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Implementing lambdas 1
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‎README.md‎

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@@ -1,3 +1,94 @@
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NT Script
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Simple scripting langauge based on ANTLR4 that compiles into Java
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Simple scripting langauge based on ANTLR4 that compiles into Java
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## Language Reference ##
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- Variable assignment
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- `@name = <value>`
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- `@stringVariable = "hello world"`
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- `@daysInWeek = 7`
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- `@boolVal = True`
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- Conditionals
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- ```
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IF @boolVal
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<Do stuff>
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END
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- Loops
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- ```
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FOREACH @item IN @array
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<statements>
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END
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- Function call
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- `fnName{namedArg1=@variable1, namedArg3=@variable3}`
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- Lambda expr
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- ```
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@param1 = "text"
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@param2 = 456789
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@fn = FUNCTION @param1, @param2
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<statements>
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END
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## API ##
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The compiler will generate only method bodies from the script. annotate method that you wish to generate
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```
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public abstract class Test {
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@ScriptMeta.ScriptTarget
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public abstract Result test();
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}
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```
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To call java method from the script first define an annotated proxy
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```
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@ScriptMeta.Function("print")
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public class PrintFn {
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@ScriptMeta.Handler
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public void print(@ScriptMeta.NamedParam("val") Object o, @ScriptMeta.NamedParam("int") int i) {
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System.out.println(o);
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System.out.println(i);
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}
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}
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```
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and provide its instanceto the context via add the builder
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```
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NTScript context = new NTScript.Builder()
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.package_("cz.neumimto.test")
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.debugOutput("/tmp/test")
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.implementingType(Test.class)
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.withEnum(Result.class)
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.add(List.of(new PrintFn()))
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.setClassNamePattern("aaa")
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.build();
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Class aClass = script.parseScript("""
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@textVariable = "abcd"
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print{val=@textVariable}
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RETURN Result.OK
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""");
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```
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The compiler will generate class as follows:
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```
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public class aaa0 extends Test {
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public PrintFn PrintFn;
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public Result test() {
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String var1 = "abcd";
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PrintFn.print(var1, null) ;
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return Result.OK
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}
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}
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```
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- After calling constructor you should inject the PrintFn field.
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- If you are using some sort of DI such as Guice you can use Builder methods `classAnnotations` and `fieldAnnotations` for simpler initialization.

‎src/main/java/cz/neumimto/nts/NTScript.java‎

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Original file line numberDiff line numberDiff line change
@@ -145,10 +145,10 @@ public ClassVisitor wrap(TypeDescription instrumentedType, ClassVisitor classVis
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List<Scope> scopes = visitor.getImpl().getScopes();
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148-
for (int i = scopes.size()-1; i > 1; i--) {
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for (int i = scopes.size()-1; i > 0; i--) {
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Scope scope = scopes.get(i);
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151-
bb = bb.defineMethod("lambda$"+i+"$a", void.class, Opcodes.ACC_PRIVATE | Opcodes.ACC_SYNTHETIC)
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bb = bb.defineMethod(Scope.LAMBDA_METHOD_NAME.apply(i), void.class, Opcodes.ACC_PRIVATE | Opcodes.ACC_SYNTHETIC)
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.intercept(new Implementation() {
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@Override
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public ByteCodeAppender appender(Target implementationTarget) {
@@ -191,9 +191,7 @@ private Implementation getImplementation(VisitorImpl visitor) {
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public ByteCodeAppender appender(Target implementationTarget) {
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return (methodVisitor, implementationContext, instrumentedMethod) -> {
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List<StackManipulation> impl = visitor.getImpl().getScopes().iterator().next().impl;
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List<StackManipulation> list = new ArrayList<>();
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list.addAll(impl);
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List<StackManipulation> impl = visitor.getImpl().getScopes().get(0).impl;
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StackManipulation.Size size = new StackManipulation.Compound(
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impl

‎src/main/java/cz/neumimto/nts/Scope.java‎

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@@ -4,8 +4,11 @@
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import net.bytebuddy.implementation.bytecode.StackManipulation;
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import java.util.*;
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import java.util.function.Function;
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public class Scope {
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public static Function<Integer, String> LAMBDA_METHOD_NAME = i -> "lambda$a$" + i;
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public final Map<String, Variable> variables;
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private final List<Scope> parentsForVarLookup;

‎src/main/java/cz/neumimto/nts/ScriptContext.java‎

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@@ -2,15 +2,18 @@
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import cz.neumimto.nts.bytecode.Variable;
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import net.bytebuddy.description.type.TypeDescription;
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import net.bytebuddy.dynamic.scaffold.InstrumentedType;
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import net.bytebuddy.implementation.bytecode.member.MethodVariableAccess;
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import java.lang.reflect.Method;
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import java.util.*;
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import static cz.neumimto.nts.annotations.ScriptMeta.*;
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import static cz.neumimto.nts.annotations.ScriptMeta.Function;
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import static cz.neumimto.nts.annotations.ScriptMeta.Handler;
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public class ScriptContext {
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private List<Scope> scopes = new ArrayList<>();
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int currentScopeIdx = 0;
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private final Collection<Object> mechanics;

