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Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs.

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/*
 * Copyright 2011 The Closure Compiler Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.javascript.jscomp;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;

import com.google.common.base.Preconditions;
import com.google.common.base.Predicates;
import com.google.common.collect.HashBasedTable;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.google.common.collect.Ordering;
import com.google.common.collect.Table;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.jscomp.base.format.SimpleFormat;
import com.google.javascript.jscomp.modules.Module;
import com.google.javascript.jscomp.modules.ModuleMetadataMap.ModuleType;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.JSDocInfo.Marker;
import com.google.javascript.rhino.JSDocInfo.Visibility;
import com.google.javascript.rhino.JSTypeExpression;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.SourcePosition;
import com.google.javascript.rhino.StaticRef;
import com.google.javascript.rhino.StaticScope;
import com.google.javascript.rhino.StaticSlot;
import com.google.javascript.rhino.StaticSourceFile;
import com.google.javascript.rhino.StaticSymbolTable;
import com.google.javascript.rhino.jstype.EnumType;
import com.google.javascript.rhino.jstype.FunctionType;
import com.google.javascript.rhino.jstype.JSType;
import com.google.javascript.rhino.jstype.JSTypeNative;
import com.google.javascript.rhino.jstype.JSTypeRegistry;
import com.google.javascript.rhino.jstype.ObjectType;
import com.google.javascript.rhino.jstype.SimpleReference;
import com.google.javascript.rhino.jstype.SimpleSlot;
import com.google.javascript.rhino.jstype.StaticTypedScope;
import com.google.javascript.rhino.jstype.StaticTypedSlot;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.TreeSet;
import java.util.function.Predicate;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.jspecify.nullness.Nullable;

/**
 * A symbol table for people that want to use Closure Compiler as an indexer.
 *
 * 

Contains an index of all the symbols in the code within a compilation job. The API is designed * for people who want to visit all the symbols, rather than people who want to lookup a specific * symbol by a certain key. * *

We can use this to combine different types of symbol tables. For example, one class might have * a {@code StaticSymbolTable} of all variable references, and another class might have a {@code * StaticSymbolTable} of all type names in JSDoc comments. This class allows you to combine them * into a unified index. * *

Most passes build their own "partial" symbol table that implements the same interface * (StaticSymbolTable, StaticSlot, and friends). Individual compiler passes usually need more or * less metadata about the certainty of symbol information. Building a complete symbol table with * all the necessary metadata for all passes would be too slow. However, as long as these "partial" * symbol tables implement the proper interfaces, we should be able to add them to this symbol table * to make it more complete. * *

If clients want fast lookup, they should build their own wrapper around this symbol table that * indexes symbols or references by the desired lookup key. * *

By design, when this symbol table creates symbols for types, it tries to mimic the symbol * table you would get in an OO language. For example, the "type Foo" and "the constructor that * creates objects of type Foo" are the same symbol. The types of "Foo.prototype" and "new Foo()" * also have the same symbol. Although JSCompiler internally treats these as distinct symbols, we * assume that most clients will not care about the distinction. * * @see #addSymbolsFrom For more information on how to write plugins for this symbol table. */ public final class SymbolTable { private static final Logger logger = Logger.getLogger(SymbolTable.class.getName()); /** * The name we use for the JavaScript built-in Global object. It's anonymous in JavaScript, so we * have to give it an invalid identifier to avoid conflicts with user-defined property names. */ public static final String GLOBAL_THIS = "*global*"; /** * All symbols in the program, uniquely identified by the node where they're declared and their * name. */ private final Table symbols = HashBasedTable.create(); /** * All syntactic scopes in the program, uniquely identified by the node where they're declared. */ private final Map scopes = new LinkedHashMap<>(); /** All Nodes with JSDocInfo in the program. */ private final List docInfos = new ArrayList<>(); private @Nullable SymbolScope globalScope = null; private final AbstractCompiler compiler; private final JSTypeRegistry registry; /** Clients should get a symbol table by asking the compiler at the end of a compilation job. */ SymbolTable(AbstractCompiler compiler, JSTypeRegistry registry) { this.compiler = compiler; this.registry = registry; } public Iterable getReferences(Symbol symbol) { return Collections.unmodifiableCollection(symbol.references.values()); } public ImmutableList getReferenceList(Symbol symbol) { return ImmutableList.copyOf(symbol.references.values()); } public ImmutableList getAllSymbols() { return ImmutableList.copyOf(symbols.values()); } /** Get the symbols in their natural ordering. Always returns a mutable list. */ public List getAllSymbolsSorted() { return getNaturalSymbolOrdering().sortedCopy(symbols.values()); } /** * Gets the 'natural' ordering of symbols. * *

Right now, we only guarantee that symbols in the global scope will come before symbols in * local scopes. After that, the order is deterministic but undefined. */ public Ordering getNaturalSymbolOrdering() { return symbolOrdering; } public SymbolScope getScope(Symbol slot) { return slot.scope; } public Collection getAllJSDocInfoNodes() { return Collections.unmodifiableList(docInfos); } /** * Gets the scope that contains the given node. If {@code n} is a function name, we return the * scope that contains the function, not the function itself. */ public @Nullable SymbolScope getEnclosingScope(Node n) { Node current = n.getParent(); if (n.isName() && n.getParent().isFunction()) { current = current.getParent(); } for (; current != null; current = current.getParent()) { if (scopes.containsKey(current)) { return scopes.get(current); } } return null; } /** * Gets the scope that contains the given node. If {@code n} is a function name, we return the * scope that contains the function, not the function itself. The returned scope is either * function or global scope. */ public SymbolScope getEnclosingFunctionScope(Node n) { Node current = n.getParent(); if (n.isName() && current != null && current.isFunction()) { current = current.getParent(); } for (; current != null; current = current.getParent()) { SymbolScope scope = scopes.get(current); if (scope != null && !scope.isBlockScope()) { return scope; } } return globalScope; } /** * If {@code sym} is a function, try to find a Symbol for a parameter with the given name. * *

Returns null if we couldn't find one. * *

Notice that this just makes a best effort, and may not be able to find parameters for * non-conventional function definitions. For example, we would not be able to find "y" in this * code: * var x = x() ? function(y) {} : function(y) {}; * */ public @Nullable Symbol getParameterInFunction(Symbol sym, String paramName) { SymbolScope scope = getScopeInFunction(sym); if (scope != null) { Symbol param = scope.getSlot(paramName); if (param != null && param.scope == scope) { return param; } } return null; } private @Nullable SymbolScope getScopeInFunction(Symbol sym) { FunctionType type = sym.getFunctionType(); if (type == null) { return null; } Node functionNode = type.getSource(); if (functionNode == null) { return null; } return scopes.get(functionNode); } /** * All local scopes are associated with a function, and some functions are associated with a * symbol. Returns the symbol associated with the given scope. */ public Symbol getSymbolForScope(SymbolScope scope) { if (scope.getSymbolForScope() == null) { scope.setSymbolForScope(findSymbolForScope(scope)); } return scope.getSymbolForScope(); } /** * Find the symbol associated with the given scope. Notice that we won't always be able to figure * out this association dynamically, so sometimes we'll just create the association when we create * the scope. */ private @Nullable Symbol findSymbolForScope(SymbolScope scope) { Node rootNode = scope.getRootNode(); if (rootNode.getParent() == null) { return globalScope.getSlot(GLOBAL_THIS); } if (!rootNode.isFunction()) { return null; } String name = NodeUtil.getBestLValueName(NodeUtil.getBestLValue(rootNode)); return name == null ? null : scope.getParentScope().getQualifiedSlot(name); } /** * Get all symbols associated with the type of the given symbol. * *

