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
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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
48v8::Persistent<v8::Context> CreateShellContext();
49void RunShell(v8::Handle<v8::Context> context);
50int RunMain(int argc, char* argv[]);
51bool ExecuteString(v8::Handle<v8::String> source,
52                   v8::Handle<v8::Value> name,
53                   bool print_result,
54                   bool report_exceptions);
55v8::Handle<v8::Value> Print(const v8::Arguments& args);
56v8::Handle<v8::Value> Read(const v8::Arguments& args);
57v8::Handle<v8::Value> Load(const v8::Arguments& args);
58v8::Handle<v8::Value> Quit(const v8::Arguments& args);
59v8::Handle<v8::Value> Version(const v8::Arguments& args);
60v8::Handle<v8::String> ReadFile(const char* name);
61void ReportException(v8::TryCatch* handler);
62
63
64static bool run_shell;
65
66
67int 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.
87const 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.
94v8::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.
115v8::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.
137v8::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.
156v8::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.
177v8::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
188v8::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.
194v8::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
216int 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.
248void 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.
267bool 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
302void 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