The Tor Browser: comparison js/src/frontend/NameFunctions.cpp

--1:000000000000
+:18988c4c0e58
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+* vim: set ts=8 sts=4 et sw=4 tw=99:
+* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "frontend/NameFunctions.h"
+#include "jsfun.h"
+#include "jsprf.h"
+#include "frontend/BytecodeCompiler.h"
+#include "frontend/ParseNode.h"
+#include "frontend/SharedContext.h"
+#include "vm/StringBuffer.h"
+using namespace js;
+using namespace js::frontend;
+namespace {
+class NameResolver
+{
+static const size_t MaxParents = 100;
+ExclusiveContext *cx;
+size_t nparents;                /* number of parents in the parents array */
+ParseNode *parents[MaxParents]; /* history of ParseNodes we've been looking at */
+StringBuffer *buf;              /* when resolving, buffer to append to */
+/* Test whether a ParseNode represents a function invocation */
+bool call(ParseNode *pn) {
+return pn && pn->isKind(PNK_CALL);
+}
+/*
+* Append a reference to a property named |name| to |buf|. If |name| is
+* a proper identifier name, then we append '.name'; otherwise, we
+* append '["name"]'.
+*
+* Note that we need the IsIdentifier check for atoms from both
+* PNK_NAME nodes and PNK_STRING nodes: given code like a["b c"], the
+* front end will produce a PNK_DOT with a PNK_NAME child whose name
+* contains spaces.
+*/
+bool appendPropertyReference(JSAtom *name) {
+if (IsIdentifier(name))
+return buf->append(".") && buf->append(name);
+/* Quote the string as needed. */
+JSString *source = js_QuoteString(cx, name, '"');
+return source && buf->append("[") && buf->append(source) && buf->append("]");
+}
+/* Append a number to buf. */
+bool appendNumber(double n) {
+char number[30];
+int digits = JS_snprintf(number, sizeof(number), "%g", n);
+return buf->appendInflated(number, digits);
+}
+/* Append "[<n>]" to buf, referencing a property named by a numeric literal. */
+bool appendNumericPropertyReference(double n) {
+return buf->append("[") && appendNumber(n) && buf->append("]");
+}
+/*
+* Walk over the given ParseNode, converting it to a stringified name that
+* respresents where the function is being assigned to.
+*/
+bool nameExpression(ParseNode *n) {
+switch (n->getKind()) {
+case PNK_DOT:
+return nameExpression(n->expr()) && appendPropertyReference(n->pn_atom);
+case PNK_NAME:
+return buf->append(n->pn_atom);
+case PNK_THIS:
+return buf->append("this");
+case PNK_ELEM:
+return nameExpression(n->pn_left) &&
+buf->append("[") &&
+nameExpression(n->pn_right) &&
+buf->append("]");
+case PNK_NUMBER:
+return appendNumber(n->pn_dval);
+default:
+/*
+* Technically this isn't an "abort" situation, we're just confused
+* on what to call this function, but failures in naming aren't
+* treated as fatal.
+*/
+return false;
+}
+}
+/*
+* When naming an anonymous function, the process works loosely by walking
+* up the AST and then translating that to a string. The stringification
+* happens from some far-up assignment and then going back down the parse
+* tree to the function definition point.
+*
+* This function will walk up the parse tree, gathering relevant nodes used
+* for naming, and return the assignment node if there is one. The provided
+* array and size will be filled in, and the returned node could be nullptr
+* if no assignment is found. The first element of the array will be the
+* innermost node relevant to naming, and the last element will be the
+* outermost node.
+*/
+ParseNode *gatherNameable(ParseNode **nameable, size_t *size) {
+*size = 0;
+for (int pos = nparents - 1; pos >= 0; pos--) {
+ParseNode *cur = parents[pos];
+if (cur->isAssignment())
+return cur;
+switch (cur->getKind()) {
+case PNK_NAME:     return cur;  /* found the initialized declaration */
+case PNK_THIS:     return cur;  /* Setting a property of 'this'. */
+case PNK_FUNCTION: return nullptr; /* won't find an assignment or declaration */
+case PNK_RETURN:
+/*
+* Normally the relevant parent of a node is its direct parent, but
+* sometimes with code like:
+*
+*    var foo = (function() { return function() {}; })();
+*
+* the outer function is just a helper to create a scope for the
+* returned function. Hence the name of the returned function should
+* actually be 'foo'.  This loop sees if the current node is a
+* PNK_RETURN, and if there is a direct function call we skip to
+* that.
+*/
+for (int tmp = pos - 1; tmp > 0; tmp--) {
+if (isDirectCall(tmp, cur)) {
+pos = tmp;
+break;
+} else if (call(cur)) {
+/* Don't skip too high in the tree */
+break;
+}
+cur = parents[tmp];
+}
+break;
+case PNK_COLON:
+/*
+* Record the PNK_COLON but skip the PNK_OBJECT so we're not
+* flagged as a contributor.
+*/
+pos--;
+/* fallthrough */
+default:
+/* Save any other nodes we encounter on the way up. */
+JS_ASSERT(*size < MaxParents);
+nameable[(*size)++] = cur;
+break;
+}
+}
+return nullptr;
+}
+/*
+* Resolve the name of a function. If the function already has a name
