This is based on the Expression Evaluator grammar by Terrence Parr. The grammar for this example: grammar Expr002; options { output=AST; ASTLabelType=CommonTree; // type of $stat.tree ref etc… } prog : ( stat )+ ; stat : expr NEWLINE -> expr | ID ‘=’ expr NEWLINE -> ^(‘=’ ID expr) | NEWLINE -> ; expr … Read more
None; no copies are done. The address of the caller’s Data return value is actually passed as a hidden argument to the function, and the createData function simply writes into the caller’s stack frame. This is known as the named return value optimisation. Also see the c++ faq on this topic. commercial-grade C++ compilers implement … Read more
To augment Dave’s answer, here is a translation schema for ‘for-comprehensions’ from Scala language specification: A comprehension for (enums) yield e evaluates expression e for each binding generated by the enumerators enums. An enumerator sequence always starts with a generator; this can be followed by further generators, value definitions, or guards. A generator p <- … Read more
The best paper I ever read on compilers is dated 1964 “META II a syntax-oriented compiler writing language” by Val Schorre. (http://doi.acm.org/10.1145/800257.808896) In 10 pages, he shows you how to build an astoundingly simple but very effective compiler-compiler, provides you with with the compiler-compiler grammar and provides you with enough details for you to hand … Read more