add is_valid_integer format check API

cpp/include/cudf/strings/convert/is_valid_fixed_point.hpp

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2019, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+
+#include <cudf/column/column.hpp>
+
+namespace cudf {
+namespace strings {
+/**
+ * @addtogroup strings_convert
+ * @{
+ * @file
+ */
+
+/**
+ * @brief Returns a boolean column identifying strings in which all
+ * characters are valid for conversion to integers.
+ * 
+ * @param strings Strings instance for this operation.
+ * @param allow_decimal identification whether the format is decimal or not
+ * @param input_type input data type for check overflow
+ * @param mr Device memory resource used to allocate the returned column's device memory.
+ * @return New column of boolean results for each string.
+ */
+std::unique_ptr<column> is_valid_fixed_point(
+  strings_column_view const& strings,
+  bool allow_decimal,
+  data_type input_type,
+  rmm::mr::device_memory_resource* mr = rmm::mr::get_current_device_resource());
+
+/** @} */  // end of doxygen group
+}  // namespace strings
+}  // namespace cudf
+

cpp/src/strings/convert/is_valid_fixed_point.cu

@@ -0,0 +1,173 @@
+/*
+ * Copyright (c) 2019-2020, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <cudf/column/column.hpp>
+#include <cudf/column/column_device_view.cuh>
+#include <cudf/column/column_factories.hpp>
+#include <cudf/detail/null_mask.hpp>
+#include <cudf/detail/nvtx/ranges.hpp>
+#include <cudf/strings/detail/utilities.hpp>
+#include <cudf/strings/string_view.cuh>
+#include <cudf/strings/strings_column_view.hpp>
+#include <cudf/utilities/traits.hpp>
+#include <cudf/utilities/type_dispatcher.hpp>
+#include <strings/utilities.cuh>
+#include <strings/utilities.hpp>
+
+#include <thrust/logical.h>
+
+namespace cudf {
+namespace strings {
+
+/**
+   * Parses this UTF8String(trimmed if needed) to INT8/16/32/64...
+   *
+   * Note that, in this method we accumulate the result in negative format, and convert it to
+   * positive format at the end, if this string is not started with '-'. This is because min value
+   * is bigger than max value in digits, e.g. Long.MAX_VALUE is '9223372036854775807' and
+   * Long.MIN_VALUE is '-9223372036854775808'.
+   *
+   * This code is mostly copied from LazyLong.parseLong in Hive.
+   *
+ * @param d_str String to check.
+ * @param allow_decimal Decimal format or not
+ * @param min_value min_value that corresponds to the type that is checking
+ * @return true if string has valid integer characters
+   */
+__device__ bool is_valid_fixed_point(string_view const& d_str, bool allow_decimal, long min_value)
+{
+  int offset = 0;
+  size_type bytes = d_str.size_bytes();
+  const char* data    = d_str.data();
+  while (offset < bytes && data[offset] == ' ') ++offset;
+  if (offset == bytes)  return false;
+
+  int end = bytes - 1;
+  while (end > offset && data[end] == ' ') --end;
+
+  char c_sign = data[offset];
+  const bool negative = c_sign == '-';
+  if (negative || c_sign == '+'){
+    if (end - offset == 0)  return false;
+    ++offset;
+  }
+
+  const char separator = '.';
+  const int radix = 10;
+  const long stop_value = min_value / radix;
+  long result = 0;
+
+  while (offset <= end) {
+    const char c = data[offset];
+    ++offset;
+    // We allow decimals and will return a truncated integral in that case.
+    // Therefore we won't throw an exception here (checking the fractional
+    // part happens below.
+    if (c == separator && allow_decimal)  break;
+
+    int digit;
+    if (c >= '0' && c <= '9'){
+      digit = c - '0';
+    } else {
+      return false;
+    }
+
+    // We are going to process the new digit and accumulate the result. However, before doing
+    // this, if the result is already smaller than the stopValue(Long.MIN_VALUE / radix), then
+    // result * 10 will definitely be smaller than minValue, and we can stop.
+    if (result < stop_value)  return false;
+
+    result = result * radix - digit;
+
+    // Since the previous result is less than or equal to stopValue(Long.MIN_VALUE / radix), we
+    // can just use `result > 0` to check overflow. If result overflows, we should stop.
+    if (result > 0) return false;
+  }
+  // This is the case when we've encountered a decimal separator. The fractional
+  // part will not change the number, but we will verify that the fractional part
+  // is well formed.
+  while (offset <= end) {
+    char currentByte = data[offset];
+    if (currentByte < '0' || currentByte > '9') return false;
+    ++offset;
+  }
+
+  if (!negative) {
+    result = -result;
+    if (result < 0) return false;
+  }
+
+  return true;
+}
+
+namespace detail {
+
+std::unique_ptr<column> is_valid_fixed_point(
+  strings_column_view const& strings,
+  bool allow_decimal,
+  data_type input_type,
+  rmm::cuda_stream_view stream,
+  rmm::mr::device_memory_resource* mr = rmm::mr::get_current_device_resource())
+{
+  auto strings_column = column_device_view::create(strings.parent(), stream);
+  auto d_column       = *strings_column;
+  auto d_allow_decimal = allow_decimal;
+
+  // ready a min_value corresponds to the input type in order to check overflow
+  long d_min_value = 0;
+  switch (input_type.id()) {
+    case type_id::INT8: d_min_value = -128;
+    case type_id::INT16: d_min_value = -32768;
+    case type_id::INT32: d_min_value = -2147483648;
+    case type_id::INT64: d_min_value = -9223372036854775808;
+    default: CUDF_FAIL("Unsupported current data type check when convert string type");
+  }
+
+  // create output column
+  auto results   = make_numeric_column(data_type{type_id::BOOL8},
+                                     strings.size(),
+                                     cudf::detail::copy_bitmask(strings.parent(), stream, mr),
+                                     strings.null_count(),
+                                     stream,
+                                     mr);
+  auto d_results = results->mutable_view().data<bool>();
+  thrust::transform(rmm::exec_policy(stream),
+                    thrust::make_counting_iterator<size_type>(0),
+                    thrust::make_counting_iterator<size_type>(strings.size()),
+                    d_results,
+                    [d_column,d_allow_decimal,d_min_value] __device__(size_type idx) {
+                      if (d_column.is_null(idx)) return false;
+                      return strings::is_valid_fixed_point(d_column.element<string_view>(idx), d_allow_decimal, d_min_value);
+                    });
+  results->set_null_count(strings.null_count());
+  return results;
+}
+
+}  // namespace detail
+
+// external API
+
+std::unique_ptr<column> is_valid_fixed_point(strings_column_view const& strings,
+                                          bool allow_decimal,
+                                          data_type input_type,
+                                          rmm::mr::device_memory_resource* mr)
+{
+  CUDF_FUNC_RANGE();
+  return detail::is_valid_fixed_point(strings, allow_decimal, input_type, rmm::cuda_stream_default, mr);
+}
+
+}  // namespace strings
+}  // namespace cudf
+

