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. :-)

6 files changed, 16 insertions, 38 deletions

diff --git a/examples/pdf-filter-tokens.cc b/examples/pdf-filter-tokens.cc
index 59c85271..3d4bad8b 100644
--- a/examples/pdf-filter-tokens.cc
+++ b/examples/pdf-filter-tokens.cc
@@ -193,15 +193,12 @@ main(int argc, char* argv[])
         pdf.processFile(infilename);
         std::vector<QPDFPageObjectHelper> pages =
             QPDFPageDocumentHelper(pdf).getAllPages();
-        for (std::vector<QPDFPageObjectHelper>::iterator iter = pages.begin();
-             iter != pages.end();
-             ++iter) {
+        for (auto& page: pages) {
             // Attach two token filters to each page of this file.
             // When the file is written, or when the pages' contents
             // are retrieved in any other way, the filters will be
             // applied. See comments on the filters for additional
             // details.
-            QPDFPageObjectHelper& page(*iter);
             page.addContentTokenFilter(
                 std::shared_ptr<QPDFObjectHandle::TokenFilter>(
                     new StringReverser));
diff --git a/examples/pdf-invert-images.cc b/examples/pdf-invert-images.cc
index bd36f33f..b784c8e3 100644
--- a/examples/pdf-invert-images.cc
+++ b/examples/pdf-invert-images.cc
@@ -131,14 +131,11 @@ main(int argc, char* argv[])
         // For each page...
         std::vector<QPDFPageObjectHelper> pages =
             QPDFPageDocumentHelper(qpdf).getAllPages();
-        for (std::vector<QPDFPageObjectHelper>::iterator iter = pages.begin();
-             iter != pages.end();
-             ++iter) {
-            QPDFPageObjectHelper& page(*iter);
+        for (auto& page: pages) {
             // Get all images on the page.
             std::map<std::string, QPDFObjectHandle> images = page.getImages();
-            for (auto& iter2: images) {
-                QPDFObjectHandle& image = iter2.second;
+            for (auto& iter: images) {
+                QPDFObjectHandle& image = iter.second;
                 QPDFObjectHandle image_dict = image.getDict();
                 QPDFObjectHandle color_space = image_dict.getKey("/ColorSpace");
                 QPDFObjectHandle bits_per_component =
diff --git a/examples/pdf-mod-info.cc b/examples/pdf-mod-info.cc
index 425a25ba..2b8e3c47 100644
--- a/examples/pdf-mod-info.cc
+++ b/examples/pdf-mod-info.cc
@@ -132,10 +132,7 @@ main(int argc, char* argv[])
         QPDFObjectHandle filetrailer = file.getTrailer();
         QPDFObjectHandle fileinfo;
 
-        for (std::map<std::string, std::string>::const_iterator it =
-                 Keys.begin();
-             Keys.end() != it;
-             ++it) {
+        for (auto const& it: Keys) {
             if (!fileinfo.isInitialized()) {
                 if (filetrailer.hasKey("/Info")) {
                     QTC::TC("examples", "pdf-mod-info has info");
@@ -146,12 +143,12 @@ main(int argc, char* argv[])
                     filetrailer.replaceKey("/Info", fileinfo);
                 }
             }
-            if (it->second == "") {
-                fileinfo.removeKey(it->first);
+            if (it.second == "") {
+                fileinfo.removeKey(it.first);
             } else {
-                QPDFObjectHandle elt = fileinfo.newString(it->second);
+                QPDFObjectHandle elt = fileinfo.newString(it.second);
                 elt.makeDirect();
-                fileinfo.replaceKey(it->first, elt);
+                fileinfo.replaceKey(it.first, elt);
             }
         }
         QPDFWriter w(file, fl_tmp.c_str());
diff --git a/examples/pdf-overlay-page.cc b/examples/pdf-overlay-page.cc
index 64a8d48f..f9603d9c 100644
--- a/examples/pdf-overlay-page.cc
+++ b/examples/pdf-overlay-page.cc
@@ -42,11 +42,7 @@ stamp_page(char const* infile, char const* stampfile, char const* outfile)
     // For each page...
     std::vector<QPDFPageObjectHelper> pages =
         QPDFPageDocumentHelper(inpdf).getAllPages();
-    for (std::vector<QPDFPageObjectHelper>::iterator iter = pages.begin();
-         iter != pages.end();
-         ++iter) {
-        QPDFPageObjectHelper& ph = *iter;
-
+    for (auto& ph: pages) {
         // Find a unique resource name for the new form XObject
         QPDFObjectHandle resources = ph.getAttribute("/Resources", true);
         int min_suffix = 1;
diff --git a/examples/pdf-set-form-values.cc b/examples/pdf-set-form-values.cc
index 10394c7b..c28149ad 100644
--- a/examples/pdf-set-form-values.cc
+++ b/examples/pdf-set-form-values.cc
@@ -52,23 +52,17 @@ main(int argc, char* argv[])
         QPDFAcroFormDocumentHelper afdh(qpdf);
         QPDFPageDocumentHelper pdh(qpdf);
         std::vector<QPDFPageObjectHelper> pages = pdh.getAllPages();
-        for (std::vector<QPDFPageObjectHelper>::iterator page_iter =
-                 pages.begin();
-             page_iter != pages.end();
-             ++page_iter) {
+        for (auto const& page: pages) {
             // Get all widget annotations for each page. Widget
             // annotations are the ones that contain the details of
             // what's in a form field.
             std::vector<QPDFAnnotationObjectHelper> annotations =
-                afdh.getWidgetAnnotationsForPage(*page_iter);
-            for (std::vector<QPDFAnnotationObjectHelper>::iterator annot_iter =
-                     annotations.begin();
-                 annot_iter != annotations.end();
-                 ++annot_iter) {
+                afdh.getWidgetAnnotationsForPage(page);
+            for (auto& annot: annotations) {
                 // For each annotation, find its associated field. If
                 // it's a text field, set its value.
                 QPDFFormFieldObjectHelper ffh =
-                    afdh.getFieldForAnnotation(*annot_iter);
+                    afdh.getFieldForAnnotation(annot);
                 if (ffh.getFieldType() == "/Tx") {
                     // Set the value. Passing false as the second
                     // value prevents qpdf from setting
@@ -81,7 +75,7 @@ main(int argc, char* argv[])
                     // additional details, please see comments in
                     // QPDFFormFieldObjectHelper.hh for this method.
                     ffh.setV(value, false);
-                    ffh.generateAppearance(*annot_iter);
+                    ffh.generateAppearance(annot);
                 }
             }
         }
diff --git a/examples/pdf-split-pages.cc b/examples/pdf-split-pages.cc
index a8e65260..150de0df 100644
--- a/examples/pdf-split-pages.cc
+++ b/examples/pdf-split-pages.cc
@@ -27,10 +27,7 @@ process(char const* whoami, char const* infile, std::string outprefix)
     int pageno_len =
         QIntC::to_int(QUtil::uint_to_string(pages.size()).length());
     int pageno = 0;
-    for (std::vector<QPDFPageObjectHelper>::iterator iter = pages.begin();
-         iter != pages.end();
-         ++iter) {
-        QPDFPageObjectHelper& page(*iter);
+    for (auto& page: pages) {
         std::string outfile =
             outprefix + QUtil::int_to_string(++pageno, pageno_len) + ".pdf";
         QPDF outpdf;