Use pkgTagSection::Key in more places in src:apt

The speed critical paths were converted earlier, but the remaining
could benefit a tiny bit from this as well especially as we have the
facility now available and can therefore brush up the code in various
places in the process as well.

Also takes the time to add the hidden Exists method advertised in
the headers, but previously not implemented.

8 files changed, 55 insertions, 48 deletions

diff --git a/apt-pkg/deb/deblistparser.cc b/apt-pkg/deb/deblistparser.cc
index a1247dd98..6f47053a5 100644
--- a/apt-pkg/deb/deblistparser.cc
+++ b/apt-pkg/deb/deblistparser.cc
@@ -126,7 +126,7 @@ unsigned char debListParser::ParseMultiArch(bool const showErrors)	/*{{{*/
       {
 	 if (showErrors == true)
 	    _error->Warning("Architecture: all package '%s' can't be Multi-Arch: same",
-		  Section.FindS("Package").c_str());
+		  Package().c_str());
 	 MA = pkgCache::Version::No;
       }
       else
@@ -140,7 +140,7 @@ unsigned char debListParser::ParseMultiArch(bool const showErrors)	/*{{{*/
    {
       if (showErrors == true)
 	 _error->Warning("Unknown Multi-Arch type '%s' for package '%s'",
-	       MultiArch.to_string().c_str(), Section.FindS("Package").c_str());
+	       MultiArch.to_string().c_str(), Package().c_str());
       MA = pkgCache::Version::No;
    }
 
@@ -256,21 +256,20 @@ bool debListParser::NewVersion(pkgCache::VerIterator &Ver)
 // ListParser::AvailableDescriptionLanguages				/*{{{*/
 std::vector<std::string> debListParser::AvailableDescriptionLanguages()
 {
-   std::vector<std::string> const understood = APT::Configuration::getLanguages(true);
    std::vector<std::string> avail;
    static constexpr int prefixLen = 12;
    char buf[32] = "Description-";
-   if (Section.Exists("Description") == true)
-      avail.push_back("");
-   for (std::vector<std::string>::const_iterator lang = understood.begin(); lang != understood.end(); ++lang)
+   if (Section.Exists(pkgTagSection::Key::Description))
+      avail.emplace_back();
+   for (auto const &lang : APT::Configuration::getLanguages(true))
    {
-      if (unlikely(lang->size() > sizeof(buf) - prefixLen)) {
-	 _error->Warning("Ignoring translated description %s", lang->c_str());
+      if (unlikely(lang.size() > sizeof(buf) - prefixLen)) {
+	 _error->Warning("Ignoring translated description %s", lang.c_str());
 	 continue;
       }
-      memcpy(buf + prefixLen, lang->c_str(), lang->size());
-      if (Section.Exists(StringView(buf, prefixLen + lang->size())) == true)
-	 avail.push_back(*lang);
+      memcpy(buf + prefixLen, lang.c_str(), lang.size());
+      if (Section.Exists(StringView(buf, prefixLen + lang.size())) == true)
+	 avail.push_back(lang);
    }
    return avail;
 }
diff --git a/apt-pkg/deb/debrecords.cc b/apt-pkg/deb/debrecords.cc
index 8fb17ae0b..e2ffaefff 100644
--- a/apt-pkg/deb/debrecords.cc
+++ b/apt-pkg/deb/debrecords.cc
@@ -16,6 +16,7 @@
 #include <apt-pkg/fileutl.h>
 #include <apt-pkg/pkgcache.h>
 #include <apt-pkg/strutl.h>
+#include <apt-pkg/tagfile-keys.h>
 #include <apt-pkg/tagfile.h>
 
 #include <algorithm>
@@ -57,13 +58,13 @@ debRecordParserBase::debRecordParserBase() : Parser(), d(NULL) {}
 // RecordParserBase::FileName - Return the archive filename on the site	/*{{{*/
 string debRecordParserBase::FileName()
 {
-   return Section.FindS("Filename");
+   return Section.Find(pkgTagSection::Key::Filename).to_string();
 }
 									/*}}}*/
 // RecordParserBase::Name - Return the package name			/*{{{*/
 string debRecordParserBase::Name()
 {
-   string Result = Section.FindS("Package");
+   auto Result = Section.Find(pkgTagSection::Key::Package).to_string();
 
