Add conv function (#114)

* Initial commit

* Consider negative input and add more test cases

* Use kResultNullInternal and consider more spark test cases

* Use unsigned long in the converting

* Return null for empty input

cpp/src/gandiva/function_registry_string.cc

@@ -325,6 +325,10 @@ std::vector<NativeFunction> GetStringFunctionRegistry() {
 
       NativeFunction("url_decoder", {}, DataTypeVector{utf8()}, utf8(),
                      kResultNullIfNull, "url_decoder",
+                     NativeFunction::kNeedsContext | NativeFunction::kCanReturnErrors),
+
+      NativeFunction("conv", {}, DataTypeVector{utf8(), int32(), int32()}, utf8(),
+                     kResultNullInternal, "conv",
                      NativeFunction::kNeedsContext | NativeFunction::kCanReturnErrors)};
 
   return string_fn_registry_;

cpp/src/gandiva/precompiled/string_ops.cc

@@ -1568,4 +1568,80 @@ const char* url_decoder(gdv_int64 context, const char* input, gdv_int32 input_le
   return out_str;
 }
 
-}  // extern "C"
+FORCE_INLINE
+const char* conv(gdv_int64 context, const char* input, gdv_int32 input_len, bool in1_valid,
+                 gdv_int32 from_base, bool in2_valid, gdv_int32 to_base, bool in3_valid,
+                 bool* out_valid, gdv_int32* out_len) {
+  if (!in1_valid || !in2_valid || !in3_valid || input_len == 0) {
+    *out_len = 0;
+    *out_valid = false;
+    return ""; 
+  }
+
+  // Consistent with spark, only support base belonging to [2, 36].
+  const int MIN_BASE = 2;
+  const int MAX_BASE = 36;
+  if (from_base < MIN_BASE || from_base > MAX_BASE ||
+      fabs(to_base) < MIN_BASE || fabs(to_base) > MAX_BASE) {
+    *out_len = 0;
+    *out_valid = false;
+    return "";
+  } 
+
+  from_base = from_base < 0 ? -from_base : from_base;
+  bool is_negative_input;
+  unsigned long unsigned_decimal_value;
+  if (input[0] == '-') {
+    is_negative_input = true;
+    unsigned_decimal_value = strtoul(input + 1, nullptr, from_base);
+  } else {
+    is_negative_input = false;
+    unsigned_decimal_value = strtoul(input, nullptr, from_base);
+  }
+
+  bool has_negative_mark = false;
+  if (is_negative_input && to_base < 0) {
+    has_negative_mark = true;
+  } else if (is_negative_input && to_base > 0) {
+    // Use the max value for 64-bit to convert it to positive.
+    unsigned_decimal_value = strtoul("FFFFFFFFFFFFFFFF", nullptr, 16) - unsigned_decimal_value + 1;
+  }
+  to_base = to_base < 0 ? -to_base : to_base;
+
+  char reverse_ret[64];
+  int i = 0;
+  while (unsigned_decimal_value > 0) {
+    int remainder = unsigned_decimal_value % to_base;
+    char c;
+    if (remainder < 10) {
+      c = (char)(remainder + (int)'0');
+    } else { 
+      c = (char)(remainder - 10 + (int)'A');
+    }
+    reverse_ret[i] = c;
+    i++;
+    unsigned_decimal_value = unsigned_decimal_value / to_base;
+  }
+  if (has_negative_mark) {
+    reverse_ret[i] = '-';
+    i++;
+  }
+  *out_len = i;
+  char ret[*out_len];
+  for (int i = 0; i < *out_len; i++) {
+    ret[i] = reverse_ret[*out_len - i - 1];
+  }
+
+  char* out_str = reinterpret_cast<char*>(gdv_fn_context_arena_malloc(context, *out_len));
+  if (ret == nullptr) {
+    gdv_fn_context_set_error_msg(context, "Could not allocate memory for output string");
+    *out_len = 0;
+    *out_valid = false;
+    return "";
+  }
+  memcpy(out_str, ret, *out_len);
+  *out_valid = true;
+  return out_str;
+}
+
+}  // extern "C"

cpp/src/gandiva/precompiled/string_ops_test.cc

@@ -1142,4 +1142,70 @@ TEST(TestStringOps, TestURLDecoder) {
   EXPECT_EQ(std::string(out_str, out_len), exp_str);
 }
 
