[2428] Interface to get count of sources in lexer

And use it in the master loader, instead of keeping it separately there.

src/lib/dns/master_lexer.cc

@@ -149,6 +149,11 @@ MasterLexer::popSource() {
     impl_->has_previous_ = false;
 }
 
+size_t
+MasterLexer::getSourceCount() const {
+    return (impl_->sources_.size());
+}
+
 std::string
 MasterLexer::getSourceName() const {
     if (impl_->sources_.empty()) {

src/lib/dns/master_lexer.h

@@ -405,6 +405,11 @@ public:
     /// \throw isc::InvalidOperation Called with no pushed source.
     void popSource();
 
+    /// \brief Get number of sources inside the lexer.
+    ///
+    /// This method never throws.
+    size_t getSourceCount() const;
+
     /// \brief Return the name of the current input source name.
     ///
     /// If it's a file, it will be the C string given at the corresponding

src/lib/dns/master_loader.cc

@@ -63,7 +63,6 @@ public:
         initialized_(false),
         ok_(true),
         many_errors_((options & MANY_ERRORS) != 0),
-        source_count_(0),
         complete_(false),
         seen_error_(false)
     {}
@@ -94,11 +93,10 @@ public:
             }
         }
         initialized_ = true;
-        ++source_count_;
     }
 
     bool popSource() {
-        if (--source_count_ == 0) {
+        if (lexer_.getSourceCount() == 1) {
             return (false);
         }
         lexer_.popSource();
@@ -108,7 +106,6 @@ public:
     void pushStreamSource(std::istream& stream) {
         lexer_.pushSource(stream);
         initialized_ = true;
-        ++source_count_;
     }
 
     // Get a string token. Handle it as error if it is not string.
@@ -200,7 +197,6 @@ private:
     bool ok_;                   // Is it OK to continue loading?
     const bool many_errors_;    // Are many errors allowed (or should we abort
                                 // on the first)
-    size_t source_count_;       // How many sources are currently pushed.
 public:
     bool complete_;             // All work done.
     bool seen_error_;           // Was there at least one error during the

src/lib/dns/tests/master_lexer_unittest.cc

@@ -60,8 +60,10 @@ TEST_F(MasterLexerTest, preOpen) {
 }
 
 TEST_F(MasterLexerTest, pushStream) {
+    EXPECT_EQ(0, lexer.getSourceCount());
     lexer.pushSource(ss);
     EXPECT_EQ(expected_stream_name, lexer.getSourceName());
+    EXPECT_EQ(1, lexer.getSourceCount());
 
     // From the point of view of this test, we only have to check (though
     // indirectly) getSourceLine calls InputSource::getCurrentLine.  It should
@@ -70,18 +72,22 @@ TEST_F(MasterLexerTest, pushStream) {
 
     // By popping it the stack will be empty again.
     lexer.popSource();
+    EXPECT_EQ(0, lexer.getSourceCount());
     checkEmptySource(lexer);
 }
 
 TEST_F(MasterLexerTest, pushFile) {
     // We use zone file (-like) data, but in this test that actually doesn't
     // matter.
+    EXPECT_EQ(0, lexer.getSourceCount());
     EXPECT_TRUE(lexer.pushSource(TEST_DATA_SRCDIR "/masterload.txt"));
+    EXPECT_EQ(1, lexer.getSourceCount());
     EXPECT_EQ(TEST_DATA_SRCDIR "/masterload.txt", lexer.getSourceName());
     EXPECT_EQ(1, lexer.getSourceLine());
 
     lexer.popSource();
     checkEmptySource(lexer);
+    EXPECT_EQ(0, lexer.getSourceCount());
 
     // If we give a non NULL string pointer, its content will be intact
     // if pushSource succeeds.