Add and use algorithms for managing iterable (#2534)

Basic algorithms:
- `void apply_to_first(iterable, value, function)` apply `function` to the first `value` of `iterable`. If not found, do nothing.
- `void erase_first(iterable, value)` erase the first `value` of the `iterable`.

Algorithms designed for range-based for loops:
- `THINGS enumerate(iterable)` return a pair of `index` and `value` from an `iterable` forward.
- `THINGS renumerate(iterable)` return a pair of `index` and `value` from an `iterable` backward.
- `THINGS reverse(iterable)` return the `value` of `iterable` in a backward way.
- `THINGS range(iterable)` return all the `index` from a `iterable` forward.

src/ivoc/ivocrand.cpp

@@ -10,6 +10,7 @@
 #include "classreg.h"
 #include "oc2iv.h"
 #include "nrnisaac.h"
+#include "utils/enumerate.h"
 
 #include <vector>
 #include <ocnotify.h>
@@ -183,13 +184,11 @@ void RandomPlay::play() {
     *px_ = (*(r_->rand))();
 }
 void RandomPlay::list_remove() {
-    for (auto it = random_play_list_->begin(); it != random_play_list_->end(); ++it) {
-        if (*it == (RandomPlay*) this) {
-            // printf("RandomPlay %p removed from list cnt=%d i=%d %p\n", this, cnt, i);
-            random_play_list_->erase(it);
-            unref_deferred();
-            break;
-        }
+    if (auto it = std::find(random_play_list_->begin(), random_play_list_->end(), this);
+        it != random_play_list_->end()) {
+        // printf("RandomPlay %p removed from list cnt=%d i=%d %p\n", this, cnt, i);
+        random_play_list_->erase(it);
+        unref_deferred();
     }
 }
 void RandomPlay::update(Observable*) {

src/ivoc/ocpicker.cpp

@@ -1,6 +1,7 @@
 #include <../../nrnconf.h>
 #if HAVE_IV  // to end of file
 
+#include <algorithm>
 #include <OS/list.h>
 #include <InterViews/hit.h>
 #include <stdio.h>
@@ -103,16 +104,14 @@ void StandardPicker::event(const Event& e) {
 }
 
 void StandardPicker::unbind(int m, EventButton eb) {
-    long cnt = handlers_[m]->size();
-    for (long i = 0, j = 0; i < cnt; ++i) {
-        ButtonHandler* b = handlers_[m]->at(j);
+    for (auto& b: *handlers_[m]) {
         if (b->eb_ == Event::any || b->eb_ == eb) {
             delete b;
-            handlers_[m]->erase(handlers_[m]->begin() + j);
-        } else {
-            ++j;
+            b = nullptr;
         }
     }
+    handlers_[m]->erase(std::remove(handlers_[m]->begin(), handlers_[m]->end(), nullptr),
+                        handlers_[m]->end());
 }
 
 void StandardPicker::bind(int m, EventButton eb, OcHandler* h) {

src/ivoc/scene.cpp

@@ -51,6 +51,7 @@
 #include "scenepic.h"
 #include "idraw.h"
 #include "ivoc.h"
+#include "utils/enumerate.h"
 
 #define Scene_Move_Text_   "MoveText Graph"
 #define Scene_ChangeColor_ "ChangeColor Graph"
@@ -311,10 +312,7 @@ Scene::~Scene() {
     // without first deleteing all the views.
     assert(views_->empty());
 
-    if (auto it = std::find(scene_list->begin(), scene_list->end(), this);
-        it != scene_list->end()) {
-        scene_list->erase(it);
-    }
+    erase_first(*scene_list, this);
     delete views_;
 }
 
@@ -335,14 +333,12 @@ void Scene::append_view(XYView* v) {
 }
 
 void Scene::remove_view(XYView* v) {
-    if (auto it = std::find(views_->begin(), views_->end(), v); it != views_->end()) {
-        views_->erase(it);
-    }
+    erase_first(*views_, v);
 }
 
 void Scene::dismiss() {
-    for (auto it = views_->rbegin(); it != views_->rend(); ++it) {
-        OcViewGlyph* g = (*it)->parent();
+    for (auto&& item: reverse(*views_)) {
+        OcViewGlyph* g = item->parent();
         if (g && g->has_window()) {
             g->window()->dismiss();
             g->window(NULL);
@@ -513,8 +509,8 @@ void Scene::replace(GlyphIndex index, Glyph* glyph) {
 }
 