For example, given a variable x declared as /* @type {Array|Date} / var x = f(); this will * return the constructors for Array and Date. */ public Iterable getAllSymbolsForTypeOf(Symbol sym) { return getAllSymbolsForType(getType(sym)); } /** Returns the global scope. */ public SymbolScope getGlobalScope() { return globalScope; } /** Gets the symbol for the given constructor or interface. */ public Symbol getSymbolDeclaredBy(FunctionType fn) { checkState(fn.isConstructor() || fn.isInterface()); ObjectType instanceType = fn.getInstanceType(); return getSymbolForName(fn.getSource(), instanceType.getReferenceName()); } /** Gets the symbol for the given enum. */ public Symbol getSymbolDeclaredBy(EnumType enumType) { return getSymbolForName(enumType.getSource(), enumType.getElementsType().getReferenceName()); } /** Gets the symbol for the prototype if this is the symbol for a constructor or interface. */ public @Nullable Symbol getSymbolForInstancesOf(Symbol sym) { FunctionType fn = sym.getFunctionType(); if (fn != null && fn.isNominalConstructorOrInterface()) { return getSymbolForInstancesOf(fn); } return null; } /** Gets the symbol for the prototype of the given constructor or interface. */ public Symbol getSymbolForInstancesOf(FunctionType fn) { checkState(fn.isConstructor() || fn.isInterface()); ObjectType pType = fn.getPrototype(); return getSymbolForName(fn.getSource(), pType.getReferenceName()); } private @Nullable Symbol getSymbolForName(@Nullable Node source, String name) { if (name == null || globalScope == null) { return null; } SymbolScope scope = source == null ? globalScope : getEnclosingScope(source); if (scope == null) { return null; } if (scope.isModuleScope()) { // In the case of elements like // // goog.module('foo.bar'); // exports.Pinky = {}; // // we might get fully-qualified name `foo.bar.Pinky` but when looking it up within the module // - the symbol is just `Pinky`. So we need to remove module name to be able to find the // symbol in module scope. String moduleNameWithDot = Iterables.getFirst( compiler .getModuleMetadataMap() .getModulesByPath() .get(scope.getRootNode().getSourceFileName()) .googNamespaces(), null) + "."; if (name.startsWith(moduleNameWithDot)) { name = name.substring(moduleNameWithDot.length()); } } return scope.getQualifiedSlot(name); } /** * Gets all symbols associated with the given type. For union types, this may be multiple symbols. * For instance types, this will return the constructor of that instance. */ public List getAllSymbolsForType(JSType type) { if (type == null) { return ImmutableList.of(); } if (type.isUnionType()) { ImmutableList.Builder result = ImmutableList.builder(); for (JSType alt : type.toMaybeUnionType().getAlternates()) { // Our type system never has nested unions. Symbol altSym = getSymbolForTypeHelper(alt, true); if (altSym != null) { result.add(altSym); } } return result.build(); } Symbol result = getSymbolForTypeHelper(type, true); return result == null ? ImmutableList.of() : ImmutableList.of(result); } /** * Gets all symbols associated with the given type. If there is more that one symbol associated * with the given type, return null. * * @param type The type. * @param linkToCtor If true, we should link instance types back to their constructor function. If * false, we should link instance types back to their prototype. See the comments at the top * of this file for more information on how our internal type system is more granular than * Symbols. */ private @Nullable Symbol getSymbolForTypeHelper(JSType type, boolean linkToCtor) { if (type == null) { return null; } if (type.isGlobalThisType()) { return globalScope.getSlot(GLOBAL_THIS); } else if (type.isNominalConstructorOrInterface()) { return linkToCtor ? globalScope.getSlot("Function") : getSymbolDeclaredBy(type.toMaybeFunctionType()); } else if (type.isFunctionPrototypeType()) { FunctionType ownerFn = ((ObjectType) type).getOwnerFunction(); if (!ownerFn.isConstructor() && !ownerFn.isInterface()) { return null; } return linkToCtor ? getSymbolDeclaredBy(ownerFn) : getSymbolForInstancesOf(ownerFn); } else if (type.isInstanceType()) { FunctionType ownerFn = ((ObjectType) type).getConstructor(); return linkToCtor ? getSymbolDeclaredBy(ownerFn) : getSymbolForInstancesOf(ownerFn); } else if (type.isFunctionType()) { return linkToCtor ? globalScope.getSlot("Function") : globalScope.getQualifiedSlot("Function.prototype"); } else if (type.autoboxesTo() != null) { return getSymbolForTypeHelper(type.autoboxesTo(), linkToCtor); } else if (type.isEnumType()) { return getSymbolDeclaredBy((EnumType) type); } else { return null; } } /** * Methods returns debug representation of the SymbolTable. It starts with the global scope and * all its symbols recursively going to children scopes and printing their symbols. */ @SuppressWarnings("unused") public String toDebugStringTree() { // We are recursively going through scopes from global to nested and need to build parent => // children map as it doesn't exist at the moment. ImmutableListMultimap.Builder childrenScopesBuilder = ImmutableListMultimap.builder(); for (SymbolScope scope : getAllScopes()) { if (scope.getParentScope() != null) { childrenScopesBuilder.put(scope.getParentScope(), scope); } } ImmutableListMultimap childrenScopes = childrenScopesBuilder.build(); StringBuilder builder = new StringBuilder(); // Go through all scopes that don't have parent. It's likely only Global scope. for (SymbolScope scope : getAllScopes()) { if (scope.getParentScope() == null) { toDebugStringTree(builder, "", scope, childrenScopes); } } // All objects/classes have property scopes. They usually don't have parents. These scopes // confusingly are not included in "getAllScopes()" pass above. LinkedHashSet visitedScopes = new LinkedHashSet<>(getAllScopes()); for (Symbol symbol : getAllSymbols()) { if (symbol.propertyScope == null || visitedScopes.contains(symbol.propertyScope)) { continue; } visitedScopes.add(symbol.getPropertyScope()); toDebugStringTree(builder, "", symbol.propertyScope, childrenScopes); } return builder.toString(); } private void toDebugStringTree( StringBuilder builder, String prefix, SymbolScope scope, ImmutableListMultimap childrenScopes) { builder.append(prefix).append(scope); String childrenPrefix = prefix + " "; boolean printedSomething = false; if (!scope.ownSymbols.isEmpty()) { printedSomething = true; builder.append('\n').append(prefix).append(" Symbols:\n"); for (Symbol symbol : scope.ownSymbols.values()) { toDebugString(builder, childrenPrefix, symbol, /* printScope= */ false); } } if (childrenScopes.containsKey(scope)) { printedSomething = true; builder.append('\n').append(prefix).append(" Scopes:\n"); for (SymbolScope childScope : childrenScopes.get(scope)) { toDebugStringTree(builder, childrenPrefix, childScope, childrenScopes); } } if (!printedSomething) { builder.append('\n'); } builder.append('\n'); } @SuppressWarnings("unused") public String toDebugString() { StringBuilder builder = new StringBuilder(); for (Symbol symbol : getAllSymbols()) { toDebugString(builder, "", symbol, /* printScope= */ true); } return builder.toString(); } private void toDebugString( StringBuilder builder, String prefix, Symbol symbol, boolean printScope) { builder.append(prefix).append("'").append(symbol.getName()).append("'"); if (printScope) { builder.append(" in ").append(symbol.scope); } builder.append('\n'); int refCount = 0; for (Reference ref : getReferences(symbol)) { Node node = ref.getNode(); builder .append(prefix) .append( SimpleFormat.format( " Ref %d: %s line: %d col: %d len: %d %s\n", refCount, node.getSourceFileName(), node.getLineno(), node.getCharno(), node.getLength(), node.isIndexable() ? "" : "non indexable")); refCount++; } } /** Make sure all the given scopes in {@code otherSymbolTable} are in this symbol table. */ void addScopes(Collection scopes) { for (S scope : scopes) { createScopeFrom(scope); } } /** Finds all the scopes and adds them to this symbol table. */ void findScopes(Node externs, Node root) { NodeTraversal.traverseRoots( compiler, new NodeTraversal.AbstractScopedCallback() { @Override public void enterScope(NodeTraversal t) { createScopeFrom(t.getScope()); } @Override public void visit(NodeTraversal t, Node n, Node p) {} }, externs, root); } /** Gets all the scopes in this symbol table. */ public Collection getAllScopes() { return Collections.unmodifiableCollection(scopes.values()); } /** * Finds anonymous functions in local scopes, and gives them names and symbols. They will show up * as local variables with names "function%0", "function%1", etc. */ public void addAnonymousFunctions() { TreeSet scopes = new TreeSet<>(lexicalScopeOrdering); for (SymbolScope scope : getAllScopes()) { if (scope.isLexicalScope()) { scopes.add(scope); } } for (SymbolScope scope : scopes) { addAnonymousFunctionsInScope(scope); } } private void addAnonymousFunctionsInScope(SymbolScope scope) { Symbol sym = getSymbolForScope(scope); if (sym == null) { // JSCompiler has no symbol for this scope. Check to see if it's a // local function. If it is, give it a name. Node rootNode = scope.getRootNode(); if (scope.isLexicalScope() && !scope.isGlobalScope() && rootNode != null && !rootNode.isFromExterns() && scope.getParentScope() != null && rootNode.isFunction()) { SymbolScope parent = scope.getParentScope(); String innerName = "function%" + scope.getIndexInParent(); JSType type = rootNode.getJSType(); // Functions defined on anonymous objects are considered anonymous as well: // doFoo({bar() {}}); // bar is not technically anonymous, but it's a method on an anonymous object literal so // effectively it's anonymous/inaccessible. In this case, slightly correct rootNode to // be a MEMBER_FUNCTION_DEF node instead of a FUNCTION node. if (rootNode.getParent().isMemberFunctionDef()) { rootNode = rootNode.getParent(); } Symbol anonymousFunctionSymbol = declareSymbol( innerName, type, /* inferred= */ true, parent, rootNode, /* info= */ null); scope.setSymbolForScope(anonymousFunctionSymbol); } } } /** * Make sure all the symbols and references in {@code otherSymbolTable} are in this symbol table. * *

