<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"> <title>TRIO</title> <link href="trio.css" rel="stylesheet" type="text/css"> </head> <body> <!-- Generated by Doxygen 1.2.12 --> <center> <a class="qindex" href="index.html">Main Page</a> <a class="qindex" href="modules.html">Modules</a> </center> <hr><h1>User-defined Formatted Printing Functions.</h1>Functions for using customized formatting specifiers. <a href="#_details">More...</a><table border=0 cellpadding=0 cellspacing=0> <tr><td colspan=2><br><h2>Functions</h2></td></tr> <tr><td nowrap align=right valign=top>trio_pointer_t </td><td valign=bottom><a class="el" href="group___user_defined.html#a0">trio_register</a> (trio_callback_t callback, const char *name)</td></tr> <tr><td> </td><td><font size=-1><em>Register new user-defined specifier.</em> <a href="#a0">More...</a><em></em></font><br><br></td></tr> <tr><td nowrap align=right valign=top>void </td><td valign=bottom><a class="el" href="group___user_defined.html#a1">trio_unregister</a> (trio_pointer_t handle)</td></tr> <tr><td> </td><td><font size=-1><em>Unregister an existing user-defined specifier.</em> <a href="#a1">More...</a><em></em></font><br><br></td></tr> </table> <hr><a name="_details"></a><h2>Detailed Description</h2> Functions for using customized formatting specifiers. <p> <b>SYNOPSIS</b> <p> <div class="fragment"><pre> cc ... -ltrio -lm #include <trio.h> #include <triop.h> </pre></div> <p> <b>DESCRIPTION</b> <p> This documentation is incomplete. <p> <b>User-defined</b> <b>Specifier</b> <p> The user-defined specifier consists of a start character (\074 = '<'), an optional namespace string followed by a namespace separator (\072 = ':'), a format string, and an end character (\076 = '>'). <p> The namespace string can consist of alphanumeric characters, and is used to define a named reference (see below). The namespace is case-sensitive. If no namespace is specified, then we use an unnamed reference (see below). <p> The format can consist of any character except the end character ('>'), the namespace separator (':'), and the nil character (\000). <p> Any modifier can be used together with the user-defined specifier. <p> <b>Registering</b> <p> A user-defined specifier must be registered before it can be used. Unregistered user-defined specifiers are ignored. The <a class="el" href="group___user_defined.html#a0">trio_register</a> function is used to register a user-defined specifier. It takes two argument, a callback function and a namespace, and it returns a handle. The handle must be used to unregister the specifier later. <p> The following example registers a user-define specifier with the "my_namespace" namespace: <p> <div class="fragment"><pre> my_handle = trio_register(my_callback, "my_namespace"); </pre></div> <p> There can only be one user-defined specifier with a given namespace. There can be an unlimited number (subject to maximum length of the namespace) of different user-defined specifiers. <p> Passing NULL as the namespace argument results in an anonymous reference. There can be an unlimited number of anonymous references. <p> <b>REFERENCES</b> <p> There are two ways that a registered callback can be called. Either the user-defined specifier must contain the registered namespace in the format string, or the handle is passed as an argument to the formatted printing function. <p> If the namespace is used, then a user-defined pointer must be passed as an argument: <p> <div class="fragment"><pre> trio_printf("<my_namespace:format>\n", my_data); </pre></div> <p> If the handle is used, then the user-defined specifier must not contain a namespace. Instead the handle must be passed as an argument, followed by a user-defined pointer: <p> <div class="fragment"><pre> trio_printf("<format>\n", my_handle, my_data); </pre></div> <p> The two examples above are equivalent. <p> There must be exactly one user-defined pointer per user-defined specifier. This pointer can be used within the callback function with the trio_get_argument getter function (see below). <p> The format string is optional. It can be used within the callback function with the trio_get_format getter function. <p> <b>Anonymous</b> <b>References</b> Anonymous references are specified by passing NULL as the namespace. <p> The handle must be passed as an argument followed by a user-defined pointer. No namespace can be specified. <p> <div class="fragment"><pre> anon_handle = trio_register(callback, NULL); trio_printf("<format>\n", anon_handle, my_data); </pre></div> <p> <b>Restrictions</b> <p> <ul> <li> The length of the namespace string cannot exceed 63 characters. <li> The length of the user-defined format string cannot exceed 255 characters. <li> User-defined formatting cannot re-define existing specifiers. This restriction was imposed because the existing formatting specifiers have a well-defined behaviour, and any re-definition would apply globally to an application (imagine a third-party library changing the behaviour of a specifier that is crusial to your application).