Simplify CFX_FontSourceEnum_File's file iterator.

Break the methods down to their basic functionality, and built up from
there.

Change-Id: I691abaf08375425b59f2382cf95577c3917aca9d
Reviewed-on: https://pdfium-review.googlesource.com/42972
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

2 files changed, 15 insertions, 23 deletions

diff --git a/xfa/fgas/font/cfgas_fontmgr.cpp b/xfa/fgas/font/cfgas_fontmgr.cpp
index b2150f99b8..c8aed88547 100644
--- a/xfa/fgas/font/cfgas_fontmgr.cpp
+++ b/xfa/fgas/font/cfgas_fontmgr.cpp
@@ -634,20 +634,18 @@ ByteString CFX_FontSourceEnum_File::GetNextFile() {
   return bsName;
 }
 
-bool CFX_FontSourceEnum_File::HasStartPosition() {
+void CFX_FontSourceEnum_File::GetNext() {
   m_wsNext = GetNextFile().UTF8Decode();
-  return !m_wsNext.IsEmpty();
 }
 
-std::pair<bool, RetainPtr<IFX_SeekableStream>>
-CFX_FontSourceEnum_File::GetNext() {
-  if (m_wsNext.IsEmpty())
-    return {false, nullptr};
+bool CFX_FontSourceEnum_File::HasNext() const {
+  return !m_wsNext.IsEmpty();
+}
 
-  auto stream = IFX_SeekableStream::CreateFromFilename(m_wsNext.c_str(),
-                                                       FX_FILEMODE_ReadOnly);
-  m_wsNext = GetNextFile().UTF8Decode();
-  return {true, stream};
+RetainPtr<IFX_SeekableStream> CFX_FontSourceEnum_File::GetStream() const {
+  ASSERT(HasNext());
+  return IFX_SeekableStream::CreateFromFilename(m_wsNext.c_str(),
+                                                FX_FILEMODE_ReadOnly);
 }
 
 CFGAS_FontMgr::CFGAS_FontMgr()
@@ -684,16 +682,12 @@ bool CFGAS_FontMgr::EnumFontsFromFontMapper() {
 
 bool CFGAS_FontMgr::EnumFontsFromFiles() {
   CFX_GEModule::Get()->GetFontMgr()->InitFTLibrary();
-  if (!m_pFontSource->HasStartPosition())
-    return !m_InstalledFonts.empty();
-
-  bool has_next;
-  RetainPtr<IFX_SeekableStream> stream;
-  std::tie(has_next, stream) = m_pFontSource->GetNext();
-  while (has_next) {
+  m_pFontSource->GetNext();
+  while (m_pFontSource->HasNext()) {
+    RetainPtr<IFX_SeekableStream> stream = m_pFontSource->GetStream();
     if (stream)
       RegisterFaces(stream, nullptr);
-    std::tie(has_next, stream) = m_pFontSource->GetNext();
+    m_pFontSource->GetNext();
   }
   return !m_InstalledFonts.empty();
 }
diff --git a/xfa/fgas/font/cfgas_fontmgr.h b/xfa/fgas/font/cfgas_fontmgr.h
index bc2a7af2a7..3c63a1c636 100644
--- a/xfa/fgas/font/cfgas_fontmgr.h
+++ b/xfa/fgas/font/cfgas_fontmgr.h
@@ -11,7 +11,6 @@
 #include <map>
 #include <memory>
 #include <set>
-#include <utility>
 #include <vector>
 
 #include "core/fxcrt/fx_extension.h"
@@ -98,10 +97,9 @@ class CFX_FontSourceEnum_File {
   CFX_FontSourceEnum_File();
   ~CFX_FontSourceEnum_File();
 
-  bool HasStartPosition();
-
-  // <next exists, stream for next>
-  std::pair<bool, RetainPtr<IFX_SeekableStream>> GetNext();
+  void GetNext();
+  bool HasNext() const;
+  RetainPtr<IFX_SeekableStream> GetStream() const;
 
  private:
   struct HandleParentPath {