lib/inspector/walk.js
'use babel';
// AST walker module for Mozilla Parser API compatible trees
// A simple walk is one where you simply specify callbacks to be
// called on specific nodes. The last two arguments are optional. A
// simple use would be
//
// walk.simple(myTree, {
// Expression: function(node) { ... }
// });
//
// to do something with all expressions. All Parser API node types
// can be used to identify node types, as well as Expression,
// Statement, and ScopeBody, which denote categories of nodes.
//
// The base argument can be used to pass a custom (recursive)
// walker, and state can be used to give this walked an initial
// state.
export function simple(node, visitors, base, state, override) {
if (!base) base = exports.base;
(function c(node, st, override) {
let type = override || node.type, found = visitors[type];
base[type](node, st, c);
if (found) found(node, st);
})(node, state, override);
};
// An ancestor walk keeps an array of ancestor nodes (including the
// current node) and passes them to the callback as third parameter
// (and also as state parameter when no other state is present).
export function ancestor(node, visitors, base, state) {
if (!base) base = exports.base;
let ancestors = [];
(function c(node, st, override) {
let type = override || node.type, found = visitors[type];
let isNew = node != ancestors[ancestors.length - 1];
if (isNew) ancestors.push(node);
base[type](node, st, c);
if (found) found(node, st || ancestors, ancestors);
if (isNew) ancestors.pop();
})(node, state);
};
// A recursive walk is one where your functions override the default
// walkers. They can modify and replace the state parameter that's
// threaded through the walk, and can opt how and whether to walk
// their child nodes (by calling their third argument on these
// nodes).
export function recursive(node, state, funcs, base, override) {
let visitor = funcs ? exports.make(funcs, base) : base;
(function c(node, st, override) {
// console.log('visiting', node);
visitor[override || node.type](node, st, c);
})(node, state, override);
};
function makeTest(test) {
if (typeof test == "string")
return type => type == test;
else if (!test)
return () => true;
else
return test;
}
class Found {
constructor(node, state) { this.node = node; this.state = state; }
}
// Find a node with a given start, end, and type (all are optional,
// null can be used as wildcard). Returns a {node, state} object, or
// undefined when it doesn't find a matching node.
export function findNodeAt(node, start, end, test, base, state) {
test = makeTest(test);
if (!base) base = exports.base;
try {
(function c(node, st, override) {
let type = override || node.type;
if ((start == null || node.start <= start) &&
(end == null || node.end >= end))
base[type](node, st, c);
if ((start == null || node.start == start) &&
(end == null || node.end == end) &&
test(type, node))
throw new Found(node, st);
})(node, state);
} catch (e) {
if (e instanceof Found) return e;
throw e;
}
};
// Find the innermost node of a given type that contains the given
// position. Interface similar to findNodeAt.
export function findNodeAround(node, pos, test, base, state) {
test = makeTest(test);
if (!base) base = exports.base;
try {
(function c(node, st, override) {
let type = override || node.type;
if (node.start > pos || node.end < pos) return;
base[type](node, st, c);
if (test(type, node)) throw new Found(node, st);
})(node, state);
} catch (e) {
if (e instanceof Found) return e;
throw e;
}
};
// Find the outermost matching node after a given position.
export function findNodeAfter(node, pos, test, base, state) {
test = makeTest(test);
if (!base) base = exports.base;
try {
(function c(node, st, override) {
if (node.end < pos) return;
let type = override || node.type;
if (node.start >= pos && test(type, node)) throw new Found(node, st);
base[type](node, st, c);
})(node, state);
} catch (e) {
if (e instanceof Found) return e;
throw e;
}
};
// Find the outermost matching node before a given position.
export function findNodeBefore(node, pos, test, base, state) {
test = makeTest(test);
if (!base) base = exports.base;
let max;
(function c(node, st, override) {
if (node.start > pos) return;
let type = override || node.type;
if (node.end <= pos && (!max || max.node.end < node.end) && test(type, node))
max = new Found(node, st);
base[type](node, st, c);
})(node, state);
return max;
};
// Fallback to an Object.create polyfill for older environments.
const create = Object.create || function(proto) {
function Ctor() {}
Ctor.prototype = proto;
return new Ctor;
};
// Used to create a custom walker. Will fill in all missing node
// type properties with the defaults.
export function make(funcs, base) {
if (!base) base = exports.base;
let visitor = create(base);
for (var type in funcs) visitor[type] = funcs[type];
return visitor;
};
export function skipThrough(node, st, c) { c(node, st) };
export function ignore(_node, _st, _c) {};
export function ancestorNodesAtOffset(node, offset, visitors = {}) {
let result = [];
findNodeAround(node, offset, (nodeType, node) => {
result.push({
type: nodeType,
node: node
});
if (visitors[nodeType]) {
visitors[nodeType](node);
}
}, base);
return result;
};
// Node walkers.
