APPENDIX A
A Complete Front End
The complete compiler front end in this appendix is based on the informally described simple compiler of Sections 2.5–2.8. The main difference from Chapter 2 is that the front end generates jumping code for boolean expressions, as in Section 6.6. We begin with the syntax of the source language, described by a grammar that needs to be adapted for top-down parsing.
The Java code for the translator consists of five packages: main, lexer, symbols, parser, and inter. Package inter contains classes for the language constructs in the abstract syntax. Since the code for the parser interacts with the rest of the packages, it will be discussed last. Each package is stored as a separate directory with a file per class.
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