 GlyphIndex Scene::glyph_index(const Glyph* g) {
-    for (std::size_t i = 0; i < info_->size(); ++i) {
-        if ((*info_)[i].glyph_ == g) {
+    for (const auto&& [i, info]: enumerate(*info_)) {
+        if (info.glyph_ == g) {
             return i;
         }
     }
@@ -536,7 +532,7 @@ void Scene::request(Requisition& req) const {
 
 void Scene::allocate(Canvas* c, const Allocation& a, Extension& ext) {
     // printf("Scene::allocate\n");
-    for (GlyphIndex index = 0; index < info_->size(); ++index) {
+    for (std::size_t index: range(*info_)) {
         check_allocation(index);
     }
     ext.set(c, a);
@@ -693,14 +689,12 @@ void Scene::pick(Canvas* c, const Allocation& a, int depth, Hit& h) {
     if (background_ != NULL) {
         background_->pick(c, a, depth, h);
     }
-    GlyphIndex count = info_->size();
     // pick with some extra epsilon in canvas coords
     Coord epsx = XYView::current_pick_view()->x_pick_epsilon();
     Coord epsy = XYView::current_pick_view()->y_pick_epsilon();
 
     bool are_fixed = false;
-    for (GlyphIndex index = 0; index < count; ++index) {
-        SceneInfo& info = (*info_)[index];
+    for (auto&& [index, info]: enumerate(*info_)) {
         if (info.status_ & SceneInfoFixed) {
             are_fixed = true;
         } else if (info.glyph_ != NULL && (info.status_ & SceneInfoShowing)) {
@@ -720,8 +714,7 @@ void Scene::pick(Canvas* c, const Allocation& a, int depth, Hit& h) {
         const Transformer& tv = XYView::current_pick_view()->s2o();
         float scx, scy, tmp;
         tv.matrix(scx, tmp, tmp, scy, tmp, tmp);
-        for (GlyphIndex index = 0; index < count; ++index) {
-            SceneInfo& info = (*info_)[index];
+        for (auto&& [index, info]: enumerate(*info_)) {
             if ((info.status_ & SceneInfoFixed) && info.glyph_ != NULL &&
                 (info.status_ & SceneInfoShowing)) {
                 Allocation a = info.allocation_;
@@ -752,13 +745,11 @@ void Scene::pick(Canvas* c, const Allocation& a, int depth, Hit& h) {
 }
 
 long Scene::scene_list_index(Scene* s) {
-    std::size_t cnt = scene_list->size();
-    for (std::size_t i = 0; i < cnt; ++i) {
-        if (s == scene_list->at(i)) {
-            return i;
-        }
+    auto it = std::find(scene_list->begin(), scene_list->end(), s);
+    if (it == scene_list->end()) {
+        return -1;
     }
-    return -1;
+    return std::distance(scene_list->begin(), it);
 }
 
 void Scene::save_all(std::ostream& o) {

src/ivoc/scenepic.cpp

@@ -16,6 +16,7 @@
 #include "apwindow.h"
 #include "utility.h"
 #include "oc2iv.h"
+#include "utils/enumerate.h"
 
 #define Scene_SceneMover_     "Translate Scene"
 #define Scene_SceneZoom_      "ZoomInOut Scene"
@@ -309,9 +310,7 @@ MenuItem* ScenePicker::add_radio_menu(const char* name, OcHandler* h, int tool,
 }
 
 long ScenePickerImpl::info_index(const char* name) {
-    std::size_t cnt = bil_->size();
-    for (std::size_t i = 0; i < cnt; ++i) {
-        ButtonItemInfo* b = bil_->at(i);
+    for (const auto&& [i, b]: enumerate(*bil_)) {
         if (strcmp(b->name_.string(), name) == 0) {
             return i;
         }
@@ -410,8 +409,8 @@ ScenePickerImpl::ScenePickerImpl(Scene* scene)
 ScenePickerImpl::~ScenePickerImpl() {
     Resource::unref(menu_);
     Resource::unref(tg_);
-    for (auto it = bil_->rbegin(); it != bil_->rend(); ++it) {
-        delete *it;
+    for (ButtonItemInfo* bii: *bil_) {
+        delete bii;
     }
     delete bil_;
 }

src/ivoc/symdir.cpp

@@ -5,6 +5,7 @@
 #include <OS/string.h>
 #include <stdio.h>
 #include "ocobserv.h"
+#include "utils/enumerate.h"
 
 #include "nrniv_mf.h"
 #include "nrnoc2iv.h"
@@ -60,32 +61,16 @@ class SymDirectoryImpl: public Observer {
     void sort();
 };
 
-static int compare_entries(const void* k1, const void* k2) {
-    SymbolItem* e1 = *((SymbolItem**) k1);
-    SymbolItem* e2 = *((SymbolItem**) k2);
+static int compare_entries(const SymbolItem* e1, const SymbolItem* e2) {
     int i = strcmp(e1->name().string(), e2->name().string());
     if (i == 0) {
-        if (e1->array_index() > e2->array_index()) {
-            i = 1;
-        } else {
-            i = -1;
-        }
+        return e1->array_index() > e2->array_index();
     }
-    return i;
+    return i > 0;
 };
 
 void SymDirectoryImpl::sort() {
-    std::size_t cnt = symbol_lists_.size();
-    SymbolItem** slist = new SymbolItem*[cnt];
-    for (std::size_t i = 0; i < cnt; ++i) {
-        slist[i] = symbol_lists_[i];
-    }
-    qsort(slist, cnt, sizeof(SymbolItem*), compare_entries);
-    symbol_lists_.clear();
-    for (std::size_t i = 0; i < cnt; ++i) {
-        symbol_lists_.push_back(slist[i]);
-    }
-    delete[] slist;
+    std::sort(symbol_lists_.begin(), symbol_lists_.end(), compare_entries);
 }
 