Uniqueness of symbols and references is determined by the associated node. * *

If multiple symbol tables are mixed in, we do not check for consistency between symbol * tables. The first symbol we see dictates the type information for that symbol. */ void addSymbolsFrom( StaticSymbolTable otherSymbolTable) { for (S otherSymbol : otherSymbolTable.getAllSymbols()) { String name = otherSymbol.getName(); SymbolScope myScope = createScopeFrom(otherSymbolTable.getScope(otherSymbol)); StaticRef decl = findBestDeclToAdd(otherSymbolTable, otherSymbol); Symbol mySymbol = null; if (decl != null) { Node declNode = decl.getNode(); // If we have a declaration node, we can ensure the symbol is declared. mySymbol = isAnySymbolDeclared(name, declNode, myScope); if (mySymbol == null) { mySymbol = copySymbolTo(otherSymbol, declNode, myScope); } } else { // If we don't have a declaration node, we won't be able to declare // a symbol in this symbol table. But we may be able to salvage the // references if we already have a symbol. mySymbol = myScope.getOwnSlot(name); } if (mySymbol != null) { for (R otherRef : otherSymbolTable.getReferences(otherSymbol)) { if (isGoodRefToAdd(otherRef)) { mySymbol.defineReferenceAt(otherRef.getNode()); } } } } } /** * Checks if any symbol is already declared at the given node and scope for the given name. If so, * returns it. */ private Symbol isAnySymbolDeclared(String name, Node declNode, SymbolScope scope) { Symbol sym = symbols.get(declNode, name); if (sym == null) { // Sometimes, our symbol tables will disagree on where the // declaration node should be. In the rare case where this happens, // trust the existing symbol. // See SymbolTableTest#testDeclarationDisagreement. return scope.ownSymbols.get(name); } return sym; } /** Helper for addSymbolsFrom, to determine the best declaration spot. */ private @Nullable StaticRef findBestDeclToAdd( StaticSymbolTable otherSymbolTable, S slot) { StaticRef decl = slot.getDeclaration(); if (isGoodRefToAdd(decl)) { return decl; } for (R ref : otherSymbolTable.getReferences(slot)) { if (isGoodRefToAdd(ref)) { return ref; } } return null; } /** * Helper for addSymbolsFrom, to determine whether a reference is acceptable. A reference must be * in the normal source tree. */ private boolean isGoodRefToAdd(@Nullable StaticRef ref) { return ref != null && ref.getNode() != null && ref.getNode().getStaticSourceFile() != null && !NodeUtil.isInSyntheticScript(ref.getNode()) // Typechecking assigns implicitly goog.provided names a declaration node of the expr: // For example, 'some' and 'some.name' in 'goog.provide('some.name.child');' have their // declaration node set to the entire call node. Use the actual declaration instead. && !NodeUtil.isGoogProvideCall(ref.getNode()); } private Symbol copySymbolTo(StaticSlot sym, SymbolScope scope) { return copySymbolTo(sym, sym.getDeclaration().getNode(), scope); } private Symbol copySymbolTo(StaticSlot sym, Node declNode, SymbolScope scope) { // All symbols must have declaration nodes. checkNotNull(declNode); return declareSymbol( sym.getName(), getType(sym), isTypeInferred(sym), scope, declNode, sym.getJSDocInfo()); } /** * Replace all \ with \\ so there will be no \0 or \n in the string, then replace all '\0' (NULL) * with \0 and all '\n' (newline) with \n. */ private static String sanitizeSpecialChars(String s) { return s.replace("\\", "\\\\").replace("\0", "\\0").replace("\n", "\\n"); } private Symbol addSymbol( String name, JSType type, boolean inferred, SymbolScope scope, Node declNode) { name = sanitizeSpecialChars(name); Symbol symbol = new Symbol(name, type, inferred, scope); Symbol replacedSymbol = symbols.put(declNode, name, symbol); Preconditions.checkState( replacedSymbol == null, "Found duplicate symbol %s in global index. Type %s", name, type); replacedSymbol = scope.ownSymbols.put(name, symbol); Preconditions.checkState( replacedSymbol == null, "Found duplicate symbol %s in its scope. Type %s", name, type); return symbol; } private Symbol declareSymbol( String name, @Nullable JSType type, boolean inferred, SymbolScope scope, Node declNode, @Nullable JSDocInfo info) { Symbol symbol = addSymbol(name, type, inferred, scope, declNode); symbol.setJSDocInfo(info); symbol.setDeclaration(symbol.defineReferenceAt(declNode)); return symbol; } /** * Merges 'from' symbol to 'to' symbol by moving all references to point to the 'to' symbol and * removing 'from' symbol. */ private void mergeSymbol(Symbol from, Symbol to) { for (Node nodeToMove : from.references.keySet()) { if (!nodeToMove.equals(from.getDeclarationNode())) { to.defineReferenceAt(nodeToMove); } } removeSymbol(from); } private void removeSymbol(Symbol s) { SymbolScope scope = getScope(s); if (!s.equals(scope.ownSymbols.remove(s.getName()))) { throw new IllegalStateException("Symbol not found in scope " + s); } if (!s.equals(symbols.remove(s.getDeclaration().getNode(), s.getName()))) { throw new IllegalStateException("Symbol not found in table " + s); } // If s declares a property scope then all child symbols should be removed as well. // For example: // let foo = {a: 1, b: 2}; // foo declares property scope with a and b as its children. When removing foo we should also // remove a and b. if (s.propertyScope != null && s.equals(s.propertyScope.getSymbolForScope())) { // Need to iterate over copy of values list because removeSymbol() will change the map // and we'll get ConcurrentModificationException for (Symbol childSymbol : ImmutableList.copyOf(s.propertyScope.ownSymbols.values())) { removeSymbol(childSymbol); } scopes.remove(s.getDeclarationNode()); } } private void renameSymbol(SymbolScope scope, Symbol sym, String newName) { Preconditions.checkState( sym.propertyScope == null, "Renaming supported for simple symbols that don't have property scopes."); Symbol existingSym = scope.getSlot(newName); if (existingSym == null) { existingSym = declareSymbol( newName, getType(sym), isTypeInferred(sym), scope, sym.getDeclarationNode(), sym.getJSDocInfo()); } mergeSymbol(sym, existingSym); } /** * Not all symbol tables record references to "namespace" objects. For example, if you have: * goog.dom.DomHelper = function() {}; The symbol table may not record that as a reference to * "goog.dom", because that would be redundant. */ void fillNamespaceReferences() { for (Symbol symbol : getAllSymbols()) { String qName = symbol.getName(); int rootIndex = qName.indexOf('.'); if (rootIndex == -1) { continue; } Symbol root = symbol.scope.getQualifiedSlot(qName.substring(0, rootIndex)); if (root == null) { // In theory, this should never happen, but we fail quietly anyway // just to be safe. continue; } for (Reference ref : getReferences(symbol)) { Node currentNode = ref.getNode(); if (!currentNode.isQualifiedName()) { continue; } while (currentNode.isGetProp()) { currentNode = currentNode.getFirstChild(); String name = currentNode.getQualifiedName(); if (name == null) { continue; } Symbol namespace = isAnySymbolDeclared(name, currentNode, root.scope); if (namespace == null) { namespace = root.scope.getQualifiedSlot(name); } if (namespace == null && root.scope.isGlobalScope()) { // Originally UNKNOWN_TYPE has been always used for namespace symbols even though // compiler does have type information attached to a node. Unclear why. Changing code to // property type mostly works. It only fails on Foo.prototype cases for some reason. // It's pretty rare case when Foo.prototype defined in global scope though so for now // just carve it out. JSType nodeType = currentNode.getJSType(); JSType symbolType = (nodeType != null && !nodeType.isFunctionPrototypeType()) ? nodeType : registry.getNativeType(JSTypeNative.UNKNOWN_TYPE); namespace = declareSymbol( name, symbolType, true, root.scope, currentNode, null /* JsDoc info */); } if (namespace != null) { namespace.defineReferenceAt(currentNode); } } } } } void fillPropertyScopes() { // Collect all object symbols. // All symbols that came from goog.module are collected separately because they will have to // be processed first. See explanation below. List types = new ArrayList<>(); List exports = new ArrayList<>(); // Create a property scope for each named type and each anonymous object, // and populate it with that object's properties. // // We notably don't want to create a property scope for 'x' in // var x = new Foo(); // where x is just an instance of another type. for (Symbol sym : getAllSymbols()) { if (needsPropertyScope(sym)) { String name = sym.getName(); if (name.equals("exports")) { exports.add(sym); } else { types.add(sym); } } } // The order of operations here is significant. // // When we add properties to Foo, we'll remove Foo.prototype from // the symbol table and replace it with a fresh symbol in Foo's // property scope. So the symbol for Foo.prototype in // {@code instances} will be stale. // // If we order them in reverse lexicographical order symbols x.y and x will be processed before // foo. This is wrong as foo is in fact property of x.y namespace. So we must process all // module$exports$ symbols first. That's why we collected them in a separate list. Collections.sort(types, getNaturalSymbolOrdering().reverse()); Iterable allTypes = Iterables.concat(types, exports); // If you thought we are done with tricky case - you were wrong. There is another one! // The problem with the same property scope appearing several times. For example when using // aliases: // // const OBJ = {one: 1}; // function() { // const alias = OBJ; // console.log(alias.one); // } // // In this case both 'OBJ' and 'alias' are considered property scopes and are candidates for // processing even though they share the same "type" which is "{one: 1}". As they share the same // type we need to process only one of them. To do that we build a "type => root symbol" map. // In this case the map will be {one: 1} => OBJ. Using this map will skip 'alias' when creating // property scopes. // // NOTE: we are using IdentityHashMap to compare types using == because we need to find symbols // that point to the exact same type instance. IdentityHashMap symbolThatDeclaresType = new IdentityHashMap<>(); for (Symbol s : allTypes) { // Symbols are sorted in reverse order so that those with more outer scope will come later in // the list, and therefore override those set by aliases in more inner scope. The sorting // happens few lines above. JSType type = s.getType(); Symbol symbolForType = getSymbolForTypeHelper(type, /* linkToCtor= */ false); if ((type.isNominalConstructorOrInterface() || type.isFunctionPrototypeType() || type.isEnumType()) && !s.equals(symbolForType)) { // Some cases can't be handled by sorting. For example // // goog.module('some.Foo'); // class Foo {} // exports = Foo; // // goog.module('some.bar'); // const Foo = goog.require('some.Foo'); // // Both Foo symbols (declaration and alias) have the same type and equal candidates to // become "symbol that declares Foo type". But in reality we should use the Foo in some.Foo // module. So if symbolForType exists and not equal to current symbol - it means it's an // alias. continue; } symbolThatDeclaresType.put(s.getType(), s); } for (Symbol s : allTypes) { // Create property scopes only based on "root" symbols for each type to handle aliases. if (s.getType() == null || s.equals(symbolThatDeclaresType.get(s.getType()))) { createPropertyScopeFor(s); } } // Now we need to set the new property scope symbol to all aliases. for (Symbol s : allTypes) { if (s.getType() != null && symbolThatDeclaresType.get(s.getType()) != null) { s.propertyScope = symbolThatDeclaresType.get(s.getType()).getPropertyScope(); } } pruneOrphanedNames(); } private boolean needsPropertyScope(Symbol sym) { ObjectType type = ObjectType.cast(getType(sym)); if (type == null) { return false; } // Anonymous objects if (type.getReferenceName() == null) { return true; } // Constructors/prototypes if (type.isNominalConstructorOrInterface() || type.isFunctionPrototypeType()) { return true; } if (type.isEnumType()) { return true; } return false; } /** * Removes symbols where the namespace they're on has been removed. * *

