src/main/java/org/luaj/vm3/lib/TableLib.java

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package org.luaj.vm3.lib;

import org.luaj.vm3.LuaTable;
import org.luaj.vm3.LuaValue;
import org.luaj.vm3.Varargs;

/** 
 * Subclass of {@link LibFunction} which implements the lua standard {@code table} 
 * library. 
 * 
 * <p>
 * Typically, this library is included as part of a call to either 
 * {@link JsePlatform#standardGlobals()} or {@link JmePlatform#standardGlobals()}
 * <pre> {@code
 * Globals globals = JsePlatform.standardGlobals();
 * System.out.println( globals.get("table").get("length").call( LuaValue.tableOf() ) );
 * } </pre>
 * <p>
 * To instantiate and use it directly, 
 * link it into your globals table via {@link LuaValue#load(LuaValue)} using code such as:
 * <pre> {@code
 * Globals globals = new Globals();
 * globals.load(new JseBaseLib());
 * globals.load(new PackageLib());
 * globals.load(new TableLib());
 * System.out.println( globals.get("table").get("length").call( LuaValue.tableOf() ) );
 * } </pre>
 * <p>
 * This has been implemented to match as closely as possible the behavior in the corresponding library in C.
 * @see LibFunction
 * @see JsePlatform
 * @see JmePlatform
 * @see <a href="http://www.lua.org/manual/5.2/manual.html#6.5">Lua 5.2 Table Lib Reference</a>
 */
public class TableLib extends TwoArgFunction {

	public LuaValue call(LuaValue modname, LuaValue env) {
		LuaTable table = new LuaTable();
		table.set("concat", new concat());
		table.set("insert", new insert());
		table.set("pack", new pack());
		table.set("remove", new remove());
		table.set("sort", new sort());
		table.set("unpack", new unpack());
		env.set("table", table);
		env.get("package").get("loaded").set("table", table);
		return NIL;
	}

	static class TableLibFunction extends LibFunction {
		public LuaValue call() {
			return argerror(1, "table expected, got no value");
		}
	}

	// "concat" (table [, sep [, i [, j]]]) -> string
	static class concat extends TableLibFunction {
		public LuaValue call(LuaValue list) {
			return list.checktable().concat(EMPTYSTRING, 1, list.length());
		}

		public LuaValue call(LuaValue list, LuaValue sep) {
			return list.checktable().concat(sep.checkstring(), 1, list.length());
		}

		public LuaValue call(LuaValue list, LuaValue sep, LuaValue i) {
			return list.checktable().concat(sep.checkstring(), i.checkint(), list.length());
		}

		public LuaValue call(LuaValue list, LuaValue sep, LuaValue i, LuaValue j) {
			return list.checktable().concat(sep.checkstring(), i.checkint(), j.checkint());
		}
	}

	// "insert" (table, [pos,] value) -> prev-ele
	static class insert extends TableLibFunction {
		public LuaValue call(LuaValue list) {
			return argerror(2, "value expected");
		}

		public LuaValue call(LuaValue table, LuaValue value) {
			table.checktable().insert(table.length() + 1, value);
			return NONE;
		}

		public LuaValue call(LuaValue table, LuaValue pos, LuaValue value) {
			table.checktable().insert(pos.checkint(), value);
			return NONE;
		}
	}

	// "pack" (...) -> table
	static class pack extends VarArgFunction {
		public Varargs invoke(Varargs args) {
			LuaValue t = tableOf(args, 1);
			t.set("n", args.narg());
			return t;
		}
	}

	// "remove" (table [, pos]) -> removed-ele
	static class remove extends TableLibFunction {
		public LuaValue call(LuaValue list) {
			return list.checktable().remove(0);
		}

		public LuaValue call(LuaValue list, LuaValue pos) {
			return list.checktable().remove(pos.checkint());
		}
	}

	// "sort" (table [, comp])
	static class sort extends TwoArgFunction {
		public LuaValue call(LuaValue table, LuaValue compare) {
			table.checktable().sort(compare.isnil() ? NIL : compare.checkfunction());
			return NONE;
		}
	}

	// "unpack", // (list [,i [,j]]) -> result1, ...
	static class unpack extends VarArgFunction {
		public Varargs invoke(Varargs args) {
			LuaTable t = args.checktable(1);
			switch (args.narg()) {
			case 1:
				return t.unpack();
			case 2:
				return t.unpack(args.checkint(2));
			default:
				return t.unpack(args.checkint(2), args.checkint(3));
			}
		}
	}
}