Merge pull request #16716 from vespa-engine/arnej/small-vector-in-rename

Arnej/small vector in rename

6 files changed, 42 insertions, 14 deletions

diff --git a/eval/src/tests/instruction/generic_rename/generic_rename_test.cpp b/eval/src/tests/instruction/generic_rename/generic_rename_test.cpp
index dedb22f2763..9c17dce972f 100644
--- a/eval/src/tests/instruction/generic_rename/generic_rename_test.cpp
+++ b/eval/src/tests/instruction/generic_rename/generic_rename_test.cpp
@@ -53,8 +53,8 @@ TEST(GenericRenameTest, dense_rename_plan_can_be_created_and_executed) {
     std::vector<vespalib::string>   to({"f", "a", "b"});
     ValueType renamed = lhs.rename(from, to);
     auto plan = DenseRenamePlan(lhs, renamed, from, to);
-    std::vector<size_t> expect_loop = {15,2,7};
-    std::vector<size_t> expect_stride = {7,105,1};
+    SmallVector<size_t> expect_loop = {15,2,7};
+    SmallVector<size_t> expect_stride = {7,105,1};
     EXPECT_EQ(plan.subspace_size, 210);
     EXPECT_EQ(plan.loop_cnt, expect_loop);
     EXPECT_EQ(plan.stride, expect_stride);
@@ -84,7 +84,7 @@ TEST(GenericRenameTest, sparse_rename_plan_can_be_created) {
     ValueType renamed = lhs.rename(from, to);
     auto plan = SparseRenamePlan(lhs, renamed, from, to);
     EXPECT_EQ(plan.mapped_dims, 4);
-    std::vector<size_t> expect = {2,0,1,3};
+    SmallVector<size_t> expect = {2,0,1,3};
     EXPECT_EQ(plan.output_dimensions, expect);
 }
 
diff --git a/eval/src/vespa/eval/instruction/generic_rename.cpp b/eval/src/vespa/eval/instruction/generic_rename.cpp
index 4fe347375c4..8363d4db573 100644
--- a/eval/src/vespa/eval/instruction/generic_rename.cpp
+++ b/eval/src/vespa/eval/instruction/generic_rename.cpp
@@ -69,10 +69,10 @@ generic_rename(const Value &a,
                const ValueType &res_type, const ValueBuilderFactory &factory)
 {
     auto cells = a.cells().typify<CT>();
-    std::vector<string_id> output_address(sparse_plan.mapped_dims);
-    std::vector<string_id*> input_address;
+    SmallVector<string_id> output_address(sparse_plan.mapped_dims);
+    SmallVector<string_id*> input_address;
     for (size_t maps_to : sparse_plan.output_dimensions) {
-        input_address.push_back(&output_address[maps_to]);
+        input_address.emplace_back(&output_address[maps_to]);
     }
     auto builder = factory.create_transient_value_builder<CT>(res_type,
                                                               sparse_plan.mapped_dims,
@@ -152,7 +152,7 @@ SparseRenamePlan::SparseRenamePlan(const ValueType &input_type,
         if (index != output_dimensions.size()) {
             can_forward_index = false;
         }
-        output_dimensions.push_back(index);
+        output_dimensions.emplace_back(index);
     }
     assert(output_dimensions.size() == mapped_dims);
 }
@@ -172,8 +172,8 @@ DenseRenamePlan::DenseRenamePlan(const ValueType &lhs_type,
     const auto out_dims = output_type.nontrivial_indexed_dimensions();
     size_t num_dense_dims = lhs_dims.size();
     assert(num_dense_dims == out_dims.size());
-    std::vector<size_t> lhs_loopcnt(num_dense_dims);
-    std::vector<size_t> lhs_stride(num_dense_dims, 1);
+    SmallVector<size_t> lhs_loopcnt(num_dense_dims);
+    SmallVector<size_t> lhs_stride(num_dense_dims, 1);
     size_t lhs_size = 1;
     for (size_t i = num_dense_dims; i-- > 0; ) {
         lhs_stride[i] = lhs_size;
@@ -191,8 +191,8 @@ DenseRenamePlan::DenseRenamePlan(const ValueType &lhs_type,
             loop_cnt.back() *= lhs_loopcnt[index];
             stride.back() = lhs_stride[index];
         } else {
-            loop_cnt.push_back(lhs_loopcnt[index]);
-            stride.push_back(lhs_stride[index]);
+            loop_cnt.emplace_back(lhs_loopcnt[index]);
+            stride.emplace_back(lhs_stride[index]);
         }
         prev_index = index;
     }
diff --git a/eval/src/vespa/eval/instruction/generic_rename.h b/eval/src/vespa/eval/instruction/generic_rename.h
index 7834c967488..4d8ca54a248 100644
--- a/eval/src/vespa/eval/instruction/generic_rename.h
+++ b/eval/src/vespa/eval/instruction/generic_rename.h
@@ -6,6 +6,7 @@
 #include <vespa/eval/eval/value_type.h>
 #include <vespa/eval/eval/interpreted_function.h>
 #include <vespa/vespalib/stllike/string.h>
+#include <vespa/vespalib/util/small_vector.h>
 #include <vector>
 
