Merge pull request #666 from altrisi/extra-splitting

[Suggestion] Allow splitting lists by element value

docs/scarpet/language/Containers.md

@@ -160,11 +160,19 @@ join('-', 'foo', 'bar')  => foo-bar
 Splits a string under `expr` by `delim` which can be a regular expression. If no delimiter is specified, it splits
 by characters.
 
+If `expr` is a list, it will split the list into multiple sublists by the element (s) which equal `delim`, or which equal the empty string
+in case no delimiter is specified.
+
+Splitting a `null` value will return an empty list.
+
 <pre>
 split('foo') => [f, o, o]
 split('','foo')  => [f, o, o]
 split('.','foo.bar')  => []
 split('\\.','foo.bar')  => [foo, bar]
+split(1,[2,5,1,2,3,1,5,6]) => [[2,5],[2,3],[5,6]]
+split(1,[1,2,3,1,4,5,1] => [[], [2,3], [4,5], []]
+split(null) => []
 </pre>
 
 ### `slice(expr, from, to?)`

src/main/java/carpet/script/language/DataStructures.java

@@ -14,10 +14,8 @@ import carpet.script.value.StringValue;
 import carpet.script.value.Value;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
-import java.util.regex.PatternSyntaxException;
 import java.util.stream.Collectors;
 
 public class DataStructures {
@@ -54,30 +52,23 @@ public class DataStructures {
 
         expression.addFunction("split", (lv) ->
         {
-            String delimiter;
+            Value delimiter;
-            String hwat;
+            Value hwat;
             if (lv.size() == 1)
             {
-                hwat = lv.get(0).getString();
+                hwat = lv.get(0);
-                delimiter = "";
+                delimiter = StringValue.EMPTY;
             }
             else if (lv.size() == 2)
             {
-                delimiter = lv.get(0).getString();
+                delimiter = lv.get(0);
-                hwat = lv.get(1).getString();
+                hwat = lv.get(1);
             }
             else
             {
                 throw new InternalExpressionException("'split' takes 1 or 2 arguments");
             }
-            try
+            return hwat.split(delimiter);
-            {
-                return ListValue.wrap(Arrays.stream(hwat.split(delimiter)).map(StringValue::new).collect(Collectors.toList()));
-            }
-            catch (PatternSyntaxException pse)
-            {
-                throw new InternalExpressionException("Incorrect pattern for 'split': "+pse.getMessage());
-            }
         });
 
         expression.addFunction("slice", (lv) ->

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

@@ -347,6 +347,24 @@ public class ListValue extends AbstractListValue implements ContainerValueInterf
         return new ListValue((Collection<? extends Value>) getItems().subList(from, to));
     }
 
+    @Override
+    public Value split(Value delimiter) {
+        ListValue result = new ListValue();
+        int startIndex = 0;
+        int index = 0;
+        for (Value val : this.items)
+        {
+            index++;
+            if (val.equals(delimiter))
+            {
+                result.items.add(ListValue.wrap(this.items.subList(startIndex, index-1)));
+                startIndex = index;
+            }
+        }
+        result.items.add(ListValue.wrap(this.items.subList(startIndex, length())));
+        return result;
+    }
+
     @Override
     public double readDoubleNumber()
     {

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

@@ -203,6 +203,11 @@ public class MapValue extends AbstractListValue implements ContainerValueInterfa
         throw new InternalExpressionException("Cannot slice a map value");
     }
 
+    @Override
+    public Value split(Value delimiter) {
+    	throw new InternalExpressionException("Cannot split a map value");
+    }
+
     @Override
     public double readDoubleNumber()
     {

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

@@ -1,5 +1,7 @@
 package carpet.script.value;
 
+import java.util.ArrayList;
+
 import com.google.gson.JsonElement;
 import com.google.gson.JsonNull;
 import net.minecraft.nbt.StringTag;
@@ -68,6 +70,11 @@ public class NullValue extends NumericValue // TODO check nonsingleton code
         return StringTag.of("null");
     }
 
+    @Override
+    public Value split(Value delimiter) {
+    	return ListValue.wrap(new ArrayList<Value>());
+    }
+
     @Override
     public JsonElement toJson()
     {

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

@@ -6,10 +6,12 @@ import com.google.gson.JsonPrimitive;
 import net.minecraft.nbt.Tag;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;
+import java.util.stream.Collectors;
 
 public abstract class Value implements Comparable<Value>, Cloneable
 {
@@ -188,6 +190,19 @@ public abstract class Value implements Comparable<Value>, Cloneable
         if (from > to) return StringValue.EMPTY;
         return new StringValue(value.substring(from, to));
     }
+    
+    public Value split(Value delimiter)
+    {
+    	try
+        {
+            return ListValue.wrap(Arrays.stream(getString().split(delimiter.getString())).map(StringValue::new).collect(Collectors.toList()));
+        }
+        catch (PatternSyntaxException pse)
+        {
+            throw new InternalExpressionException("Incorrect pattern for 'split': "+pse.getMessage());
+        }
+    }
+    
     public double readDoubleNumber()
     {
         String s = getString();