65 lines
2.3 KiB
Java
65 lines
2.3 KiB
Java
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import org.luaj.vm2.LuaValue;
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import org.luaj.vm2.lib.OneArgFunction;
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import org.luaj.vm2.lib.TwoArgFunction;
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/**
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* Sample library that can be called via luaj's require() implementation.
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*
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* This library, when loaded, creates a lua package called "hyperbolic"
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* which has two functions, "sinh()" and "cosh()".
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*
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* Because the class is in the default Java package, it can be called using
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* lua code such as:
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*
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<pre> {@code
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* require 'hyperbolic'
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* print('sinh', hyperbolic.sinh)
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* print('sinh(1.0)', hyperbolic.sinh(1.0))
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* }</pre>
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*
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* When require() loads the code, two things happen: 1) the public constructor
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* is called to construct a library instance, and 2) the instance is invoked
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* as a java call with no arguments. This invocation should be used to initialize
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* the library, and add any values to globals that are desired.
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*/
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public class hyperbolic extends TwoArgFunction {
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/** Public constructor. To be loaded via require(), the library class
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* must have a public constructor.
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*/
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public hyperbolic() {}
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/** The implementation of the TwoArgFunction interface.
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* This will be called once when the library is loaded via require().
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* @param modname LuaString containing the name used in the call to require().
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* @param env LuaValue containing the environment for this function.
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* @return Value that will be returned in the require() call. In this case,
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* it is the library itself.
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*/
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public LuaValue call(LuaValue modname, LuaValue env) {
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LuaValue library = tableOf();
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library.set( "sinh", new sinh() );
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library.set( "cosh", new cosh() );
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env.set( "hyperbolic", library );
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return library;
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}
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/* Each library function is coded as a specific LibFunction based on the
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* arguments it expects and returns. By using OneArgFunction, rather than
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* LibFunction directly, the number of arguments supplied will be coerced
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* to match what the implementation expects. */
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/** Mathematical sinh function provided as a OneArgFunction. */
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static class sinh extends OneArgFunction {
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public LuaValue call(LuaValue x) {
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return LuaValue.valueOf(Math.sinh(x.checkdouble()));
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}
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}
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/** Mathematical cosh function provided as a OneArgFunction. */
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static class cosh extends OneArgFunction {
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public LuaValue call(LuaValue x) {
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return LuaValue.valueOf(Math.cosh(x.checkdouble()));
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}
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}
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}
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