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DEFINITIONS
This source file includes following definitions.
- main
- ToCString
- CreateShellContext
- Print
- Read
- Load
- Quit
- Version
- ReadFile
- RunMain
- RunShell
- ExecuteString
- ReportException
// Copyright 2012 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.
#include <v8.h>
#include <assert.h>
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef COMPRESS_STARTUP_DATA_BZ2
#error Using compressed startup data is not supported for this sample
#endif
/**
* This sample program shows how to implement a simple javascript shell
* based on V8. This includes initializing V8 with command line options,
* creating global functions, compiling and executing strings.
*
* For a more sophisticated shell, consider using the debug shell D8.
*/
v8::Persistent<v8::Context> CreateShellContext();
void RunShell(v8::Handle<v8::Context> context);
int RunMain(int argc, char* argv[]);
bool ExecuteString(v8::Handle<v8::String> source,
v8::Handle<v8::Value> name,
bool print_result,
bool report_exceptions);
v8::Handle<v8::Value> Print(const v8::Arguments& args);
v8::Handle<v8::Value> Read(const v8::Arguments& args);
v8::Handle<v8::Value> Load(const v8::Arguments& args);
v8::Handle<v8::Value> Quit(const v8::Arguments& args);
v8::Handle<v8::Value> Version(const v8::Arguments& args);
v8::Handle<v8::String> ReadFile(const char* name);
void ReportException(v8::TryCatch* handler);
static bool run_shell;
int main(int argc, char* argv[]) {
v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
run_shell = (argc == 1);
int result;
{
v8::HandleScope handle_scope;
v8::Persistent<v8::Context> context = CreateShellContext();
if (context.IsEmpty()) {
printf("Error creating context\n");
return 1;
}
context->Enter();
result = RunMain(argc, argv);
if (run_shell) RunShell(context);
context->Exit();
context.Dispose();
}
v8::V8::Dispose();
return result;
}
// Extracts a C string from a V8 Utf8Value.
const char* ToCString(const v8::String::Utf8Value& value) {
return *value ? *value : "<string conversion failed>";
}
// Creates a new execution environment containing the built-in
// functions.
v8::Persistent<v8::Context> CreateShellContext() {
// Create a template for the global object.
v8::Handle<v8::ObjectTemplate> global = v8::ObjectTemplate::New();
// Bind the global 'print' function to the C++ Print callback.
global->Set(v8::String::New("print"), v8::FunctionTemplate::New(Print));
// Bind the global 'read' function to the C++ Read callback.
global->Set(v8::String::New("read"), v8::FunctionTemplate::New(Read));
// Bind the global 'load' function to the C++ Load callback.
global->Set(v8::String::New("load"), v8::FunctionTemplate::New(Load));
// Bind the 'quit' function
global->Set(v8::String::New("quit"), v8::FunctionTemplate::New(Quit));
// Bind the 'version' function
global->Set(v8::String::New("version"), v8::FunctionTemplate::New(Version));
return v8::Context::New(NULL, global);
}
// The callback that is invoked by v8 whenever the JavaScript 'print'
// function is called. Prints its arguments on stdout separated by
// spaces and ending with a newline.
v8::Handle<v8::Value> Print(const v8::Arguments& args) {
bool first = true;
for (int i = 0; i < args.Length(); i++) {
v8::HandleScope handle_scope;
if (first) {
first = false;
} else {
printf(" ");
}
v8::String::Utf8Value str(args[i]);
const char* cstr = ToCString(str);
printf("%s", cstr);
}
printf("\n");
fflush(stdout);
return v8::Undefined();
}
// The callback that is invoked by v8 whenever the JavaScript 'read'
// function is called. This function loads the content of the file named in
// the argument into a JavaScript string.
v8::Handle<v8::Value> Read(const v8::Arguments& args) {
if (args.Length() != 1) {
return v8::ThrowException(v8::String::New("Bad parameters"));
}
v8::String::Utf8Value file(args[0]);
if (*file == NULL) {
return v8::ThrowException(v8::String::New("Error loading file"));
}
v8::Handle<v8::String> source = ReadFile(*file);
if (source.IsEmpty()) {
return v8::ThrowException(v8::String::New("Error loading file"));
}
return source;
}
// The callback that is invoked by v8 whenever the JavaScript 'load'
// function is called. Loads, compiles and executes its argument
// JavaScript file.
v8::Handle<v8::Value> Load(const v8::Arguments& args) {
for (int i = 0; i < args.Length(); i++) {
v8::HandleScope handle_scope;
v8::String::Utf8Value file(args[i]);
if (*file == NULL) {
return v8::ThrowException(v8::String::New("Error loading file"));
}
v8::Handle<v8::String> source = ReadFile(*file);
if (source.IsEmpty()) {
return v8::ThrowException(v8::String::New("Error loading file"));
}
if (!ExecuteString(source, v8::String::New(*file), false, false)) {
return v8::ThrowException(v8::String::New("Error executing file"));
}
}
return v8::Undefined();
}
// The callback that is invoked by v8 whenever the JavaScript 'quit'
// function is called. Quits.
