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Implement a sourcemeta::core::is_pointer convenience function #2295

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Merged
jviotti merged 1 commit into from
Mar 17, 2026
Merged

Implement a sourcemeta::core::is_pointer convenience function #2295

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15 changes: 15 additions & 0 deletions src/core/jsonpointer/include/sourcemeta/core/jsonpointer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -423,6 +423,21 @@ auto to_pointer(const std::basic_string<JSON::Char, JSON::CharTraits,
SOURCEMETA_CORE_JSONPOINTER_EXPORT
auto to_pointer(const WeakPointer &pointer) -> Pointer;

/// @ingroup jsonpointer
/// Check if the given string is a valid JSON Pointer per RFC 6901 without
/// constructing a JSON Pointer object. For example:
///
/// ```cpp
/// #include <sourcemeta/core/jsonpointer.h>
/// #include <cassert>
///
/// assert(sourcemeta::core::is_pointer("/foo/bar/0"));
/// assert(sourcemeta::core::is_pointer(""));
/// assert(!sourcemeta::core::is_pointer("foo"));
/// ```
SOURCEMETA_CORE_JSONPOINTER_EXPORT
auto is_pointer(std::string_view input) noexcept -> bool;

/// @ingroup jsonpointer
/// Convert a JSON Pointer into a JSON WeakPointer. For example:
///
Expand Down
13 changes: 12 additions & 1 deletion src/core/jsonpointer/jsonpointer.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
#include <ostream> // std::basic_ostream
#include <sstream> // std::basic_ostringstream, std::basic_stringstream
#include <string> // std::basic_string
#include <string_view> // std::string_view
#include <type_traits> // std::is_same_v
#include <utility> // std::move

Expand Down Expand Up @@ -302,7 +303,7 @@ auto remove(JSON &document, const WeakPointer &pointer) -> bool {
auto to_pointer(const JSON &document) -> Pointer {
assert(document.is_string());
auto stream{document.to_stringstream()};
return parse_pointer(stream);
return parse_pointer<false>(stream);
}

auto to_pointer(const std::basic_string<JSON::Char, JSON::CharTraits,
Expand Down Expand Up @@ -407,4 +408,14 @@ auto to_uri(const WeakPointer &pointer, const std::string_view base) -> URI {
return to_uri(pointer).resolve_from(URI{base}).canonicalize();
}

auto is_pointer(const std::string_view input) noexcept -> bool {
try {
std::basic_istringstream<JSON::Char> stream{std::string{input}};
parse_pointer<true>(stream);
return true;
} catch (...) {
return false;
}
}

} // namespace sourcemeta::core
94 changes: 64 additions & 30 deletions src/core/jsonpointer/parser.h
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Original file line number Diff line number Diff line change
Expand Up @@ -7,11 +7,12 @@
#include <sourcemeta/core/jsonpointer.h>
#include <sourcemeta/core/jsonpointer_error.h>

#include <cstdint> // std::uint64_t
#include <istream> // std::basic_istream
#include <sstream> // std::basic_stringstream
#include <stdexcept> // std::out_of_range
#include <string> // std::stoi
#include <cstdint> // std::uint64_t
#include <istream> // std::basic_istream
#include <sstream> // std::basic_stringstream
#include <stdexcept> // std::out_of_range
#include <string> // std::stoi
#include <type_traits> // std::conditional_t

namespace sourcemeta::core::internal {
template <typename CharT, typename Traits,
Expand Down Expand Up @@ -41,11 +42,12 @@ parse_index(std::basic_stringstream<CharT, Traits, Allocator<CharT>> &stream,
// NOLINTBEGIN(cppcoreguidelines-avoid-goto)

namespace sourcemeta::core {
template <bool CheckOnly>
auto parse_pointer(std::basic_istream<JSON::Char, JSON::CharTraits> &stream)
-> Pointer {
Pointer result;
-> std::conditional_t<CheckOnly, void, Pointer> {
[[maybe_unused]] Pointer result;
JSON::Char character = 0;
std::basic_stringstream<JSON::Char> string;
[[maybe_unused]] std::basic_stringstream<JSON::Char> string;
std::uint64_t column{0};

parse_token_begin:
Expand Down Expand Up @@ -84,15 +86,21 @@ auto parse_pointer(std::basic_istream<JSON::Char, JSON::CharTraits> &stream)
case internal::token_pointer_number_nine<JSON::Char>:
column += 1;
stream.ignore();
string.put(character);
if constexpr (!CheckOnly) {
string.put(character);
}
goto parse_token_index_rest_any;
case static_cast<JSON::Char>(JSON::CharTraits::eof()):
column += 1;
stream.ignore();
result.emplace_back("");
if constexpr (!CheckOnly) {
result.emplace_back("");
}
goto done;
case internal::token_pointer_slash<JSON::Char>:
result.emplace_back("");
if constexpr (!CheckOnly) {
result.emplace_back("");
}
goto parse_token_begin;
case internal::token_pointer_tilde<JSON::Char>:
column += 1;
Expand All @@ -101,7 +109,9 @@ auto parse_pointer(std::basic_istream<JSON::Char, JSON::CharTraits> &stream)
default:
column += 1;
stream.ignore();
string.put(character);
if constexpr (!CheckOnly) {
string.put(character);
}
goto parse_token_property_rest_any;
}

