/* This file is part of the KDE project
Copyright (C) 2000 Keunwoo Lee
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
// -*- mode: c++; c-basic-offset: 2 -*-
#include
#include
#include
/**
* Provides functions that, given a collection of QStrings, will
* automatically and intelligently assign menu accelerators to the
* QStrings in the collection.
*
* NOTE: When this file speaks of "accelerators", we really mean
* accelerators as defined by the KDE User Interface Guidelines. We
* do NOT mean "shortcuts", which are what's handled by most other KDE
* libraries with "accel" in the name.
*
* In the Qt library, the mechanism for adding a keyboard accelerator
* to a menu item is to insert an '&' before the letter. Since we
* usually don't want to disturb the original collection, the idiom in
* these functions is to populate a "target" QStringList parameter
* with the input collectin's QStrings, plus possibly some added '&'
* characters.
*
* That is the mechanism. Here is the policy, in order of decreasing
* importance (it may seem like these are implementation details, but
* IMHO the policy is an important part of the interface):
*
* 1. If the string already contains an '&' character, skip this
* string, because we consider such strings to be "user-specified"
* accelerators.
*
* 2. No accelerator may clash with a previously defined accelerator,
* including any legal (alphanumeric) user-specified accelerator
* anywhere in the collection
*
* 3. Prefer alphanumerics at the start of the string.
*
* 4. Otherwise, prefer alphanumerics at the start of a word.
*
* 5. Otherwise, choose any alphanumeric character not already
* taken. If no such character is available, give up & skip this
* string.
*
* A typical use of these functions would be to automatically assign
* accelerators to a dynamically populated popup menu. For example,
* the core code was written to automatically set accelerators for the
* "Load View Profile" popup menu for Konqueror. We quickly realized
* that it would be useful to make this facility more generally
* available, so I abstracted it out into a set of templates.
*
* TODO:
*
* + Add sugar functions for more collections.
*
* + Add more Deref classes so that we can access a wider variety of
* collections.
* */
namespace KAccelGen
{
// HELPERS
/** Static dereference class, for use as a template parameter. */
template
class Deref
{
public:
static QString deref(Iter i) { return *i; }
};
/** Static dereference class that calls the key() method on its
target; for use as a template parameter. */
template
class Deref_Key
{
public:
static QString deref(Iter i) { return i.key(); }
};
/**
* Helper to determine if the given offset in the string could be a
* legal alphanumeric accelerator.
*
* @param str base string
* @param index offset to check
*/
inline bool
isLegalAccelerator(const QString& str, uint index)
{
return index < str.length()
&& str[index].isLetterOrNumber();
}
/**
* Loads all legal predefined accelerators in the (implicitly
* specified) collection into the given QMap.
*
* @param begin start iterator
* @param end (last+1) iterator
* @param keys map to store output
*/
template
inline void
loadPredefined(Iter begin, Iter end, QMap& keys)
{
for (Iter i = begin; i != end; ++i) {
QString item = Deref::deref(i);
int user_ampersand = item.find(QChar('&'));
if( user_ampersand >= 0 ) {
// Sanity check. Note that we don't try to find an
// accelerator if the user shoots him/herself in the foot
// by adding a bad '&'.
if( isLegalAccelerator(item, user_ampersand+1) ) {
keys.insert(item[user_ampersand+1], true);
}
}
}
}
// ///////////////////////////////////////////////////////////////////
// MAIN USER FUNCTIONS
/**
* Main, maximally flexible template function that assigns
* accelerators to the elements of a collection of QStrings. Clients
* will seldom use this directly, as it's usually easier to use one of
* the wrapper functions that simply takes a collection (see below).
*
* The Deref template parameter is a class containing a static
* dereferencing function, modeled after the comparison class C in
* Stroustrup 13.4.
*
* @param begin (you know)
* @param end (you know)
* @param target collection to store generated strings
*/
template
void
generate(Iter begin, Iter end, QStringList& target)
{
// Will keep track of used accelerator chars
QMap used_accels;
// Prepass to detect manually user-coded accelerators
loadPredefined(begin, end, used_accels);
// Main pass
for (Iter i = begin; i != end; ++i) {
QString item = Iter_Deref::deref(i);
// Attempt to find a good accelerator, but only if the user
// has not manually hardcoded one.
int user_ampersand = item.find(QChar('&'));
if( user_ampersand < 0 ) {
bool found = false;
uint found_idx;
uint j;
// Check word-starting letters first.
for( j=0; j < item.length(); ++j ) {
if( isLegalAccelerator(item, j)
&& !used_accels.contains(item[j])
&& (0 == j || j > 0 && item[j-1].isSpace()) ) {
found = true;
found_idx = j;
break;
}
}
if( !found ) {
// No word-starting letter; search for any letter.
for( j=0; j < item.length(); ++j ) {
if( isLegalAccelerator(item, j)
&& !used_accels.contains(item[j]) ) {
found = true;
found_idx = j;
break;
}
}
}
if( found ) {
used_accels.insert(item[j],true);
item.insert(j,QChar('&'));
}
}
target.append( item );
}
}
/**
* Another convenience function; looks up the key instead of
* dereferencing directly for the given iterator.
*
* @param begin
* @param end
* @param target
*/
template
inline void
generateFromKeys(Iter begin, Iter end, QStringList& target)
{
generate< Iter, Deref_Key >(begin, end, target);
}
/**
* Convenience function; generates accelerators for all the items in
* a QStringList.
*
* @param source Strings for which to generate accelerators
* @param target Output for accelerator-added strings */
inline void
generate(const QStringList& source, QStringList& target)
{
generate >(source.begin(), source.end(), target);
}
/**
* Convenience function; generates accelerators for all the values in
* a QMap.
*
* @param source Map with input strings as VALUES.
* @param target Output for accelerator-added strings */
template
inline void
generateFromValues(const QMap& source, QStringList& target)
{
generate, Deref_Key > >(source.begin(), source.end(), target);
}
/**
* Convenience function; generates an accelerator mapping from all the
* keys in a QMap
*
* @param source Map with input strings as KEYS.
* @param target Output for accelerator-added strings */
template
inline void
generateFromKeys(const QMap& source, QStringList& target)
{
generateFromKeys(source.begin(), source.end(), target);
}
} // end namespace KAccelGen
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