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decompiler.js
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decompiler.js
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/* vim: set sw=4 ts=4 et tw=78: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the Narcissus JavaScript engine.
*
* The Initial Developer of the Original Code is
* Brendan Eich <brendan@mozilla.org>.
* Portions created by the Initial Developer are Copyright (C) 2010
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Shu-Yu Guo <shu@rfrn.org>
* Bruno Jouhier
* Gregor Richards
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* Narcissus - JS implemented in JS.
*
* Decompiler and pretty-printer.
*/
const lexer = require('lexer');
const parser = require('./parser');
const definitions = require('./definitions');
const tokens = definitions.tokens;
// Set constants in the local scope.
eval(definitions.consts);
function indent(n, s) {
var ss = "", d = true;
for (var i = 0, j = s.length; i < j; i++) {
if (d)
for (var k = 0; k < n; k++)
ss += " ";
ss += s[i];
d = s[i] === '\n';
}
return ss;
}
function isBlock(n) {
return n && (n.type === BLOCK);
}
function isNonEmptyBlock(n) {
return isBlock(n) && n.children.length > 0;
}
function nodeStrEscape(str) {
return str.replace(/\\/g, "\\\\")
.replace(/"/g, "\\\"")
.replace(/\n/g, "\\n")
.replace(/\r/g, "\\r")
.replace(/</g, "\\u003C")
.replace(/>/g, "\\u003E");
}
function nodeStr(n) {
if (/[\u0000-\u001F\u0080-\uFFFF]/.test(n.value)) {
// use the convoluted algorithm to avoid broken low/high characters
var str = "";
for (var i = 0; i < n.value.length; i++) {
var c = n.value[i];
if (c <= "\x1F" || c >= "\x80") {
var cc = c.charCodeAt(0).toString(16);
while (cc.length < 4) cc = "0" + cc;
str += "\\u" + cc;
} else {
str += nodeStrEscape(c);
}
}
return '"' + str + '"';
}
return '"' + nodeStrEscape(n.value) + '"';
}
function pp(n, d, inLetHead) {
var topScript = false;
if (!n)
return "";
if (!(n instanceof Object))
return n;
if (!d) {
topScript = true;
d = 1;
}
var p = "";
if (n.parenthesized)
p += "(";
switch (n.type) {
case FUNCTION:
case GETTER:
case SETTER:
if (n.type === FUNCTION)
p += "function";
else if (n.type === GETTER)
p += "get";
else
p += "set";
p += (n.name ? " " + n.name : "") + "(";
for (var i = 0, j = n.params.length; i < j; i++)
p += (i > 0 ? ", " : "") + pp(n.params[i], d);
p += ") " + pp(n.body, d);
break;
case SCRIPT:
case BLOCK:
var nc = n.children;
if (topScript) {
// No indentation.