    // Normalize mixed case package names to lower case, like dpkg does
    // See Bug#807012 for details
@@ -75,7 +76,7 @@ string debRecordParserBase::Name()
 // RecordParserBase::Homepage - Return the package homepage		/*{{{*/
 string debRecordParserBase::Homepage()
 {
-   return Section.FindS("Homepage");
+   return Section.Find(pkgTagSection::Key::Homepage).to_string();
 }
 									/*}}}*/
 // RecordParserBase::Hashes - return the available archive hashes	/*{{{*/
@@ -88,7 +89,7 @@ HashStringList debRecordParserBase::Hashes() const
       if (hash.empty() == false)
 	 hashes.push_back(HashString(*type, hash));
    }
-   auto const size = Section.FindULL("Size", 0);
+   auto const size = Section.FindULL(pkgTagSection::Key::Size, 0);
    if (size != 0)
       hashes.FileSize(size);
    return hashes;
@@ -97,7 +98,7 @@ HashStringList debRecordParserBase::Hashes() const
 // RecordParserBase::Maintainer - Return the maintainer email		/*{{{*/
 string debRecordParserBase::Maintainer()
 {
-   return Section.FindS("Maintainer");
+   return Section.Find(pkgTagSection::Key::Maintainer).to_string();
 }
 									/*}}}*/
 // RecordParserBase::RecordField - Return the value of an arbitrary field	/*{{*/
@@ -134,20 +135,20 @@ string debRecordParserBase::LongDesc(std::string const &lang)
 	    break;
 	 else if (*l == "en")
 	 {
-	    orig = Section.FindS("Description");
+	    orig = Section.Find(pkgTagSection::Key::Description).to_string();
 	    if (orig.empty() == false)
 	       break;
 	 }
       }
       if (orig.empty() == true)
-	 orig = Section.FindS("Description");
+	 orig = Section.Find(pkgTagSection::Key::Description).to_string();
    }
    else
    {
       std::string const tagname = "Description-" + lang;
       orig = Section.FindS(tagname.c_str());
       if (orig.empty() == true && lang == "en")
-	 orig = Section.FindS("Description");
+	 orig = Section.Find(pkgTagSection::Key::Description).to_string();
    }
 
    char const * const codeset = nl_langinfo(CODESET);
@@ -165,17 +166,17 @@ static const char * const SourceVerSeparators = " ()";
 // RecordParserBase::SourcePkg - Return the source package name if any	/*{{{*/
 string debRecordParserBase::SourcePkg()
 {
-   string Res = Section.FindS("Source");
-   string::size_type Pos = Res.find_first_of(SourceVerSeparators);
-   if (Pos == string::npos)
-      return Res;
-   return string(Res,0,Pos);
+   auto Res = Section.Find(pkgTagSection::Key::Source).to_string();
+   auto const Pos = Res.find_first_of(SourceVerSeparators);
+   if (Pos != std::string::npos)
+      Res.erase(Pos);
+   return Res;
 }
 									/*}}}*/
 // RecordParserBase::SourceVer - Return the source version number if present	/*{{{*/
 string debRecordParserBase::SourceVer()
 {
-   string Pkg = Section.FindS("Source");
+   auto const Pkg = Section.Find(pkgTagSection::Key::Source).to_string();
    string::size_type Pos = Pkg.find_first_of(SourceVerSeparators);
    if (Pos == string::npos)
       return "";
diff --git a/apt-pkg/deb/debsrcrecords.h b/apt-pkg/deb/debsrcrecords.h
index b572d3427..1a0bbe0fd 100644
--- a/apt-pkg/deb/debsrcrecords.h
+++ b/apt-pkg/deb/debsrcrecords.h
@@ -12,6 +12,7 @@
 
 #include <apt-pkg/fileutl.h>
 #include <apt-pkg/srcrecords.h>
+#include <apt-pkg/tagfile-keys.h>
 #include <apt-pkg/tagfile.h>
 