export const base = {};
base.Program = base.BlockStatement = (node, st, c) => {
for (let i = 0; i < node.body.length; ++i)
c(node.body[i], st, "Statement")
};
base.Statement = skipThrough;
base.EmptyStatement = ignore;
base.ExpressionStatement = base.ParenthesizedExpression =
(node, st, c) => c(node.expression, st, "Expression");
base.IfStatement = (node, st, c) => {
c(node.test, st, "Expression")
c(node.consequent, st, "Statement")
if (node.alternate) c(node.alternate, st, "Statement")
};
base.LabeledStatement = (node, st, c) => c(node.body, st, "Statement");
base.BreakStatement = base.ContinueStatement = ignore;
base.WithStatement = (node, st, c) => {
c(node.object, st, "Expression")
c(node.body, st, "Statement")
};
base.SwitchStatement = (node, st, c) => {
c(node.discriminant, st, "Expression")
for (let i = 0; i < node.cases.length; ++i) {
let cs = node.cases[i]
if (cs.test) c(cs.test, st, "Expression")
for (let j = 0; j < cs.consequent.length; ++j)
c(cs.consequent[j], st, "Statement")
}
};
base.ReturnStatement = base.YieldExpression = base.AwaitExpression = (node, st, c) => {
if (node.argument) c(node.argument, st, "Expression")
};
base.ThrowStatement = base.SpreadElement =
(node, st, c) => c(node.argument, st, "Expression");
base.TryStatement = (node, st, c) => {
c(node.block, st, "Statement")
if (node.handler) c(node.handler, st)
if (node.finalizer) c(node.finalizer, st, "Statement")
};
base.CatchClause = (node, st, c) => {
c(node.param, st, "Pattern")
c(node.body, st, "ScopeBody")
};
base.WhileStatement = base.DoWhileStatement = (node, st, c) => {
c(node.test, st, "Expression")
c(node.body, st, "Statement")
};
base.ForStatement = (node, st, c) => {
if (node.init) c(node.init, st, "ForInit")
if (node.test) c(node.test, st, "Expression")
if (node.update) c(node.update, st, "Expression")
c(node.body, st, "Statement")
};
base.ForInStatement = base.ForOfStatement = (node, st, c) => {
c(node.left, st, "ForInit")
c(node.right, st, "Expression")
c(node.body, st, "Statement")
};
base.ForInit = (node, st, c) => {
if (node.type == "VariableDeclaration") c(node, st)
else c(node, st, "Expression")
};
base.DebuggerStatement = ignore;
base.FunctionDeclaration = (node, st, c) => c(node, st, "Function");
base.VariableDeclaration = (node, st, c) => {
for (let i = 0; i < node.declarations.length; ++i)
c(node.declarations[i], st)
};
base.VariableDeclarator = (node, st, c) => {
c(node.id, st, "Pattern")
if (node.init) c(node.init, st, "Expression")
};
base.Function = (node, st, c) => {
if (node.id) c(node.id, st, "Pattern")
for (let i = 0; i < node.params.length; i++)
c(node.params[i], st, "Pattern")
c(node.body, st, node.expression ? "ScopeExpression" : "ScopeBody")
};
// FIXME drop these node types in next major version
// (They are awkward, and in ES6 every block can be a scope.)
