1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/js/src/frontend/NameFunctions.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,358 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
1.5 + * vim: set ts=8 sts=4 et sw=4 tw=99:
1.6 + * This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#include "frontend/NameFunctions.h"
1.11 +
1.12 +#include "jsfun.h"
1.13 +#include "jsprf.h"
1.14 +
1.15 +#include "frontend/BytecodeCompiler.h"
1.16 +#include "frontend/ParseNode.h"
1.17 +#include "frontend/SharedContext.h"
1.18 +#include "vm/StringBuffer.h"
1.19 +
1.20 +using namespace js;
1.21 +using namespace js::frontend;
1.22 +
1.23 +namespace {
1.24 +
1.25 +class NameResolver
1.26 +{
1.27 + static const size_t MaxParents = 100;
1.28 +
1.29 + ExclusiveContext *cx;
1.30 + size_t nparents; /* number of parents in the parents array */
1.31 + ParseNode *parents[MaxParents]; /* history of ParseNodes we've been looking at */
1.32 + StringBuffer *buf; /* when resolving, buffer to append to */
1.33 +
1.34 + /* Test whether a ParseNode represents a function invocation */
1.35 + bool call(ParseNode *pn) {
1.36 + return pn && pn->isKind(PNK_CALL);
1.37 + }
1.38 +
1.39 + /*
1.40 + * Append a reference to a property named |name| to |buf|. If |name| is
1.41 + * a proper identifier name, then we append '.name'; otherwise, we
1.42 + * append '["name"]'.
1.43 + *
1.44 + * Note that we need the IsIdentifier check for atoms from both
1.45 + * PNK_NAME nodes and PNK_STRING nodes: given code like a["b c"], the
1.46 + * front end will produce a PNK_DOT with a PNK_NAME child whose name
1.47 + * contains spaces.
1.48 + */
1.49 + bool appendPropertyReference(JSAtom *name) {
1.50 + if (IsIdentifier(name))
1.51 + return buf->append(".") && buf->append(name);
1.52 +
1.53 + /* Quote the string as needed. */
1.54 + JSString *source = js_QuoteString(cx, name, '"');
1.55 + return source && buf->append("[") && buf->append(source) && buf->append("]");
1.56 + }
1.57 +
1.58 + /* Append a number to buf. */
1.59 + bool appendNumber(double n) {
1.60 + char number[30];
1.61 + int digits = JS_snprintf(number, sizeof(number), "%g", n);
1.62 + return buf->appendInflated(number, digits);
1.63 + }
1.64 +
1.65 + /* Append "[<n>]" to buf, referencing a property named by a numeric literal. */
1.66 + bool appendNumericPropertyReference(double n) {
1.67 + return buf->append("[") && appendNumber(n) && buf->append("]");
1.68 + }
1.69 +
1.70 + /*
1.71 + * Walk over the given ParseNode, converting it to a stringified name that
1.72 + * respresents where the function is being assigned to.
1.73 + */
1.74 + bool nameExpression(ParseNode *n) {
1.75 + switch (n->getKind()) {
1.76 + case PNK_DOT:
1.77 + return nameExpression(n->expr()) && appendPropertyReference(n->pn_atom);
1.78 +
1.79 + case PNK_NAME:
1.80 + return buf->append(n->pn_atom);
1.81 +
1.82 + case PNK_THIS:
1.83 + return buf->append("this");
1.84 +
1.85 + case PNK_ELEM:
1.86 + return nameExpression(n->pn_left) &&
1.87 + buf->append("[") &&
1.88 + nameExpression(n->pn_right) &&
1.89 + buf->append("]");
1.90 +
1.91 + case PNK_NUMBER:
1.92 + return appendNumber(n->pn_dval);
1.93 +
1.94 + default:
1.95 + /*
1.96 + * Technically this isn't an "abort" situation, we're just confused
1.97 + * on what to call this function, but failures in naming aren't
1.98 + * treated as fatal.
1.99 + */
1.100 + return false;
1.101 + }
1.102 + }
1.103 +
1.104 + /*
1.105 + * When naming an anonymous function, the process works loosely by walking
1.106 + * up the AST and then translating that to a string. The stringification
1.107 + * happens from some far-up assignment and then going back down the parse
1.108 + * tree to the function definition point.
1.109 + *
1.110 + * This function will walk up the parse tree, gathering relevant nodes used
1.111 + * for naming, and return the assignment node if there is one. The provided
1.112 + * array and size will be filled in, and the returned node could be nullptr
1.113 + * if no assignment is found. The first element of the array will be the
1.114 + * innermost node relevant to naming, and the last element will be the
1.115 + * outermost node.