cpp/tests/strings/chars_types_tests.cpp

@@ -243,6 +243,21 @@ TEST_F(StringsCharsTest, Integers)
   EXPECT_TRUE(cudf::strings::all_integer(cudf::strings_column_view(strings2)));
 }
 
+TEST_F(StringsCharsTest, ValidIntegers)
+{
+  cudf::test::strings_column_wrapper strings1(
+    {"+175", "-34", "9.8", "17+2", "+-14", "1234567890", "67de", "", "1e10", "-", "++", ""});
+  auto results = cudf::strings::is_valid_fixed_point(cudf::strings_column_view(strings1), true, data_type::INT64);
+  cudf::test::fixed_width_column_wrapper<bool> expected1({1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0});
+  CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected1);
+
+  cudf::test::strings_column_wrapper strings2(
+    {"0", "+0", "-0", "1234567890", "-27341132", "+012", "023", "-045", "-1.1", "+1000.1"});
+  results = cudf::strings::is_valid_fixed_point(cudf::strings_column_view(strings2), true, data_type::INT64);
+  cudf::test::fixed_width_column_wrapper<bool> expected2({1, 1, 1, 1, 1, 1, 1, 1, 1, 1});
+  CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, expected2);
+}
+
 TEST_F(StringsCharsTest, Floats)
 {
   cudf::test::strings_column_wrapper strings1({"+175",
@@ -390,3 +405,4 @@ TEST_F(StringsCharsTest, EmptyStringsColumn)
   EXPECT_EQ(cudf::type_id::STRING, results->view().type().id());
   EXPECT_EQ(0, results->view().size());
 }
+