base.ScopeBody = (node, st, c) => c(node, st, "Statement");
base.ScopeExpression = (node, st, c) => c(node, st, "Expression");
base.Pattern = (node, st, c) => {
if (node.type == "Identifier")
c(node, st, "VariablePattern")
else if (node.type == "MemberExpression")
c(node, st, "MemberPattern")
else
c(node, st)
};
base.VariablePattern = ignore;
base.MemberPattern = skipThrough;
base.RestElement = (node, st, c) => c(node.argument, st, "Pattern");
base.ArrayPattern = (node, st, c) => {
for (let i = 0; i < node.elements.length; ++i) {
let elt = node.elements[i]
if (elt) c(elt, st, "Pattern")
}
};
base.ObjectPattern = (node, st, c) => {
for (let i = 0; i < node.properties.length; ++i) {
if (node.properties[i].type !== 'RestProperty') {
c(node.properties[i].value, st, "Pattern");
} else {
c(node.properties[i], st);
}
}
};
base.Expression = skipThrough;
base.ThisExpression = base.Super = base.MetaProperty = ignore;
base.ArrayExpression = (node, st, c) => {
for (let i = 0; i < node.elements.length; ++i) {
let elt = node.elements[i]
if (elt) c(elt, st, "Expression")
}
};
base.ObjectExpression = (node, st, c) => {
for (let i = 0; i < node.properties.length; ++i)
c(node.properties[i], st)
};
base.SpreadProperty = (node, st, c) => {
c(node.argument, st);
};
base.FunctionExpression = base.ArrowFunctionExpression = base.FunctionDeclaration
base.SequenceExpression = base.TemplateLiteral = (node, st, c) => {
for (let i = 0; i < node.expressions.length; ++i)
c(node.expressions[i], st, "Expression")
};
base.UnaryExpression = base.UpdateExpression = (node, st, c) => {
c(node.argument, st, "Expression")
};
base.BinaryExpression = base.LogicalExpression = (node, st, c) => {
c(node.left, st, "Expression")
c(node.right, st, "Expression")
};
base.AssignmentExpression = base.AssignmentPattern = (node, st, c) => {
c(node.left, st, "Pattern")
c(node.right, st, "Expression")
};
base.ConditionalExpression = (node, st, c) => {
c(node.test, st, "Expression")
c(node.consequent, st, "Expression")
c(node.alternate, st, "Expression")
};
base.NewExpression = base.CallExpression = (node, st, c) => {
c(node.callee, st, "Expression")
if (node.arguments) for (let i = 0; i < node.arguments.length; ++i)
c(node.arguments[i], st, "Expression")
};
base.MemberExpression = (node, st, c) => {
c(node.object, st, "Expression")
if (node.computed) c(node.property, st, "Expression")
};
base.ExportNamedDeclaration = base.ExportDefaultDeclaration = (node, st, c) => {
if (node.declaration)
c(node.declaration, st, node.type == "ExportNamedDeclaration" || node.declaration.id ? "Statement" : "Expression")
if (node.source) c(node.source, st, "Expression")
};
base.ExportAllDeclaration = (node, st, c) => {
c(node.source, st, "Expression")
};
base.ImportDeclaration = (node, st, c) => {
for (let i = 0; i < node.specifiers.length; i++)
c(node.specifiers[i], st)
c(node.source, st, "Expression")
};
base.ImportSpecifier = base.ImportDefaultSpecifier = base.ImportNamespaceSpecifier = base.Identifier = base.Literal = ignore;
// Babel spec literals
base.StringLiteral = base.NumericLiteral = base.BooleanLiteral = base.NullLiteral = base.RegExpLiteral = ignore;
base.RestProperty = (node, st, c) => {
c(node.argument, st);
};
base.TaggedTemplateExpression = (node, st, c) => {
c(node.tag, st, "Expression")
c(node.quasi, st)
};
base.ClassDeclaration = base.ClassExpression = (node, st, c) => c(node, st, "Class");
base.Class = (node, st, c) => {
if (node.id) c(node.id, st, "Pattern")
if (node.superClass) c(node.superClass, st, "Expression")
for (let i = 0; i < node.body.body.length; i++)
c(node.body.body[i], st)
};
base.MethodDefinition = base.Property = base.ObjectProperty = (node, st, c) => {
if (node.computed) c(node.key, st, "Expression")
c(node.value, st, "Expression")
};
base.ClassMethod = base.ObjectMethod = (node, state, c) => {
c(node, state, 'FunctionDeclaration');
};
base.ClassProperty = (node, state, c) => {
c(node.key, state);
if (node.value)
c(node.value, state);
};
base.ExportSpecifier = (node, state, c) => {
c(node.local, state);
};
// JSX stuff
base.JSXElementName = base.JSXAttributeName = base.JSXAttributeValue = skipThrough;
base.JSXIdentifier = base.JSXEmptyExpression = base.JSXText = ignore;
base.JSXElement = (node, state, c) => {
c(node.openingElement, state);
node.children.forEach(child => c(child, state));
if (node.closingElement) {
c(node.closingElement, state);
}
};
base.JSXOpeningElement = (node, state, c) => {
c(node.name, state, 'JSXElementName');
node.attributes.forEach(attr => c(attr, state));
};
base.JSXClosingElement = (node, state, c) => {
c(node.name, state, 'JSXElementName');
};
base.JSXAttribute = (node, state, c) => {
c(node.name, state, 'JSXAttributeName');
if (node.value) {
c(node.value, state, 'JSXAttributeValue');
}
};
base.JSXExpressionContainer = (node, state, c) => {
c(node.expression, state, 'Expression');
};
base.JSXSpreadAttribute = (node, state, c) => {
c(node.argument, state, 'Expression');
};
base.JSXNamespacedName = (node, state, c) => {
c(node.namespace, state);
c(node.name, state);
};
base.JSXMemberExpression = (node, state, c) => {
c(node.object, state);
c(node.property, state);
};