added documentation and did some slight restructuring. it's party time.

nexgb/xgbgen/size.go

@@ -1,21 +1,30 @@
 package main
 
+// Size corresponds to an expression that represents the number of bytes
+// in some *thing*. Generally, sizes are used to allocate buffers and to
+// inform X how big requests are.
+// Size is basically a thin layer over an Expression that yields easy methods
+// for adding and multiplying sizes.
 type Size struct {
 	Expression
 }
 
+// newFixedSize creates a new Size with some fixed and known value.
 func newFixedSize(fixed uint) Size {
 	return Size{&Value{v: fixed}}
 }
 
+// newExpressionSize creates a new Size with some expression.
 func newExpressionSize(variable Expression) Size {
 	return Size{variable}
 }
 
+// Add adds s1 and s2 and returns a new Size.
 func (s1 Size) Add(s2 Size) Size {
 	return Size{newBinaryOp("+", s1, s2)}
 }
 
+// Multiply mupltiplies s1 and s2 and returns a new Size.
 func (s1 Size) Multiply(s2 Size) Size {
 	return Size{newBinaryOp("*", s1, s2)}
 }