v8::Handle<v8::Value> Quit(const v8::Arguments& args) {
// If not arguments are given args[0] will yield undefined which
// converts to the integer value 0.
int exit_code = args[0]->Int32Value();
fflush(stdout);
fflush(stderr);
exit(exit_code);
return v8::Undefined();
}
v8::Handle<v8::Value> Version(const v8::Arguments& args) {
return v8::String::New(v8::V8::GetVersion());
}
// Reads a file into a v8 string.
v8::Handle<v8::String> ReadFile(const char* name) {
FILE* file = fopen(name, "rb");
if (file == NULL) return v8::Handle<v8::String>();
fseek(file, 0, SEEK_END);
int size = ftell(file);
rewind(file);
char* chars = new char[size + 1];
chars[size] = '\0';
for (int i = 0; i < size;) {
int read = static_cast<int>(fread(&chars[i], 1, size - i, file));
i += read;
}
fclose(file);
v8::Handle<v8::String> result = v8::String::New(chars, size);
delete[] chars;
return result;
}
// Process remaining command line arguments and execute files
int RunMain(int argc, char* argv[]) {
for (int i = 1; i < argc; i++) {
const char* str = argv[i];
if (strcmp(str, "--shell") == 0) {
run_shell = true;
} else if (strcmp(str, "-f") == 0) {
// Ignore any -f flags for compatibility with the other stand-
// alone JavaScript engines.
continue;
} else if (strncmp(str, "--", 2) == 0) {
printf("Warning: unknown flag %s.\nTry --help for options\n", str);
} else if (strcmp(str, "-e") == 0 && i + 1 < argc) {
// Execute argument given to -e option directly.
v8::Handle<v8::String> file_name = v8::String::New("unnamed");
v8::Handle<v8::String> source = v8::String::New(argv[++i]);
if (!ExecuteString(source, file_name, false, true)) return 1;
} else {
// Use all other arguments as names of files to load and run.
v8::Handle<v8::String> file_name = v8::String::New(str);
v8::Handle<v8::String> source = ReadFile(str);
if (source.IsEmpty()) {
printf("Error reading '%s'\n", str);
continue;
}
if (!ExecuteString(source, file_name, false, true)) return 1;
}
}
return 0;
}
// The read-eval-execute loop of the shell.
void RunShell(v8::Handle<v8::Context> context) {
printf("V8 version %s [sample shell]\n", v8::V8::GetVersion());
static const int kBufferSize = 256;
// Enter the execution environment before evaluating any code.
v8::Context::Scope context_scope(context);
v8::Local<v8::String> name(v8::String::New("(shell)"));
while (true) {
char buffer[kBufferSize];
printf("> ");
char* str = fgets(buffer, kBufferSize, stdin);
if (str == NULL) break;
v8::HandleScope handle_scope;
ExecuteString(v8::String::New(str), name, true, true);
}
printf("\n");
}
// Executes a string within the current v8 context.
bool ExecuteString(v8::Handle<v8::String> source,
v8::Handle<v8::Value> name,
bool print_result,
bool report_exceptions) {
v8::HandleScope handle_scope;
v8::TryCatch try_catch;
v8::Handle<v8::Script> script = v8::Script::Compile(source, name);
if (script.IsEmpty()) {
// Print errors that happened during compilation.
if (report_exceptions)
ReportException(&try_catch);
return false;
} else {
v8::Handle<v8::Value> result = script->Run();
if (result.IsEmpty()) {
assert(try_catch.HasCaught());
// Print errors that happened during execution.
if (report_exceptions)
ReportException(&try_catch);
return false;
} else {
assert(!try_catch.HasCaught());
if (print_result && !result->IsUndefined()) {
// If all went well and the result wasn't undefined then print
// the returned value.
v8::String::Utf8Value str(result);
const char* cstr = ToCString(str);
printf("%s\n", cstr);
}
return true;
}
}
}
void ReportException(v8::TryCatch* try_catch) {
v8::HandleScope handle_scope;
v8::String::Utf8Value exception(try_catch->Exception());
const char* exception_string = ToCString(exception);
v8::Handle<v8::Message> message = try_catch->Message();
if (message.IsEmpty()) {
// V8 didn't provide any extra information about this error; just
// print the exception.
printf("%s\n", exception_string);
} else {
// Print (filename):(line number): (message).
v8::String::Utf8Value filename(message->GetScriptResourceName());
const char* filename_string = ToCString(filename);
int linenum = message->GetLineNumber();
printf("%s:%i: %s\n", filename_string, linenum, exception_string);
// Print line of source code.
v8::String::Utf8Value sourceline(message->GetSourceLine());
const char* sourceline_string = ToCString(sourceline);
printf("%s\n", sourceline_string);
// Print wavy underline (GetUnderline is deprecated).
int start = message->GetStartColumn();
for (int i = 0; i < start; i++) {
printf(" ");
}
int end = message->GetEndColumn();
for (int i = start; i < end; i++) {
printf("^");
}
printf("\n");
v8::String::Utf8Value stack_trace(try_catch->StackTrace());
if (stack_trace.length() > 0) {
const char* stack_trace_string = ToCString(stack_trace);
printf("%s\n", stack_trace_string);
}
}
}