diff -r c72e3115a297 -r 67c6e5d32e68 src/model.cpp
--- a/src/model.cpp	Sun Jan 29 15:49:36 2017 +0200
+++ b/src/model.cpp	Sun Jan 29 21:02:11 2017 +0200
@@ -1,7 +1,9 @@
 #include "model.h"
 #include "ldObject.h"
+#include "documentmanager.h"
 
-Model::Model() {}
+Model::Model(DocumentManager* manager) :
+    _manager {manager} {}
 
 Model::~Model()
 {
@@ -197,3 +199,262 @@
 {
 	return _objects.isEmpty();
 }
+
+DocumentManager* Model::documentManager() const
+{
+	return _manager;
+}
+
+// =============================================================================
+//
+static void CheckTokenCount (const QStringList& tokens, int num)
+{
+	if (countof(tokens) != num)
+		throw QString (format ("Bad amount of tokens, expected %1, got %2", num, countof(tokens)));
+}
+
+// =============================================================================
+//
+static void CheckTokenNumbers (const QStringList& tokens, int min, int max)
+{
+	bool ok;
+	QRegExp scientificRegex ("\\-?[0-9]+\\.[0-9]+e\\-[0-9]+");
+
+	for (int i = min; i <= max; ++i)
+	{
+		// Check for floating point
+		tokens[i].toDouble (&ok);
+		if (ok)
+			return;
+
+		// Check hex
+		if (tokens[i].startsWith ("0x"))
+		{
+			tokens[i].mid (2).toInt (&ok, 16);
+
+			if (ok)
+				return;
+		}
+
+		// Check scientific notation, e.g. 7.99361e-15
+		if (scientificRegex.exactMatch (tokens[i]))
+			return;
+
+		throw QString (format ("Token #%1 was `%2`, expected a number (matched length: %3)",
+		    (i + 1), tokens[i], scientificRegex.matchedLength()));
+	}
+}
+
+// =============================================================================
+//
+static Vertex ParseVertex (QStringList& s, const int n)
+{
+	Vertex v;
+	v.apply ([&] (Axis ax, double& a) { a = s[n + ax].toDouble(); });
+	return v;
+}
+
+static int32 StringToNumber (QString a, bool* ok = nullptr)
+{
+	int base = 10;
+
+	if (a.startsWith ("0x"))
+	{
+		a.remove (0, 2);
+		base = 16;
+	}
+
+	return a.toLong (ok, base);
+}
+
+// =============================================================================
+// This is the LDraw code parser function. It takes in a string containing LDraw
+// code and returns the object parsed from it. parseLine never returns null,
+// the object will be LDError if it could not be parsed properly.
+// =============================================================================
+LDObject* Model::insertFromString(int position, QString line)
+{
+	try
+	{
+		QStringList tokens = line.split(" ", QString::SkipEmptyParts);
+
+		if (countof(tokens) <= 0)
+		{
+			// Line was empty, or only consisted of whitespace
+			return emplaceAt<LDEmpty>(position);
+		}
+
+		if (countof(tokens[0]) != 1 or not tokens[0][0].isDigit())
+			throw QString ("Illogical line code");
+
+		int num = tokens[0][0].digitValue();
+
+		switch (num)
+		{
+		    case 0:
+		    {
+			    // Comment
+			    QString commentText = line.mid (line.indexOf ("0") + 2);
+				QString commentTextSimplified = commentText.simplified();
+
+				// Handle BFC statements
+				if (countof(tokens) > 2 and tokens[1] == "BFC")
+				{
+					for (BfcStatement statement : iterateEnum<BfcStatement>())
+					{
+						if (commentTextSimplified == format("BFC %1", LDBfc::statementToString (statement)))
+							return emplaceAt<LDBfc>(position, statement);
+					}
+
+					// MLCAD is notorious for stuffing these statements in parts it
+					// creates. The above block only handles valid statements, so we
+					// need to handle MLCAD-style invertnext, clip and noclip separately.
