(String) Add partition and to_padded_string (#4)

Copy extra string functions from volume-cartographer.

CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.15 FATAL_ERROR)
-project(EduceLabCore VERSION 0.2.1)
+project(EduceLabCore VERSION 0.3.0)
 
 # Setup project directories
 set(EXECUTABLE_OUTPUT_PATH ${CMAKE_BINARY_DIR}/bin)

include/educelab/core/utils/String.hpp

@@ -5,7 +5,9 @@
 #include <algorithm>
 #include <charconv>
 #include <exception>
+#include <iomanip>
 #include <locale>
+#include <sstream>
 #include <string>
 #include <string_view>
 #include <type_traits>
@@ -189,6 +191,39 @@ static auto split(std::string_view s, const Ds&... ds)
     return tokens;
 }
 
+/** @brief Partition a string by a separator substring */
+static auto partition(std::string_view s, const std::string_view sep)
+    -> std::tuple<std::string_view, std::string_view, std::string_view>
+{
+    // Find the starting position
+    const auto startPos = s.find(sep);
+
+    // Didn't find the delimiter
+    if (startPos == std::string::npos) {
+        return {s, "", ""};
+    }
+
+    // Split into parts
+    auto pre = s.substr(0, startPos);
+    auto mid = s.substr(startPos, sep.size());
+    auto post = s.substr(startPos + sep.size());
+
+    // Return the parts
+    return {pre, mid, post};
+}
+
+/** @brief Convert an Integer to a padded string */
+template <
+    typename Integer,
+    std::enable_if_t<std::is_integral_v<Integer>, bool> = true>
+auto to_padded_string(Integer val, const int padding, const char fill = '0')
+    -> std::string
+{
+    std::stringstream stream;
+    stream << std::setw(padding) << std::setfill(fill) << val;
+    return stream.str();
+}
+
 /**
  * @brief Convert a string to a numeric type.
  *

tests/src/TestString.cpp

@@ -1,6 +1,7 @@
 #include <gtest/gtest.h>
 
 #include <string>
+#include <tuple>
 
 #include "educelab/core/utils/String.hpp"
 
@@ -151,17 +152,50 @@ TEST(String, Split)
     EXPECT_EQ(split("This is only a test."), expected);
 }
 
+TEST(String, Partition)
+{
+    // key=value
+    const auto [p0, m0, s0] = partition("key=value", "=");
+    EXPECT_EQ(p0, "key");
+    EXPECT_EQ(m0, "=");
+    EXPECT_EQ(s0, "value");
+
+    // {} replacement
+    const auto [p1, m1, s1] = partition("prefix{}suffix", "{}");
+    EXPECT_EQ(p1, "prefix");
+    EXPECT_EQ(m1, "{}");
+    EXPECT_EQ(s1, "suffix");
+
+    // to existing strings
+    std::string p2, m2, s2;
+    std::tie(p2, m2, s2) = partition("abc", "b");
+    EXPECT_EQ(p2, "a");
+    EXPECT_EQ(m2, "b");
+    EXPECT_EQ(s2, "c");
+}
+
+TEST(String, ToPaddedString)
+{
+    // zero-pad (default)
+    EXPECT_EQ(to_padded_string(5, 3), "005");
+    EXPECT_EQ(to_padded_string(5, 10), "0000000005");
+
+    // zero-pad (custom)
+    EXPECT_EQ(to_padded_string(5, 3, '5'), "555");
+    EXPECT_EQ(to_padded_string(5, 3, 'x'), "xx5");
+}
+
 TEST(String, ToNumeric)
 {
     std::string test{"100.3456 unparsed"};
-    EXPECT_EQ(to_numeric<int8_t>(test), int8_t(100));
-    EXPECT_EQ(to_numeric<uint8_t>(test), uint8_t(100));
-    EXPECT_EQ(to_numeric<int16_t>(test), int16_t(100));
-    EXPECT_EQ(to_numeric<uint16_t>(test), uint16_t(100));
-    EXPECT_EQ(to_numeric<int32_t>(test), int32_t(100));
-    EXPECT_EQ(to_numeric<uint32_t>(test), uint32_t(100));
-    EXPECT_EQ(to_numeric<int64_t>(test), int64_t(100));
-    EXPECT_EQ(to_numeric<uint64_t>(test), uint64_t(100));
+    EXPECT_EQ(to_numeric<int8_t>(test), std::int8_t{100});
+    EXPECT_EQ(to_numeric<uint8_t>(test), std::uint8_t{100});
+    EXPECT_EQ(to_numeric<int16_t>(test), std::int16_t{100});
+    EXPECT_EQ(to_numeric<uint16_t>(test), std::uint16_t{100});
+    EXPECT_EQ(to_numeric<int32_t>(test), std::int32_t{100});
+    EXPECT_EQ(to_numeric<uint32_t>(test), std::uint32_t{100});
+    EXPECT_EQ(to_numeric<int64_t>(test), std::int64_t{100});
+    EXPECT_EQ(to_numeric<uint64_t>(test), std::uint64_t{100});
 
     EXPECT_EQ(to_numeric<float>(test), 100.3456F);
     EXPECT_EQ(to_numeric<double>(test), 100.3456);