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-rw-r--r--libbutl/char-scanner.cxx20
-rw-r--r--libbutl/char-scanner.hxx31
-rw-r--r--libbutl/char-scanner.ixx31
-rw-r--r--libbutl/fdstream.hxx12
4 files changed, 80 insertions, 14 deletions
diff --git a/libbutl/char-scanner.cxx b/libbutl/char-scanner.cxx
index 42a72cc..a2baaf3 100644
--- a/libbutl/char-scanner.cxx
+++ b/libbutl/char-scanner.cxx
@@ -4,12 +4,20 @@
#include <libbutl/char-scanner.hxx>
-#include <istream>
-
using namespace std;
namespace butl
{
+ char_scanner::
+ char_scanner (istream& is, bool crlf)
+ : is_ (is),
+ buf_ (dynamic_cast<fdbuf*> (is.rdbuf ())),
+ gptr_ (nullptr),
+ egptr_ (nullptr),
+ crlf_ (crlf)
+ {
+ }
+
auto char_scanner::
peek () -> xchar
{
@@ -22,14 +30,14 @@ namespace butl
if (eos_)
return xchar (xchar::traits_type::eof (), line, column);
- xchar::int_type v (is_.peek ());
+ int_type v (peek_ ());
if (v == xchar::traits_type::eof ())
eos_ = true;
else if (crlf_ && v == 0x0D)
{
- is_.get ();
- xchar::int_type v1 (is_.peek ());
+ get_ ();
+ int_type v1 (peek_ ());
if (v1 != '\n')
{
@@ -62,7 +70,7 @@ namespace butl
//
if (!eos (c))
{
- is_.get ();
+ get_ ();
if (c == '\n')
{
diff --git a/libbutl/char-scanner.hxx b/libbutl/char-scanner.hxx
index e71f286..80a1f2a 100644
--- a/libbutl/char-scanner.hxx
+++ b/libbutl/char-scanner.hxx
@@ -6,8 +6,10 @@
#define LIBBUTL_CHAR_SCANNER_HXX
#include <string> // char_traits
-#include <iosfwd>
#include <cstdint> // uint64_t
+#include <istream>
+
+#include <libbutl/fdstream.hxx>
#include <libbutl/export.hxx>
@@ -23,8 +25,11 @@ namespace butl
// 0x0A) and convert them to just '\n' (0x0A). Note that a standalone
// 0x0D is treated "as if" it was followed by 0x0A.
//
- char_scanner (std::istream& is, bool crlf = true)
- : is_ (is), crlf_ (crlf) {}
+ // Note also that if the stream happens to be ifdstream, then it includes
+ // a number of optimizations that assume nobody else is messing with the
+ // stream.
+ //
+ char_scanner (std::istream& is, bool crlf = true);
char_scanner (const char_scanner&) = delete;
char_scanner& operator= (const char_scanner&) = delete;
@@ -43,9 +48,9 @@ namespace butl
class xchar
{
public:
- typedef std::char_traits<char> traits_type;
- typedef traits_type::int_type int_type;
- typedef traits_type::char_type char_type;
+ using traits_type = std::char_traits<char>;
+ using int_type = traits_type::int_type;
+ using char_type = traits_type::char_type;
int_type value;
std::uint64_t line;
@@ -90,8 +95,22 @@ namespace butl
std::uint64_t column = 1;
protected:
+ using int_type = xchar::int_type;
+ using char_type = xchar::char_type;
+
+ int_type
+ peek_ ();
+
+ void
+ get_ ();
+
+ protected:
std::istream& is_;
+ fdbuf* buf_; // NULL if not ifdstream.
+ const char_type* gptr_;
+ const char_type* egptr_;
+
bool crlf_;
bool eos_ = false;
diff --git a/libbutl/char-scanner.ixx b/libbutl/char-scanner.ixx
index 2d96207..0e00dfd 100644
--- a/libbutl/char-scanner.ixx
+++ b/libbutl/char-scanner.ixx
@@ -29,4 +29,35 @@ namespace butl
unget_ = true;
ungetc_ = c;
}
+
+ inline auto char_scanner::
+ peek_ () -> int_type
+ {
+ if (gptr_ != egptr_)
+ return *gptr_;
+
+ int_type r (is_.peek ());
+
+ // Update buffer pointers for the next chunk.
+ //
+ if (buf_ != nullptr)
+ {
+ gptr_ = buf_->gptr ();
+ egptr_ = buf_->egptr ();
+ }
+
+ return r;
+ }
+
+ inline void char_scanner::
+ get_ ()
+ {
+ if (gptr_ != egptr_)
+ {
+ buf_->gbump (1);
+ ++gptr_;
+ }
+ else
+ is_.get (); // About as fast as ignore() and way faster than tellg().
+ }
}
diff --git a/libbutl/fdstream.hxx b/libbutl/fdstream.hxx
index e1f5790..dd33263 100644
--- a/libbutl/fdstream.hxx
+++ b/libbutl/fdstream.hxx
@@ -122,8 +122,10 @@ namespace butl
fd () const {return fd_.get ();}
public:
- using int_type = std::basic_streambuf<char>::int_type;
- using traits_type = std::basic_streambuf<char>::traits_type;
+ using base = std::basic_streambuf<char>;
+
+ using int_type = base::int_type;
+ using traits_type = base::traits_type;
// basic_streambuf input interface.
//
@@ -134,6 +136,12 @@ namespace butl
virtual int_type
underflow ();
+ // Direct access to the get area. Use with caution.
+ //
+ using base::gptr;
+ using base::egptr;
+ using base::gbump;
+
private:
bool
load ();