From 2815449aa1c2a3c813f50ff85325cc2a3334430c Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 28 Mar 2021 16:12:35 +0300
Subject: [PATCH] Refactor lexical conversion of vertex attributes

There was an error in the size of the base string for the GENERIC
attribute, causing it to never match.  Using a utility function makes
it less dependent on magic numbers.

Color is still handled specially because of the type suffix.
---
 source/core/vertexformat.cpp | 66 ++++++++++++++++++++----------------
 1 file changed, 36 insertions(+), 30 deletions(-)

diff --git a/source/core/vertexformat.cpp b/source/core/vertexformat.cpp
index 2ce02e2e..65bbea49 100644
--- a/source/core/vertexformat.cpp
+++ b/source/core/vertexformat.cpp
@@ -105,12 +105,40 @@ VertexAttribute make_indexed_attribute(VertexAttribute attr, unsigned index)
 	return static_cast<VertexAttribute>(base+index*8);
 }
 
+
+bool convert_attribute(const string &str, const char *name, int min_size, int max_size, VertexAttribute &attr, VertexAttribute base_attr)
+{
+	string::const_iterator i = str.begin();
+	for(; *name; ++name, ++i)
+		if(*i!=*name)
+			return false;
+	if(i==str.end() || *i<'0'+min_size || *i>'0'+max_size)
+		return false;
+	VertexAttribute result = static_cast<VertexAttribute>(base_attr+(*i-'0'-min_size));
+
+	if(++i!=str.end())
+	{
+		if(*i!='_' || ++i==str.end())
+			return false;
+		try
+		{
+			result = make_indexed_attribute(result, lexical_cast<unsigned>(string(i, str.end())));
+		}
+		catch(...)
+		{
+			// The operator>> will throw a more appropriate exception
+			return false;
+		}
+	}
+
+	attr = result;
+	return true;
+}
+
 void operator>>(const LexicalConverter &conv, VertexAttribute &a)
 {
 	const string &str = conv.get();
-	if(str.size()==7 && !str.compare(0, 6, "VERTEX") && str[6]>='2' && str[6]<='4')
-		a = static_cast<VertexAttribute>(VERTEX2+(str[6]-'2'));
-	else if(str=="NORMAL3")
+	if(str=="NORMAL3")
 		a = NORMAL3;
 	else if(str.size()==12 && !str.compare(0, 5, "COLOR") && str[5]>='3' && str[5]<='4' && !str.compare(6, 6, "_FLOAT"))
 		a = static_cast<VertexAttribute>(COLOR3_FLOAT+(str[5]-'3'));
@@ -120,33 +148,11 @@ void operator>>(const LexicalConverter &conv, VertexAttribute &a)
 		a = TANGENT3;
 	else if(str=="BINORMAL3")
 		a = BINORMAL3;
-	else if(str.size()==6 && !str.compare(0, 5, "GROUP") && str[5]>='1' && str[5]<='4')
-		a = static_cast<VertexAttribute>(GROUP1+(str[5]-'1'));
-	else if(str.size()==7 && !str.compare(0, 6, "WEIGHT") && str[6]>='1' && str[6]<='4')
-		a = static_cast<VertexAttribute>(WEIGHT1+(str[6]-'1'));
-	else if(str.size()>=9 && !str.compare(0, 8, "TEXCOORD") && str[8]>='1' && str[8]<='4')
-	{
-		if(str.size()==9)
-			a = static_cast<VertexAttribute>(TEXCOORD1+(str[8]-'1'));
-		else if(str.size()==11 && str[9]=='_' && str[10]>='0' && str[10]<='3')
-			a = make_indexed_attribute(static_cast<VertexAttribute>(TEXCOORD1+(str[8]-'1')), str[10]-'0');
-		else
-			throw lexical_error(format("conversion of '%s' to VertexAttribute", str));
-	}
-	else if(str.size()>=10 && !str.compare(0, 6, "GENERIC") && str[7]>='1' && str[7]<='4' && str[8]=='_')
-	{
-		unsigned n;
-		try
-		{
-			n = lexical_cast<unsigned>(str.substr(9));
-		}
-		catch(const lexical_error &)
-		{
-			throw lexical_error(format("conversion of '%s' to VertexAttribute", str));
-		}
-		a = make_indexed_attribute(static_cast<VertexAttribute>(GENERIC1+(str[7]-'1')), n);
-	}
-	else
+	else if(!convert_attribute(str, "VERTEX", 2, 4, a, VERTEX2) &&
+		!convert_attribute(str, "GROUP", 1, 4, a, GROUP1) &&
+		!convert_attribute(str, "WEIGHT", 1, 4, a, WEIGHT1) &&
+		!convert_attribute(str, "TEXCOORD", 1, 4, a, TEXCOORD1) &&
+		!convert_attribute(str, "GENERIC", 1, 4, a, GENERIC1))
 		throw lexical_error(format("conversion of '%s' to VertexAttribute", str));
 }
 
-- 
2.45.2