After filling property scopes, we may have two symbols represented in different ways. For * example, "A.superClass_.foo" and B.prototype.foo". * *

This resolves that ambiguity by pruning the duplicates. If we have a lexical symbol with a * constructor in its property chain, then we assume there's also a property path to this symbol. * In other words, we can remove "A.superClass_.foo" because it's rooted at "A", and we built a * property scope for "A" above. */ void pruneOrphanedNames() { nextSymbol: for (Symbol s : getAllSymbols()) { String currentName = s.getName(); if (s.isProperty() || compiler.getModuleMap().getClosureModule(currentName) != null) { continue; } int dot = -1; while (-1 != (dot = currentName.lastIndexOf('.'))) { currentName = currentName.substring(0, dot); Symbol owner = s.scope.getQualifiedSlot(currentName); if (owner != null && getType(owner) != null && (getType(owner).isNominalConstructorOrInterface() || getType(owner).isFunctionPrototypeType() || getType(owner).isEnumType())) { removeSymbol(s); continue nextSymbol; } } } } /** * Create symbols and references for all properties of types in this symbol table. * *

This gets a little bit tricky, because of the way this symbol table conflates "type Foo" and * "the constructor of type Foo". So if you have: * SymbolTable symbolTable = for("var x = new Foo();"); * Symbol x = symbolTable.getGlobalScope().getSlot("x"); * Symbol type = symbolTable.getAllSymbolsForType(getType(x)).get(0); * Then type.getPropertyScope() will have the properties of the constructor "Foo". To get * the properties of instances of "Foo", you will need to call: * Symbol instance = symbolTable.getSymbolForInstancesOf(type); * As described at the top of this file, notice that "new Foo()" and "Foo.prototype" are * represented by the same symbol. */ void fillPropertySymbols(Node externs, Node root) { new PropertyRefCollector().process(externs, root); } /** Index JSDocInfo. */ void fillJSDocInfo(Node externs, Node root) { NodeTraversal.traverseRoots( compiler, new JSDocInfoCollector(compiler.getTypeRegistry()), externs, root); // Create references to parameters in the JSDoc. for (Symbol sym : getAllSymbols()) { JSDocInfo info = sym.getJSDocInfo(); if (info == null) { continue; } for (Marker marker : info.getMarkers()) { SourcePosition pos = marker.getNameNode(); if (pos == null) { continue; } Node paramNode = pos.getItem(); String name = paramNode.getString(); Symbol param = getParameterInFunction(sym, name); if (param == null) { // There is no reference to this parameter in the actual JavaScript // code, so we'll try to create a special JsDoc-only symbol in // a JsDoc-only scope. SourcePosition typePos = marker.getType(); JSType type = null; if (typePos != null) { type = typePos.getItem().getJSType(); } if (sym.docScope == null) { sym.docScope = new SymbolScope( null /* root */, null /* parent scope */, null /* type of this */, sym); } // Check to make sure there's no existing symbol. In theory, this // should never happen, but we check anyway and fail silently // if our assumptions are wrong. (We do not want to put the symbol // table into an invalid state). Symbol existingSymbol = isAnySymbolDeclared(name, paramNode, sym.docScope); if (existingSymbol == null) { declareSymbol(name, type, type == null, sym.docScope, paramNode, /* info= */ null); } } else { param.defineReferenceAt(paramNode); } } } } /** Records the visibility of each symbol. */ void fillSymbolVisibility(Node externs, Node root) { CollectFileOverviewVisibility collectPass = new CollectFileOverviewVisibility(compiler); collectPass.process(externs, root); ImmutableMap visibilityMap = collectPass.getFileOverviewVisibilityMap(); NodeTraversal.traverseRoots(compiler, new VisibilityCollector(visibilityMap), externs, root); } /** * Build a property scope for the given symbol. Any properties of the symbol will be added to the * property scope. * *

It is important that property scopes are created in order from the leaves up to the root, so * this should only be called from #fillPropertyScopes. If you try to create a property scope for * a parent before its leaf, then the leaf will get cut and re-added to the parent property scope, * and weird things will happen. */ // This function uses == to compare types to be exact same instances. private void createPropertyScopeFor(Symbol s) { // In order to build a property scope for s, we will need to build // a property scope for all its implicit prototypes first. This means // that sometimes we will already have built its property scope // for a previous symbol. if (s.propertyScope != null) { return; } ObjectType type = getType(s) == null ? null : getType(s).toObjectType(); if (type == null) { return; } // For cases like // const foo = goog.require('some.foo'); // where createPropertyScopeFor() is called for 'foo' - instead of creating new PropertyScope we // reuse ModuleScope corresponding to 'some.foo' module. if (s.getName().equals("exports") && s.getDeclarationNode().isModuleBody()) { s.propertyScope = scopes.get(s.getDeclarationNode()); return; } // Create an empty property scope for the given symbol, maybe with a parent scope if it has // an implicit prototype. SymbolScope parentPropertyScope = maybeGetParentPropertyScope(type); s.setPropertyScope(new SymbolScope(null, parentPropertyScope, type, s)); // If this symbol represents some 'a.b.c.prototype', add any instance properties of a.b.c // into the symbol scope. ObjectType instanceType = type; Iterable propNames = type.getOwnPropertyNames(); if (instanceType.isFunctionPrototypeType()) { // Guard against modifying foo.prototype when foo is a regular (non-constructor) function. if (instanceType.getOwnerFunction().hasInstanceType()) { // Merge the properties of "Foo.prototype" and "new Foo()" together. instanceType = instanceType.getOwnerFunction().getInstanceType(); propNames = Iterables.concat(propNames, instanceType.getOwnPropertyNames()); } } // Add all declared properties in propNames into the property scope for (String propName : propNames) { StaticSlot newProp = instanceType.getSlot(propName); if (newProp.getDeclaration() == null) { // Skip properties without declarations. We won't know how to index // them, because we index things by node. continue; } // We have symbol tables that do not do type analysis. They just try // to build a complete index of all objects in the program. So we might // already have symbols for things like "Foo.bar". If this happens, // throw out the old symbol and use the type-based symbol. Symbol oldProp = symbols.get(newProp.getDeclaration().getNode(), s.getName() + "." + propName); if (oldProp != null && compiler.getModuleMap().getClosureModule(oldProp.getName()) != null) { // This handles cases like: // goog.provide('a.b.c'); // goog.provide('a.b.c.Foo'); // Here were are creating scope for module 'a.b.c' and 'Foo' looks like a property of that // module. But it's a module by itself - so we don't move it to the scope of 'a.b.c' and // instead keeping 'a.b.c.Foo' in global namespace. continue; } // If we've already have an entry in the table for this symbol, // then skip it. This should only happen if we screwed up, // and declared multiple distinct properties with the same name // at the same node. We bail out here to be safe. if (symbols.get(newProp.getDeclaration().getNode(), newProp.getName()) != null) { if (logger.isLoggable(Level.FINE)) { logger.fine("Found duplicate symbol " + newProp); } continue; } Symbol newSym = copySymbolTo(newProp, s.propertyScope); if (oldProp != null) { if (newSym.getJSDocInfo() == null) { newSym.setJSDocInfo(oldProp.getJSDocInfo()); } newSym.setPropertyScope(oldProp.propertyScope); for (Reference ref : oldProp.references.values()) { newSym.defineReferenceAt(ref.getNode()); } // All references/scopes from oldProp were updated to use the newProp. Time to remove // oldProp. removeSymbol(oldProp); } } } /** * If this type has an implicit prototype set, returns the SymbolScope corresponding to the * properties of the implicit prototype. Otherwise returns null. * *