 #include <string>
@@ -40,9 +41,9 @@ class APT_HIDDEN debSrcRecordParser : public pkgSrcRecords::Parser
    virtual bool Jump(unsigned long const &Off) APT_OVERRIDE {iOffset = Off; return Tags.Jump(Sect,Off);};
 
    virtual std::string Package() const APT_OVERRIDE;
-   virtual std::string Version() const APT_OVERRIDE {return Sect.FindS("Version");};
-   virtual std::string Maintainer() const APT_OVERRIDE {return Sect.FindS("Maintainer");};
-   virtual std::string Section() const APT_OVERRIDE {return Sect.FindS("Section");};
+   virtual std::string Version() const APT_OVERRIDE {return Sect.Find(pkgTagSection::Key::Version).to_string();};
+   virtual std::string Maintainer() const APT_OVERRIDE {return Sect.Find(pkgTagSection::Key::Maintainer).to_string();};
+   virtual std::string Section() const APT_OVERRIDE {return Sect.Find(pkgTagSection::Key::Section).to_string();};
    virtual const char **Binaries() APT_OVERRIDE;
    virtual bool BuildDepends(std::vector<BuildDepRec> &BuildDeps, bool const &ArchOnly, bool const &StripMultiArch = true) APT_OVERRIDE;
    virtual unsigned long Offset() APT_OVERRIDE {return iOffset;};
diff --git a/apt-pkg/depcache.cc b/apt-pkg/depcache.cc
index f7d9832a0..a5b586f5b 100644
--- a/apt-pkg/depcache.cc
+++ b/apt-pkg/depcache.cc
@@ -23,6 +23,7 @@
 #include <apt-pkg/prettyprinters.h>
 #include <apt-pkg/progress.h>
 #include <apt-pkg/strutl.h>
+#include <apt-pkg/tagfile-keys.h>
 #include <apt-pkg/tagfile.h>
 #include <apt-pkg/version.h>
 #include <apt-pkg/versionmatch.h>
@@ -310,8 +311,8 @@ bool pkgDepCache::readStateFile(OpProgress * const Prog)		/*{{{*/
       off_t amt = 0;
       bool const debug_autoremove = _config->FindB("Debug::pkgAutoRemove",false);
       while(tagfile.Step(section)) {
-	 string const pkgname = section.FindS("Package");
-	 string pkgarch = section.FindS("Architecture");
+	 auto const pkgname = section.Find(pkgTagSection::Key::Package);
+	 auto pkgarch = section.Find(pkgTagSection::Key::Architecture);
 	 if (pkgarch.empty() == true)
 	    pkgarch = "any";
 	 pkgCache::PkgIterator pkg = Cache->FindPkg(pkgname, pkgarch);
@@ -379,8 +380,8 @@ bool pkgDepCache::writeStateFile(OpProgress * const /*prog*/, bool const Install
    pkgTagSection section;
    std::set<string> pkgs_seen;
    while(tagfile.Step(section)) {
-	 string const pkgname = section.FindS("Package");
-	 string pkgarch = section.FindS("Architecture");
+	 auto const pkgname = section.Find(pkgTagSection::Key::Package);
+	 auto pkgarch = section.Find(pkgTagSection::Key::Architecture);
 	 if (pkgarch.empty() == true)
 	    pkgarch = "native";
 	 // Silently ignore unknown packages and packages with no actual
diff --git a/apt-pkg/edsp/edsplistparser.cc b/apt-pkg/edsp/edsplistparser.cc
index 0be543e3c..5419069f2 100644
--- a/apt-pkg/edsp/edsplistparser.cc
+++ b/apt-pkg/edsp/edsplistparser.cc
@@ -19,6 +19,7 @@
 #include <apt-pkg/pkgsystem.h>
 #include <apt-pkg/string_view.h>
 #include <apt-pkg/strutl.h>
+#include <apt-pkg/tagfile-keys.h>
 #include <apt-pkg/tagfile.h>
 
 #include <array>
@@ -141,8 +142,8 @@ bool eippListParser::ParseStatus(pkgCache::PkgIterator &Pkg,
       {"triggers-pending",pkgCache::State::TriggersPending},
       {"installed",pkgCache::State::Installed},
    }};
-   auto const status = Section.Find("Status");
-   if (status.empty() == false)
+   auto const status = Section.Find(pkgTagSection::Key::Status);
+   if (not status.empty())
    {
       for (auto && sv: statusvalues)
       {
diff --git a/apt-pkg/indexcopy.cc b/apt-pkg/indexcopy.cc
index 88c2150ff..82baba337 100644
--- a/apt-pkg/indexcopy.cc
+++ b/apt-pkg/indexcopy.cc
@@ -22,6 +22,7 @@
 #include <apt-pkg/metaindex.h>
 #include <apt-pkg/progress.h>
 #include <apt-pkg/strutl.h>
+#include <apt-pkg/tagfile-keys.h>
 #include <apt-pkg/tagfile.h>
 
