clarify laziness of blocks and added more care to context execution

src/main/java/carpet/script/CarpetExpression.java

@@ -365,6 +365,23 @@ public class CarpetExpression
      * block(0,0,0) == block('bedrock')  => 1
      * block('hopper[facing=north]{Items:[{Slot:1b,id:"minecraft:slime_ball",Count:16b}]}') => hopper
      * </pre>
+     * <p>Retrieving a block with <code>block</code> function has also a side-effect of evaluating its current state and data.
+     * so if you use it later it will reflect block state and data of the block that was when block was called, rather than
+     * when it was used. Block values passed in various places like <code>scan</code> functions, etc, are not fully evaluated
+     * unless its properties are needed. This means that if the block at the location changes before its queried in the program
+     * this might result in getting the later state, which might not be desired. Consider the following example:</p>
+     * <pre>
+     * set(10,10,10,'stone');
+     * scan(10,10,10,0,0,0, b = _);
+     * set(10,10,10,'air');
+     * print(b); // 'air', block was remembered 'lazily', and evaluated by `print`, when it was already set to air
+     *
+     * set(10,10,10,'stone');
+     * scan(10,10,10,0,0,0, b = block(_));
+     * set(10,10,10,'air');
+     * print(b); // 'stone', block was evaluated 'eagerly' but call to `block`
+     *
+     * </pre>
      * <h2>World Manipulation</h2>
      * <p>All the functions below can be used with block value, queried with coord triple, or 3-long list.
      * All <code>pos</code> in the functions referenced below refer to either method of passing block position</p>
@@ -669,7 +686,10 @@ public class CarpetExpression
             {
                 throw new InternalExpressionException("Block requires at least one parameter");
             }
-            Value retval = BlockValue.fromParams(cc, lv, 0, true).block;
+            BlockValue retval = BlockValue.fromParams(cc, lv, 0, true).block;
+            // fixing block state and data
+            retval.getBlockState();
+            retval.getData();
             return (c_, t_) -> retval;
         });
 
@@ -2086,7 +2106,8 @@ public class CarpetExpression
                         c.setVariable("_z", (c_, t_) -> new NumericValue(zFinal).bindTo("_z"));
                         Value blockValue = BlockValue.fromCoords(((CarpetContext)c), xFinal,yFinal,zFinal).bindTo("_");
                         c.setVariable( "_", (cc_, t_c) -> blockValue);
-                        if (expr.evalValue(c, Context.BOOLEAN).getBoolean())
+                        Value result = expr.evalValue(c, t);
+                        if (t != Context.VOID && result.getBoolean())
                         {
                             sCount += 1;
                         }
@@ -2138,7 +2159,8 @@ public class CarpetExpression
                         c.setVariable("_z", (c_, t_) -> new NumericValue(zFinal).bindTo("_z"));
                         Value blockValue = BlockValue.fromCoords(((CarpetContext)c), xFinal,yFinal,zFinal).bindTo("_");
                         c.setVariable( "_", (cc_, t_c) -> blockValue);
-                        if (expr.evalValue(c, Context.BOOLEAN).getBoolean())
+                        Value result = expr.evalValue(c, t);
+                        if (t != Context.VOID && result.getBoolean())
                         {
                             sCount += 1;
                         }

src/main/java/carpet/script/Expression.java

@@ -994,8 +994,9 @@ public class Expression implements Cloneable
 
         addLazyBinaryOperator(";",precedence.get("nextop;"), true, (c, t, lv1, lv2) ->
         {
-            Value v1 = lv1.evalValue(c, Context.VOID);
+            lv1.evalValue(c, Context.VOID);
-            return lv2;
+            Value v2 = lv2.evalValue(c, t);
+            return (cc, tt) -> v2;
         });
 
