tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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breakpoint-11.js (1230B)


      1 // Setting a breakpoint in a generator function works, and we can
      2 // traverse the stack and evaluate expressions in the context of older
      3 // generator frames.
      4 
      5 var g = newGlobal({newCompartment: true});
      6 var dbg = Debugger(g);
      7 dbg.onDebuggerStatement = function (frame) {
      8    function hit(frame) {
      9        frame.older.eval("q += 16");
     10    }
     11 
     12    var s = frame.script;
     13    var offs = s.getLineOffsets(g.line0 + 9);
     14    for (var i = 0; i < offs.length; i++)
     15        s.setBreakpoint(offs[i], {hit: hit});
     16 };
     17 
     18 g.eval("line0 = Error().lineNumber;\n" +
     19       "function* g(x) {\n" +   // + 1
     20       "    var q = 10;\n" +    // + 2
     21       "    yield* x;\n" +      // + 3
     22       "    return q;\n" +      // + 4
     23       "}\n" +                  // + 5
     24       "function* range(n) {\n" + // + 6
     25       "    debugger;\n" +      // + 7
     26       "    for (var i = 0; i < n; i++)\n" + // + 8
     27       "        yield i;\n" +   // + 9  <-- breakpoint
     28       "    return;\n" + // so that line 9 only has the yield
     29       "}");
     30 
     31 g.eval("var iter = g(range(2))");
     32 g.eval("var first = iter.next().value");
     33 g.eval("var second = iter.next().value");
     34 g.eval("var third = iter.next().value");
     35 
     36 assertEq(g.first, 0);
     37 assertEq(g.second, 1);
     38 assertEq(g.third, 42);