2 files changed, 31 insertions, 7 deletions
diff --git a/src/core/common/SourceContextReader.cpp b/src/core/common/SourceContextReader.cpp
index 65a6281..d5d379c 100644
--- a/src/core/common/SourceContextReader.cpp
+++ b/src/core/common/SourceContextReader.cpp
@@ -56,8 +56,8 @@ SourceContext SourceContextReader::readContext(CharReader &reader,
 	size_t offs = 0;
 	auto it = std::lower_bound(cache.begin(), cache.end(), start);
 	if (it != cache.begin()) {
-		it--;  // Go to the previous entry
-		offs = *it; // Read the corresponding byte offset
+		it--;        // Go to the previous entry
+		offs = *it;  // Read the corresponding byte offset
 		size_t line = it - cache.begin() + 1;
 		ctx.startLine = line;
 		ctx.endLine = line;
@@ -182,17 +182,23 @@ SourceContext SourceContextReader::readContext(CharReader &reader,
 		}
 
 		// Update the relative position and length, set the "truncated" flags
-		size_t us = static_cast<size_t>(s), ue = static_cast<size_t>(e);
-		ctx.relPos = start - lineBufStart - us;
-		ctx.relLen = std::min(ctx.relLen, ue - us);
+		ctx.relPos = std::max<ssize_t>(0, start - lineBufStart - s);
+		ctx.relLen = std::min<ssize_t>(ctx.relLen, e - s);
 		ctx.truncatedStart = s > ts || lastLineStart < lineBufStart;
 		ctx.truncatedEnd = e < te;
 
 		// Copy the selected area to the output string
-		ctx.text = std::string{&lineBuf[s], ue - us};
+		ctx.text = std::string{&lineBuf[s], static_cast<size_t>(e - s)};
 	}
 
 	return ctx;
 }
+
+SourceContext SourceContextReader::readContext(CharReader &reader,
+                                               const SourceRange &range,
+                                               const std::string &filename)
+{
+	return readContext(reader, range, MAX_MAX_CONTEXT_LENGTH, filename);
+}
 }
 
diff --git a/src/core/common/SourceContextReader.hpp b/src/core/common/SourceContextReader.hpp
index 35e71b3..cd29880 100644
--- a/src/core/common/SourceContextReader.hpp
+++ b/src/core/common/SourceContextReader.hpp
@@ -82,7 +82,25 @@ public:
 	 * @return a SourceContext instance describing the
 	 */
 	SourceContext readContext(CharReader &reader, const SourceRange &range,
-	                          size_t maxContextLength = MAX_MAX_CONTEXT_LENGTH,
+	                          size_t maxContextLength,
+	                          const std::string &filename = "");
+
+	/**
+	 * Returns the context for the char reader and the given SourceRange.
+	 * Returns an invalid source context if either the given range is invalid
+	 * or the byte offset described in the SourceRange cannot be reached because
+	 * the CharReader cannot be seeked back to this position. Does not limit
+	 * the output context.
+	 *
+	 * @param reader is the CharReader instance from which the context should be
+	 * read.
+	 * @param range describes the Range within the source file for which the
+	 * context should be extraced.
+	 * @param filename is the filename that should be stored in the returned
+	 * context.
+	 * @return a SourceContext instance describing the
+	 */
+	SourceContext readContext(CharReader &reader, const SourceRange &range,
 	                          const std::string &filename = "");
 };
 }