Expand All @@ -110,20 +120,26 @@ auto parse_pointer(std::basic_istream<JSON::Char, JSON::CharTraits> &stream)
*/

parse_token_index_end:
string.put(character);
if constexpr (!CheckOnly) {
string.put(character);
}
character = static_cast<JSON::Char>(stream.peek());
switch (character) {
case internal::token_pointer_slash<JSON::Char>:
column += 1;
stream.ignore();
result.emplace_back(internal::parse_index(string, column));
internal::reset(string);
if constexpr (!CheckOnly) {
result.emplace_back(internal::parse_index(string, column));
internal::reset(string);
}
goto parse_token_content;
case static_cast<JSON::Char>(JSON::CharTraits::eof()):
column += 1;
stream.ignore();
result.emplace_back(internal::parse_index(string, column));
internal::reset(string);
if constexpr (!CheckOnly) {
result.emplace_back(internal::parse_index(string, column));
internal::reset(string);
}
goto done;
default:
goto parse_token_property_rest_any;
Expand All @@ -135,14 +151,18 @@ auto parse_pointer(std::basic_istream<JSON::Char, JSON::CharTraits> &stream)
case internal::token_pointer_slash<JSON::Char>:
column += 1;
stream.ignore();
result.emplace_back(internal::parse_index(string, column));
internal::reset(string);
if constexpr (!CheckOnly) {
result.emplace_back(internal::parse_index(string, column));
internal::reset(string);
}
goto parse_token_content;
case static_cast<JSON::Char>(JSON::CharTraits::eof()):
column += 1;
stream.ignore();
result.emplace_back(internal::parse_index(string, column));
internal::reset(string);
if constexpr (!CheckOnly) {
result.emplace_back(internal::parse_index(string, column));
internal::reset(string);
}
goto done;
case internal::token_pointer_number_zero<JSON::Char>:
case internal::token_pointer_number_one<JSON::Char>:
Expand All @@ -156,7 +176,9 @@ auto parse_pointer(std::basic_istream<JSON::Char, JSON::CharTraits> &stream)
case internal::token_pointer_number_nine<JSON::Char>:
column += 1;
stream.ignore();
string.put(character);
if constexpr (!CheckOnly) {
string.put(character);
}
goto parse_token_index_rest_any;

default:
Expand All @@ -172,17 +194,23 @@ auto parse_pointer(std::basic_istream<JSON::Char, JSON::CharTraits> &stream)
column += 1;
switch (character) {
case internal::token_pointer_slash<JSON::Char>:
result.emplace_back(string.str());
internal::reset(string);
if constexpr (!CheckOnly) {
result.emplace_back(string.str());
internal::reset(string);
}
goto parse_token_content;
case internal::token_pointer_tilde<JSON::Char>:
goto parse_token_escape_tilde;
case static_cast<JSON::Char>(JSON::CharTraits::eof()):
result.emplace_back(string.str());
internal::reset(string);
if constexpr (!CheckOnly) {
result.emplace_back(string.str());
internal::reset(string);
}
goto done;
default:
string.put(character);
if constexpr (!CheckOnly) {
string.put(character);
}
goto parse_token_property_rest_any;
}

Expand All @@ -196,17 +224,23 @@ auto parse_pointer(std::basic_istream<JSON::Char, JSON::CharTraits> &stream)
// See https://www.rfc-editor.org/rfc/rfc6901#section-3
switch (character) {
case internal::token_pointer_number_zero<JSON::Char>:
string.put(internal::token_pointer_tilde<JSON::Char>);
if constexpr (!CheckOnly) {
string.put(internal::token_pointer_tilde<JSON::Char>);
}
goto parse_token_property_rest_any;
case internal::token_pointer_number_one<JSON::Char>:
string.put(internal::token_pointer_slash<JSON::Char>);
if constexpr (!CheckOnly) {
string.put(internal::token_pointer_slash<JSON::Char>);
}
goto parse_token_property_rest_any;
default:
throw PointerParseError(column);
}

done:
return result;
if constexpr (!CheckOnly) {
return result;
}
}

// NOLINTEND(cppcoreguidelines-avoid-goto)
Expand Down
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