Crafting a Compiler: Bottom-Up Parsing

Chapter 6: Bottom-Up Parsing

Lab

Getting Started

Locate and install the lab6 project into your eclipse workspace as directed by your instructor, following the usual instructions, including those for an ant build.
Browse this lab document to get an idea of the work you will do for this assignment.

Abstract: In Lab 5, you implemented the Add Haque language using recursive-descent parsing. In this lab, you implement the same language using bottom-up parsing.

Assignment

Here is a summary of the files for this project:

`addhaque.cup`	The CUP grammar specification file.
`TestFiles`	The directory of test files for this project
`bup.java`	Contains the `main` for your bottom-up parser. There is a corresponding `ant` target `bup` that executes the bottom-up parser on each test file in the `TestFiles` directory.

Augment the given CUP grammar specification to include actions that compute the values of the expressions bottom-up. For each outermost expression, print the value associated with the expression. For this part, you will modify only the file addhaque.cup.
Note that this file is already suitable for bottom-up parsing! You should not use your top-down grammar from Lab 5 for this lab.
However, some modifications to the grammar can make your job substantially easier.
Notes:
- In adding actions to the CUP specification file, consider changing the grammar to ease processing (while recognizing the same language, of course!).
- Be certainly only to modify the addhaque.cup file.
- Do not use any global variables in your approach. Have each rule generate results that are passed up as the parse proceeds.
- There is an additional semantic type available for your use: IntPair. If a nonterminal is declared of that type, then for semantic symbol s you can use s.int1 and s.int2. You may find this useful for mean in your bottom-up parser.