+* listed, then it is skipped. Otherwise an intelligent name is guessed to
+* assign to the function's displayAtom field
+*/
+bool resolveFun(ParseNode *pn, HandleAtom prefix, MutableHandleAtom retAtom) {
+JS_ASSERT(pn != nullptr && pn->isKind(PNK_FUNCTION));
+RootedFunction fun(cx, pn->pn_funbox->function());
+StringBuffer buf(cx);
+this->buf = &buf;
+retAtom.set(nullptr);
+/* If the function already has a name, use that */
+if (fun->displayAtom() != nullptr) {
+if (prefix == nullptr) {
+retAtom.set(fun->displayAtom());
+return true;
+}
+if (!buf.append(prefix) ||
+!buf.append("/") ||
+!buf.append(fun->displayAtom()))
+return false;
+retAtom.set(buf.finishAtom());
+return !!retAtom;
+}
+/* If a prefix is specified, then it is a form of namespace */
+if (prefix != nullptr && (!buf.append(prefix) || !buf.append("/")))
+return false;
+/* Gather all nodes relevant to naming */
+ParseNode *toName[MaxParents];
+size_t size;
+ParseNode *assignment = gatherNameable(toName, &size);
+/* If the function is assigned to something, then that is very relevant */
+if (assignment) {
+if (assignment->isAssignment())
+assignment = assignment->pn_left;
+if (!nameExpression(assignment))
+return true;
+}
+/*
+* Other than the actual assignment, other relevant nodes to naming are
+* those in object initializers and then particular nodes marking a
+* contribution.
+*/
+for (int pos = size - 1; pos >= 0; pos--) {
+ParseNode *node = toName[pos];
+if (node->isKind(PNK_COLON)) {
+ParseNode *left = node->pn_left;
+if (left->isKind(PNK_NAME) || left->isKind(PNK_STRING)) {
+if (!appendPropertyReference(left->pn_atom))
+return false;
+} else if (left->isKind(PNK_NUMBER)) {
+if (!appendNumericPropertyReference(left->pn_dval))
+return false;
+}
+} else {
+/*
+* Don't have consecutive '<' characters, and also don't start
+* with a '<' character.
+*/
+if (!buf.empty() && *(buf.end() - 1) != '<' && !buf.append("<"))
+return false;
+}
+}
+/*
+* functions which are "genuinely anonymous" but are contained in some
+* other namespace are rather considered as "contributing" to the outer
+* function, so give them a contribution symbol here.
+*/
+if (!buf.empty() && *(buf.end() - 1) == '/' && !buf.append("<"))
+return false;
+if (buf.empty())
+return true;
+retAtom.set(buf.finishAtom());
+if (!retAtom)
+return false;
+fun->setGuessedAtom(retAtom);
+return true;
+}
+/*
+* Tests whether parents[pos] is a function call whose callee is cur.
+* This is the case for functions which do things like simply create a scope
+* for new variables and then return an anonymous function using this scope.
+*/
+bool isDirectCall(int pos, ParseNode *cur) {
+return pos >= 0 && call(parents[pos]) && parents[pos]->pn_head == cur;
+}
+public:
+explicit NameResolver(ExclusiveContext *cx) : cx(cx), nparents(0), buf(nullptr) {}
+/*
+* Resolve all names for anonymous functions recursively within the
+* ParseNode instance given. The prefix is for each subsequent name, and
+* should initially be nullptr.
+*/
+bool resolve(ParseNode *cur, HandleAtom prefixArg = js::NullPtr()) {
+RootedAtom prefix(cx, prefixArg);
+if (cur == nullptr)
+return true;
+if (cur->isKind(PNK_FUNCTION) && cur->isArity(PN_CODE)) {
+RootedAtom prefix2(cx);
+if (!resolveFun(cur, prefix, &prefix2))
+return false;
+/*
+* If a function looks like (function(){})() where the parent node
+* of the definition of the function is a call, then it shouldn't
+* contribute anything to the namespace, so don't bother updating
+* the prefix to whatever was returned.
+*/
+if (!isDirectCall(nparents - 1, cur))
+prefix = prefix2;
+}
+if (nparents >= MaxParents)
+return true;
+parents[nparents++] = cur;
+switch (cur->getArity()) {
+case PN_NULLARY:
+break;
+case PN_NAME:
+if (!resolve(cur->maybeExpr(), prefix))
+return false;
+break;
+case PN_UNARY:
+if (!resolve(cur->pn_kid, prefix))
+return false;
+break;
+case PN_BINARY:
+case PN_BINARY_OBJ:
+if (!resolve(cur->pn_left, prefix))
+return false;
+/*
+* FIXME? Occasionally pn_left == pn_right for something like
+* destructuring assignment in (function({foo}){}), so skip the
+* duplicate here if this is the case because we want to traverse
+* everything at most once.
+*/
+if (cur->pn_left != cur->pn_right)
+if (!resolve(cur->pn_right, prefix))
+return false;
+break;
+case PN_TERNARY:
+if (!resolve(cur->pn_kid1, prefix))
+return false;
+if (!resolve(cur->pn_kid2, prefix))
+return false;
+if (!resolve(cur->pn_kid3, prefix))
+return false;
+break;
+case PN_CODE:
+JS_ASSERT(cur->isKind(PNK_FUNCTION));
+if (!resolve(cur->pn_body, prefix))
+return false;
+break;
+case PN_LIST:
+for (ParseNode *nxt = cur->pn_head; nxt; nxt = nxt->pn_next)
+if (!resolve(nxt, prefix))
+return false;
+break;
+}
+nparents--;
+return true;
+}
+};
+} /* anonymous namespace */
+bool
+frontend::NameFunctions(ExclusiveContext *cx, ParseNode *pn)
+{
+NameResolver nr(cx);
+return nr.resolve(pn);
+}

The Tor Browser / file comparison

comparison: js/src/frontend/NameFunctions.cpp

js/src/frontend/NameFunctions.cpp