+					if (commentTextSimplified == "BFC CERTIFY INVERTNEXT")
+						return emplaceAt<LDBfc>(position, BfcStatement::InvertNext);
+					else if (commentTextSimplified == "BFC CERTIFY CLIP")
+						return emplaceAt<LDBfc>(position, BfcStatement::Clip);
+					else if (commentTextSimplified == "BFC CERTIFY NOCLIP")
+						return emplaceAt<LDBfc>(position, BfcStatement::NoClip);
+				}
+
+				if (countof(tokens) > 2 and tokens[1] == "!LDFORGE")
+				{
+					// Handle LDForge-specific types, they're embedded into comments too
+					if (tokens[2] == "OVERLAY")
+					{
+						CheckTokenCount (tokens, 9);
+						CheckTokenNumbers (tokens, 5, 8);
+
+						LDOverlay* obj = emplaceAt<LDOverlay>(position);
+						obj->setFileName (tokens[3]);
+						obj->setCamera (tokens[4].toLong());
+						obj->setX (tokens[5].toLong());
+						obj->setY (tokens[6].toLong());
+						obj->setWidth (tokens[7].toLong());
+						obj->setHeight (tokens[8].toLong());
+						return obj;
+					}
+					else if (tokens[2] == "BEZIER_CURVE")
+					{
+						CheckTokenCount (tokens, 16);
+						CheckTokenNumbers (tokens, 3, 15);
+						LDBezierCurve* obj = emplaceAt<LDBezierCurve>(position);
+						obj->setColor (StringToNumber (tokens[3]));
+
+						for (int i = 0; i < 4; ++i)
+							obj->setVertex (i, ParseVertex (tokens, 4 + (i * 3)));
+
+						return obj;
+					}
+				}
+
+				// Just a regular comment:
+				return emplaceAt<LDComment>(position, commentText);
+		    }
+
+		    case 1:
+		    {
+			    // Subfile
+			    CheckTokenCount (tokens, 15);
+				CheckTokenNumbers (tokens, 1, 13);
+				LDDocument* document = _manager->getDocumentByName(tokens[14]);
+
+				// If we cannot open the file, mark it an error. Note we cannot use LDParseError
+				// here because the error object needs the document reference.
+				if (not document)
+				{
+					LDError* obj = emplaceAt<LDError>(position, line, format ("Could not open %1", tokens[14]));
+					obj->setFileReferenced (tokens[14]);
+					return obj;
+				}
+
+				Vertex referncePosition = ParseVertex (tokens, 2);  // 2 - 4
+				Matrix transform;
+
+				for (int i = 0; i < 9; ++i)
+					transform.value(i) = tokens[i + 5].toDouble(); // 5 - 13
+
+				LDSubfileReference* obj = emplaceAt<LDSubfileReference>(position, document, transform, referncePosition);
+				obj->setColor (StringToNumber (tokens[1]));
+				return obj;
+		    }
+
+		    case 2:
+		    {
+			    CheckTokenCount (tokens, 8);
+				CheckTokenNumbers (tokens, 1, 7);
+
+				// Line
+				LDLine* obj = emplaceAt<LDLine>(position);
+				obj->setColor (StringToNumber (tokens[1]));
+
+				for (int i = 0; i < 2; ++i)
+					obj->setVertex (i, ParseVertex (tokens, 2 + (i * 3)));   // 2 - 7
+
+				return obj;
+		    }
+
+		    case 3:
+		    {
+			    CheckTokenCount (tokens, 11);
+				CheckTokenNumbers (tokens, 1, 10);
+
+				// Triangle
+				LDTriangle* obj = emplaceAt<LDTriangle>(position);
+				obj->setColor (StringToNumber (tokens[1]));
+
+				for (int i = 0; i < 3; ++i)
+					obj->setVertex (i, ParseVertex (tokens, 2 + (i * 3)));   // 2 - 10
+
+				return obj;
+		    }
+
+		    case 4:
+		    case 5:
+		    {
+			    CheckTokenCount (tokens, 14);
+				CheckTokenNumbers (tokens, 1, 13);
+
+				// Quadrilateral / Conditional line
+				LDObject* obj;
+
+				if (num == 4)
+					obj = emplaceAt<LDQuad>(position);
+				else
+					obj = emplaceAt<LDCondLine>(position);
+
+				obj->setColor (StringToNumber (tokens[1]));
+
+				for (int i = 0; i < 4; ++i)
+					obj->setVertex (i, ParseVertex (tokens, 2 + (i * 3)));   // 2 - 13
+
+				return obj;
+		    }
+
+		    default:
+			    throw QString {"Unknown line code number"};
+		}
+	}
+	catch (QString& errorMessage)
+	{
+		// Strange line we couldn't parse
+		return emplaceAt<LDError>(position, line, errorMessage);
+	}
+}
+
+LDObject* Model::addFromString(QString line)
+{
+	return insertFromString(size(), line);
+}
+
+LDObject* Model::replaceWithFromString(LDObject* object, QString line)
+{
+	if (object and object->model() == this)
+	{
+		int position = object->lineNumber();
+		removeAt(position);
+		return insertFromString(position, line);
+	}
+	else
+		return nullptr;
+}