(zig) fixed output of vector.drain()

zig/src/main.zig

@@ -6,18 +6,19 @@ const fs = std.fs;
 const vec = @import("vector.zig");
 
 pub fn main() !void {
-    var GPA = std.heap.GeneralPurposeAllocator(.{}){};
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
-    const allocator = GPA.allocator();
+    const allocator = gpa.allocator();
-    var temp = try vec.vector(u8).new(allocator);
+    var test_vector = try vec.vector(u8).new(allocator);
 
     for (0..12) |n|
     {
-        try temp.push(@truncate(n));
+        try test_vector.push(@truncate(n));
     }
-    std.debug.print("{X}\n", .{temp.array[0..temp.length]});
+    std.debug.print("{X}\n", .{test_vector.array[0..test_vector.length]});
 
-    const blargh = try temp.drain(.{3, 6});
+    const blargh: []u8 = try test_vector.drain(.{3, 6});
+    defer allocator.free(blargh);
     std.debug.print("drained slice: {X}\n", .{blargh});
-    std.debug.print("vector after drain: {X}\n", .{temp.array[0..temp.length]});
+    std.debug.print("vector after drain: {X}\n", .{test_vector.array[0..test_vector.length]});
 }
 

zig/src/vector.zig

@@ -9,6 +9,7 @@ pub fn vector(comptime T: type) type
 
         const VectorError: type = error {
             OutOfBounds,
+            FailedToAllocateMemory,
         };
 
         allocator: std.mem.Allocator,
@@ -36,6 +37,11 @@ pub fn vector(comptime T: type) type
             };
         }
 
+        pub fn len(self: *Self) usize
+        {
+            return self.length;
+        }
+
         pub fn push(self: *Self, item: VectorType) !void
         {
             if (self.length >= self.array.len)
@@ -65,10 +71,17 @@ pub fn vector(comptime T: type) type
                 return VectorError.OutOfBounds;
             }
 
+            const slice_length: usize = range[1] - range[0] + 1;
+            const slice: []VectorType = self.allocator.alloc(VectorType, slice_length)
+            catch
+            {
+                return VectorError.FailedToAllocateMemory;
+            };
+
             // TODO: return array instead of pointer
-            const slice: []VectorType = self.array[range[0]..range[1]];
+            @memcpy(slice.ptr, self.array[range[0]..range[1] + 1]);
-            @memmove(self.array.ptr, self.array[range[1]..]);
+            @memmove(self.array.ptr + range[0], self.array[range[1]..self.length]);
-            self.length -= range[1] - range[0] + 1;
+            self.length -= slice_length;
 
             return slice;
         }