Give a more informative exception on SubRip parse failures.

5 files changed, 38 insertions, 8 deletions

diff --git a/src/exceptions.cc b/src/exceptions.cc
index 4d9d29f..d59d32a 100644
--- a/src/exceptions.cc
+++ b/src/exceptions.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2014-2015 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2014-2016 Carl Hetherington <cth@carlh.net>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -19,8 +19,10 @@
 
 #include "compose.hpp"
 #include "exceptions.h"
+#include <boost/foreach.hpp>
 
 using std::string;
+using std::list;
 using namespace sub;
 
 ProgrammingError::ProgrammingError (string file, int line)
@@ -28,3 +30,10 @@ ProgrammingError::ProgrammingError (string file, int line)
 {
 
 }
+
+SubripError::SubripError (string saw, string expecting, list<string> context)
+	: runtime_error ("Error in SubRip file: saw " + (saw.empty() ? "an empty string" : saw) + " when expecting " + expecting)
+	, _context (context)
+{
+
+}
diff --git a/src/exceptions.h b/src/exceptions.h
index c6f7f1a..c7a3c71 100644
--- a/src/exceptions.h
+++ b/src/exceptions.h
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2014 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2014-2016 Carl Hetherington <cth@carlh.net>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -22,6 +22,7 @@
 
 #include <stdexcept>
 #include <string>
+#include <list>
 
 namespace sub {
 
@@ -53,9 +54,14 @@ public:
 class SubripError : public std::runtime_error
 {
 public:
-	SubripError (std::string saw, std::string expecting)
-		: std::runtime_error ("Error in SubRip file: saw " + saw + " while expecting " + expecting)
-	{}
+	SubripError (std::string saw, std::string expecting, std::list<std::string> context);
+
+	std::list<std::string> context () const {
+		return _context;
+	}
+
+private:
+	std::list<std::string> _context;
 };
 
 class MXFError : public std::runtime_error
diff --git a/src/subrip_reader.cc b/src/subrip_reader.cc
index 94a48c0..6fab0ff 100644
--- a/src/subrip_reader.cc
+++ b/src/subrip_reader.cc
@@ -83,6 +83,12 @@ SubripReader::read (function<optional<string> ()> get_line)
 		trim_right_if (*line, boost::is_any_of ("\n\r"));
 		remove_unicode_bom (line);
 
+		/* Keep some history in case there is an error to report */
+		_context.push_back (*line);
+		if (_context.size() > 5) {
+			_context.pop_front ();
+		}
+
 		switch (state) {
 		case COUNTER:
 		{
@@ -109,7 +115,13 @@ SubripReader::read (function<optional<string> ()> get_line)
 
 			boost::algorithm::split (p, *line, boost::algorithm::is_any_of (" "));
 			if (p.size() != 3 && p.size() != 7) {
-				throw SubripError (*line, "a time/position line");
+				for (int i = 0; i < 2; ++i) {
+					optional<string> ex = get_line ();
+					if (ex) {
+						_context.push_back (*ex);
+					}
+				}
+				throw SubripError (*line, "a time/position line", _context);
 			}
 
 			rs.from = convert_time (p[0]);
@@ -138,7 +150,7 @@ SubripReader::convert_time (string t)
 	vector<string> a;
 	boost::algorithm::split (a, t, boost::is_any_of (":"));
 	if (a.size() != 3) {
-		throw SubripError (t, "time in the format h:m:s,ms");
+		throw SubripError (t, "time in the format h:m:s,ms", _context);
 	}
 
 	vector<string> b;
diff --git a/src/subrip_reader.h b/src/subrip_reader.h
index 5f5f343..138d703 100644
--- a/src/subrip_reader.h
+++ b/src/subrip_reader.h
@@ -44,10 +44,12 @@ private:
 	friend struct ::subrip_reader_convert_time_test;
 	SubripReader () {}
 
-	static Time convert_time (std::string t);
+	Time convert_time (std::string t);
 	void convert_line (std::string t, RawSubtitle& p);
 	void maybe_content (RawSubtitle& p);
 	void read (boost::function<boost::optional<std::string> ()> get_line);
+
+	std::list<std::string> _context;
 };
 
 }
diff --git a/src/wscript b/src/wscript
index 9136ea1..a22c712 100644
--- a/src/wscript
+++ b/src/wscript
@@ -49,6 +49,7 @@ def build(bld):
               colour.h
               dcp_reader.h
               effect.h
+              exceptions.h
               font_size.h
               interop_dcp_reader.h
               rational.h