JezK
Edit File: expression-trees.js
// Copyright 2010 the V8 project authors. All rights reserved. // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following // disclaimer in the documentation and/or other materials provided // with the distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived // from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // Flags: --always-opt --nocompilation-cache // Given a binary operation string and an ordered array of leaf // strings, return an array of all binary tree strings with the leaves // (in order) as the fringe. function makeTrees(op, leaves) { var len = leaves.length; if (len == 1) { // One leaf is a leaf. return leaves; } else { // More than one leaf requires an interior node. var result = []; // Split the leaves into left and right subtrees in all possible // ways. For each split recursively compute all possible subtrees. for (var i = 1; i < len; ++i) { var leftTrees = makeTrees(op, leaves.slice(0, i)); var rightTrees = makeTrees(op, leaves.slice(i, len)); // Adjoin every possible left and right subtree. for (var j = 0; j < leftTrees.length; ++j) { for (var k = 0; k < rightTrees.length; ++k) { var string = "(" + leftTrees[j] + op + rightTrees[k] + ")"; result.push(string); } } } return result; } } // All 429 possible bitwise OR trees with eight leaves. var identifiers = ['a','b','c','d','e','f','g','h']; var or_trees = makeTrees("|", identifiers); var and_trees = makeTrees("&", identifiers); // Set up leaf masks to set 8 least-significant bits. var a = 1 << 0; var b = 1 << 1; var c = 1 << 2; var d = 1 << 3; var e = 1 << 4; var f = 1 << 5; var g = 1 << 6; var h = 1 << 7; for (var i = 0; i < or_trees.length; ++i) { for (var j = 0; j < 8; ++j) { var or_fun = new Function("return " + or_trees[i]); if (j == 0) assertEquals(255, or_fun()); // Set the j'th variable to a string to force a bailout. eval(identifiers[j] + "+= ''"); assertEquals(255, or_fun()); // Set it back to a number for the next iteration. eval(identifiers[j] + "= +" + identifiers[j]); } } // Set up leaf masks to clear 8 least-significant bits. a ^= 255; b ^= 255; c ^= 255; d ^= 255; e ^= 255; f ^= 255; g ^= 255; h ^= 255; for (i = 0; i < and_trees.length; ++i) { for (var j = 0; j < 8; ++j) { var and_fun = new Function("return " + and_trees[i]); if (j == 0) assertEquals(0, and_fun()); // Set the j'th variable to a string to force a bailout. eval(identifiers[j] + "+= ''"); assertEquals(0, and_fun()); // Set it back to a number for the next iteration. eval(identifiers[j] + "= +" + identifiers[j]); } }