 #include <iostream>
@@ -413,8 +414,8 @@ bool IndexCopy::GrabFirst(string Path,string &To,unsigned int Depth)
 /* */
 bool PackageCopy::GetFile(string &File,unsigned long long &Size)
 {
-   File = Section->FindS("Filename");
-   Size = Section->FindULL("Size");
+   File = Section->Find(pkgTagSection::Key::Filename).to_string();
+   Size = Section->FindULL(pkgTagSection::Key::Size);
    if (File.empty() || Size == 0)
       return _error->Error("Cannot find filename or size tag");
    return true;
@@ -447,18 +448,13 @@ bool SourceCopy::GetFile(string &File,unsigned long long &Size)
       else
 	 checksumField.append(*type);
 
-      Files = Section->FindS(checksumField.c_str());
+      Files = Section->FindS(checksumField);
       if (Files.empty() == false)
 	 break;
    }
    if (Files.empty() == true)
       return false;
 
-   // Stash the / terminated directory prefix
-   string Base = Section->FindS("Directory");
-   if (Base.empty() == false && Base[Base.length()-1] != '/')
-      Base += '/';
-   
    // Read the first file triplet
    const char *C = Files.c_str();
    string sSize;
@@ -472,7 +468,8 @@ bool SourceCopy::GetFile(string &File,unsigned long long &Size)
    
    // Parse the size and append the directory
    Size = strtoull(sSize.c_str(), NULL, 10);
-   File = Base + File;
+   auto const Base = Section->Find(pkgTagSection::Key::Directory);
+   File = flCombine(Base.to_string(), File);
    return true;
 }
 									/*}}}*/
diff --git a/apt-pkg/policy.cc b/apt-pkg/policy.cc
index c5328c517..b30eddb37 100644
--- a/apt-pkg/policy.cc
+++ b/apt-pkg/policy.cc
@@ -21,7 +21,9 @@
 #include <apt-pkg/fileutl.h>
 #include <apt-pkg/pkgcache.h>
 #include <apt-pkg/policy.h>
+#include <apt-pkg/string_view.h>
 #include <apt-pkg/strutl.h>
+#include <apt-pkg/tagfile-keys.h>
 #include <apt-pkg/tagfile.h>
 #include <apt-pkg/version.h>
 #include <apt-pkg/versionmatch.h>
@@ -425,12 +427,12 @@ bool ReadPinFile(pkgPolicy &Plcy,string File)
       if (Tags.Count() == 0)
          continue;
 
-      string Name = Tags.FindS("Package");
-      if (Name.empty() == true)
+      auto Name = Tags.Find(pkgTagSection::Key::Package);
+      if (Name.empty())
 	 return _error->Error(_("Invalid record in the preferences file %s, no Package header"), File.c_str());
       if (Name == "*")
-	 Name = string();
-      
+	 Name = APT::StringView{};
+
       const char *Start;
       const char *End;
       if (Tags.Find("Pin",Start,End) == false)
@@ -479,7 +481,7 @@ bool ReadPinFile(pkgPolicy &Plcy,string File)
          return _error->Error(_("No priority (or zero) specified for pin"));
       }
 
-      istringstream s(Name);
+      std::istringstream s(Name.to_string());
       string pkg;
       while(!s.eof())
       {
diff --git a/apt-pkg/tagfile.cc b/apt-pkg/tagfile.cc
index ebad1a4c5..047f88986 100644
--- a/apt-pkg/tagfile.cc
+++ b/apt-pkg/tagfile.cc
@@ -626,6 +626,11 @@ bool pkgTagSection::Exists(StringView Tag) const
    unsigned int tmp;
    return Find(Tag, tmp);
 }
+bool pkgTagSection::Exists(Key key) const
+{
+   unsigned int tmp;
+   return Find(key, tmp);
+}
 									/*}}}*/
 // TagSection::Find - Locate a tag					/*{{{*/
 // ---------------------------------------------------------------------