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      1 // Copyright 2011 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #include <v8.h>
     29 #include <assert.h>
     30 #include <fcntl.h>
     31 #include <string.h>
     32 #include <stdio.h>
     33 #include <stdlib.h>
     34 
     35 #ifdef COMPRESS_STARTUP_DATA_BZ2
     36 #error Using compressed startup data is not supported for this sample
     37 #endif
     38 
     39 /**
     40  * This sample program shows how to implement a simple javascript shell
     41  * based on V8.  This includes initializing V8 with command line options,
     42  * creating global functions, compiling and executing strings.
     43  *
     44  * For a more sophisticated shell, consider using the debug shell D8.
     45  */
     46 
     47 
     48 v8::Persistent<v8::Context> CreateShellContext();
     49 void RunShell(v8::Handle<v8::Context> context);
     50 int RunMain(int argc, char* argv[]);
     51 bool ExecuteString(v8::Handle<v8::String> source,
     52                    v8::Handle<v8::Value> name,
     53                    bool print_result,
     54                    bool report_exceptions);
     55 v8::Handle<v8::Value> Print(const v8::Arguments& args);
     56 v8::Handle<v8::Value> Read(const v8::Arguments& args);
     57 v8::Handle<v8::Value> Load(const v8::Arguments& args);
     58 v8::Handle<v8::Value> Quit(const v8::Arguments& args);
     59 v8::Handle<v8::Value> Version(const v8::Arguments& args);
     60 v8::Handle<v8::String> ReadFile(const char* name);
     61 void ReportException(v8::TryCatch* handler);
     62 
     63 
     64 static bool run_shell;
     65 
     66 
     67 int main(int argc, char* argv[]) {
     68   v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
     69   run_shell = (argc == 1);
     70   v8::HandleScope handle_scope;
     71   v8::Persistent<v8::Context> context = CreateShellContext();
     72   if (context.IsEmpty()) {
     73     printf("Error creating context\n");
     74     return 1;
     75   }
     76   context->Enter();
     77   int result = RunMain(argc, argv);
     78   if (run_shell) RunShell(context);
     79   context->Exit();
     80   context.Dispose();
     81   v8::V8::Dispose();
     82   return result;
     83 }
     84 
     85 
     86 // Extracts a C string from a V8 Utf8Value.
     87 const char* ToCString(const v8::String::Utf8Value& value) {
     88   return *value ? *value : "<string conversion failed>";
     89 }
     90 
     91 
     92 // Creates a new execution environment containing the built-in
     93 // functions.
     94 v8::Persistent<v8::Context> CreateShellContext() {
     95   // Create a template for the global object.
     96   v8::Handle<v8::ObjectTemplate> global = v8::ObjectTemplate::New();
     97   // Bind the global 'print' function to the C++ Print callback.
     98   global->Set(v8::String::New("print"), v8::FunctionTemplate::New(Print));
     99   // Bind the global 'read' function to the C++ Read callback.
    100   global->Set(v8::String::New("read"), v8::FunctionTemplate::New(Read));
    101   // Bind the global 'load' function to the C++ Load callback.
    102   global->Set(v8::String::New("load"), v8::FunctionTemplate::New(Load));
    103   // Bind the 'quit' function
    104   global->Set(v8::String::New("quit"), v8::FunctionTemplate::New(Quit));
    105   // Bind the 'version' function
    106   global->Set(v8::String::New("version"), v8::FunctionTemplate::New(Version));
    107 
    108   return v8::Context::New(NULL, global);
    109 }
    110 
    111 
    112 // The callback that is invoked by v8 whenever the JavaScript 'print'
    113 // function is called.  Prints its arguments on stdout separated by
    114 // spaces and ending with a newline.
    115 v8::Handle<v8::Value> Print(const v8::Arguments& args) {
    116   bool first = true;
    117   for (int i = 0; i < args.Length(); i++) {
    118     v8::HandleScope handle_scope;
    119     if (first) {
    120       first = false;
    121     } else {
    122       printf(" ");
    123     }
    124     v8::String::Utf8Value str(args[i]);
    125     const char* cstr = ToCString(str);
    126     printf("%s", cstr);
    127   }
    128   printf("\n");
    129   fflush(stdout);
    130   return v8::Undefined();
    131 }
    132 
    133 
    134 // The callback that is invoked by v8 whenever the JavaScript 'read'
    135 // function is called.  This function loads the content of the file named in
    136 // the argument into a JavaScript string.