+TEST(TestStringOps, TestConv) {
+  gandiva::ExecutionContext ctx;
+  uint64_t ctx_ptr = reinterpret_cast<gdv_int64>(&ctx);
+  gdv_int32 out_len = 0;
+  const char* out_str;
+  bool out_valid;
+
+  // 10-base to 2-base
+  out_str = conv(ctx_ptr, "4", 1, true, 10, true, 2, true, &out_valid, &out_len);
+  EXPECT_EQ(out_len, 3);
+  EXPECT_EQ(out_valid, true);
+  EXPECT_EQ(std::string(out_str, out_len), "100");
+
+  // 2-bae to 10-base
+  out_str = conv(ctx_ptr, "110", 3, true, 2, true, 10, true, &out_valid, &out_len);
+  EXPECT_EQ(out_len, 1);
+  EXPECT_EQ(std::string(out_str, out_len), "6");
+
+  // 10-base to 16-base
+  out_str = conv(ctx_ptr, "15", 2, true, 10, true, 16, true, &out_valid, &out_len);
+  EXPECT_EQ(out_len, 1);
+  EXPECT_EQ(std::string(out_str, out_len), "F");
+
+  // 36-base to 16-base
+  out_str = conv(ctx_ptr, "big", 3, true, 36, true, 16, true, &out_valid, &out_len);
+  EXPECT_EQ(out_len, 4);
+  EXPECT_EQ(std::string(out_str, out_len), "3A48");
+
+  // 36-base to 16-base.
+  std::string input = "9223372036854775807";
+  out_str = conv(ctx_ptr, input.c_str(), input.length(), true, 36, true, 16, true, &out_valid, &out_len);
+  std::string expected_str = "FFFFFFFFFFFFFFFF";
+  EXPECT_EQ(out_len, expected_str.length());
+  EXPECT_EQ(std::string(out_str, out_len), expected_str);
+
+  // Space is contained in input string.
+  out_str = conv(ctx_ptr, " 15 ", 2, true, 10, true, 16, true, &out_valid, &out_len);
+  EXPECT_EQ(out_len, 1);
+  EXPECT_EQ(std::string(out_str, out_len), "F");
+
+  // Negative input and negative to_base.
+  out_str = conv(ctx_ptr, "-15", 3, true, 10, true, -16, true, &out_valid, &out_len);
+  EXPECT_EQ(out_len, 2);
+  EXPECT_EQ(std::string(out_str, out_len), "-F");
+
+  // Negative input and positive to_base
+  out_str = conv(ctx_ptr, "-15", 3, true, 10, true, 16, true, &out_valid, &out_len);
+  EXPECT_EQ(out_len, 16);
+  EXPECT_EQ(std::string(out_str, out_len), "FFFFFFFFFFFFFFF1");
+
+  // Negative input and negative base.
+  out_str = conv(ctx_ptr, "-10", 3, true, 16, true, -10, true, &out_valid, &out_len);
+  EXPECT_EQ(out_len, 3);
+  EXPECT_EQ(std::string(out_str, out_len), "-16");
+
+  // If there is an invalid digit in the number, the longest
+  // valid prefix should be converted.
+  out_str = conv(ctx_ptr, "11abc", 5, true, 10, true, 16, true, &out_valid, &out_len);
+  EXPECT_EQ(out_len, 1);
+  EXPECT_EQ(std::string(out_str, out_len), "B");
+
+  // Should return null for Empty input.
+  out_str = conv(ctx_ptr, "", 0, true, 10, true, 16, true, &out_valid, &out_len);
+  EXPECT_EQ(out_valid, false);
+}
+
 }  // namespace gandiva

cpp/src/gandiva/precompiled/types.h

@@ -517,4 +517,8 @@ double castFLOAT8_utf8(int64_t context, const char* data, int32_t len);
 
 const char* url_decoder(gdv_int64 context, const char* input, gdv_int32 input_len, gdv_int32* out_len);
 
+const char* conv(gdv_int64 context, const char* input, gdv_int32 input_len, bool in1_valid,
+                 gdv_int32 from_base, bool in2_valid, gdv_int32 to_base, bool in3_valid,
+                 bool* out_valid, gdv_int32* out_len);
+
 }  // extern "C"