tor-browser

generate-lookupswitch-tests.js (12782B)

---

/**
* A test case spec is an array of objects of the following kind:
*  { 'match': Num|Str|Null,
*    'body': Num|Str|Null,
*    'fallthrough': Boolean }
*
* If the 'match' is null, then it represents a 'default:'
* If the 'match' is not null, it represents a 'case X:' where X is the value.
* If the 'body' is null, then it means that the case body is empty.  Otherwise,
* it means that the case body is a single 'arr.push(V);' where "arr" is an input
* array to the function containing the switch statement, and V is the value.
* If 'fallthrough' is false, then the body is terminated with a break, otherwise
* it is not.
*
* So a spec: [{'match':3, 'body':null, 'fallthrough':false}, {'match':null, 'body':"foo", 'fallthrough':true}]
* Represents a switch function:
*  function(x, arr) {
*      switch(x) {
*      case 3:
*          break;
*      default:
*          arr.push('foo');
*      }
*  }
*
* GenerateSpecPermutes generates a bunch of relevant specs, using the given case match-values,
* and appends them to result the array passed into it.
*
* InterpretSwitch takes a spec, a value, and a result array, and behaves as if the switch specified
* by the spec had been called on the value and the result array.
*
* VerifySwitchSpec is there but not used in the code.  I was using it while testing the test case
* generator.  It verifies that a switch spec is sane.
*
* RunSpec uses eval to run the test directly.  It's not used currently.
*
* GenerateSwitchCode generates a string of the form "function NAME(x, arg) { .... }" which
* contains the switch modeled by its input spec.
*
* RunTest is there to be used from within the generated script.  Its code is dumped out
* to the generated script text, and invoked there.
*
* Hope all of this makes some sort of sense.
*  -kannan
*/

/** HELPERS **/

function ASSERT(cond, msg) { assertEq(cond, true, msg); }

function IsUndef(x) { return typeof(x) == 'undefined'; }
function IsNull(x) { return typeof(x) == 'object' && x == null; }
function IsNum(x) { return typeof(x) == 'number'; }
function IsStr(x) { return typeof(x) == 'string'; }
function IsBool(x) { return typeof(x) == 'boolean'; }

function Repr(x) {
   ASSERT(IsNum(x) || IsStr(x), "Repr");
   if(IsNum(x)) { return ""+x; }
   else { return "'"+x+"'"; }
}

function RandBool() { return Math.random() >= 0.5; }
function RandInt(max) {
   if(IsUndef(max)) { max = 0x7fffffff; }
   return (Math.random() * max)|0;
}

var CHARS = "abcdefghijklmnopqrstuvywxyzABCDEFGHIJKLMNOPQRSTUVYWXYZ0123456789~!@#$%^&*()-_=+{}[]";
function RandStr() {
   var arr = [];
   var len = Math.floor(Math.random() * 10) + 1;
   for(var i = 0; i < len; i++) {
       var c = Math.floor(Math.random() * CHARS.length);
       arr.push(CHARS[c]);
   }
   return arr.join('');
}

function RandVal() { return RandBool() ? RandInt() : RandStr(); }

/**
* Compare two arrays and ensure they are equal.
*/
function ArraysEqual(arr1, arr2) {
   ASSERT(arr1.length == arr2.length, "Lengths not equal");
   for(var i = 0; i < arr1.length; i++) {
       ASSERT(typeof(arr1[i]) == typeof(arr2[i]), "Types not equal for position " + i);
       ASSERT(arr1[i] == arr2[i], "Values not equal for position " + i);
   }
}

function VerifySwitchSpec(spec) {
   var foundDefault = undefined;
   for(var i = 0; i < spec.length; i++) {
       var caseSpec = spec[i],
           match = caseSpec.match,
           body = caseSpec.body,
           fallthrough = caseSpec.fallthrough;
       ASSERT(IsNum(match) || IsStr(match) || IsNull(match), "Invalid case match for " + i);
       ASSERT(IsNum(body) || IsStr(body) || IsNull(body), "Invalid case body for " + i);
       ASSERT(IsBool(fallthrough), "Invalid fallthrough for " + i);

       if(IsNull(match)) {
           ASSERT(IsUndef(foundDefault), "Duplicate default found at " + i);
           foundDefault = i;
       }
   }
}

