hex: Add from_spaced_hex()

The from_spaced_hex() is from_hex() extension where the whitespace in
the input is ignored.

include/evmc/hex.hpp

@@ -3,8 +3,8 @@
 // Licensed under the Apache License, Version 2.0.
 #pragma once
 
+#include <evmc/filter_iterator.hpp>
 #include <cstdint>
-#include <iterator>
 #include <optional>
 #include <string>
 #include <string_view>
@@ -104,7 +104,6 @@ inline bool validate_hex(std::string_view hex) noexcept
 ///
 /// In case the input is invalid the returned value is std::nullopt.
 /// This can happen if a non-hex digit or odd number of digits is encountered.
-/// Whitespace in the input is ignored.
 inline std::optional<bytes> from_hex(std::string_view hex)
 {
     bytes bs;
@@ -135,4 +134,25 @@ constexpr std::optional<T> from_hex(std::string_view s) noexcept
         return {};
     return r;
 }
+
+/// Decodes hex encoded string to bytes. The whitespace in the input is ignored.
+///
+/// In case the input is invalid the returned value is std::nullopt.
+/// This can happen if a non-hex digit or odd number of digits is encountered.
+/// The whitespace (as defined by std::isspace) in the input is ignored.
+template <typename InputIterator>
+std::optional<bytes> from_spaced_hex(InputIterator begin, InputIterator end) noexcept
+{
+    bytes bs;
+    if (!from_hex(skip_space_iterator{begin, end}, skip_space_iterator{end, end},
+                  std::back_inserter(bs)))
+        return {};
+    return bs;
+}
+
+/// @copydoc from_spaced_hex
+inline std::optional<bytes> from_spaced_hex(std::string_view hex) noexcept
+{
+    return from_spaced_hex(hex.begin(), hex.end());
+}
 }  // namespace evmc

test/unittests/hex_test.cpp

@@ -2,7 +2,6 @@
 // Copyright 2021 The EVMC Authors.
 // Licensed under the Apache License, Version 2.0.
 
-#include <evmc/filter_iterator.hpp>
 #include <evmc/hex.hpp>
 #include <gtest/gtest.h>
 
@@ -82,21 +81,12 @@ TEST(hex, validate_hex)
     EXPECT_FALSE(validate_hex("WXYZ"));
 }
 
-TEST(hex, from_hex_skip_space)
+TEST(hex, from_spaced_hex)
 {
-    // Combine from_hex with skip_space_iterator.
-    static constexpr auto from_hex_skip_space = [](std::string_view hex) {
-        bytes out;
-        const auto status =
-            from_hex(skip_space_iterator{hex.begin(), hex.end()},
-                     skip_space_iterator{hex.end(), hex.end()}, std::back_inserter(out));
-        EXPECT_TRUE(status);
-        return out;
-    };
-    EXPECT_EQ(from_hex_skip_space("0x010203"), (bytes{0x01, 0x02, 0x03}));
-    EXPECT_EQ(from_hex_skip_space("0x 010203 "), (bytes{0x01, 0x02, 0x03}));
-    EXPECT_EQ(from_hex_skip_space(" 0 x 0 1 0 2 0 3 "), (bytes{0x01, 0x02, 0x03}));
-    EXPECT_EQ(from_hex_skip_space("\f 0\r x  0  1\t 0  2 \v0  3 \n"), (bytes{0x01, 0x02, 0x03}));
+    EXPECT_EQ(from_spaced_hex("0x010203"), (bytes{0x01, 0x02, 0x03}));
+    EXPECT_EQ(from_spaced_hex("0x 010203 "), (bytes{0x01, 0x02, 0x03}));
+    EXPECT_EQ(from_spaced_hex(" 0 x 0 1 0 2 0 3 "), (bytes{0x01, 0x02, 0x03}));
+    EXPECT_EQ(from_spaced_hex("\f 0\r x  0  1\t 0  2 \v0  3 \n"), (bytes{0x01, 0x02, 0x03}));
 }
 
 TEST(hex, from_hex_to_custom_type)

tools/evmc/main.cpp

@@ -3,7 +3,6 @@
 // Licensed under the Apache License, Version 2.0.
 
 #include <CLI/CLI.hpp>
-#include <evmc/filter_iterator.hpp>
 #include <evmc/hex.hpp>
 #include <evmc/loader.h>
 #include <evmc/tooling.hpp>
@@ -20,13 +19,11 @@ evmc::bytes load_from_hex(const std::string& str)
     {
         const auto path = str.substr(1);
         std::ifstream file{path};
-        const std::istreambuf_iterator<char> file_begin{file};
-        const std::istreambuf_iterator<char> file_end;
-        evmc::bytes out;
-        if (!evmc::from_hex(evmc::skip_space_iterator{file_begin, file_end},
-                            evmc::skip_space_iterator{file_end, file_end}, std::back_inserter(out)))
+        auto out = evmc::from_spaced_hex(std::istreambuf_iterator<char>{file},
+                                         std::istreambuf_iterator<char>{});
+        if (!out)
             throw std::invalid_argument{"invalid hex in " + path};
-        return out;
+        return out.value();
     }
 
     return evmc::from_hex(str).value();  // Should be validated already.