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handle labels properly

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(they can't be handled the same way as variables in a scope)
This commit is contained in:
Mihai Bazon
2012-08-21 12:37:05 +03:00
parent 159333f4c5
commit 92bd53b513
2 changed files with 43 additions and 41 deletions
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8
lib/ast.js
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@@ -158,15 +158,13 @@ var AST_With = DEFNODE("With", "expression", {
var AST_Scope = DEFNODE("Scope", null, {
$documentation: "Base class for all statements introducing a lexical scope",
initialize: function() {
this.labels = {}; // map name to AST_Label (labels defined in this scope)
this.variables = {}; // map name to AST_SymbolVar (variables defined in this scope; includes functions)
this.functions = {}; // map name to AST_SymbolDefun (functions defined in this scope)
this.uses_with = false; // will be set to true if this or some nested scope uses the `with` statement
this.uses_eval = false; // will be set to true if this or nested scope uses the global `eval`
this.parent_scope = null; // the parent scope
this.enclosed = []; // a list of variables this or from outer scope(s) that are accessed from this or inner scopes
this.enclosed = []; // a list of variables from this or outer scope(s) that are referenced from this or inner scopes
this.cname = -1; // the current index for mangling functions/variables
this.lname = -1; // the current index for mangling labels
}
}, AST_BlockStatement);
@@ -568,7 +566,9 @@ function TreeWalker(callback) {
TreeWalker.prototype = {
_visit: function(node, descend) {
this.stack.push(node);
var ret = this.visit(node, descend);
var ret = this.visit(node, function(){
descend.call(node);
});
if (!ret && descend) {
descend.call(node);
}

76
lib/scope.js
View File

@@ -8,11 +8,12 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
// pass 1: setup scope chaining and handle definitions
var scope = null;
var labels = {};
var tw = new TreeWalker(function(node, descend){
if (node instanceof AST_Scope) {
var save_scope = node.parent_scope = scope;
scope = node;
descend.call(node);
descend();
scope = save_scope;
return true; // don't descend again in TreeWalker
}
@@ -21,6 +22,15 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
s.uses_with = true;
return;
}
if (node instanceof AST_LabeledStatement) {
var l = node.label;
if (labels[l.name])
throw new Error(string_template("Label {name} defined twice", l));
labels[l.name] = l;
descend();
delete labels[l.name];
return true; // no descend again
}
if (node instanceof AST_SymbolLambda) {
scope.def_function(node);
}
@@ -35,9 +45,6 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
else if (node instanceof AST_SymbolVar) {
scope.def_variable(node);
}
else if (node instanceof AST_Label) {
scope.def_label(node);
}
else if (node instanceof AST_SymbolCatch) {
// XXX: this is wrong according to ECMA-262 (12.4). the
// `catch` argument name should be visible only inside the
@@ -51,7 +58,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
node.scope = scope;
}
if (node instanceof AST_LabelRef) {
var sym = scope.find_label(node);
var sym = labels[node.name];
if (!sym) throw new Error("Undefined label " + node.name);
node.reference(sym);
}
@@ -153,11 +160,6 @@ AST_Scope.DEFMETHOD("find_variable", function(name){
(this.parent_scope && this.parent_scope.find_variable(name));
});
AST_Scope.DEFMETHOD("find_label", function(name){
if (name instanceof AST_Symbol) name = name.name;
return this.labels[name];
});
AST_Scope.DEFMETHOD("def_function", function(symbol){
this.functions[symbol.name] = symbol;
this.def_variable(symbol);
@@ -174,25 +176,11 @@ AST_Scope.DEFMETHOD("def_variable", function(symbol){
symbol.scope = this;
});
AST_Scope.DEFMETHOD("def_label", function(symbol){
this.labels[symbol.name] = symbol;
symbol.scope = this;
});
AST_Scope.DEFMETHOD("next_mangled", function(for_label){
AST_Scope.DEFMETHOD("next_mangled", function(){
var ext = this.enclosed, n = ext.length;
out: while (true) {
var m = base54(for_label
? (++this.lname)
: (++this.cname));
var m = base54(++this.cname);
if (!is_identifier(m)) continue; // skip over "do"
// labels are easy, since they can't be referenced from nested
// scopes. XXX: not sure that will be the case when the `let`
// keyword is to be supported.
if (for_label) return m;
// if it's for functions or variables, we must ensure that the
// mangled name does not shadow a name from some parent scope
// that is referenced in this or in inner scopes.
@@ -201,7 +189,6 @@ AST_Scope.DEFMETHOD("next_mangled", function(for_label){
var name = sym.mangled_name || sym.name;
if (m == name) continue out;
}
return m;
}
});
@@ -214,10 +201,14 @@ AST_SymbolDeclaration.DEFMETHOD("mangle", function(){
|| this.scope.uses_eval
|| this.scope.uses_with
|| this.mangled_name)) {
this.mangled_name = this.scope.next_mangled(this instanceof AST_Label);
this.mangled_name = this.scope.next_mangled();
}
});
AST_Label.DEFMETHOD("mangle", function(){
throw new Error("Don't call this");
});
AST_SymbolDeclaration.DEFMETHOD("unreferenced", function(){
return this.definition().references.length == 0;
});
@@ -227,20 +218,31 @@ AST_SymbolDeclaration.DEFMETHOD("definition", function(){
});
AST_Toplevel.DEFMETHOD("mangle_names", function(){
var tw = new TreeWalker(function(node){
// We only need to mangle declarations. Special logic wired
// into the code generator will display the mangled name if
// it's present (and for AST_SymbolRef-s it'll use the mangled
// name of the AST_SymbolDeclaration that it points to).
// We only need to mangle declaration nodes. Special logic wired
// into the code generator will display the mangled name if it's
// present (and for AST_SymbolRef-s it'll use the mangled name of
// the AST_SymbolDeclaration that it points to).
var lname = -1;
var tw = new TreeWalker(function(node, descend){
if (node instanceof AST_LabeledStatement) {
// lname is incremented when we get to the AST_Label
var save_nesting = lname;
descend();
lname = save_nesting;
return true; // don't descend again in TreeWalker
}
if (node instanceof AST_Scope) {
var a = node.variables;
for (var i in a) if (HOP(a, i)) {
a[i].mangle();
}
var a = node.labels;
for (var i in a) if (HOP(a, i)) {
a[i].mangle();
}
return;
}
if (node instanceof AST_Label) {
var name;
do name = base54(++lname); while (!is_identifier(name));
node.mangled_name = name;
return;
}
});
this.walk(tw);