    137 v8::Handle<v8::Value> Read(const v8::Arguments& args) {
    138   if (args.Length() != 1) {
    139     return v8::ThrowException(v8::String::New("Bad parameters"));
    140   }
    141   v8::String::Utf8Value file(args[0]);
    142   if (*file == NULL) {
    143     return v8::ThrowException(v8::String::New("Error loading file"));
    144   }
    145   v8::Handle<v8::String> source = ReadFile(*file);
    146   if (source.IsEmpty()) {
    147     return v8::ThrowException(v8::String::New("Error loading file"));
    148   }
    149   return source;
    150 }
    151 
    152 
    153 // The callback that is invoked by v8 whenever the JavaScript 'load'
    154 // function is called.  Loads, compiles and executes its argument
    155 // JavaScript file.
    156 v8::Handle<v8::Value> Load(const v8::Arguments& args) {
    157   for (int i = 0; i < args.Length(); i++) {
    158     v8::HandleScope handle_scope;
    159     v8::String::Utf8Value file(args[i]);
    160     if (*file == NULL) {
    161       return v8::ThrowException(v8::String::New("Error loading file"));
    162     }
    163     v8::Handle<v8::String> source = ReadFile(*file);
    164     if (source.IsEmpty()) {
    165       return v8::ThrowException(v8::String::New("Error loading file"));
    166     }
    167     if (!ExecuteString(source, v8::String::New(*file), false, false)) {
    168       return v8::ThrowException(v8::String::New("Error executing file"));
    169     }
    170   }
    171   return v8::Undefined();
    172 }
    173 
    174 
    175 // The callback that is invoked by v8 whenever the JavaScript 'quit'
    176 // function is called.  Quits.
    177 v8::Handle<v8::Value> Quit(const v8::Arguments& args) {
    178   // If not arguments are given args[0] will yield undefined which
    179   // converts to the integer value 0.
    180   int exit_code = args[0]->Int32Value();
    181   fflush(stdout);
    182   fflush(stderr);
    183   exit(exit_code);
    184   return v8::Undefined();
    185 }
    186 
    187 
    188 v8::Handle<v8::Value> Version(const v8::Arguments& args) {
    189   return v8::String::New(v8::V8::GetVersion());
    190 }
    191 
    192 
    193 // Reads a file into a v8 string.
    194 v8::Handle<v8::String> ReadFile(const char* name) {
    195   FILE* file = fopen(name, "rb");
    196   if (file == NULL) return v8::Handle<v8::String>();
    197 
    198   fseek(file, 0, SEEK_END);
    199   int size = ftell(file);
    200   rewind(file);
    201 
    202   char* chars = new char[size + 1];
    203   chars[size] = '\0';
    204   for (int i = 0; i < size;) {
    205     int read = fread(&chars[i], 1, size - i, file);
    206     i += read;
    207   }
    208   fclose(file);
    209   v8::Handle<v8::String> result = v8::String::New(chars, size);
    210   delete[] chars;
    211   return result;
    212 }
    213 
    214 
    215 // Process remaining command line arguments and execute files
    216 int RunMain(int argc, char* argv[]) {
    217   for (int i = 1; i < argc; i++) {
    218     const char* str = argv[i];
    219     if (strcmp(str, "--shell") == 0) {
    220       run_shell = true;
    221     } else if (strcmp(str, "-f") == 0) {
    222       // Ignore any -f flags for compatibility with the other stand-
    223       // alone JavaScript engines.
    224       continue;
    225     } else if (strncmp(str, "--", 2) == 0) {
    226       printf("Warning: unknown flag %s.\nTry --help for options\n", str);
    227     } else if (strcmp(str, "-e") == 0 && i + 1 < argc) {
    228       // Execute argument given to -e option directly.
    229       v8::Handle<v8::String> file_name = v8::String::New("unnamed");
    230       v8::Handle<v8::String> source = v8::String::New(argv[++i]);
    231       if (!ExecuteString(source, file_name, false, true)) return 1;
    232     } else {
    233       // Use all other arguments as names of files to load and run.
