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Add a URITemplate::is_uritemplate static method #2382

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Merged
jviotti merged 1 commit into from
May 14, 2026
Merged

Add a URITemplate::is_uritemplate static method #2382

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54 changes: 37 additions & 17 deletions src/core/uritemplate/helpers.h
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Original file line number Diff line number Diff line change
Expand Up @@ -177,9 +177,10 @@ inline auto parse_varname(const std::string_view input, std::size_t position)
return position;
}

template <bool CheckOnly>
inline auto
parse_variable_list(const std::string_view input, std::size_t position,
std::vector<URITemplateVariableSpecification> &variables)
std::vector<URITemplateVariableSpecification> *variables)
-> std::size_t {
while (true) {
const auto start = position;
Expand All @@ -189,9 +190,9 @@ parse_variable_list(const std::string_view input, std::size_t position,
throw URITemplateParseError(position + 1);
}

const auto name = input.substr(start, position - start);
std::uint16_t length = 0;
bool explode = false;
[[maybe_unused]] const auto name = input.substr(start, position - start);
[[maybe_unused]] std::uint16_t length = 0;
[[maybe_unused]] bool explode = false;

if (position >= input.size()) {
throw URITemplateParseError(1);
Expand Down Expand Up @@ -225,14 +226,20 @@ parse_variable_list(const std::string_view input, std::size_t position,
throw URITemplateParseError(prefix_start + 1);
}

length = value;
if constexpr (!CheckOnly) {
length = value;
}
} else if (input[position] == '*') {
explode = true;
if constexpr (!CheckOnly) {
explode = true;
}
position++;
}

variables.push_back(URITemplateVariableSpecification{
.name = name, .length = length, .explode = explode});
if constexpr (!CheckOnly) {
variables->push_back(URITemplateVariableSpecification{
.name = name, .length = length, .explode = explode});
}

if (position >= input.size()) {
throw URITemplateParseError(1);
Expand All @@ -250,8 +257,10 @@ parse_variable_list(const std::string_view input, std::size_t position,
return position;
}

template <typename T>
auto parse_expression(const std::string_view input) -> URITemplateParseResult {
template <typename T, bool CheckOnly>
auto parse_expression(const std::string_view input)
-> std::conditional_t<CheckOnly, std::optional<std::size_t>,
URITemplateParseResult> {
if constexpr (std::is_same_v<T, URITemplateTokenLiteral>) {
if (input.empty() || input[0] == '{') {
return std::nullopt;
Expand All @@ -272,9 +281,13 @@ auto parse_expression(const std::string_view input) -> URITemplateParseResult {
position++;
}

return std::make_pair(
URITemplateToken{URITemplateTokenLiteral{input.substr(0, position)}},
position);
if constexpr (CheckOnly) {
return position;
} else {
return std::make_pair(
URITemplateToken{URITemplateTokenLiteral{input.substr(0, position)}},
position);
}
} else {
if (input.empty() || input[0] != '{') {
return std::nullopt;
Expand All @@ -297,10 +310,17 @@ auto parse_expression(const std::string_view input) -> URITemplateParseResult {
var_start = 1;
}

std::vector<URITemplateVariableSpecification> variables;
const auto end_position = parse_variable_list(input, var_start, variables);
return std::make_pair(URITemplateToken{T{std::move(variables)}},
end_position + 1);
if constexpr (CheckOnly) {
const auto end_position =
parse_variable_list<true>(input, var_start, nullptr);
return end_position + 1;
} else {
std::vector<URITemplateVariableSpecification> variables;
const auto end_position =
parse_variable_list<false>(input, var_start, &variables);
return std::make_pair(URITemplateToken{T{std::move(variables)}},
end_position + 1);
}
}
}

Expand Down
15 changes: 15 additions & 0 deletions src/core/uritemplate/include/sourcemeta/core/uritemplate.h
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,21 @@ class SOURCEMETA_CORE_URITEMPLATE_EXPORT URITemplate {
/// ```
URITemplate(const std::string_view source);

/// Check whether the given string is a valid RFC 6570 URI Template
/// without building the parsed representation. For example:
///
/// ```cpp
/// #include <sourcemeta/core/uritemplate.h>
///
/// #include <cassert>
///
/// assert(sourcemeta::core::URITemplate::is_uritemplate(
/// "http://example.com/~{username}/"));
/// assert(!sourcemeta::core::URITemplate::is_uritemplate("{var"));
/// ```
[[nodiscard]] static auto is_uritemplate(std::string_view input) noexcept
-> bool;