Note that currently we only handle cases where the implicit prototype is a) a class or b) is * an instance object. */ private @Nullable SymbolScope maybeGetParentPropertyScope(ObjectType symbolObjectType) { ObjectType proto = symbolObjectType.getImplicitPrototype(); if (proto == null || proto == symbolObjectType) { return null; } final Symbol parentSymbol; if (isEs6ClassConstructor(proto)) { // given `class Foo {} class Bar extends Foo {}`, `Foo` is the implicit prototype of `Bar`. parentSymbol = getSymbolDeclaredBy(proto.toMaybeFunctionType()); } else if (proto.getConstructor() != null) { // given // /** @constructor */ function Foo() {} // /** @constructor */ function Bar() {} // goog.inherits(Bar, Foo); // the implicit prototype of Bar.prototype is the instance of Foo. parentSymbol = getSymbolForInstancesOf(proto.getConstructor()); } else { return null; } if (parentSymbol == null) { return null; } createPropertyScopeFor(parentSymbol); return parentSymbol.getPropertyScope(); } private boolean isEs6ClassConstructor(JSType type) { return type.isFunctionType() && type.toMaybeFunctionType().getSource() != null && type.toMaybeFunctionType().getSource().isClass(); } /** Fill in references to "this" variables. */ void fillThisReferences(Node externs, Node root) { new ThisRefCollector().process(externs, root); } /** Fill in references to "super" variables. */ void fillSuperReferences(Node externs, Node root) { NodeTraversal.Callback collectSuper = new AbstractPostOrderCallback() { @Override public void visit(NodeTraversal t, Node n, Node parent) { // Process only 'super' nodes with types. if (!n.isSuper() || n.getJSType() == null) { return; } Symbol classSymbol = getSymbolForTypeHelper(n.getJSType(), /* linkToCtor= */ false); if (classSymbol != null) { classSymbol.defineReferenceAt(n); } } }; NodeTraversal.traverseRoots(compiler, collectSuper, externs, root); } /** * This function connects imported symbol back to its declaration. For example: * *

   * goog.module('some.Foo');
   * class Foo {}
   * exports = Foo;
   *
   * goog.module('some.bar');
   * const Foo = goog.require('some.Foo');
   * 
* * This method will add a reference from the `Foo` symbol in `some.Bar` module pointing to the * `class Foo` in `some.Foo` module. */ private void addRefsInGoogRequireStatement(Node n, Map googModuleScopes) { if (compiler.getOptions().shouldRewriteModules()) { // When modules are rewritten - there is no need to connect imported names back to definitions // as that was done with the help of Preprocessor tables in ClosureRewriteModule pass. return; } Node require = n.getLastChild(); String moduleName = require.getSecondChild().getString(); Module module = compiler.getModuleMap().getClosureModule(moduleName); ModuleType moduleType = module == null ? null : module.metadata().moduleType(); SymbolScope moduleScope = googModuleScopes.get(moduleName); if (n.isName()) { // This is `const Foo = goog.require('some.Foo');` case. // The type of Foo is either a class/interface in which case we can find its symbol that // declared class/interface. Symbol declaration = getSymbolForTypeHelper(n.getJSType(), false); if (declaration != null) { declaration.defineReferenceAt(n); } // This import might be for a constant like `const constant = goog.require('some.constant');`. // Try to find it in the corresponding definition in module. switch (moduleType) { case GOOG_MODULE: case LEGACY_GOOG_MODULE: // For goog.module search for 'exports' node and use that it as declaration. It would be // better to use right-handside of exports: `exports = constant;` but it's difficult to // get symbol for the right-handside. So do a more limited approach. declaration = moduleScope.getOwnSlot("exports"); break; case GOOG_PROVIDE: // For goog.provide `some.constant` should be defined in global namespace. declaration = getSymbolForName(null, moduleName); break; default: // skip } if (declaration != null) { declaration.defineReferenceAt(n); } } else if (n.isDestructuringLhs()) { // This is `const {one} = goog.require('some.foo')` case. // For each imported symbol in destructuring we need to find corresponding declaration symbol // in `some.foo` namespace and connect them. checkState(n.getFirstChild().isObjectPattern()); // Iterate through all symbols in destructuring. for (Node stringKey : n.getFirstChild().children()) { checkState(stringKey.isStringKey()); String varName = stringKey.getString(); Symbol varDeclaration = null; // AST of goog.module and goog.provide differs significantly so we need to lookup variables // differently. switch (moduleType) { case GOOG_MODULE: case LEGACY_GOOG_MODULE: varDeclaration = moduleScope.getOwnSlot(varName); break; case GOOG_PROVIDE: varDeclaration = getSymbolForName(null, moduleName + "." + varName); break; default: // skip } if (varDeclaration != null) { varDeclaration.defineReferenceAt(stringKey); } } } } /** * Connects goog.module/goog.provide calls with goog.require/goog.requireType. For each * goog.module/goog.provide call creates a symbol and all goog.require/goog.requireType added as * references. */ void fillGoogProvideModuleRequires(Node externs, Node root) { // small optimization to keep symbols created within this function for fast access instead of // going through SymbolTable.getSymbolForName() every time. Map declaredNamespaces = new LinkedHashMap<>(); // Map containind goog.module names to Scope object representing them. For goog.provide // namespaces there is no scope as elements of goog.provide are global. Map moduleScopes = new LinkedHashMap<>(); Predicate looksLikeGoogCall = (Node n) -> { if (!n.isCall()) { return false; } Node left = n.getFirstChild(); Node arg = n.getSecondChild(); // We want only nodes of type `goog.xyz('somestring')`. if (!(left.isGetProp() && left.getFirstChild().isName() && left.getFirstChild().getString().equals("goog")) || arg == null || !arg.isStringLit()) { return false; } return true; }; NodeTraversal.Callback collectModuleScopes = new AbstractPostOrderCallback() { @Override public void visit(NodeTraversal t, Node n, Node parent) { if (!looksLikeGoogCall.test(n)) { return; } Node arg = n.getSecondChild(); String namespaceName = "ns$" + arg.getString(); switch (n.getFirstChild().getString()) { case "module": case "provide": Symbol ns = declareSymbol( namespaceName, /* type= */ null, /* inferred= */ false, getGlobalScope(), arg, /* info= */ null); declaredNamespaces.put(namespaceName, ns); if (n.getGrandparent().isModuleBody()) { moduleScopes.put(arg.getString(), scopes.get(n.getGrandparent())); } break; default: // do nothing. Some other goog.xyz call. } } }; NodeTraversal.Callback processRequireStatements = new AbstractPostOrderCallback() { @Override public void visit(NodeTraversal t, Node n, Node parent) { if (!looksLikeGoogCall.test(n)) { return; } Node arg = n.getSecondChild(); String namespaceName = "ns$" + arg.getString(); switch (n.getFirstChild().getString()) { case "require": case "requireType": case "forwardDeclare": addRefsInGoogRequireStatement(n.getParent(), moduleScopes); Symbol symbol = declaredNamespaces.get(namespaceName); // We expect that namespace was already processed by that point, but in some broken // code it might be missing. In which case just skip it. if (symbol != null) { symbol.defineReferenceAt(arg); } break; default: // do nothing. Some other goog.xyz call. } } }; NodeTraversal.traverseRoots(compiler, collectModuleScopes, externs, root); NodeTraversal.traverseRoots(compiler, processRequireStatements, externs, root); } /** * Flattens symbols within a module scope (goog.module). In goog.module we often have different * variations of declaring Foo, exports.Foo, exports = {Foo}. In some cases there are both Foo and * exports.Foo = Foo while in others there is only exports.Foo. Semantically they are the same to * the user so we flatten them into Foo. All 'exports.Foo' symbols renamed or merged into 'Foo' * (depending on whether it already exists). That way we get more predictable table which is * required for better index data and integration with other languages, e.g. JS <=> TS indexing. * *