for (var i = 0, j = nc.length; i < j; i++) {
if (i > 0)
p += "\n";
p += pp(nc[i], d);
var eoc = p[p.length - 1];
if (eoc != ";")
p += ";";
}
break;
}
p += "{";
if (n.id !== undefined)
p += " /* " + n.id + " */";
p += "\n";
for (var i = 0, j = nc.length; i < j; i++) {
if (i > 0)
p += "\n";
p += indent(4, pp(nc[i], d));
var eoc = p[p.length - 1];
if (eoc != ";")
p += ";";
}
p += "\n}";
break;
case LET_BLOCK:
p += "let (" + pp(n.variables, d, true) + ") ";
if (n.expression)
p += pp(n.expression, d);
else
p += pp(n.block, d);
break;
case IF:
p += "if (" + pp(n.condition, d) + ") ";
var tp = n.thenPart, ep = n.elsePart;
var b = isBlock(tp) || isBlock(ep);
if (!b)
p += "{\n";
p += (b ? pp(tp, d) : indent(4, pp(tp, d))) + "\n";
if (ep) {
if (!b)
p += "} else {\n";
else
p += " else ";
p += (b ? pp(ep, d) : indent(4, pp(ep, d))) + "\n";
}
if (!b)
p += "}";
break;
case SWITCH:
p += "switch (" + pp(n.discriminant, d) + ") {\n";
for (var i = 0, j = n.cases.length; i < j; i++) {
var ca = n.cases[i];
if (ca.type === CASE)
p += " case " + pp(ca.caseLabel, d) + ":\n";
else
p += " default:\n";
ps = pp(ca.statements, d);
p += ps.slice(2, ps.length - 2) + "\n";
}
p += "}";
break;
case FOR:
p += "for (" + pp(n.setup, d) + "; "
+ pp(n.condition, d) + "; "
+ pp(n.update, d) + ") ";
var pb = pp(n.body, d);
if (!isBlock(n.body))
p += "{\n" + indent(4, pb) + ";\n}";
else if (n.body)
p += pb;
break;
case WHILE:
p += "while (" + pp(n.condition, d) + ") ";
var pb = pp(n.body, d);
if (!isBlock(n.body))
p += "{\n" + indent(4, pb) + ";\n}";
else
p += pb;
break;
case FOR_IN:
var u = n.varDecl;
p += n.isEach ? "for each (" : "for (";
p += (u ? pp(u, d) : pp(n.iterator, d)) + " in " +
pp(n.object, d) + ") ";
var pb = pp(n.body, d);
if (!isBlock(n.body))
p += "{\n" + indent(4, pb) + ";\n}";
else if (n.body)
p += pb;
break;
case DO:
p += "do " + pp(n.body, d);
p += " while (" + pp(n.condition, d) + ");";
break;
case BREAK:
p += "break" + (n.label ? " " + n.label : "") + ";";
break;
case CONTINUE:
p += "continue" + (n.label ? " " + n.label : "") + ";";
break;
case TRY:
p += "try ";
p += pp(n.tryBlock, d);
for (var i = 0, j = n.catchClauses.length; i < j; i++) {
var t = n.catchClauses[i];
p += " catch (" + pp(t.varName, d) +
(t.guard ? " if " + pp(t.guard, d) : "") +
") ";
p += pp(t.block, d);
}
if (n.finallyBlock) {
p += " finally ";
p += pp(n.finallyBlock, d);
}
break;
case THROW:
p += "throw " + pp(n.exception, d);
break;
case RETURN:
p += "return";
if (n.value)
p += " " + pp(n.value, d);
break;
case YIELD:
p += "yield";
if (n.value)
p += " " + pp(n.value, d);
break;
case GENERATOR:
p += pp(n.expression, d) + " " + pp(n.tail, d);
break;
case WITH:
p += "with (" + pp(n.object, d) + ") ";
p += pp(n.body, d);
break;
case LET:
case VAR:
case CONST:
var nc = n.children;
if (!inLetHead) {
p += tokens[n.type] + " ";
}
for (var i = 0, j = nc.length; i < j; i++) {
if (i > 0)
p += ", ";
var u = nc[i];
p += pp(u.name, d);
if (u.initializer)
p += " = " + pp(u.initializer, d);
}
break;
case DEBUGGER:
p += "debugger NYI\n";
break;
case SEMICOLON:
if (n.expression) {
p += pp(n.expression, d) + ";";
}
break;
case LABEL:
p += n.label + ":\n" + pp(n.statement, d);
break;
case COMMA:
case LIST:
