Added seek function to CharReader, improved getOffset

2 files changed, 34 insertions, 9 deletions

diff --git a/src/core/common/CharReader.cpp b/src/core/common/CharReader.cpp
index 6fd3d45..07482ff 100644
--- a/src/core/common/CharReader.cpp
+++ b/src/core/common/CharReader.cpp
@@ -502,16 +502,31 @@ size_t CharReader::readRaw(char *buf, size_t size)
 	return res;
 }
 
+size_t CharReader::seek(size_t requestedOffset)
+{
+	// Fetch the current offset
+	const ssize_t currentOffs = getOffset();
+	const ssize_t relativeOffs = requestedOffset - currentOffs;
+
+	// Perform the actual seeking, move the peek cursor to the read cursor
+	const ssize_t reachedOffs =  currentOffs + buffer->moveCursor(readCursor, relativeOffs);
+	buffer->copyCursor(readCursor, peekCursor);
+	coherent = true;
+
+	// Clamp to values larger or equal to zero
+	return reachedOffs < 0 ? 0 : reachedOffs;
+}
+
 bool CharReader::atEnd() const { return buffer->atEnd(readCursor); }
 
-SourceOffset CharReader::getOffset() const
+size_t CharReader::getOffset() const
 {
 	return buffer->offset(readCursor) + offs;
 }
 
-SourcePosition CharReader::getPosition() const
+size_t CharReader::getPeekOffset() const
 {
-	return getOffset();
+	return buffer->offset(readCursor) + offs;
 }
 
 SourceLocation CharReader::getLocation() const
diff --git a/src/core/common/CharReader.hpp b/src/core/common/CharReader.hpp
index 5a4d906..cbd7b74 100644
--- a/src/core/common/CharReader.hpp
+++ b/src/core/common/CharReader.hpp
@@ -297,8 +297,7 @@ public:
 	 * @param relativeOffs is a positive or negative integer number specifying
 	 * the number of bytes the cursor should be moved forward (positive numbers)
 	 * or backwards (negative numbers).
-	 * @return the actual number of bytes the cursor was moved. This number is
-	 * smaller than the relativeOffs given in the constructor if the
+	 * @return the actual number of bytes the cursor was moved.
 	 */
 	ssize_t moveCursor(CursorId cursor, ssize_t relativeOffs);
 
@@ -523,6 +522,17 @@ public:
 	size_t readRaw(char *buf, size_t size);
 
 	/**
+	 * Moves read and peek cursor to the requested offset. Returns the offset
+	 * that was actually reached.
+	 *
+	 * @param requestedOffset is the requested offset. This offset may no longer
+	 * be reachable by the CharReader.
+	 * @return the actually reached offset. The operation was successful, if
+	 * the requested and reached offset are equal.
+	 */
+	size_t seek(size_t requestedOffset);
+
+	/**
 	 * Returns true if there are no more characters as the stream was closed.
 	 *
 	 * @return true if there is no more data.
@@ -534,14 +544,14 @@ public:
 	 *
 	 * @return the offset of the read cursor in bytes.
 	 */
-	SourceOffset getOffset() const;
+	size_t getOffset() const;
 
 	/**
-	 * Returns the offset of the read cursor in bytes.
+	 * Returns the offset of the peek cursor in bytes.
 	 *
-	 * @return the offset of the read cursor in bytes.
+	 * @return the offset of the peek cursor in bytes.
 	 */
-	SourcePosition getPosition() const;
+	size_t getPeekOffset() const;
 
 	/**
 	 * Returns a SourceLocation object describing the exact position (including