CharSequence added in to stdlib

compiler/frontend/src/jet/Library.jet

@@ -43,13 +43,16 @@ class Boolean : Comparable<Boolean> {
   fun equals(other : Any?) : Boolean
 }
 
-class String() : Comparable<String> {
+trait CharSequence {
   fun get(index : Int) : Char
+
   val length : Int
 
+  fun toString() : String
+}
+
+class String() : Comparable<String>, CharSequence {
   fun plus(other : Any?) : String
 
   fun equals(other : Any?) : Boolean
 }
-
-

compiler/frontend/src/org/jetbrains/jet/lang/types/JetStandardLibrary.java

@@ -52,6 +52,7 @@ public class JetStandardLibrary {
 
     private ClassDescriptor numberClass;
 
+    private ClassDescriptor charSequenceClass;
     private ClassDescriptor stringClass;
     private ClassDescriptor arrayClass;
     private ClassDescriptor iterableClass;
@@ -59,6 +60,9 @@ public class JetStandardLibrary {
     private ClassDescriptor comparableClass;
 
     private JetType stringType;
+    private JetType nullableStringType;
+    private JetType charSequenceType;
+    private JetType nullableCharSequenceType;
 
     private JetType nullableTuple0Type;
 
@@ -67,7 +71,6 @@ public class JetStandardLibrary {
     }
 
     private JetType tuple0Type;
-    private JetType nullableStringType;
 
     private Set<FunctionDescriptor> typeInfoFunction;
 
@@ -127,6 +130,7 @@ public class JetStandardLibrary {
             this.libraryScope = JetStandardClasses.STANDARD_CLASSES_NAMESPACE.getMemberScope();
             this.numberClass = (ClassDescriptor) libraryScope.getClassifier("Number");
             this.stringClass = (ClassDescriptor) libraryScope.getClassifier("String");
+            this.charSequenceClass = (ClassDescriptor) libraryScope.getClassifier("CharSequence");
             this.arrayClass = (ClassDescriptor) libraryScope.getClassifier("Array");
 
             this.iterableClass = (ClassDescriptor) libraryScope.getClassifier("Iterable");
@@ -136,6 +140,8 @@ public class JetStandardLibrary {
             this.typeInfoFunction = libraryScope.getFunctions("typeinfo");
 
             this.stringType = new JetTypeImpl(getString());
+            this.charSequenceType = new JetTypeImpl(getCharSequence());
+            this.nullableCharSequenceType = TypeUtils.makeNullable(charSequenceType);
             this.nullableStringType = TypeUtils.makeNullable(stringType);
 
             this.tuple0Type = new JetTypeImpl(JetStandardClasses.getTuple(0));
@@ -230,6 +236,12 @@ public class JetStandardLibrary {
         return stringClass;
     }
 
+    @NotNull
+    public ClassDescriptor getCharSequence() {
+        initStdClasses();
+        return charSequenceClass;
+    }
+
     @NotNull
     public ClassDescriptor  getArray() {
         initStdClasses();
@@ -311,6 +323,12 @@ public class JetStandardLibrary {
         return stringType;
     }
 
+    @NotNull
+    public JetType getCharSequenceType() {
+        initStdClasses();
+        return charSequenceType;
+    }
+
     @NotNull
     public JetType getByteType() {
         return getPrimitiveJetType(PrimitiveType.BYTE);
@@ -371,11 +389,18 @@ public class JetStandardLibrary {
         );
     }
 
+    @NotNull
     public JetType getNullableStringType() {
         initStdClasses();
         return nullableStringType;
     }
 
+    @NotNull
+    public JetType getNullableCharSequenceType() {
+        initStdClasses();
+        return nullableCharSequenceType;
+    }
+
     @NotNull
     public JetType getNullablePrimitiveJetType(PrimitiveType primitiveType) {
         initStdClasses();