/// Get the number of tokens in the template
[[nodiscard]] auto size() const noexcept -> std::uint64_t;

Expand Down
51 changes: 40 additions & 11 deletions src/core/uritemplate/uritemplate.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -8,23 +8,28 @@

namespace sourcemeta::core {

template <typename T>
template <typename T, bool CheckOnly>
static auto try_parse(std::string_view &remaining, std::size_t &offset,
std::vector<URITemplateToken> &tokens) -> bool {
if (auto result = parse_expression<T>(remaining)) {
tokens.emplace_back(std::move(result->first));
remaining.remove_prefix(result->second);
offset += result->second;
std::vector<URITemplateToken> *tokens) -> bool {
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@augmentcode augmentcode Bot May 14, 2026 •
edited
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src/core/uritemplate/uritemplate.cc:13: When instantiated with CheckOnly=true, the tokens parameter becomes unused due to the if constexpr branch, and this repo enables -Wunused-parameter, so this will likely produce a compiler warning. The same unused-parameter pattern also shows up in the check-only instantiations at the other locations listed below.

Severity: low

Other Locations
  • src/core/uritemplate/uritemplate.cc:31
  • src/core/uritemplate/helpers.h:183

Fix This in Augment

🤖 Was this useful? React with 👍 or 👎, or 🚀 if it prevented an incident/outage.

if (auto result = parse_expression<T, CheckOnly>(remaining)) {
if constexpr (CheckOnly) {
remaining.remove_prefix(*result);
offset += *result;
} else {
tokens->emplace_back(std::move(result->first));
remaining.remove_prefix(result->second);
offset += result->second;
}
return true;
}

return false;
}

template <typename... Ts>
template <bool CheckOnly, typename... Ts>
static auto try_parse_any(std::string_view &remaining, std::size_t &offset,
std::vector<URITemplateToken> &tokens) -> bool {
return (try_parse<Ts>(remaining, offset, tokens) || ...);
std::vector<URITemplateToken> *tokens) -> bool {
return (try_parse<Ts, CheckOnly>(remaining, offset, tokens) || ...);
}

URITemplate::URITemplate(const std::string_view source) {
Expand All @@ -33,15 +38,15 @@ URITemplate::URITemplate(const std::string_view source) {

while (!remaining.empty()) {
try {
if (!try_parse_any<URITemplateTokenReservedExpansion,
if (!try_parse_any<false, URITemplateTokenReservedExpansion,
URITemplateTokenFragmentExpansion,
URITemplateTokenLabelExpansion,
URITemplateTokenPathExpansion,
URITemplateTokenPathParameterExpansion,
URITemplateTokenQueryExpansion,
URITemplateTokenQueryContinuationExpansion,
URITemplateTokenVariable, URITemplateTokenLiteral>(
remaining, offset, this->tokens_)) {
remaining, offset, &this->tokens_)) {
break;
}
} catch (URITemplateParseError &error) {
Expand All @@ -50,6 +55,30 @@ URITemplate::URITemplate(const std::string_view source) {
}
}

auto URITemplate::is_uritemplate(const std::string_view input) noexcept
-> bool {
try {
std::string_view remaining{input};
std::size_t offset = 0;
while (!remaining.empty()) {
if (!try_parse_any<true, URITemplateTokenReservedExpansion,
URITemplateTokenFragmentExpansion,
URITemplateTokenLabelExpansion,
URITemplateTokenPathExpansion,
URITemplateTokenPathParameterExpansion,
URITemplateTokenQueryExpansion,
URITemplateTokenQueryContinuationExpansion,
URITemplateTokenVariable, URITemplateTokenLiteral>(
remaining, offset, nullptr)) {
return false;
}
}
return true;
} catch (...) {
return false;
}
}

auto URITemplate::size() const noexcept -> std::uint64_t {
return static_cast<std::uint64_t>(this->tokens_.size());
}
Expand Down
3 changes: 2 additions & 1 deletion test/uritemplate/uritemplate_parse_error_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,8 @@
EXPECT_EQ(error.column(), expected_column); \
} catch (...) { \
FAIL(); \
}
} \
EXPECT_FALSE(sourcemeta::core::URITemplate::is_uritemplate(input))

TEST(URITemplate_parse_error, unclosed_brace) {
EXPECT_URITEMPLATE_PARSE_ERROR("{var", 1);
Expand Down
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