 // SymDirectory
@@ -307,9 +292,8 @@ int SymDirectory::array_index(int i) const {
 }
 
 int SymDirectory::index(const String& name) const {
-    long cnt = count();
-    for (long i = 0; i < cnt; ++i) {
-        if (name == impl_->symbol_lists_[i]->name()) {
+    for (const auto&& [i, symbol]: enumerate(impl_->symbol_lists_)) {
+        if (name == symbol->name()) {
             return i;
         }
     }
@@ -451,8 +435,7 @@ void SymDirectoryImpl::load(int type) {
 }
 
 void SymDirectoryImpl::load(int type, Symlist* sl) {
-    Symbol* sym;
-    for (sym = sl->first; sym; sym = sym->next) {
+    for (Symbol* sym = sl->first; sym; sym = sym->next) {
         if (type == -1) {
             switch (sym->type) {
             case SECTION:
@@ -490,9 +473,8 @@ void SymDirectoryImpl::load_aliases() {
     IvocAliases* a = (IvocAliases*) obj_->aliases;
     if (!a)
         return;
-    for (const auto& kv: a->symtab_) {
-        Symbol* s = kv.second;
-        append(s, NULL, obj_);
+    for (const auto& [_, s]: a->symtab_) {
+        append(s, nullptr, obj_);
     }
 }
 

src/ivoc/xmenu.cpp

@@ -1,9 +1,9 @@
-
 #include <../../nrnconf.h>
 
 #include "oc2iv.h"
 #include "classreg.h"
 #include "gui-redirect.h"
+#include "utils/enumerate.h"
 
 #if HAVE_IV  // to end of file except for a few small fragments.
 
@@ -992,8 +992,8 @@ void HocPanel::map_window(int scroll) {
 // HocPanel
 static void var_freed(void* pd, int size) {
     if (hoc_panel_list) {
-        for (auto it = hoc_panel_list->rbegin(); it != hoc_panel_list->rend(); ++it) {
-            (*it)->check_valid_pointers(pd, size);
+        for (auto&& elem: reverse(*hoc_panel_list)) {
+            elem->check_valid_pointers(pd, size);
         }
     }
 }
@@ -1034,10 +1034,7 @@ HocPanel::~HocPanel() {
     for (auto& item: elist_) {
         item->HocItem::unref();
     }
-    if (auto it = std::find(hoc_panel_list->begin(), hoc_panel_list->end(), this);
-        it != hoc_panel_list->end()) {
-        hoc_panel_list->erase(it);
-    }
+    erase_first(*hoc_panel_list, this);
     ilist_.clear();
     ilist_.shrink_to_fit();
     elist_.clear();
@@ -1073,10 +1070,7 @@ void HocPanel::keep_updated(HocUpdateItem* hui, bool add) {
     if (add) {
         update_list_->push_back(hui);
     } else {
-        if (auto it = std::find(update_list_->begin(), update_list_->end(), hui);
-            it != update_list_->end()) {
-            update_list_->erase(it);
-        }
+        erase_first(*update_list_, hui);
     }
 }
 
@@ -2279,22 +2273,22 @@ void Oc::notifyHocValue() {
     ParseTopLevel ptl;
     ptl.save();
     if (hoc_panel_list) {
-        for (auto it = hoc_panel_list->rbegin(); it != hoc_panel_list->rend(); ++it) {
-            (*it)->notifyHocValue();
+        for (auto&& e: reverse(*hoc_panel_list)) {
+            e->notifyHocValue();
         }
     }
     ptl.restore();
 }
 
 void HocPanel::notifyHocValue() {
-    for (auto it = elist_.rbegin(); it != elist_.rend(); ++it) {
-        (*it)->update_hoc_item();
+    for (auto&& e: reverse(elist_)) {
+        e->update_hoc_item();
     }
 }
 
 void HocPanel::check_valid_pointers(void* v, int size) {
-    for (auto it = elist_.rbegin(); it != elist_.rend(); ++it) {
-        (*it)->check_pointer(v, size);
+    for (auto&& e: reverse(elist_)) {
+        e->check_pointer(v, size);
     }
 }
 
@@ -2321,8 +2315,8 @@ void HocVarLabel::check_pointer(void* v, int) {
 }
 
 void HocPanel::data_path(HocDataPaths* hdp, bool append) {
-    for (auto it = elist_.rbegin(); it != elist_.rend(); ++it) {
-        (*it)->data_path(hdp, append);
+    for (auto&& e: reverse(elist_)) {
+        e->data_path(hdp, append);
     }
 }