org.snapscript.tree.variable.Variable Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of snap Show documentation
Dynamic scripting for the JVM
The newest version!
package org.snapscript.tree.variable;

import java.util.concurrent.atomic.AtomicReference;

import org.snapscript.core.Compilation;
import org.snapscript.core.Context;
import org.snapscript.core.Evaluation;
import org.snapscript.core.constraint.Constraint;
import org.snapscript.core.convert.proxy.ProxyWrapper;
import org.snapscript.core.error.ErrorHandler;
import org.snapscript.core.link.ImplicitImportLoader;
import org.snapscript.core.module.Module;
import org.snapscript.core.module.Path;
import org.snapscript.core.scope.Scope;
import org.snapscript.core.scope.index.Address;
import org.snapscript.core.scope.index.ScopeIndex;
import org.snapscript.core.scope.index.LocalValueFinder;
import org.snapscript.core.variable.Value;
import org.snapscript.core.variable.bind.VariableBinder;
import org.snapscript.tree.NameReference;

public class Variable implements Compilation {
   
   private final NameReference reference;
   
   public Variable(Evaluation identifier) {
      this.reference = new NameReference(identifier);
   }
   
   @Override
   public Evaluation compile(Module module, Path path, int line) throws Exception {
      Scope scope = module.getScope();
      Context context = module.getContext();
      ErrorHandler handler = context.getHandler();
      ProxyWrapper wrapper = context.getWrapper();
      String name = reference.getName(scope);
      
      return new CompileResult(handler, wrapper, name);
   }
   
   private static class CompileResult extends Evaluation {
      
      private final AtomicReference location;
      private final ImplicitImportLoader loader;
      private final LocalValueFinder finder;
      private final VariableBinder binder;
      private final String name;
      
      public CompileResult(ErrorHandler handler, ProxyWrapper wrapper, String name) {
         this.binder = new VariableBinder(handler, wrapper, name);
         this.location = new AtomicReference();
         this.finder = new LocalValueFinder(name);
         this.loader = new ImplicitImportLoader();
         this.name = name;
      }
   
      @Override
      public void define(Scope scope) throws Exception{
         ScopeIndex index = scope.getIndex();
         Address address = index.get(name);
         
         if(address == null) {
            loader.loadImports(scope, name); // static reference
         } else {
            location.set(address);
         }
      }
      
      @Override
      public Constraint compile(Scope scope, Constraint left) throws Exception{
         Address address = location.get();
         Value value = finder.findValue(scope, address);
         
         if(value == null) {
            return binder.compile(scope);
         }
         return value.getConstraint();
      } 
      
      @Override
      public Value evaluate(Scope scope, Value left) throws Exception{
         Address address = location.get();
         Value value = finder.findValue(scope, address);
         
         if(value == null) {
            return binder.bind(scope);
         }
         return value;
      } 
   }
}