class ExprAST {
public:
virtual ~ExprAST() {}
- virtual Value *Codegen() = 0;
+ <b>virtual Value *Codegen() = 0;</b>
};
/// NumberExprAST - Expression class for numeric literals like "1.0".
double Val;
public:
explicit NumberExprAST(double val) : Val(val) {}
- virtual Value *Codegen();
+ <b>virtual Value *Codegen();</b>
};
...
</pre>
href="http://en.wikipedia.org/wiki/Static_single_assignment_form">Static Single
Assignment</a> - the concepts are really quite natural once you grok them.</p>
+<p>Note that instead of adding virtual methods to the ExprAST class hierarchy,
+it could also make sense to use a visitor pattern or some other way to model
+this. Again, this tutorial won't dwell on good software engineering practices:
+for our purposes, adding virtual methods is simplest.</p>
+
<p>The
second thing we want is an "Error" method like we used for parser, which will
be used to report errors found during code generation (for example, use of an