bundles/org.simantics.scl.compiler/src/org/simantics/scl/compiler/internal/elaboration/constraints/Constraint.java

   1 package org.simantics.scl.compiler.internal.elaboration.constraints;
   2
   3 import java.util.ArrayList;
   4
   5 import org.simantics.scl.compiler.constants.Constant;
   6 import org.simantics.scl.compiler.elaboration.expressions.EApply;
   7 import org.simantics.scl.compiler.elaboration.expressions.EApplyType;
   8 import org.simantics.scl.compiler.elaboration.expressions.ELiteral;
   9 import org.simantics.scl.compiler.elaboration.expressions.EVariable;
  10 import org.simantics.scl.compiler.elaboration.expressions.Expression;
  11 import org.simantics.scl.compiler.elaboration.expressions.Variable;
  12 import org.simantics.scl.compiler.internal.codegen.utils.TransientClassBuilder;
  13 import org.simantics.scl.compiler.top.SCLCompilerConfiguration;
  14 import org.simantics.scl.compiler.types.TPred;
  15 import org.simantics.scl.compiler.types.Type;
  16 import org.simantics.scl.compiler.types.Types;
  17 import org.simantics.scl.compiler.types.util.Typed;
  18 import org.simantics.scl.runtime.tuple.Tuple0;
  19
  20 public class Constraint implements Typed {
  21     public static final Constraint[] EMPTY_ARRAY = new Constraint[0];
  22
  23     public static final int STATE_UNSOLVED = 0;
  24     public static final int STATE_HAS_INSTANCE = 1;
  25     public static final int STATE_HAS_SUBCLASS = 2;
  26     public static final int STATE_GIVEN = 3;
  27
  28     public static final Expression GIVEN_GENERATOR = new ELiteral(new Constant(Types.UNIT) {
  29         @Override
  30         public Object realizeValue(TransientClassBuilder classBuilder) {
  31             return Tuple0.INSTANCE;
  32         }
  33     });
  34
  35     public TPred constraint;
  36     int state = STATE_UNSOLVED;
  37     public final Variable evidence;
  38     Expression generator;
  39     Type[] generatorParameters;
  40     Constraint[] dependsOn;
  41     boolean handled;
  42     long demandLocation;
  43
  44     public Constraint(TPred constraint, Variable evidence, long demandLocation) {
  45         if(SCLCompilerConfiguration.DEBUG) {
  46             if(constraint == null || evidence == null)
  47                 throw new NullPointerException();
  48         }
  49         this.constraint = constraint;
  50         this.evidence = evidence;
  51         this.demandLocation = demandLocation;
  52     }
  53
  54     public void setGenerator(int newState, Expression generator, Type[] generatorParameters, Constraint ... dependsOn) {
  55         if(SCLCompilerConfiguration.DEBUG) {
  56             if(generator == null)
  57                 throw new NullPointerException();
  58             for(Type generatorParameter : generatorParameters)
  59                 if(generatorParameter == null)
  60                     throw new NullPointerException();
  61         }
  62         this.state = newState;
  63         this.generator = generator;
  64         this.dependsOn = dependsOn;
  65         this.generatorParameters = generatorParameters;
  66     }
  67
  68     public Expression generate(long loc) {
  69         Expression result = generator;
  70         for(Type p : generatorParameters)
  71             result = new EApplyType(loc, result, p);
  72         for(Constraint dep : dependsOn) {
  73             result = new EApply(loc, result, new EVariable(loc, dep.evidence));
  74         }
  75         return result;
  76     }
  77
  78     public void collect(ConstraintEnvironment environment, ArrayList<Constraint> unsolvedConstraints, ArrayList<Constraint> solvedConstraints) {
  79         if(!handled) {
  80             switch(state) {
  81             case STATE_UNSOLVED:
  82                 unsolvedConstraints.add(this);
  83                 break;
  84             case STATE_HAS_SUBCLASS:
  85                 // Try to find constant evidence and prefer that
  86                 // to subclass
  87                 {
  88                     Reduction reduction = environment.reduce(constraint);
  89                     if(reduction != null && reduction.demands.length == 0) {
  90                         generator = reduction.generator;
  91                         generatorParameters = reduction.parameters;
  92                         dependsOn = Constraint.EMPTY_ARRAY;
  93                         state = STATE_HAS_INSTANCE;
  94                     }
  95                 }
  96                 // Intentionally no break
  97             case STATE_HAS_INSTANCE:
  98                 for(Constraint dep : dependsOn)
  99                     dep.collect(environment, unsolvedConstraints, solvedConstraints);
 100                 solvedConstraints.add(this);
 101                 break;
 102             }
 103             handled = true;
 104         }
 105     }
 106
 107     @Override
 108     public Type getType() {
 109         return constraint;
 110     }
 111
 112     public long getDemandLocation() {
 113         return demandLocation;
 114     }
 115 }