‎src/main/java/cz/neumimto/nts/bytecode/InvokeDynamic.java‎

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@@ -1,5 +1,7 @@
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package cz.neumimto.nts.bytecode;
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import cz.neumimto.nts.Scope;
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import cz.neumimto.nts.ScriptContext;
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import net.bytebuddy.description.type.TypeDescription;
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import net.bytebuddy.implementation.Implementation;
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import net.bytebuddy.implementation.bytecode.StackManipulation;
@@ -12,10 +14,19 @@
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import java.lang.invoke.LambdaMetafactory;
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import java.lang.invoke.MethodHandles;
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import java.lang.invoke.MethodType;
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import java.util.List;
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import java.util.Map;
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import java.util.stream.Collectors;
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public class InvokeDynamic implements StackManipulation {
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private final Map<String, Variable> fnVars;
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private ScriptContext scriptContext;
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public InvokeDynamic(ScriptContext scriptContext, Map<String, Variable> fnVars) {
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this.scriptContext = scriptContext;
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this.fnVars = fnVars;
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}
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@Override
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public boolean isValid() {
@@ -24,24 +35,26 @@ public boolean isValid() {
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@Override
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public Size apply(MethodVisitor methodVisitor, Implementation.Context implementationContext) {
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// String descriptor = "(%s)Ljava/lang/Runnable;";
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// String k = ctx.localVariables().values().stream().map(a-> new TypeDescription.ForLoadedType(a.aClass).getDescriptor()).collect(Collectors.joining());
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// descriptor = descriptor.replaceAll("%s",ctx.thisType().getDescriptor() + k);
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//
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// methodVisitor.visitInvokeDynamicInsn("run",
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// descriptor,
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// new Handle(Opcodes.H_INVOKESTATIC,
34-
// new TypeDescription.ForLoadedType(LambdaMetafactory.class).getInternalName(),
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// "metafactory",
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// MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class, MethodType.class, String.class, Object[].class).toMethodDescriptorString(),
37-
// false),
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// Type.VOID_TYPE,
39-
// new Handle(Opcodes.H_INVOKESPECIAL,
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// this.ctx.thisType().getInternalName(),
41-
// methodName,
42-
// "("+k+")V",
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// false),
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// Type.VOID_TYPE);
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String descriptor = "(%s)Ljava/lang/Runnable;";
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String k = fnVars.values().stream()
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.map(a-> new TypeDescription.ForLoadedType(a.getRuntimeType()).getDescriptor())
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.collect(Collectors.joining());
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descriptor = descriptor.replaceAll("%s",scriptContext.getInsnType().getDescriptor() + k);
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methodVisitor.visitInvokeDynamicInsn("run",
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descriptor,
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new Handle(Opcodes.H_INVOKESTATIC,
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new TypeDescription.ForLoadedType(LambdaMetafactory.class).getInternalName(),
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"metafactory",
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MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class, MethodType.class, String.class, Object[].class).toMethodDescriptorString(),
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false),
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Type.VOID_TYPE,
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new Handle(Opcodes.H_INVOKESPECIAL,
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scriptContext.getInsnType().getInternalName(),
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Scope.LAMBDA_METHOD_NAME.apply(scriptContext.getScopes().size() - 1),
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"("+k+")V",
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false),
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Type.VOID_TYPE);
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return null;
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}
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}

‎src/main/java/cz/neumimto/nts/bytecode/VisitorImpl.java‎

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@@ -255,7 +255,7 @@ public ScriptContext visitLambda(ntsParser.LambdaContext ctx) {
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addInsn(fnVar.load());
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}
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258-
addInsn(new InvokeDynamic());
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addInsn(new InvokeDynamic(scriptContext, fnVars));
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scriptContext.createNewScopeWithVars(fnVars);
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visitChildren(ctx.statement_list());

‎src/test/java/cz/neumimto/nts/P.java‎

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@ScriptMeta.Function("print")
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public class P {
7-
int i = 0;
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@ScriptMeta.Handler
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public void print(@ScriptMeta.NamedParam("val") Object o, @ScriptMeta.NamedParam("int") int i) {
109
System.out.println(o);
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System.out.println(i);
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}
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}

‎src/test/java/cz/neumimto/nts/Tests.java‎

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@@ -66,9 +66,9 @@ public void test() throws Exception {
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@lesser = @int <= 70000
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69-
# @function = fn @int @lesser
70-
# print{val=@int}
71-
# END
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@function = fn @int @lesser
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print{val="FN"}
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END
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RETURN Result.OK

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