1.116 + */
1.117 + ParseNode *gatherNameable(ParseNode **nameable, size_t *size) {
1.118 + *size = 0;
1.119 +
1.120 + for (int pos = nparents - 1; pos >= 0; pos--) {
1.121 + ParseNode *cur = parents[pos];
1.122 + if (cur->isAssignment())
1.123 + return cur;
1.124 +
1.125 + switch (cur->getKind()) {
1.126 + case PNK_NAME: return cur; /* found the initialized declaration */
1.127 + case PNK_THIS: return cur; /* Setting a property of 'this'. */
1.128 + case PNK_FUNCTION: return nullptr; /* won't find an assignment or declaration */
1.129 +
1.130 + case PNK_RETURN:
1.131 + /*
1.132 + * Normally the relevant parent of a node is its direct parent, but
1.133 + * sometimes with code like:
1.134 + *
1.135 + * var foo = (function() { return function() {}; })();
1.136 + *
1.137 + * the outer function is just a helper to create a scope for the
1.138 + * returned function. Hence the name of the returned function should
1.139 + * actually be 'foo'. This loop sees if the current node is a
1.140 + * PNK_RETURN, and if there is a direct function call we skip to
1.141 + * that.
1.142 + */
1.143 + for (int tmp = pos - 1; tmp > 0; tmp--) {
1.144 + if (isDirectCall(tmp, cur)) {
1.145 + pos = tmp;
1.146 + break;
1.147 + } else if (call(cur)) {
1.148 + /* Don't skip too high in the tree */
1.149 + break;
1.150 + }
1.151 + cur = parents[tmp];
1.152 + }
1.153 + break;
1.154 +
1.155 + case PNK_COLON:
1.156 + /*
1.157 + * Record the PNK_COLON but skip the PNK_OBJECT so we're not
1.158 + * flagged as a contributor.
1.159 + */
1.160 + pos--;
1.161 + /* fallthrough */
1.162 +
1.163 + default:
1.164 + /* Save any other nodes we encounter on the way up. */
1.165 + JS_ASSERT(*size < MaxParents);
1.166 + nameable[(*size)++] = cur;
1.167 + break;
1.168 + }
1.169 + }
1.170 +
1.171 + return nullptr;
1.172 + }
1.173 +
1.174 + /*
1.175 + * Resolve the name of a function. If the function already has a name
1.176 + * listed, then it is skipped. Otherwise an intelligent name is guessed to
1.177 + * assign to the function's displayAtom field
1.178 + */
1.179 + bool resolveFun(ParseNode *pn, HandleAtom prefix, MutableHandleAtom retAtom) {
1.180 + JS_ASSERT(pn != nullptr && pn->isKind(PNK_FUNCTION));
1.181 + RootedFunction fun(cx, pn->pn_funbox->function());
1.182 +
1.183 + StringBuffer buf(cx);
1.184 + this->buf = &buf;
1.185 +
1.186 + retAtom.set(nullptr);
1.187 +
1.188 + /* If the function already has a name, use that */
1.189 + if (fun->displayAtom() != nullptr) {
1.190 + if (prefix == nullptr) {
1.191 + retAtom.set(fun->displayAtom());
1.192 + return true;
1.193 + }
1.194 + if (!buf.append(prefix) ||
1.195 + !buf.append("/") ||
1.196 + !buf.append(fun->displayAtom()))
1.197 + return false;
1.198 + retAtom.set(buf.finishAtom());
1.199 + return !!retAtom;
1.200 + }
1.201 +
1.202 + /* If a prefix is specified, then it is a form of namespace */
1.203 + if (prefix != nullptr && (!buf.append(prefix) || !buf.append("/")))
1.204 + return false;
1.205 +
1.206 + /* Gather all nodes relevant to naming */
1.207 + ParseNode *toName[MaxParents];
1.208 + size_t size;
1.209 + ParseNode *assignment = gatherNameable(toName, &size);
1.210 +
1.211 + /* If the function is assigned to something, then that is very relevant */
1.212 + if (assignment) {
1.213 + if (assignment->isAssignment())
1.214 + assignment = assignment->pn_left;
1.215 + if (!nameExpression(assignment))
1.216 + return true;
1.217 + }
1.218 +
1.219 + /*
1.220 + * Other than the actual assignment, other relevant nodes to naming are
1.221 + * those in object initializers and then particular nodes marking a
1.222 + * contribution.
1.223 + */
1.224 + for (int pos = size - 1; pos >= 0; pos--) {
1.225 + ParseNode *node = toName[pos];
1.226 +
1.227 + if (node->isKind(PNK_COLON)) {
1.228 + ParseNode *left = node->pn_left;
1.229 + if (left->isKind(PNK_NAME) || left->isKind(PNK_STRING)) {
1.230 + if (!appendPropertyReference(left->pn_atom))
1.231 + return false;
1.232 + } else if (left->isKind(PNK_NUMBER)) {
1.233 + if (!appendNumericPropertyReference(left->pn_dval))
1.234 + return false;
1.235 + }
1.236 + } else {
1.237 + /*
1.238 + * Don't have consecutive '<' characters, and also don't start
1.239 + * with a '<' character.
