bastools/api

BT API

The BASIC Tokenizer API is a set of reusable code that can be used to parse a text-based AppleSoft BASIC program an generate the appropriate tokens. It also has multiple types of visitors that can re-write that parse tree to rearrange the code (calling them optimizations is a bit over-the-top).

Overview

Generally, the usage pattern is:

1. Setup the Configuration.
2. Read the tokens.
3. Parse the tokens into a Program.
4. Apply transformations, if applicable.

Code snippets

Configuration config = Configuration.builder()
        .sourceFile(this.sourceFile)
        .build();

The Configuration class also allows the BASIC start address to be set (defaults to 0x801), set the maximum line length (this is in bytes, and defaults to 255, but feel free to experiment). Some of the classes report output via the debug stream, which defaults to a simple null stream (no output) - replace with System.out or another PrintStream.

Queue<Token> tokens = TokenReader.tokenize(config.sourceFile);

The list of tokens is a loose interpretation. It includes more of a compiler sense of tokens -- numbers, end of line markers (they're significant), AppleSoft tokens, strings, comments, identifiers, etc.

Parser parser = new Parser(tokens);
Program program = parser.parse();

The Program is now the parsed version of the BASIC program. Various Visitors may be used to report, gather information, or manipulate the tree in various ways.

Optimizations

Visitors