/**
* Do a manual interpretation of a particular spec, given an input
* and outputting to an output array.
*/
function InterpretSwitch(spec, input, outputArray) {
   var foundMatch = undefined, foundDefault = undefined;
   // Go through cases, trying to find a matching clause.
   for(var i = 0; i < spec.length; i++) {
       var caseSpec = spec[i], match = caseSpec.match;

       if(IsNull(match)) {
           foundDefault = i;
           continue;
       } else if(match === input) {
           foundMatch = i;
           break;
       }
   }
   // Select either matching clause or default.
   var matchI = IsNum(foundMatch) ? foundMatch : foundDefault;

   // If match or default was found, interpret body from that point on.
   if(IsNum(matchI)) {
       for(var i = matchI; i < spec.length; i++) {
           var caseSpec = spec[i],
               match = caseSpec.match,
               body = caseSpec.body,
               fallthrough = caseSpec.fallthrough;
           if(!IsNull(body)) { outputArray.push(body); }
           if(!fallthrough) { break; }
       }
   }
}

/**
* Generate the code string for a javascript function containing the
* switch specified by the spec, in pure JS syntax.
*/
function GenerateSwitchCode(spec, name) {
   var lines = [];
   if(!name) { name = ""; }

   lines.push("function "+name+"(x, arr) {");
   lines.push("    switch(x) {");
   for(var i = 0; i < spec.length; i++) {
       var caseSpec = spec[i],
           match = caseSpec.match,
           body = caseSpec.body,
           fallthrough = caseSpec.fallthrough;

       if(IsNull(match))   { lines.push("    default:"); }
       else                { lines.push("    case "+Repr(match)+":"); }

       if(!IsNull(body))   { lines.push("        arr.push("+Repr(body)+");"); }
       if(!fallthrough)    { lines.push("        break;"); }
   }
   lines.push("    }");
   lines.push("}");
   return lines.join("\n");
}

/**
* Generates all possible specs for a given set of case match values.
*/
function GenerateSpecPermutes(matchVals, resultArray) {
   ASSERT((0 < matchVals.length) && (matchVals.length <= 5), "Invalid matchVals");
   var maxPermuteBody = (1 << matchVals.length) - 1;
   for(var bod_pm = 0; bod_pm <= maxPermuteBody; bod_pm++) {
       var maxPermuteFallthrough = (1 << matchVals.length) - 1;

       for(var ft_pm = 0; ft_pm <= maxPermuteFallthrough; ft_pm++) {
           // use bod_m and ft_pm to decide the placement of null vs value bodies,
           // and the placement of fallthroughs vs breaks.
           // Empty bodies always fall through, so fallthrough bitmask 1s must be
           // a subset of the body bitmask 1s.
           if((bod_pm | ft_pm) != bod_pm) {
               continue;
           }

           var spec = [];
           for(var k = 0; k < matchVals.length; k++) {
               var match = matchVals[k];
               var body = ((bod_pm & (1 << k)) > 0) ? null : RandVal();
               var fallthrough = ((ft_pm & (1 << k)) > 0) ? true : false;
               var caseSpec = {'match':match, 'body':body, 'fallthrough':fallthrough};
               spec.push(caseSpec);
           }

           // Variant specs for following cases:

           // Default with empty body, fallthrough
           GenerateDefaultPermutes(spec, null, true, resultArray);
           // Default with nonempty body, fallthrough
           GenerateDefaultPermutes(spec, RandVal(), true, resultArray);
           // Default with nonempty body, break
           GenerateDefaultPermutes(spec, RandVal(), false, resultArray);
       }
   }
}
function GenerateDefaultPermutes(spec, body, fallthrough, resultArray) {
   if(spec.length <= 2) {
       for(var i = 0; i <= spec.length; i++) {
           var copy = CopySpec(spec);
           if(IsNull(body)) {
               copy.splice(i,0,{'match':null, 'body':null, 'fallthrough':true});
           } else {
               copy.splice(i,0,{'match':null, 'body':body, 'fallthrough':fallthrough});
           }
           resultArray.push(copy);
       }
   } else {
       var posns = [0, Math.floor(spec.length / 2), spec.length];
       posns.forEach(function (i) {
           var copy = CopySpec(spec);
           if(IsNull(body)) {
               copy.splice(i,0,{'match':null, 'body':null, 'fallthrough':true});
           } else {
               copy.splice(i,0,{'match':null, 'body':body, 'fallthrough':fallthrough});
           }
           resultArray.push(copy);
       });
   }
}
function CopySpec(spec) {
   var newSpec = [];
   for(var i = 0; i < spec.length; i++) {
       var caseSpec = spec[i];
       newSpec.push({'match':caseSpec.match,
                     'body':caseSpec.body,
                     'fallthrough':caseSpec.fallthrough});
   }
   return newSpec;
}


function RunSpec(spec, matchVals) {
   var code = GenerateSwitchCode(spec);