         //assigns const procedure to the lhs, returning its previous value
@@ -1053,13 +1054,13 @@ public class Expression implements Cloneable
                 if (lv.get(i).evalValue(c, Context.BOOLEAN).getBoolean())
                 {
                     //int iFinal = i;
-                    Value ret = lv.get(i+1).evalValue(c);
+                    Value ret = lv.get(i+1).evalValue(c, t);
                     return (cc, tt) -> ret;
                 }
             }
             if (lv.size()%2 == 1)
             {
-                Value ret = lv.get(lv.size() - 1).evalValue(c);
+                Value ret = lv.get(lv.size() - 1).evalValue(c, t);
                 return (cc, tt) -> ret;
             }
             return (cc, tt) -> Value.NULL;
@@ -1746,7 +1747,7 @@ public class Expression implements Cloneable
             c.setVariable("_",(cc, tt) -> new NumericValue(0).bindTo("_"));
             while (i<limit && condition.evalValue(c, Context.BOOLEAN).getBoolean() )
             {
-                lastOne = expr.evalValue(c);
+                lastOne = expr.evalValue(c, t);
                 i++;
                 long seriously = i;
                 c.setVariable("_", (cc, tt) -> new NumericValue(seriously).bindTo("_"));
@@ -1777,8 +1778,8 @@ public class Expression implements Cloneable
             {
                 long whyYouAsk = i;
                 c.setVariable("_", (cc, tt) -> new NumericValue(whyYouAsk).bindTo("_"));
-                lastOne = expr.evalValue(c);
+                lastOne = expr.evalValue(c, t);
-                if (cond != null && cond.evalValue(c).getBoolean())
+                if (cond != null && cond.evalValue(c, Context.BOOLEAN).getBoolean())
                     break;
             }
             //revering scope
@@ -1817,7 +1818,7 @@ public class Expression implements Cloneable
                 c.setVariable("_", (cc, tt) -> next);
                 c.setVariable("_i", (cc, tt) -> new NumericValue(doYouReally).bindTo("_i"));
                 result.add(expr.evalValue(c));
-                if (cond != null && cond.evalValue(c).getBoolean())
+                if (cond != null && cond.evalValue(c, Context.BOOLEAN).getBoolean())
                 {
                     next.boundVariable = var;
                     break;
@@ -1861,9 +1862,9 @@ public class Expression implements Cloneable
                 int seriously = i;
                 c.setVariable("_", (cc, tt) -> next);
                 c.setVariable("_i", (cc, tt) -> new NumericValue(seriously).bindTo("_i"));
-                if(expr.evalValue(c).getBoolean())
+                if(expr.evalValue(c, Context.BOOLEAN).getBoolean())
                     result.add(next);
-                if (cond != null && cond.evalValue(c).getBoolean())
+                if (cond != null && cond.evalValue(c, Context.BOOLEAN).getBoolean())
                 {
                     next.boundVariable = var;
                     break;
@@ -1901,7 +1902,7 @@ public class Expression implements Cloneable
                 int seriously = i;
                 c.setVariable("_", (cc, tt) -> next);
                 c.setVariable("_i", (cc, tt) -> new NumericValue(seriously).bindTo("_i"));
-                if(expr.evalValue(c).getBoolean())
+                if(expr.evalValue(c, Context.BOOLEAN).getBoolean())
                 {
                     result = next;
                     next.boundVariable = var;
@@ -1939,7 +1940,7 @@ public class Expression implements Cloneable
                 int seriously = i;
                 c.setVariable("_", (cc, tt) -> next);
                 c.setVariable("_i", (cc, tt) -> new NumericValue(seriously).bindTo("_i"));
-                if(!expr.evalValue(c).getBoolean())
+                if(!expr.evalValue(c, Context.BOOLEAN).getBoolean())
                 {
                     result = LazyValue.FALSE;
                     next.boundVariable = var;
@@ -1983,9 +1984,10 @@ public class Expression implements Cloneable
                 int seriously = i;
                 c.setVariable("_", (cc, tt) -> next);
                 c.setVariable("_i", (cc, tt) -> new NumericValue(seriously).bindTo("_i"));
-                if(expr.evalValue(c).getBoolean())
+                Value result = expr.evalValue(c, t);
+                if(t != Context.VOID && result.getBoolean())
                     successCount++;
-                if (cond != null && cond.evalValue(c).getBoolean())
+                if (cond != null && cond.evalValue(c, Context.BOOLEAN).getBoolean())
                 {
                     next.boundVariable = var;
                     break;
@@ -2033,7 +2035,7 @@ public class Expression implements Cloneable
                 Value promiseWontChangeYou = acc;
                 c.setVariable("_a", (cc, tt) -> promiseWontChangeYou.bindTo("_a"));
                 c.setVariable("_", (cc, tt) -> next);
-                acc = expr.evalValue(c);
+                acc = expr.evalValue(c, t);
                 next.boundVariable = var;
             }
             //reverting scope

src/main/java/carpet/script/LazyValue.java

@@ -19,6 +19,6 @@ public interface LazyValue
     Value evalValue(Context c, Integer type);
 
     default Value evalValue(Context c){
-        return evalValue(c, 0);
+        return evalValue(c, Context.NONE);
     }
 }

src/main/java/carpet/script/value/BlockValue.java

@@ -144,8 +144,6 @@ public class BlockValue extends Value
             }
             if (v1 instanceof BlockValue)
             {
-                ((BlockValue) v1).getBlockState();
-                ((BlockValue) v1).getData();
                 return new LocatorResult(((BlockValue) v1), 1+offset);
             }
             if (v1 instanceof ListValue)
@@ -256,7 +254,7 @@ public class BlockValue extends Value
     @Override
     public Value clone()
     {
-        return new BlockValue(blockState, world, pos);
+        return new BlockValue(blockState, world, pos, data);
     }
 
     @Override

src/main/java/carpet/script/value/Value.java

@@ -48,6 +48,7 @@ public abstract class Value implements Comparable<Value>, Cloneable
         {
             // should not happen
             e.printStackTrace();
+            throw new InternalExpressionException("Variable of type "+getTypeString()+" is not cloneable. Tell gnembon about it, this shoudn't happen");
         }
         copy.boundVariable = var;
         return copy;