Using our compiler

Use the Makefile to build the executables necessary to run the compiler:

make

Then you can use the compile script as a front-end of our compiler.

Run the script with one argument in order to put the given program through the full pipeline.

./compile path/program.wacc

Or you can specify what stage do you want your compiler to stop (only one at a time).

./compile -t path/program.wacc

• -t : Print the program as a stream of tokens: [SYMBOL, TEXT].
• -p : Print the parse tree and check for syntactic errors only.
• -s : Check for semantic errors and build the AST.
• -a : Generate code into an assembly file.
• -x : Executes the generated program and prints to the console.

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Provided files/directories

antlr_config <

The antlr_config directory contains simple example ANTLR lexer and parser specification files BasicLexer.g4 and Basic.g4, along with a script antlrBuild that builds the corresponding Java class files using the ANTLR libraries (more details below).

lib <

The lib directory contains the ANTLR library files in antlr-4.9.1-complete.jar. You should not need to make any changes in this directory.

src <

The src directory is currently empty (apart from a simple README file) and is where we expect you to write your compiler code.

grun <

The grun script allows you to run the ANTLR TestRig program that can assist you in debugging you lexer and parser (more details below).

compile <

The compile script should be edited to provide a frontend interface to your WACC compiler. You are free to change the language used in this script, but do not change its name (more details below).

Makefile <

Your Makefile should be edited so that running 'make' in the root directory builds your WACC compiler. Currently running 'make' will call the antlrBuild script and the attempt to compile all .java files within the src directory. Depending on the structure of your code, you might not need to modify this file.

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Using the provided scripts

antlrBuild <

This script takes a pair of ANTLR lexer and parser configuration files (set within the script) and creates the corresponding Java classes that you can use in your compiler. The Java files are written to the src/antlr directory and should not be modified by hand. By default this script is set up to generate a parse tree and a listerner pattern for traversing this tree, but you can modify the compilation options within the script if you want to produce different outputs

Important! - running the antlrBuild script will overwrite the antlr directory in the src directory. We heavily suggest you do not write any of your code within the src/antlr directory

grun <

This script provides access to the ANTLR TestRig program. You will probably find this helpful for testing your lexer and parser. The script is just a wrapper for the TestRig in the project environment. You need to tell it what grammar to use what rule to start parsing with and what kind of output you want.

For example: ./grun antlr.Basic prog -tokens will run the TestRig using the 'Basic' grammar, starting from the rule for 'prog' and outputting the tokens seen by the lexer. To see how the parser groups these tokens you can use the -tree or -gui options instead, such as: ./grun antlr.Basic prog -gui In either case you will need to type in your input program and then close the input stream with ctrl-D.

Rather than typing your input programs in by hand, you can pass the TestRig a file to read by piping it in through stdin with ./grun antlr.Basic expr -gui < testfile When using the TestRig in this way you won't need to hit ctrl-D to close the input stream as the EOF character in the file does this for you.

compile <

This script currently writes a TODO: message to the console, but you should update it to call the the main class of your compiler with appropriate arguments. Note that the lab's automated testing service will be using this script as the access point to your compiler.

You will need to add the ANTLR jar file to the classpath of your calls to Java if you want to be able to use any of the built in ANTLR features. You can do this be setting the -cp option on the command line e.g. java -cp bin:lib/antlr-4.9.1-complete.jar ...rest of call... note that the bin: ensures that the bin directory is still part of your java classpath.