";
}
// Include this.depth in the name to make sure the name does not
// collide with any variables in nested/enclosing scopes.
prefix += this.depth.toString(36) + "$";
this.scan();
var index = 0;
while (this.declares(prefix + index)) {
++index;
}
var name = prefix + index;
return this.bindings[name] = types.builders.identifier(name);
};
Sp.injectTemporary = function(identifier, init) {
identifier || (identifier = this.declareTemporary());
var bodyPath = this.path.get("body");
if (namedTypes.BlockStatement.check(bodyPath.value)) {
bodyPath = bodyPath.get("body");
}
bodyPath.unshift(
b.variableDeclaration(
"var",
[b.variableDeclarator(identifier, init || null)]
)
);
return identifier;
};
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.types);
this.didScan = true;
}
};
Sp.getBindings = function () {
this.scan();
return this.bindings;
};
Sp.getTypes = function () {
this.scan();
return this.types;
};
function scanScope(path, bindings, scopeTypes) {
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, scopeTypes);
}
}
function recursiveScanScope(path, bindings, scopeTypes) {
var node = path.value;
if (path.parent &&
namedTypes.FunctionExpression.check(path.parent.node) &&
path.parent.node.id) {
addPattern(path.parent.get("id"), bindings);
}
if (!node) {
// None of the remaining cases matter if node is falsy.
} else if (isArray.check(node)) {
path.each(function(childPath) {
recursiveScanChild(childPath, bindings, scopeTypes);
});
} else if (namedTypes.Function.check(node)) {
path.get("params").each(function(paramPath) {
addPattern(paramPath, bindings);
});
recursiveScanChild(path.get("body"), bindings, scopeTypes);
} else if (namedTypes.TypeAlias && namedTypes.TypeAlias.check(node)) {
addTypePattern(path.get("id"), scopeTypes);
} else if (namedTypes.VariableDeclarator.check(node)) {
addPattern(path.get("id"), bindings);
recursiveScanChild(path.get("init"), bindings, scopeTypes);
} else if (node.type === "ImportSpecifier" ||
node.type === "ImportNamespaceSpecifier" ||
node.type === "ImportDefaultSpecifier") {
addPattern(
// Esprima used to use the .name field to refer to the local
// binding identifier for ImportSpecifier nodes, but .id for
// ImportNamespaceSpecifier and ImportDefaultSpecifier nodes.
// ESTree/Acorn/ESpree use .local for all three node types.
path.get(node.local ? "local" :
node.name ? "name" : "id"),
bindings
);
} else if (Node.check(node) && !Expression.check(node)) {
types.eachField(node, function(name, child) {
var childPath = path.get(name);
if (!pathHasValue(childPath, child)) {
throw new Error("");
}
recursiveScanChild(childPath, bindings, scopeTypes);
});
}
}
function pathHasValue(path, value) {
if (path.value === value) {
return true;
}
// Empty arrays are probably produced by defaults.emptyArray, in which
// case is makes sense to regard them as equivalent, if not ===.
if (Array.isArray(path.value) &&
path.value.length === 0 &&
Array.isArray(value) &&
value.length === 0) {
return true;
}
return false;
}
function recursiveScanChild(path, bindings, scopeTypes) {
var node = path.value;
if (!node || Expression.check(node)) {
// Ignore falsy values and Expressions.
} else if (namedTypes.FunctionDeclaration.check(node) &&
node.id !== null) {
addPattern(path.get("id"), bindings);
} else if (namedTypes.ClassDeclaration &&
namedTypes.ClassDeclaration.check(node)) {
addPattern(path.get("id"), bindings);
} else if (ScopeType.check(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, scopeTypes);
// 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, scopeTypes);
}
}
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.AssignmentPattern &&
namedTypes.AssignmentPattern.check(pattern)) {
addPattern(patternPath.get('left'), bindings);
} else if (namedTypes.ObjectPattern &&
namedTypes.ObjectPattern.check(pattern)) {
patternPath.get('properties').each(function(propertyPath) {
var property = propertyPath.value;
if (namedTypes.Pattern.check(property)) {
addPattern(propertyPath, bindings);
} else if (namedTypes.Property.check(property)) {
addPattern(propertyPath.get('value'), bindings);
} else if (namedTypes.SpreadProperty &&
namedTypes.SpreadProperty.check(property)) {
addPattern(propertyPath.get('argument'), bindings);
}
});
} else if (namedTypes.ArrayPattern &&
namedTypes.ArrayPattern.check(pattern)) {
patternPath.get('elements').each(function(elementPath) {
var element = elementPath.value;
if (namedTypes.Pattern.check(element)) {
addPattern(elementPath, bindings);
} else if (namedTypes.SpreadElement &&
namedTypes.SpreadElement.check(element)) {
addPattern(elementPath.get("argument"), bindings);
}
});
} else if (namedTypes.PropertyPattern &&
namedTypes.PropertyPattern.check(pattern)) {
addPattern(patternPath.get('pattern'), bindings);
} else if ((namedTypes.SpreadElementPattern &&
namedTypes.SpreadElementPattern.check(pattern)) ||
(namedTypes.SpreadPropertyPattern &&
namedTypes.SpreadPropertyPattern.check(pattern))) {
addPattern(patternPath.get('argument'), bindings);
}
}
function addTypePattern(patternPath, types) {
var pattern = patternPath.value;
namedTypes.Pattern.assert(pattern);
if (namedTypes.Identifier.check(pattern)) {
if (hasOwn.call(types, pattern.name)) {
types[pattern.name].push(patternPath);
} else {
types[pattern.name] = [patternPath];
}
}
}
Sp.lookup = function(name) {
for (var scope = this; scope; scope = scope.parent)
if (scope.declares(name))
break;
return scope;
};
Sp.lookupType = function(name) {
for (var scope = this; scope; scope = scope.parent)
if (scope.declaresType(name))
break;
return scope;
};
Sp.getGlobalScope = function() {
var scope = this;
while (!scope.isGlobal)
scope = scope.parent;
return scope;
};
return Scope;
};