   // Generate roughly 200 inputs for the test case spec, exercising
   // every match value, as well as 3 randomly generated values for every
   // iteration of the match values.
   var inputs = [];
   while(inputs.length < 500) {
       for(var i = 0; i < matchVals.length; i++) { inputs.push(matchVals[i]); }
       for(var i = 0; i < 3; i++) { inputs.push(RandVal()); }
   }

   // Interpret the lookupswitch with the inputs.
   var interpResults = [];
   for(var i = 0; i < inputs.length; i++) {
       InterpretSwitch(spec, inputs[i], interpResults);
   }

   // Run compiled lookupswitch with the inputs.
   var fn = eval("_ = " + code);
   print("Running spec: " + code);
   var compileResults = RunCompiled(fn, inputs);
   print("Done Running spec");

   // Verify that they produce the same output.
   ASSERT(interpResults.length == compileResults.length, "Length mismatch");
   for(var i = 0; i < interpResults.length; i++) {
       ASSERT(interpResults[i] == compileResults[i], "Value mismatch");
   }
}
function RunCompiled(fn, inputs) {
   var results = [];
   var len = inputs.length;
   for(var i = 0; i < len; i++) { fn(inputs[i], results); }
   return results;
}

function PrintSpec(spec, inputs, fname) {
   var code = GenerateSwitchCode(spec, fname);
   var input_s = fname + ".INPUTS = [" + inputs.map(Repr).join(', ') + "];";
   var spec_s = fname + ".SPEC = " + JSON.stringify(spec) + ";";
   print(code + "\n" + input_s + "\n" + spec_s);
}

function RunTest(test) {
   // Exercise every test case as well as one case which won't match with any of the
   // ("But what if it randomly generates a string case match whose value is
   //   UNMATCHED_CASE?!", you ask incredulously.  Well, RandStr limits itself to 11 chars.
   //   So there.)
   var inputs = test.INPUTS;
   inputs.push("UNMATCHED_CASE");
   var spec = test.SPEC;

   var results1 = [];
   for(var i = 0; i < 80; i++) {
       for(var j = 0; j < inputs.length; j++) {
           test(inputs[j], results1);
       }
   }

   var results2 = [];
   for(var i = 0; i < 80; i++) {
       for(var j = 0; j < inputs.length; j++) {
           InterpretSwitch(spec, inputs[j], results2);
       }
   }
   ArraysEqual(results1, results2);
}

// NOTES:
//  * RunTest is used within the generated test script.
//  * InterpretSwitch is printed out into the generated test script.

print("/////////////////////////////////////////");
print("// This is a generated file!");
print("// See jit-tests/etc/generate-lookupswitch-tests.js for the code");
print("// that generated this code!");
print("/////////////////////////////////////////");
print("");
print("/////////////////////////////////////////");
print("// PRELUDE                             //");
print("/////////////////////////////////////////");
print("");
print("// Avoid eager compilation of the global-scope.");
print("try{} catch (x) {};");
print("");
print(ASSERT);
print(IsNull);
print(IsNum);
print(ArraysEqual);
print(InterpretSwitch);
print(RunTest);
print("");
print("/////////////////////////////////////////");
print("// TEST CASES                          //");
print("/////////////////////////////////////////");
print("");
print("var TESTS = [];");
var MATCH_SETS = [["foo", "bar", "zing"]];
var count = 0;
for(var i = 0; i < MATCH_SETS.length; i++) {
   var matchSet = MATCH_SETS[i];
   var specs = [];
   GenerateSpecPermutes(matchSet, specs);
   for(var j = 0; j < specs.length; j++) {
       count++;
       PrintSpec(specs[j], matchSet.slice(), 'test_'+count);
       print("TESTS.push(test_"+count+");\n");
   }
}

print("");
print("/////////////////////////////////////////");
print("// RUNNER                              //");
print("/////////////////////////////////////////");
print("");
print("for(var i = 0; i < TESTS.length; i++) {");
print("  RunTest(TESTS[i]);");
print("}");