 namespace vespalib::eval { struct ValueBuilderFactory; }
@@ -13,8 +14,8 @@ namespace vespalib::eval { struct ValueBuilderFactory; }
 namespace vespalib::eval::instruction {
  
 struct DenseRenamePlan {
-    std::vector<size_t> loop_cnt;
-    std::vector<size_t> stride;
+    SmallVector<size_t> loop_cnt;
+    SmallVector<size_t> stride;
     const size_t subspace_size;
     DenseRenamePlan(const ValueType &lhs_type,
                     const ValueType &output_type,
@@ -28,7 +29,7 @@ struct DenseRenamePlan {
 
 struct SparseRenamePlan {
     size_t mapped_dims;
-    std::vector<size_t> output_dimensions;
+    SmallVector<size_t> output_dimensions;
     bool can_forward_index;
     SparseRenamePlan(const ValueType &input_type,
                      const ValueType &output_type,
diff --git a/vespalib/src/tests/small_vector/small_vector_test.cpp b/vespalib/src/tests/small_vector/small_vector_test.cpp
index 808571acef6..6d8238fefb4 100644
--- a/vespalib/src/tests/small_vector/small_vector_test.cpp
+++ b/vespalib/src/tests/small_vector/small_vector_test.cpp
@@ -243,4 +243,24 @@ TEST(SmallVectorTest, equal_operator) {
                   SmallVector<EqOnly>({EqOnly{1},EqOnly{5},EqOnly{3}}));
 }
 
+// to check "back() const"
+template<size_t N>
+int last_value_of(const SmallVector<int,N> &v) {
+    return v.back();
+}
+
+TEST(SmallVectorTest, check_back_method) {
+    SmallVector<int> vec;
+    for (int i = 0; i < 1000; ++i) {
+        vec.emplace_back(17);
+        EXPECT_EQ(vec.back(), 17);
+        EXPECT_EQ(last_value_of(vec), 17);
+        vec.back() = 42;
+        EXPECT_EQ(vec[i], 42);
+        vec.back() = i;
+        EXPECT_EQ(last_value_of(vec), i);
+    }
+    EXPECT_EQ(&vec.back(), vec.end() - 1);
+}
+
 GTEST_MAIN_RUN_ALL_TESTS()
diff --git a/vespalib/src/vespa/vespalib/util/arrayref.h b/vespalib/src/vespa/vespalib/util/arrayref.h
index 03634a7a094..2433f9251cf 100644
--- a/vespalib/src/vespa/vespalib/util/arrayref.h
+++ b/vespalib/src/vespa/vespalib/util/arrayref.h
@@ -2,6 +2,7 @@
 #pragma once
 
 #include "array.h"
+#include "small_vector.h"
 #include <vector>
 
 namespace vespalib {
@@ -17,6 +18,8 @@ public:
     ArrayRef(T * v, size_t sz) noexcept : _v(v), _sz(sz) { }
     template<typename A=std::allocator<T>>
     ArrayRef(std::vector<T, A> & v) noexcept : _v(&v[0]), _sz(v.size()) { }
+    template<size_t N>
+    ArrayRef(SmallVector<T, N> &v) noexcept :  _v(&v[0]), _sz(v.size()) { }
     ArrayRef(Array<T> &v) noexcept : _v(&v[0]), _sz(v.size()) { }
     T & operator [] (size_t i) { return _v[i]; }
     const T & operator [] (size_t i) const { return _v[i]; }
@@ -35,6 +38,8 @@ public:
     ConstArrayRef(const T *v, size_t sz) noexcept : _v(v), _sz(sz) { }
     template<typename A=std::allocator<T>>
     ConstArrayRef(const std::vector<T, A> & v) noexcept : _v(&v[0]), _sz(v.size()) { }
+    template<size_t N>
+    ConstArrayRef(const SmallVector<T, N> &v) noexcept :  _v(&v[0]), _sz(v.size()) { }
     ConstArrayRef(const ArrayRef<T> & v) noexcept : _v(&v[0]), _sz(v.size()) { }
     ConstArrayRef(const Array<T> &v) noexcept : _v(&v[0]), _sz(v.size()) { }
     ConstArrayRef() noexcept : _v(nullptr), _sz(0) {}
diff --git a/vespalib/src/vespa/vespalib/util/small_vector.h b/vespalib/src/vespa/vespalib/util/small_vector.h
index 21a21fc2cbb..9cbc10951cf 100644
--- a/vespalib/src/vespa/vespalib/util/small_vector.h
+++ b/vespalib/src/vespa/vespalib/util/small_vector.h
@@ -186,6 +186,8 @@ public:
     const T *end() const { return (_data + _size); }
     T &operator[](size_t idx) { return _data[idx]; }
     const T &operator[](size_t idx) const { return _data[idx]; }
+    T &back() { return _data[_size - 1]; }
+    const T &back() const { return _data[_size - 1]; }
     void clear() {
         small_vector::destroy_objects(_data, _size);
         _size = 0;