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<title>MuJS Examples</title>
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<h1>MuJS Examples</h1>
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<a href="introduction.html">Introduction</a>
<a href="reference.html">Reference</a>
<a href="examples.html">Examples</a>
<a href="license.html">License</a>
<a href="http://git.ghostscript.com/?p=mujs.git;a=summary">Source</a>
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<article>
<h2>A stand-alone interpreter</h2>
<pre>
#include <stdio.h>
#include <mujs.h>
int main(int argc, char **argv)
{
char line[256];
js_State *J = js_newstate(NULL, NULL, JS_STRICT);
while (fgets(line, sizeof line, stdin))
js_dostring(J, line);
js_freestate(J);
}
</pre>
<h2>Hello, world!</h2>
<pre>
#include <stdio.h>
#include <mujs.h>
static void hello(js_State *J)
{
const char *name = js_tostring(J, 1);
printf("Hello, %s!\n", name);
js_pushundefined(J);
}
int main(int argc, char **argv)
{
js_State *J = js_newstate(NULL, NULL, JS_STRICT);
js_newcfunction(J, hello, "hello", 1);
js_setglobal(J, "hello");
js_dostring(J, "hello('world');");
js_freestate(J);
}
</pre>
<h2>Configuration file</h2>
<pre>
js_dofile(J, "config.js")
js_getglobal(J, "foo");
foo = js_tonumber(J, -1);
js_pop(J, 1);
</pre>
<h2>Object manipulation</h2>
<pre>
// t = { foo: 42, bar: true }
js_newobject(J);
{
js_pushnumber(J, 42);
js_setproperty(J, -2, "foo");
js_pushboolean(J, 1);
js_setproperty(J, -2, "bar");
}
js_setglobal(J, "t");
</pre>
<h2>Callbacks from C to JS (by name)</h2>
<pre>
static int call_callback(js_State *J, const char *arg1, int arg2)
{
int result;
/* Find the function to call. */
js_getglobal(J, "my_callback");
/* Push arguments to function. */
js_pushnull(J); /* the 'this' object to use */
js_pushstring(J, arg1);
js_pushnumber(J, arg2);
/* Call function and check for exceptions. */
if (js_pcall(J, 2)) {
fprintf(stderr, "an exception occurred in the javascript callback\n");
js_pop(J, 1);
return -1;
}
/* Retrieve return value. */
result = js_tonumber(J, -1);
js_pop(J, 1);
return result;
}
</pre>
<h2>Callbacks from C to JS</h2>
<pre>
const char *handle = NULL; /* handle to stowed away js function */
static void set_callback(js_State *J)
{
if (handle)
js_unref(J, handle); /* delete old function */
js_copy(J, 1);
handle = js_ref(J); /* stow the js function in the registry */
}
static void call_callback(js_State *J, int arg1, int arg2)
{
js_getregistry(J, handle); /* retrieve the js function from the registry */
js_pushnull(J);
js_pushnumber(J, arg1);
js_pushnumber(J, arg2);
js_pcall(J, 2);
js_pop(J, 1);
}
</pre>
<h2>Complete userdata example</h2>
<pre>
#include <stdio.h>
#include <mujs.h>
#define TAG "File"
static void new_File(js_State *J)
{
FILE *file;
if (js_isundefined(J, 1)) {
file = stdin;
} else {
const char *filename = js_tostring(J, 1);
file = fopen(filename, "r");
if (!file)
js_error(J, "cannot open file: '%s'", filename);
}
js_currentfunction(J);
js_getproperty(J, -1, "prototype");
js_newuserdata(J, TAG, file);
}
static void File_prototype_readByte(js_State *J)
{
FILE *file = js_touserdata(J, 0, TAG);
js_pushnumber(J, getc(file));
}
static void File_prototype_readLine(js_State *J)
{
char line[256], *s;
FILE *file = js_touserdata(J, 0, TAG);
s = fgets(line, sizeof line, file);
if (s)
js_pushstring(J, line);
else
js_pushnull(J);
}
static void File_prototype_close(js_State *J)
{
FILE *file = js_touserdata(J, 0, TAG);
fclose(file);
js_pushundefined(J);
}
void initfile(js_State *J)
{
js_getglobal(J, "Object");
js_getproperty(J, -1, "prototype"); // File.prototype.[[Prototype]] = Object.prototype
js_newuserdata(J, TAG, stdin); // File.prototype.[[Userdata]] = stdin
{
js_newcfunction(J, File_prototype_readByte, "File.prototype.readByte", 0);
js_defproperty(J, -2, "readByte", JS_DONTENUM);
js_newcfunction(J, File_prototype_readLine, "File.prototype.readLine", 0);
js_defproperty(J, -2, "readLine", JS_DONTENUM);
js_newcfunction(J, File_prototype_close, "File.prototype.close", 0);
js_defproperty(J, -2, "close", JS_DONTENUM);
}
js_newcconstructor(J, new_File, new_File, "File", 1);
js_defglobal(J, "File", JS_DONTENUM);
}
</pre>
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