Code clean up: use range-style for loops wherever possible

Where not possible, use "auto" to get the iterator type.

Editorial note: I have avoid this change for a long time because of
not wanting to make gratuitous changes to version history, which can
obscure when certain changes were made, but with having recently
touched every single file to apply automatic code formatting and with
making several broad changes to the API, I decided it was time to take
the plunge and get rid of the older (pre-C++11) verbose iterator
syntax. The new code is just easier to read and understand, and in
many cases, it will be more effecient as fewer temporary copies are
being made.

m-holger, if you're reading, you can see that I've finally come
around. :-)

1 files changed, 22 insertions, 56 deletions

diff --git a/libqpdf/QPDF_optimization.cc b/libqpdf/QPDF_optimization.cc
index 0c453126..d22aa378 100644
--- a/libqpdf/QPDF_optimization.cc
+++ b/libqpdf/QPDF_optimization.cc
@@ -90,10 +90,7 @@ QPDF::optimize(
 
     // Traverse document-level items
     std::set<std::string> keys = this->m->trailer.getKeys();
-    for (std::set<std::string>::iterator iter = keys.begin();
-         iter != keys.end();
-         ++iter) {
-        std::string const& key = *iter;
+    for (auto const& key: keys) {
         if (key == "/Root") {
             // handled separately
         } else {
@@ -105,17 +102,13 @@ QPDF::optimize(
     }
 
     keys = root.getKeys();
-    for (std::set<std::string>::iterator iter = keys.begin();
-         iter != keys.end();
-         ++iter) {
+    for (auto const& key: keys) {
         // Technically, /I keys from /Thread dictionaries are supposed
         // to be handled separately, but we are going to disregard
         // that specification for now.  There is loads of evidence
         // that pdlin and Acrobat both disregard things like this from
         // time to time, so this is almost certain not to cause any
         // problems.
-
-        std::string const& key = *iter;
         updateObjectMaps(
             ObjUser(ObjUser::ou_root_key, key),
             root.getKey(key),
@@ -212,10 +205,7 @@ QPDF::pushInheritedAttributesToPageInternal(
 
         std::set<std::string> inheritable_keys;
         std::set<std::string> keys = cur_pages.getKeys();
-        for (std::set<std::string>::iterator iter = keys.begin();
-             iter != keys.end();
-             ++iter) {
-            std::string const& key = *iter;
+        for (auto const& key: keys) {
             if ((key == "/MediaBox") || (key == "/CropBox") ||
                 (key == "/Resources") || (key == "/Rotate")) {
                 if (!allow_changes) {
@@ -298,11 +288,7 @@ QPDF::pushInheritedAttributesToPageInternal(
 
         if (!inheritable_keys.empty()) {
             QTC::TC("qpdf", "QPDF opt inheritable keys");
-            for (std::set<std::string>::iterator iter =
-                     inheritable_keys.begin();
-                 iter != inheritable_keys.end();
-                 ++iter) {
-                std::string const& key = (*iter);
+            for (auto const& key: inheritable_keys) {
                 key_ancestors[key].pop_back();
                 if (key_ancestors[key].empty()) {
                     QTC::TC("qpdf", "QPDF opt erase empty key ancestor");
@@ -315,14 +301,11 @@ QPDF::pushInheritedAttributesToPageInternal(
     } else if (type == "/Page") {
         // Add all available inheritable attributes not present in
         // this object to this object.
-        for (std::map<std::string, std::vector<QPDFObjectHandle>>::iterator
-                 iter = key_ancestors.begin();
-             iter != key_ancestors.end();
-             ++iter) {
-            std::string const& key = (*iter).first;
+        for (auto const& iter: key_ancestors) {
+            std::string const& key = iter.first;
             if (!cur_pages.hasKey(key)) {
                 QTC::TC("qpdf", "QPDF opt resource inherited");
-                cur_pages.replaceKey(key, (*iter).second.back());
+                cur_pages.replaceKey(key, iter.second.back());
             } else {
                 QTC::TC("qpdf", "QPDF opt page resource hides ancestor");
             }
@@ -404,10 +387,7 @@ QPDF::updateObjectMapsInternal(
         }
 
         std::set<std::string> keys = dict.getKeys();
-        for (std::set<std::string>::iterator iter = keys.begin();
-             iter != keys.end();
-             ++iter) {
-            std::string const& key = *iter;
+        for (auto const& key: keys) {
             if (is_page_node && (key == "/Thumb")) {
                 // Traverse page thumbnail dictionaries as a special
                 // case.
@@ -454,42 +434,28 @@ QPDF::filterCompressedObjects(std::map<int, int> const& object_stream_data)
     std::map<ObjUser, std::set<QPDFObjGen>> t_obj_user_to_objects;
     std::map<QPDFObjGen, std::set<ObjUser>> t_object_to_obj_users;
 
-    for (std::map<ObjUser, std::set<QPDFObjGen>>::iterator i1 =
-             this->m->obj_user_to_objects.begin();
-         i1 != this->m->obj_user_to_objects.end();
-         ++i1) {
-        ObjUser const& ou = (*i1).first;
-        std::set<QPDFObjGen> const& objects = (*i1).second;
-        for (std::set<QPDFObjGen>::const_iterator i2 = objects.begin();
-             i2 != objects.end();
-             ++i2) {
-            QPDFObjGen const& og = (*i2);
-            std::map<int, int>::const_iterator i3 =
-                object_stream_data.find(og.getObj());
-            if (i3 == object_stream_data.end()) {
+    for (auto const& i1: this->m->obj_user_to_objects) {
+        ObjUser const& ou = i1.first;
+        std::set<QPDFObjGen> const& objects = i1.second;
+        for (auto const& og: objects) {
+            auto i2 = object_stream_data.find(og.getObj());
+            if (i2 == object_stream_data.end()) {
                 t_obj_user_to_objects[ou].insert(og);
             } else {
-                t_obj_user_to_objects[ou].insert(QPDFObjGen((*i3).second, 0));
+                t_obj_user_to_objects[ou].insert(QPDFObjGen(i2->second, 0));
             }
         }
     }
 
-    for (std::map<QPDFObjGen, std::set<ObjUser>>::iterator i1 =
-             this->m->object_to_obj_users.begin();
-         i1 != this->m->object_to_obj_users.end();
-         ++i1) {
-        QPDFObjGen const& og = (*i1).first;
-        std::set<ObjUser> const& objusers = (*i1).second;
-        for (std::set<ObjUser>::const_iterator i2 = objusers.begin();
-             i2 != objusers.end();
-             ++i2) {
-            ObjUser const& ou = (*i2);
-            std::map<int, int>::const_iterator i3 =
-                object_stream_data.find(og.getObj());
-            if (i3 == object_stream_data.end()) {
+    for (auto const& i1: this->m->object_to_obj_users) {
+        QPDFObjGen const& og = i1.first;
+        std::set<ObjUser> const& objusers = i1.second;
+        for (auto const& ou: objusers) {
+            auto i2 = object_stream_data.find(og.getObj());
+            if (i2 == object_stream_data.end()) {
                 t_object_to_obj_users[og].insert(ou);
             } else {
-                t_object_to_obj_users[QPDFObjGen((*i3).second, 0)].insert(ou);
+                t_object_to_obj_users[QPDFObjGen(i2->second, 0)].insert(ou);
             }
         }
     }