This is not a correct operation in 100% of times. For example it will produce very incorrect * result for: * *

   *   class Foo {}
   *   exports.Foo = NotFoo;
   * 
* * But that should be very rare case and the code is misleading and should be avoided. */ void flattenGoogModuleExports() { for (SymbolScope moduleScope : getAllScopes()) { if (!moduleScope.isModuleScope()) { continue; } for (Symbol sym : ImmutableList.copyOf(moduleScope.ownSymbols.values())) { if (sym.getName().startsWith("exports.")) { renameSymbol(moduleScope, sym, sym.getName().substring("exports.".length())); } } } } /* * Checks whether symbol is a quoted object literal key. In the following object: * * var foo = {'one': 1, two: 2}; * * 'one' is quoted key. while two is not. */ private boolean isSymbolAQuotedObjectKey(Symbol symbol) { Node node = symbol.getDeclarationNode(); return node != null && node.isStringKey() && node.isQuotedStringKey(); } /** * Heuristic method to check whether symbol was created by DeclaredGlobalExternsOnWindow.java * pass. */ private boolean isSymbolDuplicatedExternOnWindow(Symbol symbol) { Node node = symbol.getDeclarationNode(); // Check that node is of type "window.foo"; return !node.isIndexable() && node.isGetProp() && node.getFirstChild().isName() && node.getFirstChild().getString().equals("window"); } /** * DeclaredGLobalExternsOnWindow.java pass duplicates all global variables so that: * *
   * var foo;
   * 
* * becomes * *
   * var foo;
   * window.foo;
   * 
* * This function finds all such cases and merges window.foo symbol back to foo. It changes * window.foo references to point to foo symbol. */ private void mergeExternSymbolsDuplicatedOnWindow() { // To find duplicated symbols we rely on the fact that duplicated symbol share the same // source position as original symbol and going to use filename => sourcePosition => symbol // table. Table externSymbols = HashBasedTable.create(); for (Symbol symbol : ImmutableList.copyOf(symbols.values())) { if (symbol.getDeclarationNode() == null || symbol.getDeclarationNode().getStaticSourceFile() == null || !symbol.getDeclarationNode().getStaticSourceFile().isExtern()) { continue; } String sourceFile = symbol.getSourceFileName(); int position = symbol.getDeclarationNode().getSourcePosition(); if (!externSymbols.contains(sourceFile, position)) { externSymbols.put(sourceFile, position, symbol); continue; } Symbol existingSymbol = externSymbols.get(sourceFile, position); // Consider 2 possibilies: either symbol or existingSymbol might be the generated symbol we // are looking for. if (isSymbolDuplicatedExternOnWindow(existingSymbol)) { mergeSymbol(existingSymbol, symbol); externSymbols.put(sourceFile, position, symbol); } else if (isSymbolDuplicatedExternOnWindow(symbol)) { mergeSymbol(symbol, existingSymbol); } } } /** * Removes various generated symbols that are invisible to users and pollute or mess up index. * Jscompiler does transpilations that might introduce extra nodes/symbols. Most of these symbols * should not get into final SymbolTable because SymbolTable should contain only symbols that * correspond to a symbol in original source code (before transpilation). */ void removeGeneratedSymbols() { // Need to iterate over copy of values list because removeSymbol() will change the map // and we'll get ConcurrentModificationException for (Symbol symbol : ImmutableList.copyOf(symbols.values())) { if (isSymbolAQuotedObjectKey(symbol)) { // Quoted object keys are not considered symbols. Only unquoted keys and dot-access // properties are considered symbols. Remove the quoted key. boolean symbolAlreadyRemoved = !getScope(symbol).ownSymbols.containsKey(symbol.getName()); if (!symbolAlreadyRemoved) { removeSymbol(symbol); } } else if (symbol.getDeclarationNode() != null && symbol.getDeclarationNode().isModuleBody()) { // Symbols that represent whole module (goog.module) aren't needed for indexing. We already // recorded imports/references of that module in fillGoogProvideModuleRequires() function. // Individual exported functions/variables also have their own symbols. removeSymbol(symbol); } } mergeExternSymbolsDuplicatedOnWindow(); } /** * Given a scope from another symbol table, returns the {@code SymbolScope} rooted at the same * node. Creates one if it doesn't exist yet. */ private SymbolScope createScopeFrom(StaticScope otherScope) { Node otherScopeRoot = otherScope.getRootNode(); SymbolScope myScope = scopes.get(otherScopeRoot); if (myScope == null) { StaticScope otherScopeParent = otherScope.getParentScope(); // If otherScope is a global scope, and we already have a global scope, // then something has gone seriously wrong. // // Not all symbol tables are rooted at the same global node, and // we do not want to mix and match symbol tables that are rooted // differently. if (otherScopeParent == null) { // The global scope must be created before any local scopes. checkState(globalScope == null, "Global scopes found at different roots"); } myScope = new SymbolScope( otherScopeRoot, otherScopeParent == null ? null : createScopeFrom(otherScopeParent), getTypeOfThis(otherScope), null); scopes.put(otherScopeRoot, myScope); if (myScope.isGlobalScope()) { globalScope = myScope; } } return myScope; } /** A symbol-table entry */ public static final class Symbol extends SimpleSlot { // Use a linked hash map, so that the results are deterministic // (and so the declaration always comes first). private final Map references = new LinkedHashMap<>(); private final SymbolScope scope; private @Nullable SymbolScope propertyScope = null; private @Nullable Reference declaration = null; private @Nullable JSDocInfo docInfo = null; /** * Stored separately from {@link #docInfo}, because the visibility stored in JSDocInfo is not */ private @Nullable Visibility visibility = null; // A scope for symbols that are only documented in JSDoc. private @Nullable SymbolScope docScope = null; Symbol(String name, JSType type, boolean inferred, SymbolScope scope) { super(name, type, inferred); this.scope = scope; } @Override public boolean equals(Object o) { if (!(o instanceof Symbol)) { return false; } Symbol other = (Symbol) o; return isTypeInferred() == other.isTypeInferred() && Objects.equals(getName(), other.getName()) && Objects.equals(getType(), other.getType()) && Objects.equals(scope, other.scope); } @Override public int hashCode() { return Objects.hash(Boolean.valueOf(isTypeInferred()), getName(), getType(), scope); } @Override public Reference getDeclaration() { return declaration; } public FunctionType getFunctionType() { return JSType.toMaybeFunctionType(getType()); } public Reference defineReferenceAt(Node n) { return references.computeIfAbsent(n, (Node k) -> new Reference(this, k)); } /** Sets the declaration node. May only be called once. */ void setDeclaration(Reference ref) { checkState(this.declaration == null); this.declaration = ref; } public @Nullable Node getDeclarationNode() { return declaration == null ? null : declaration.getNode(); } public @Nullable String getSourceFileName() { Node n = getDeclarationNode(); return n == null ? null : n.getSourceFileName(); } public SymbolScope getPropertyScope() { return propertyScope; } void setPropertyScope(SymbolScope scope) { this.propertyScope = scope; if (scope != null) { this.propertyScope.setSymbolForScope(this); } } @Override public JSDocInfo getJSDocInfo() { return docInfo; } void setJSDocInfo(JSDocInfo info) { this.docInfo = info; } public @Nullable Visibility getVisibility() { return this.visibility; } void setVisibility(Visibility v) { this.visibility = v; } /** Whether this is a property of another variable. */ public boolean isProperty() { return scope.isPropertyScope(); } /** Whether this is a variable in a lexical scope. */ public boolean isLexicalVariable() { return scope.isLexicalScope(); } /** Whether this is a variable that's only in JSDoc. */ public boolean isDocOnlyParameter() { return scope.isDocScope(); } @Override public String toString() { Node n = getDeclarationNode(); int lineNo = n == null ? -1 : n.getLineno(); return getName() + "@" + getSourceFileName() + ":" + lineNo; } } /** Reference */ public static final class Reference extends SimpleReference { Reference(Symbol symbol, Node node) { super(symbol, node); } } /** Scope of a symbol */ public static final class SymbolScope { private final Node rootNode; private final SymbolScope parent; private final JSType typeOfThis; private final Map ownSymbols = new LinkedHashMap<>(); private final int scopeDepth; // Index of current scope in the parent scope. Used to generate unique names for variables // having the same name but defined in different scopes. private final int indexInParent; private int numberOfChildScopes = 0; // The symbol associated with a property scope or doc scope. private Symbol mySymbol; SymbolScope( @Nullable Node rootNode, @Nullable SymbolScope parent, @Nullable JSType typeOfThis, @Nullable Symbol mySymbol) { this.rootNode = rootNode; this.parent = parent; this.typeOfThis = typeOfThis; this.scopeDepth = parent == null ? 