    234       v8::Handle<v8::String> file_name = v8::String::New(str);
    235       v8::Handle<v8::String> source = ReadFile(str);
    236       if (source.IsEmpty()) {
    237         printf("Error reading '%s'\n", str);
    238         continue;
    239       }
    240       if (!ExecuteString(source, file_name, false, true)) return 1;
    241     }
    242   }
    243   return 0;
    244 }
    245 
    246 
    247 // The read-eval-execute loop of the shell.
    248 void RunShell(v8::Handle<v8::Context> context) {
    249   printf("V8 version %s [sample shell]\n", v8::V8::GetVersion());
    250   static const int kBufferSize = 256;
    251   // Enter the execution environment before evaluating any code.
    252   v8::Context::Scope context_scope(context);
    253   v8::Local<v8::String> name(v8::String::New("(shell)"));
    254   while (true) {
    255     char buffer[kBufferSize];
    256     printf("> ");
    257     char* str = fgets(buffer, kBufferSize, stdin);
    258     if (str == NULL) break;
    259     v8::HandleScope handle_scope;
    260     ExecuteString(v8::String::New(str), name, true, true);
    261   }
    262   printf("\n");
    263 }
    264 
    265 
    266 // Executes a string within the current v8 context.
    267 bool ExecuteString(v8::Handle<v8::String> source,
    268                    v8::Handle<v8::Value> name,
    269                    bool print_result,
    270                    bool report_exceptions) {
    271   v8::HandleScope handle_scope;
    272   v8::TryCatch try_catch;
    273   v8::Handle<v8::Script> script = v8::Script::Compile(source, name);
    274   if (script.IsEmpty()) {
    275     // Print errors that happened during compilation.
    276     if (report_exceptions)
    277       ReportException(&try_catch);
    278     return false;
    279   } else {
    280     v8::Handle<v8::Value> result = script->Run();
    281     if (result.IsEmpty()) {
    282       assert(try_catch.HasCaught());
    283       // Print errors that happened during execution.
    284       if (report_exceptions)
    285         ReportException(&try_catch);
    286       return false;
    287     } else {
    288       assert(!try_catch.HasCaught());
    289       if (print_result && !result->IsUndefined()) {
    290         // If all went well and the result wasn't undefined then print
    291         // the returned value.
    292         v8::String::Utf8Value str(result);
    293         const char* cstr = ToCString(str);
    294         printf("%s\n", cstr);
    295       }
    296       return true;
    297     }
    298   }
    299 }
    300 
    301 
    302 void ReportException(v8::TryCatch* try_catch) {
    303   v8::HandleScope handle_scope;
    304   v8::String::Utf8Value exception(try_catch->Exception());
    305   const char* exception_string = ToCString(exception);
    306   v8::Handle<v8::Message> message = try_catch->Message();
    307   if (message.IsEmpty()) {
    308     // V8 didn't provide any extra information about this error; just
    309     // print the exception.
    310     printf("%s\n", exception_string);
    311   } else {
    312     // Print (filename):(line number): (message).
    313     v8::String::Utf8Value filename(message->GetScriptResourceName());
    314     const char* filename_string = ToCString(filename);
    315     int linenum = message->GetLineNumber();
    316     printf("%s:%i: %s\n", filename_string, linenum, exception_string);
    317     // Print line of source code.
    318     v8::String::Utf8Value sourceline(message->GetSourceLine());
    319     const char* sourceline_string = ToCString(sourceline);
    320     printf("%s\n", sourceline_string);
    321     // Print wavy underline (GetUnderline is deprecated).
    322     int start = message->GetStartColumn();
    323     for (int i = 0; i < start; i++) {
    324       printf(" ");
    325     }
    326     int end = message->GetEndColumn();
    327     for (int i = start; i < end; i++) {
    328       printf("^");
    329     }
    330     printf("\n");
    331     v8::String::Utf8Value stack_trace(try_catch->StackTrace());
    332     if (stack_trace.length() > 0) {
    333       const char* stack_trace_string = ToCString(stack_trace);
    334       printf("%s\n", stack_trace_string);
    335     }
    336   }
    337 }
    338