var nc = n.children;
for (var i = 0, j = nc.length; i < j; i++) {
if (i > 0)
p += ", ";
p += pp(nc[i], d);
}
break;
case ASSIGN:
var nc = n.children;
var t = n.assignOp;
p += pp(nc[0], d) + " " + (t ? tokens[t] : "") + "="
+ " " + pp(nc[1], d);
break;
case HOOK:
var nc = n.children;
p += "(" + pp(nc[0], d) + " ? "
+ pp(nc[1], d) + " : "
+ pp(nc[2], d);
p += ")";
break;
case OR:
case AND:
var nc = n.children;
p += "(" + pp(nc[0], d) + " " + tokens[n.type] + " "
+ pp(nc[1], d);
p += ")";
break;
case BITWISE_OR:
case BITWISE_XOR:
case BITWISE_AND:
case EQ:
case NE:
case STRICT_EQ:
case STRICT_NE:
case LT:
case LE:
case GE:
case GT:
case IN:
case INSTANCEOF:
case LSH:
case RSH:
case URSH:
case PLUS:
case MINUS:
case MUL:
case DIV:
case MOD:
var nc = n.children;
p += "(" + pp(nc[0], d) + " " + tokens[n.type] + " "
+ pp(nc[1], d) + ")";
break;
case DELETE:
case VOID:
case TYPEOF:
p += tokens[n.type] + " " + pp(n.children[0], d);
break;
case NOT:
case BITWISE_NOT:
p += tokens[n.type] + pp(n.children[0], d);
break;
case UNARY_PLUS:
p += "+" + pp(n.children[0], d);
break;
case UNARY_MINUS:
p += "-" + pp(n.children[0], d);
break;
case INCREMENT:
case DECREMENT:
if (n.postfix) {
p += pp(n.children[0], d) + tokens[n.type];
} else {
p += tokens[n.type] + pp(n.children[0], d);
}
break;
case DOT:
var nc = n.children;
p += pp(nc[0], d) + "." + pp(nc[1], d);
break;
case INDEX:
var nc = n.children;
p += pp(nc[0], d) + "[" + pp(nc[1], d) + "]";
break;
case CALL:
var nc = n.children;
p += pp(nc[0], d) + "(" + pp(nc[1], d) + ")";
break;
case NEW:
case NEW_WITH_ARGS:
var nc = n.children;
p += "new " + pp(nc[0], d);
if (nc[1])
p += "(" + pp(nc[1], d) + ")";
break;
case ARRAY_INIT:
p += "[";
var nc = n.children;
for (var i = 0, j = nc.length; i < j; i++) {
if(nc[i])
p += pp(nc[i], d);
p += ","
}
p += "]";
break;
case ARRAY_COMP:
p += "[" + pp (n.expression, d) + " ";
p += pp(n.tail, d);
p += "]";
break;
case COMP_TAIL:
var nc = n.children;
for (var i = 0, j = nc.length; i < j; i++) {
if (i > 0)
p += " ";
p += pp(nc[i], d);
}
if (n.guard)
p += " if (" + pp(n.guard, d) + ")";
break;
case OBJECT_INIT:
var nc = n.children;
if (nc[0] && nc[0].type === PROPERTY_INIT)
p += "{\n";
else
p += "{";
for (var i = 0, j = nc.length; i < j; i++) {
if (i > 0) {
p += ",\n";
}
var t = nc[i];
if (t.type === PROPERTY_INIT) {
var tc = t.children;
var l;
/*
* See if the left needs to be quoted.
*
* N.B. If negative numeral prop names ever get converted
* internally to numbers by the parser, we need to quote
* those also.
*/
var propName = tc[0].value;
if (typeof propName === "string" && !lexer.isIdentifier(propName)) {
l = nodeStr(tc[0]);
} else {
l = pp(tc[0], d);
}
p += indent(4, l) + ": " +
indent(4, pp(tc[1], d)).substring(4);
} else {
p += indent(4, pp(t, d));
}
}
p += "\n}";
break;
case NULL:
p += "null";
break;
case THIS:
p += "this";
break;
case TRUE:
p += "true";
break;
case FALSE:
p += "false";
break;
case IDENTIFIER:
case NUMBER:
case REGEXP:
p += n.value;
break;
case STRING:
p += nodeStr(n);
break;
case GROUP:
p += "(" + pp(n.children[0], d) + ")";
break;
default:
throw "PANIC: unknown operation " + tokens[n.type] + " " + n.toSource();
}
if (n.parenthesized)
p += ")";
return p;
}
exports.pp = pp;