0 : (parent.getScopeDepth() + 1); this.mySymbol = mySymbol; if (parent == null) { this.indexInParent = 0; } else { this.indexInParent = parent.numberOfChildScopes; parent.numberOfChildScopes++; } } Symbol getSymbolForScope() { return mySymbol; } void setSymbolForScope(Symbol sym) { this.mySymbol = sym; } /** Gets a unique index for the symbol in this scope. */ public int getIndexOfSymbol(Symbol sym) { return Iterables.indexOf(ownSymbols.values(), Predicates.equalTo(sym)); } Node getRootNode() { return rootNode; } public SymbolScope getParentScope() { return parent; } /** * Get the slot for a fully-qualified name (e.g., "a.b.c") by trying to find property scopes at * each part of the path. */ public @Nullable Symbol getQualifiedSlot(String name) { Symbol fullyNamedSym = getSlot(name); if (fullyNamedSym != null) { return fullyNamedSym; } int dot = name.lastIndexOf('.'); if (dot != -1) { Symbol owner = getQualifiedSlot(name.substring(0, dot)); if (owner != null && owner.getPropertyScope() != null) { return owner.getPropertyScope().getSlot(name.substring(dot + 1)); } } return null; } public @Nullable Symbol getSlot(String name) { Symbol own = getOwnSlot(name); if (own != null) { return own; } Symbol ancestor = parent == null ? null : parent.getSlot(name); if (ancestor != null) { return ancestor; } return null; } Symbol getOwnSlot(String name) { return ownSymbols.get(name); } public JSType getTypeOfThis() { return typeOfThis; } public boolean isGlobalScope() { return getParentScope() == null && getRootNode() != null; } public boolean isModuleScope() { return getRootNode() != null && getRootNode().isModuleBody(); } /** * Returns whether this is a doc scope. A doc scope is a table for symbols that are documented * solely within a JSDoc comment. */ public boolean isDocScope() { return getRootNode() == null && mySymbol != null && mySymbol.docScope == this; } public boolean isPropertyScope() { return getRootNode() == null && !isDocScope(); } public boolean isLexicalScope() { return getRootNode() != null; } public boolean isBlockScope() { return getRootNode() != null && NodeUtil.createsBlockScope(getRootNode()); } public int getScopeDepth() { return scopeDepth; } public int getIndexInParent() { return indexInParent; } @Override public String toString() { Node n = getRootNode(); if (isGlobalScope()) { return "GlobalScope"; } else if (n != null) { String type = "Scope"; if (isModuleScope()) { type = "ModuleScope"; } else if (isBlockScope()) { type = "BlockScope"; } else if (isLexicalScope()) { type = "LexicalScope"; } return type + "@" + n.getSourceFileName() + ":" + n.getLineno(); } else { return "PropertyScope@" + getSymbolForScope(); } } } private class PropertyRefCollector extends AbstractPostOrderCallback implements CompilerPass { @Override public void process(Node externs, Node root) { NodeTraversal.traverseRoots(compiler, this, externs, root); } private boolean maybeDefineReference(Node n, String propName, Symbol ownerSymbol) { if (ownerSymbol == null) { return false; } // If current symbol is ObjectType - try using ObjectType.getPropertyNode to find a node. // That function searches for property in all extended classes and interfaces, which supports // multiple extended interfaces. JSType owner = ownerSymbol.getType(); if (owner != null && owner.isObjectType()) { Node propNode = owner.toObjectType().getPropertyNode(propName); Symbol propSymbol = symbols.get(propNode, propName); if (propSymbol != null) { propSymbol.defineReferenceAt(n); return true; } } // Use PropertyScope to find property. PropertyScope doesn't support multiple parents so all // cases where multiple parents can occur (e.g. class implementing 2+ interfaces) must be // handled above. if (ownerSymbol.getPropertyScope() != null) { Symbol prop = ownerSymbol.getPropertyScope().getSlot(propName); if (prop != null) { prop.defineReferenceAt(n); return true; } } return false; } // Try to find the symbol by its fully qualified name. private boolean tryDefineLexicalQualifiedNameRef(String name, Node n) { if (name != null) { Symbol lexicalSym = getEnclosingScope(n).getQualifiedSlot(name); if (lexicalSym != null) { lexicalSym.defineReferenceAt(n); return true; } } return false; } // Try to remove a reference by its fully qualified name. // If the symbol has no references left, remove it completely. private void tryRemoveLexicalQualifiedNameRef(String name, Node n) { if (name != null) { Symbol lexicalSym = getEnclosingScope(n).getQualifiedSlot(name); if (lexicalSym != null && lexicalSym.isLexicalVariable() && lexicalSym.getDeclaration().getNode() == n) { removeSymbol(lexicalSym); } } } private boolean maybeDefineTypedReference(Node n, String propName, JSType owner) { if (owner.isGlobalThisType()) { Symbol sym = globalScope.getSlot(propName); if (sym != null) { sym.defineReferenceAt(n); return true; } } else if (owner.isNominalConstructorOrInterface()) { return maybeDefineReference(n, propName, getSymbolDeclaredBy(owner.toMaybeFunctionType())); } else if (owner.isEnumType()) { return maybeDefineReference(n, propName, getSymbolDeclaredBy(owner.toMaybeEnumType())); } else { boolean defined = false; for (Symbol ctor : getAllSymbolsForType(owner)) { if (maybeDefineReference(n, propName, getSymbolForInstancesOf(ctor))) { defined = true; } } if (defined) { return true; } } // Handle cases like accessing properties on a imported module. // const foo = goog.require('some.module.foo'); // foo.doSomething(); // here n is foo, propName is doSomething and owner is module type. if (owner.isObjectType() && owner.toMaybeObjectType() != null) { Node propNodeDecl = owner.assertObjectType().getPropertyNode(propName); if (propNodeDecl == null) { return false; } // There is no handy way to find symbol object the given property node. So we do // property node => namespace node => namespace symbol => property symbol. if (propNodeDecl != null && (propNodeDecl.isGetProp() || propNodeDecl.isOptChainGetProp())) { Node namespace = propNodeDecl.getFirstChild(); Symbol namespaceSym = getSymbolForName(namespace, namespace.getQualifiedName()); if (namespaceSym != null && namespaceSym.getPropertyScope() != null) { Symbol propSym = namespaceSym.getPropertyScope().getSlot(propName); if (propSym != null && propSym.getDeclarationNode() != n) { propSym.defineReferenceAt(n); return true; } } } // Here handle the case of goog.module exports that have shape of: // // goog.module('foo.bar'); // function doOne() { ... } // exports = {doOne}; // // propNodeDecl is `doOne` node on the last line with exports. From that node and propName // `doOne` we need to get symbol for the `function doOne`. To achieve that we get scope of // `doOne` node which should be whole module scope and look for symbol with corresponding // name. This relies on the assumption that function name in module scope exported name. But // if export is renamed: `exports = {doOneRenamed: doOne}`, then this approach will fail. SymbolScope propNodeDeclScope = getEnclosingScope(propNodeDecl); if (propNodeDeclScope == null || !propNodeDeclScope.isModuleScope()) { return false; } Symbol symbol = getSymbolForName(propNodeDecl, propName); if (symbol != null && symbol.getDeclarationNode() != n) { symbol.defineReferenceAt(n); return true; } } return false; } @Override public void visit(NodeTraversal t, Node n, Node parent) { // There are two ways to define a property reference: // 1) As a fully qualified lexical symbol (e.g., x.y) // 2) As a property of another object (e.g., x's y) // Property definitions should take precedence over lexical // definitions. e.g., for "a.b", it's more useful to record // this as "property b of the type of a", than as "symbol a.b". if (n.isGetProp() || n.isOptChainGetProp()) { JSType owner = n.getFirstChild().getJSType(); if (owner != null) { boolean defined = maybeDefineTypedReference(n, n.getString(), owner); if (defined) { tryRemoveLexicalQualifiedNameRef(n.getQualifiedName(), n); return; } } tryDefineLexicalQualifiedNameRef(n.getQualifiedName(), n); } else if (n.isStringKey()) { JSType owner = parent.getJSType(); if (owner != null) { boolean defined = maybeDefineTypedReference(n, n.getString(), owner); if (defined) { tryRemoveLexicalQualifiedNameRef(NodeUtil.getBestLValueName(n), n); return; } } tryDefineLexicalQualifiedNameRef(NodeUtil.getBestLValueName(n), n); } } } private class ThisRefCollector extends NodeTraversal.AbstractScopedCallback implements CompilerPass { // The 'this' symbols in the current scope chain. // // If we don't know how to declare 'this' in a scope chain, // then null should be on the stack. But this should be a rare // occurrence. We should strive to always be able to come up // with some symbol for 'this'. // // This list only has entries for function scopes and the global scope, and doesn't store a // separate `this` value for other block scopes. private final List thisStack = new ArrayList<>(); @Override public void process(Node externs, Node root) { NodeTraversal.traverseRoots(compiler, this, externs, root); } @Override public void enterScope(NodeTraversal t) { Symbol symbol = null; if (t.inGlobalScope()) { // Declare the global this at the first input root. // This is a bizarre place to put it, but