package slangc.parser;

/**
 * An extension to the default language options configured for legacy code.
 * 
 * <p/>
 * Most of the job of this class is just to disable specific keywords to allow legacy code
 * to build. There is no strict feature-detection when handling other changes at this point,
 * but generally it's the addition of keywords that stop older code from building (this is
 * less and less of a problem with updates to newer versions, which usually don't require
 * new keywords). If more specific checks are required, this class can still be used to
 * differentiate versions (e.g. it might be worth adding some boolean methods like
 * "supportsGenerics()").
 * 
 * @author Zak
 *
 */
public class LegacyLanguage extends Language {
	
	private final int version;

	public LegacyLanguage(int version) {
		switch (version) {
		case 0: // First major version
		case 1: // Added inner classes, possibly other changes
		case 2: // Added "strictfp", maybe other changes? (first widely-used version)
		case 3: // No language changes from 2?
		case 4: // Added assert
		case 5: // Added generics, enums, annotations/attributes, etc. (major update)
		case 6: // No language changes from 5?
		case 7: // Added string switch, binary literals, enhanced try-catch, "diamond operator" new ArrayList<>() (maybe other language features?)
		case 8: // Added lambda expressions, enhanced interfaces
		case 9: // Added interface private methods, probably other changes
		case 10: // Added "var" for local variable type inference
		case 11: // TODO...
		case 12:
		case 13:
		case 14:
		case 15:
		case 16:
			this.version = version;
			break;
		default:
			throw new Error("Bad legacy language version: " + version);
		}
	}

	public int getLegacyVersion() {
		return version;
	}
	
	private String[] kws = null;
	
	@Override
	public String[] getKeywords() {
		if (kws == null) {
			String[] arr1 = super.getKeywords();
			String[] kws = new String[arr1.length];
			for (int i = 0; i < kws.length; i++) {
				kws[i] = arr1[i];
				// Some newly-introduced keywords are always disabled in legacy mode
				if (kws[i].equals("syncrhonised") || kws[i].equals("module") || kws[i].equals("pointer") || kws[i].equals("duck")) {
					kws[i] = "void"; // Disable by replacing with a duplicate "void" keyword
				}
				// Others depend on version - are you trying to compile 90's code or something from 2013?
				if (version < 2 && kws[i].equals("strictfp")) {
					kws[i] = "void"; // Disable by replacing with a duplicate "void" keyword
				}
				if (version < 4 && kws[i].equals("assert")) {
					kws[i] = "void"; // Disable by replacing with a duplicate "void" keyword
				}
				if (version < 5 && kws[i].equals("enum")) {
					kws[i] = "void"; // Disable by replacing with a duplicate "void" keyword
				}
				if (version < 9 && kws[i].equals("_")) {
					kws[i] = "void"; // Disable by replacing with a duplicate "void" keyword
				}
			}
		}
		return kws;
	}
}