Pascal编写的PL/0编译器源代码

用Pascal语言编写的PL/0编译器源代码。PL/0 is a programming language, intended as an educational programming language, that is similar to but much simpler than Pascal, a general-purpose programming language. It serves as an example of how to construct a compiler. It was originally introduced in the book, Algorithms + Data Structures = Programs, by Niklaus Wirth in 1976. It features quite limited language constructs: there are no real numbers, very few basic arithmetic operations and no control-flow constructs other than "if" and &quo t;while" blocks. While these limitations make writing real applications in this language impractical, it helps the compiler remain compact and simple.