1.240 + */
1.241 + if (!buf.empty() && *(buf.end() - 1) != '<' && !buf.append("<"))
1.242 + return false;
1.243 + }
1.244 + }
1.245 +
1.246 + /*
1.247 + * functions which are "genuinely anonymous" but are contained in some
1.248 + * other namespace are rather considered as "contributing" to the outer
1.249 + * function, so give them a contribution symbol here.
1.250 + */
1.251 + if (!buf.empty() && *(buf.end() - 1) == '/' && !buf.append("<"))
1.252 + return false;
1.253 +
1.254 + if (buf.empty())
1.255 + return true;
1.256 +
1.257 + retAtom.set(buf.finishAtom());
1.258 + if (!retAtom)
1.259 + return false;
1.260 + fun->setGuessedAtom(retAtom);
1.261 + return true;
1.262 + }
1.263 +
1.264 + /*
1.265 + * Tests whether parents[pos] is a function call whose callee is cur.
1.266 + * This is the case for functions which do things like simply create a scope
1.267 + * for new variables and then return an anonymous function using this scope.
1.268 + */
1.269 + bool isDirectCall(int pos, ParseNode *cur) {
1.270 + return pos >= 0 && call(parents[pos]) && parents[pos]->pn_head == cur;
1.271 + }
1.272 +
1.273 + public:
1.274 + explicit NameResolver(ExclusiveContext *cx) : cx(cx), nparents(0), buf(nullptr) {}
1.275 +
1.276 + /*
1.277 + * Resolve all names for anonymous functions recursively within the
1.278 + * ParseNode instance given. The prefix is for each subsequent name, and
1.279 + * should initially be nullptr.
1.280 + */
1.281 + bool resolve(ParseNode *cur, HandleAtom prefixArg = js::NullPtr()) {
1.282 + RootedAtom prefix(cx, prefixArg);
1.283 + if (cur == nullptr)
1.284 + return true;
1.285 +
1.286 + if (cur->isKind(PNK_FUNCTION) && cur->isArity(PN_CODE)) {
1.287 + RootedAtom prefix2(cx);
1.288 + if (!resolveFun(cur, prefix, &prefix2))
1.289 + return false;
1.290 +
1.291 + /*
1.292 + * If a function looks like (function(){})() where the parent node
1.293 + * of the definition of the function is a call, then it shouldn't
1.294 + * contribute anything to the namespace, so don't bother updating
1.295 + * the prefix to whatever was returned.
1.296 + */
1.297 + if (!isDirectCall(nparents - 1, cur))
1.298 + prefix = prefix2;
1.299 + }
1.300 + if (nparents >= MaxParents)
1.301 + return true;
1.302 + parents[nparents++] = cur;
1.303 +
1.304 + switch (cur->getArity()) {
1.305 + case PN_NULLARY:
1.306 + break;
1.307 + case PN_NAME:
1.308 + if (!resolve(cur->maybeExpr(), prefix))
1.309 + return false;
1.310 + break;
1.311 + case PN_UNARY:
1.312 + if (!resolve(cur->pn_kid, prefix))
1.313 + return false;
1.314 + break;
1.315 + case PN_BINARY:
1.316 + case PN_BINARY_OBJ:
1.317 + if (!resolve(cur->pn_left, prefix))
1.318 + return false;
1.319 +
1.320 + /*
1.321 + * FIXME? Occasionally pn_left == pn_right for something like
1.322 + * destructuring assignment in (function({foo}){}), so skip the
1.323 + * duplicate here if this is the case because we want to traverse
1.324 + * everything at most once.
1.325 + */
1.326 + if (cur->pn_left != cur->pn_right)
1.327 + if (!resolve(cur->pn_right, prefix))
1.328 + return false;
1.329 + break;
1.330 + case PN_TERNARY:
1.331 + if (!resolve(cur->pn_kid1, prefix))
1.332 + return false;
1.333 + if (!resolve(cur->pn_kid2, prefix))
1.334 + return false;
1.335 + if (!resolve(cur->pn_kid3, prefix))
1.336 + return false;
1.337 + break;
1.338 + case PN_CODE:
1.339 + JS_ASSERT(cur->isKind(PNK_FUNCTION));
1.340 + if (!resolve(cur->pn_body, prefix))
1.341 + return false;
1.342 + break;
1.343 + case PN_LIST:
1.344 + for (ParseNode *nxt = cur->pn_head; nxt; nxt = nxt->pn_next)
1.345 + if (!resolve(nxt, prefix))
1.346 + return false;
1.347 + break;
1.348 + }
1.349 + nparents--;
1.350 + return true;
1.351 + }
1.352 +};
1.353 +
1.354 +} /* anonymous namespace */
1.355 +
1.356 +bool
1.357 +frontend::NameFunctions(ExclusiveContext *cx, ParseNode *pn)
1.358 +{
1.359 + NameResolver nr(cx);
1.360 + return nr.resolve(pn);
1.361 +}
