a-visual-llk-parser-generator
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A Visual IDE-Style LL(k) Parser Generator that uses an editable tree with icons for tokens and non-terminals to represent the grammar symbols and grammar rules.

The tool is completely interactive. Errors in the grammar are indicated by adorning the affected icons as the rule-tree is edited, and the generated parser code is displayed in an adjacent pane so the effect of edits on the rule-tree can be immediately verified.

The visual tree representation of grammar rules completely eliminates the need to use and understand cryptic specifications as used in YACC, ANTLR and JavaCC. The grammar is saved to (and read from) data files using pure-Java mechanisms.

The built-in scanner can also be customized for the application via the GUI.

1. Download the VisualLangLab.zip file. When unzipped, there should be five files: ReadMe.1st (summary instructions), VisualLangLab.jar (the Java executable), docs (the documentation directory) demos (some interesting demos) and test-cases (a directory for the test cases and data).
2. Start VisualLangLab by double clicking the VisualLangLab.jar icon (or using the command line: java -jar VisualLangLab.jar).
3. Recommended: Go directly to the Java-1.4 grammar (use the File->Open menu to choose the grammar file demos/java-1.4/java14C.lkv). Explore VisualLangLab features using this grammar. Please do not change any demo grammar files. Reading the documentation (in the file docs/index.html) at this stage is highly recommended.
4. You may generate the Java-1.4 parser using the File->Write code menu. Compile the generated parser (a file called java14C.java) as described below, and run as follows: java java14C -f <source-file>. A successful parse produces no output (error messages). Note: VisualLangLab.jar must be in the classpath during compilation as well as during execution.
5. The test-cases directory also contains several other pairs of grammar and input files (e.g. test_00_00.lkv and test_00_00.txt). Note: the grammar files (*.lkv) can be opened by VisualLangLab, but are not human-readable. The input files (*.txt) are text files, and contain parser testing input and comments.
6. Open a grammar file using the File->Open menu. (The file-chooser dialog only displays *.lkv files by default.)
7. Generate parser code using the File->Write code menu. A file named fooBar.java is created in the directory containing the grammar file (fooBar.lkv being the name of the grammar file).
8. Compile the parser: javac fooBar.java . Note: VisualLangLab.jar must be in the CLASSPATH.
9. Run the parser: java fooBar -f fooBar.txt. Note: VisualLangLab.jar must be in the CLASSPATH. The fooBar.txt files are the *.txt files in the test-cases directory.
10. When the demo runs as expected, the parser produces the output OK. Any other output indicates an error.
11. The parser generated from the grammar test_Exp_99.lkv (an expression evaluator) should be run with the input files named test_Exp_00.txt, test_Exp_01.txt etc.