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

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