we need some // location with a real file path (because all symbols // must have a path). // Note that root.lastChild.firstChild is the first non-extern input. Node firstInputRoot = t.getScopeRoot().getLastChild().getFirstChild(); if (firstInputRoot != null) { symbol = addSymbol( GLOBAL_THIS, registry.getNativeType(JSTypeNative.GLOBAL_THIS), false /* declared */, globalScope, firstInputRoot); symbol.setDeclaration(new Reference(symbol, firstInputRoot)); } thisStack.add(symbol); } else if (t.getScopeRoot().isFunction()) { // Otherwise, declare a "this" property when possible. Node scopeRoot = t.getScopeRoot(); SymbolScope scope = scopes.get(scopeRoot); if (NodeUtil.getFunctionBody(scopeRoot).hasChildren()) { Symbol scopeSymbol = getSymbolForScope(scope); if (scopeSymbol != null) { SymbolScope propScope = scopeSymbol.getPropertyScope(); if (propScope != null) { // If a function is assigned multiple times, we only want // one addressable "this" symbol. symbol = propScope.getOwnSlot("this"); if (symbol == null) { JSType rootType = t.getScopeRoot().getJSType(); FunctionType fnType = rootType == null ? null : rootType.toMaybeFunctionType(); JSType type = fnType == null ? null : fnType.getTypeOfThis(); symbol = addSymbol("this", type, /* inferred= */ false, scope, scopeRoot); } } } } else { logger.fine("Skipping empty function: " + scopeRoot); } thisStack.add(symbol); } // Don't add to the `thisStack` for other block scopes. } @Override public void exitScope(NodeTraversal t) { if (t.inGlobalScope() || t.getScopeRoot().isFunction()) { thisStack.remove(thisStack.size() - 1); } } @Override public void visit(NodeTraversal t, Node n, Node parent) { if (!n.isThis()) { return; } Symbol symbol = Iterables.getLast(thisStack); if (symbol != null) { Reference ref = symbol.defineReferenceAt(n); if (symbol.getDeclaration() == null) { symbol.setDeclaration(ref); } } } } /** Collects references to types in JSDocInfo. */ private class JSDocInfoCollector extends AbstractPostOrderCallback { private final JSTypeRegistry typeRegistry; private JSDocInfoCollector(JSTypeRegistry registry) { this.typeRegistry = registry; } @Override public void visit(NodeTraversal t, Node n, Node parent) { JSDocInfo info = n.getJSDocInfo(); if (info == null) { return; } docInfos.add(n); for (Node typeAst : info.getTypeNodes()) { SymbolScope scope = scopes.get(t.getScopeRoot()); visitTypeNode(info.getTemplateTypes(), scope == null ? globalScope : scope, typeAst); } } private boolean isNativeSourcelessType(String name) { switch (name) { case "null": case "undefined": case "void": return true; default: return false; } } public void visitTypeNode( ImmutableMap templateTypeNames, SymbolScope scope, Node n) { if (n.isStringLit() && !isNativeSourcelessType(n.getString()) && !templateTypeNames.containsKey(n.getString())) { Symbol symbol = lookupPossiblyDottedName(scope, n.getString()); if (symbol != null) { Node ref = n; String typeString = n.getOriginalName() != null ? n.getOriginalName() : n.getString(); // Qualified names in JSDoc types are kept as a single string: "foo.bar.MyType". In order // to have good indexing we need to make the SymbolTable reference include only "MyType" // instead of "foo.bar.MyType". To do that we clone the type node and change the source // info of the clone to include only the last part of the type ("MyType"). if (typeString.contains(".")) { String lastPart = typeString.substring(typeString.lastIndexOf('.') + 1); Node copy = n.cloneNode(); copy.setLinenoCharno( copy.getLineno(), copy.getCharno() + copy.getLength() - lastPart.length()); copy.setLength(lastPart.length()); ref = copy; } symbol.defineReferenceAt(ref); } } for (Node child = n.getFirstChild(); child != null; child = child.getNext()) { visitTypeNode(templateTypeNames, scope, child); } } // TODO(peterhal): @template types. private Symbol lookupPossiblyDottedName(SymbolScope scope, String dottedName) { // Try the dotted name to start. Symbol result = scope.getQualifiedSlot(dottedName); if (result != null) { return result; } // If we can't find this type, it might be a reference to a // primitive type (like {string}). Autobox it to check. JSType type = typeRegistry.getGlobalType(dottedName); JSType autobox = type == null ? null : type.autoboxesTo(); return autobox == null ? getSymbolForTypeHelper(type, true) : getSymbolForTypeHelper(autobox, true); } } /** Collects the visibility information for each name/property. */ private class VisibilityCollector extends AbstractPostOrderCallback { private final ImmutableMap fileVisibilityMap; private VisibilityCollector(ImmutableMap fileVisibilityMap) { this.fileVisibilityMap = fileVisibilityMap; } @Override public void visit(NodeTraversal t, Node n, Node parent) { if (n.isName()) { visitName(t, n); } else if (n.isGetProp() || n.isOptChainGetProp()) { visitProperty(n, parent); } } private void visitName(NodeTraversal t, Node n) { Symbol symbol = symbols.get(n, n.getString()); if (symbol == null) { return; } // Visibility already set. if (symbol.getVisibility() != null) { return; } Var var = t.getScope().getVar(n.getString()); if (var == null) { return; } Visibility v = AccessControlUtils.getEffectiveNameVisibility(n, var, fileVisibilityMap); if (v == null) { return; } symbol.setVisibility(v); } private void visitProperty(Node getprop, Node parent) { String propertyName = getprop.getString(); Symbol symbol = symbols.get(getprop, propertyName); if (symbol == null) { return; } // Visibility already set. if (symbol.getVisibility() != null) { return; } JSType jsType = getprop.getFirstChild().getJSType(); if (jsType == null) { return; } boolean isOverride = parent.getJSDocInfo() != null && parent.isAssign() && parent.getFirstChild() == getprop; if (isOverride) { // Don't bother with AccessControlUtils for overridden properties. // AccessControlUtils currently has complicated logic for detecting // visibility mismatches for overridden properties that is still // too tightly coupled to CheckAccessControls. TODO(brndn): simplify. symbol.setVisibility(Visibility.INHERITED); } else { ObjectType referenceType = ObjectType.cast(jsType.dereference()); Visibility v = AccessControlUtils.getEffectivePropertyVisibility( getprop, referenceType, fileVisibilityMap); if (v == null) { return; } symbol.setVisibility(v); } } } // Comparators private final Ordering sourceNameOrdering = Ordering.natural().nullsFirst(); private final Ordering nodeOrdering = new Ordering() { @Override public int compare(Node a, Node b) { int result = sourceNameOrdering.compare(a.getSourceFileName(), b.getSourceFileName()); if (result != 0) { return result; } // Source position is a bit mask of line in the top 4 bits, so this // is a quick way to compare order without computing absolute position. return a.getSourcePosition() - b.getSourcePosition(); } }; private final Ordering lexicalScopeOrdering = new Ordering() { @Override public int compare(SymbolScope a, SymbolScope b) { checkState(a.isLexicalScope() && b.isLexicalScope(), "We can only sort lexical scopes"); int result = nodeOrdering.compare(a.getRootNode(), b.getRootNode()); if (result != 0) { return result; } // If result = 0 it means that rootNodes either the same or that one of them was added // by compiler during transpilation and uses the same source info as original node. // In that case compare scopes by depth because one of them (probably generated one) is // a child of the other scope. // TODO(b/62349230): remove this once transpilation is disabled. No two different scopes // should have the same source info. return a.getScopeDepth() - b.getScopeDepth(); } }; private final Ordering symbolOrdering = new Ordering() { @Override public int compare(Symbol a, Symbol b) { SymbolScope scopeA = getScope(a); SymbolScope scopeB = getScope(b); // More deeply nested symbols should go later. int result = getLexicalScopeDepth(scopeA) - getLexicalScopeDepth(scopeB); if (result != 0) { return result; } // After than, just use lexicographic ordering. // This ensures "a.b" comes before "a.b.c". return a.getName().compareTo(b.getName()); } }; /** * For a lexical scope, just returns the normal scope depth. * *

For a property scope, returns the number of scopes we have to search to find the nearest * lexical scope, plus that lexical scope's depth. * *

For a doc info scope, returns 0. */ private int getLexicalScopeDepth(SymbolScope scope) { if (scope.isLexicalScope() || scope.isDocScope()) { return scope.getScopeDepth(); } else { checkState(scope.isPropertyScope()); Symbol sym = scope.getSymbolForScope(); checkNotNull(sym); return getLexicalScopeDepth(getScope(sym)) + 1; } } private @Nullable JSType getType(StaticSlot sym) { if (sym instanceof StaticTypedSlot) { return ((StaticTypedSlot) sym).getType(); } return null; } private @Nullable JSType getTypeOfThis(StaticScope s) { if (s instanceof StaticTypedScope) { return ((StaticTypedScope) s).getTypeOfThis(); } return null; } private boolean isTypeInferred(StaticSlot sym) { if (sym instanceof StaticTypedSlot) { return ((StaticTypedSlot) sym).isTypeInferred(); } return true; } }





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