</ul> <b>CALLBACK</b> <b>FUNCTION</b> <p> The callback function will be called if a matching user-defined specifier is found within the formatting string. The callback function takes one input parameter, an opaque reference which is needed by the private functions. It returns an <code>int</code>, which is currently ignored. The prototype is <p> <div class="fragment"><pre> int (*trio_callback_t)(void *ref); </pre></div> <p> See the Example section for full examples. <p> <b>PRINTING</b> <b>FUNCTIONS</b> <p> The following printing functions must only be used inside a callback function. These functions will print to the same output medium as the printf function which invoked the callback function. For example, if the user-defined specifier is used in an sprintf function, then these print functions will output their result to the same string. <p> <b>Elementary</b> <b>Printing</b> <p> There are a number of function to print elementary data types. <p> <ul> <li> trio_print_int Print a signed integer. For example: <div class="fragment"><pre> trio_print_int(42); </pre></div> <li> trio_print_uint Print an unsigned integer. <li> trio_print_double Print a floating-point number. <li> trio_print_string Print a string. For example: <div class="fragment"><pre> trio_print_string("Hello World"); trio_print_string(trio_get_format()); </pre></div> <li> trio_print_pointer Print a pointer.</ul> <b>Formatted</b> <b>Printing</b> <p> The functions trio_print_ref, trio_vprint_ref, and trio_printv_ref outputs a formatted string just like its printf equivalents. <p> <div class="fragment"><pre> trio_print_ref(ref, "There are %d towels\n", 42); trio_print_ref(ref, "%<recursive>\n", recursive_writer, trio_get_argument()); </pre></div> <p> <b>GETTER</b> <b>AND</b> <b>SETTER</b> <b>FUNCTIONS</b> <p> The following getter and setter functions must only be used inside a callback function. They can either operate on the modifiers or on special data. <p> <b>Modifiers</b> <p> The value of a modifier, or a boolean indication of its presence or absence, can be found or set with the getter and setter functions. The generic prototypes of the these getter and setter functions are <p> <div class="fragment"><pre> int trio_get_???(void *ref); void trio_set_???(void *ref, int); </pre></div> <p> where ??? <code>refers</code> to a modifier. For example, to get the width of the user-defined specifier use <p> <div class="fragment"><pre> int width = trio_get_width(ref); </pre></div> <p> <b>Special</b> <b>Data</b> <p> Consider the following user-defined specifier, in its two possible referencing presentations. <p> <div class="fragment"><pre> trio_printf("%<format>\n", namespace_writer, argument); trio_printf("%<namespace:format>\n", argument); </pre></div> <p> trio_get_format will get the <code>format</code> string, and trio_get_argument} will get the <code>argument</code> parameter. There are no associated setter functions. <p> <b>EXAMPLES</b> <p> The following examples show various types of user-defined specifiers. Although each specifier is demonstrated in isolation, they can all co-exist within the same application. <p> <b>Time</b> <b>Example</b> <p> Print the time in the format "HOUR:MINUTE:SECOND" if "time" is specified inside the user-defined specifier. <p> <div class="fragment"><pre> static int time_writer(void *ref) { const char *format; time_t *data; char buffer[256]; format = trio_get_format(ref); if ((format) && (strcmp(format, "time") == 0)) { data = trio_get_argument(ref); if (data == NULL) return -1; strftime(buffer, sizeof(buffer), "%H:%M:%S", localtime(data)); trio_print_string(ref, buffer); } return 0; } </pre></div> <p> <div class="fragment"><pre> int main(void) { void *handle; time_t now = time(NULL); handle = trio_register(time_print, "my_time"); trio_printf("%<time>\n", handle, &now); trio_printf("%<my_time:time>\n", &now); trio_unregister(handle); return 0; } </pre></div> <p> <b>Complex</b> <b>Numbers</b> <b>Example</b> <p> Consider a complex number consisting of a real part, re, and an imaginary part, im. <p> <div