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Bug 433529: Part 1 - Statically resolve names for anonymous functions. r=jimb

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This commit is contained in:
Alex Crichton 2012-08-18 21:33:20 -07:00
parent 89b1606202
commit 6af1c4a887
4 changed files with 334 additions and 0 deletions
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1
js/src/Makefile.in
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@ -120,6 +120,7 @@ CPPSRCS = \
BytecodeCompiler.cpp \
BytecodeEmitter.cpp \
FoldConstants.cpp \
NameFunctions.cpp \
ParallelArray.cpp \
ParseMaps.cpp \
ParseNode.cpp \

6
js/src/frontend/BytecodeCompiler.cpp
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@ -11,6 +11,7 @@
#include "frontend/BytecodeEmitter.h"
#include "frontend/FoldConstants.h"
#include "frontend/NameFunctions.h"
#include "vm/GlobalObject.h"
#include "jsinferinlines.h"
@ -191,6 +192,8 @@ frontend::CompileScript(JSContext *cx, HandleObject scopeChain, StackFrame *call
if (!FoldConstants(cx, pn, &parser))
return NULL;
if (!NameFunctions(cx, pn))
return NULL;
pc.functionList = NULL;
@ -331,6 +334,9 @@ frontend::CompileFunctionBody(JSContext *cx, HandleFunction fun, CompileOptions
if (!funbce.init())
return false;
if (!NameFunctions(cx, pn))
return NULL;
if (fn->pn_body) {
JS_ASSERT(fn->pn_body->isKind(PNK_ARGSBODY));
fn->pn_body->append(pn);

303
js/src/frontend/NameFunctions.cpp Normal file
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@ -0,0 +1,303 @@
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sw=4 et 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 "frontend/ParseNode.h"
#include "frontend/SharedContext.h"
#include "jsfun.h"
#include "jsprf.h"
#include "vm/String-inl.h"
#include "vm/StringBuffer.h"
using namespace js;
using namespace js::frontend;
class NameResolver
{
static const size_t MaxParents = 100;
JSContext *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_LP);
}
/*
* Some special atoms like 'prototype' and '__proto__' aren't useful to show
* up in function names.
*/
bool special(JSAtom *atom) {
return cx->runtime->atomState.protoAtom == atom ||
cx->runtime->atomState.classPrototypeAtom == atom;
}
/*
* 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()) &&
(special(n->pn_atom) ||
(buf->append(".") && buf->append(n->pn_atom)));
case PNK_NAME:
return buf->append(n->pn_atom);
case PNK_LB:
return nameExpression(n->pn_left) &&
buf->append("[") &&
nameExpression(n->pn_right) &&
buf->append("]");
case PNK_NUMBER: {
char number[30];
int digits = JS_snprintf(number, sizeof(number), "%g", n->pn_dval);
return buf->appendInflated(number, digits);
}
/*
* 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.
*/
default:
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 NULL 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_FUNCTION: return NULL; /* won't find an assignment or declaration */
default: break; /* move on, nothing relevant */
/* These nodes are relevant to the naming process, so append */
case PNK_COLON:
case PNK_LP:
case PNK_NEW:
JS_ASSERT(*size < MaxParents);
nameable[(*size)++] = cur;
break;
}
/*
* 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.
*/
if (cur->isKind(PNK_RETURN)) {
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];
}
}
}
return NULL;
}
/*
* 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
*/
JSAtom *resolveFun(ParseNode *pn, JSAtom *prefix) {
JS_ASSERT(pn != NULL && pn->isKind(PNK_FUNCTION));
JSFunction *fun = pn->pn_funbox->function();
if (nparents == 0)
return NULL;
StringBuffer buf(cx);
this->buf = &buf;
/* If the function already has a name, use that */
if (fun->displayAtom() != NULL) {
if (prefix == NULL)
return fun->atom();
if (!buf.append(prefix) ||
!buf.append("/") ||
!buf.append(fun->displayAtom()))
return NULL;
return buf.finishAtom();
}
/* If a prefix is specified, then it is a form of namespace */
if (prefix != NULL && (!buf.append(prefix) || !buf.append("/")))
return NULL;
/* 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 NULL;
}
/*
* 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)) {
if (!node->pn_left->isKind(PNK_NAME))
continue;
/* special atoms are skipped, but others are dot-appended */
if (!special(node->pn_left->pn_atom)) {
if (!buf.append(".") || !buf.append(node->pn_left->pn_atom))
return NULL;
}
} else {
/*
* Don't have consecutive '<' characters, and also don't start
* with a '<' character.
*/
if (!buf.empty() && *(buf.end() - 1) != '<' && !buf.append("<"))
return NULL;
}
}
/*
* 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 NULL;
return buf.finishAtom();
}
/*
* 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:
NameResolver(JSContext *cx) : cx(cx), nparents(0), buf(NULL) {}
/*
* Resolve all names for anonymous functions recursively within the
* ParseNode instance given. The prefix is for each subsequent name, and
* should initially be NULL.
*/
void resolve(ParseNode *cur, JSAtom *prefix = NULL) {
if (cur == NULL)
return;
if (cur->isKind(PNK_FUNCTION) && cur->isArity(PN_FUNC)) {
JSAtom *prefix2 = resolveFun(cur, prefix);
/*
* 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;
parents[nparents++] = cur;
switch (cur->getArity()) {
case PN_NULLARY:
break;
case PN_NAME:
resolve(cur->maybeExpr(), prefix);
break;
case PN_UNARY:
resolve(cur->pn_kid, prefix);
break;
case PN_BINARY:
resolve(cur->pn_left, prefix);
/*
* 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)
resolve(cur->pn_right, prefix);
break;
case PN_TERNARY:
resolve(cur->pn_kid1, prefix);
resolve(cur->pn_kid2, prefix);
resolve(cur->pn_kid3, prefix);
break;
case PN_FUNC:
JS_ASSERT(cur->isKind(PNK_FUNCTION));
resolve(cur->pn_body, prefix);
break;
case PN_LIST:
for (ParseNode *nxt = cur->pn_head; nxt; nxt = nxt->pn_next)
resolve(nxt, prefix);
break;
}
nparents--;
}
};
bool
frontend::NameFunctions(JSContext *cx, ParseNode *pn)
{
NameResolver nr(cx);
nr.resolve(pn);
return true;
}

24
js/src/frontend/NameFunctions.h Normal file
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@ -0,0 +1,24 @@
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sw=4 et 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/. */
#ifndef NameFunctions_h__
#define NameFunctions_h__
struct JSContext;
namespace js {
namespace frontend {
struct ParseNode;
bool
NameFunctions(JSContext *cx, ParseNode *pn);
} /* namespace frontend */
} /* namespace js */
#endif /* NameFunctions_h__ */