class="fragment"><pre> struct Complex { double re; double im; }; </pre></div> <p> This example can print such a complex number in one of two formats. The default format is "re + i im". If the alternative modifier is used, then the format is "r exp(i theta)", where r is the length of the complex vector (re, im) and theta is its angle. <p> <div class="fragment"><pre> static int complex_print(void *ref) { struct Complex *data; const char *format; data = (struct Complex *)trio_get_argument(ref); if (data) { format = trio_get_format(ref); if (trio_get_alternative(ref)) { double r, theta; r = sqrt(pow(data->re, 2) + pow(data->im, 2)); theta = acos(data->re / r); trio_print_ref(ref, "%#f exp(i %#f)", r, theta); } else { trio_print_ref(ref, "%#f + i %#f", data->re, data->im); } } return 0; } </pre></div> <p> <div class="fragment"><pre> int main(void) { void *handle; handle = trio_register(complex_print, "complex"); /* Normal format. With handle and the with namespace */ trio_printf("%<>\n", handle, &complex); trio_printf("%<complex:>\n", &complex); /* In exponential notation */ trio_printf("%#<>\n", handle, &complex); trio_printf("%#<complex:unused data>\n", &complex); trio_unregister(handle); return 0; } </pre></div> <p> <b>RETURN</b> <b>VALUES</b> <p> <a class="el" href="group___user_defined.html#a0">trio_register</a> returns a handle, or NULL if an error occured. <p> <b>SEE</b> <b>ALSO</b> <p> <a class="el" href="group___printf.html#a0">trio_printf</a> <p> <b>NOTES</b> <p> User-defined specifiers, <a class="el" href="group___user_defined.html#a0">trio_register</a>, and <a class="el" href="group___user_defined.html#a1">trio_unregister</a> are not thread-safe. In multi-threaded applications they must be guarded by mutexes. Trio provides two special callback functions, called ":enter" and ":leave", which are invoked every time a thread-unsafe operation is attempted. As the thread model is determined by the application, these callback functions must be implemented by the application. <p> The following callback functions are for demonstration-purposes only. Replace their bodies with locking and unlocking of a mutex to achieve thread-safety. <div class="fragment"><pre> static int enter_region(void *ref) { fprintf(stderr, "Enter Region\n"); return 1; } static int leave_region(void *ref) { fprintf(stderr, "Leave Region\n"); return 1; } </pre></div> These two callbacks must be registered before other callbacks are registered. <div class="fragment"><pre> trio_register(enter_region, ":enter"); trio_register(leave_region, ":leave"); another_handle = trio_register(another_callback, NULL); </pre></div> <hr><h2>Function Documentation</h2> <a name="a0" doxytag="trio.c::trio_register"></a><p> <table width="100%" cellpadding="2" cellspacing="0" border="0"> <tr> <td class="md"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top"> trio_pointer_t trio_register </td> <td class="md" valign="top">( </td> <td class="md" nowrap valign="top">trio_callback_t </td> <td class="mdname" nowrap> <em>callback</em>, </td> </tr> <tr> <td></td> <td></td> <td class="md" nowrap>const char * </td> <td class="mdname" nowrap> <em>name</em></td> </tr> <tr> <td></td> <td class="md">) </td> <td class="md" colspan="2"></td> </tr> </table> </td> </tr> </table> <table cellspacing=5 cellpadding=0 border=0> <tr> <td> </td> <td> <p> Register new user-defined specifier. <p> <dl compact><dt><b> Parameters: </b><dd> <table border=0 cellspacing=2 cellpadding=0> <tr><td valign=top><em>callback</em> </td><td> </td></tr> <tr><td valign=top><em>name</em> </td><td> </td></tr> </table> </dl><dl compact><dt><b> Returns: </b><dd> Handle. </dl> </td> </tr> </table> <a name="a1" doxytag="trio.c::trio_unregister"></a><p> <table width="100%" cellpadding="2" cellspacing="0" border="0"> <tr> <td class="md"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top"> void trio_unregister </td> <td class="md" valign="top">( </td> <td class="md" nowrap valign="top">trio_pointer_t </td> <td class="mdname1" valign="top" nowrap> <em>handle</em> </td> <td class="md" valign="top">) </td> <td class="md" nowrap></td> </tr> </table> </td> </tr> </table> <table cellspacing=5 cellpadding=0 border=0> <tr> <td> </td> <td> <p> Unregister an existing user-defined specifier. <p> <dl compact><dt><b> Parameters: </b><dd> <table border=0 cellspacing=2 cellpadding=0> <tr><td valign=top><em>handle</em> </td><td> </td></tr> </table> </dl> </td> </tr> </table> <HR> <center class="copyright">Copyright (C) 2001 Bjørn Reese and Daniel Stenberg.</center> </body> </html>