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Merged
jviotti merged 2 commits into from
Apr 8, 2026
Merged

Support registering context and arguments to default routes #2340

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d3b3ec8
Support registering context and arguments to default routes
jviotti Apr 8, 2026
239739a
Simpler
jviotti Apr 8, 2026
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8 changes: 8 additions & 0 deletions src/core/uritemplate/include/sourcemeta/core/uritemplate_router.h
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,8 @@ namespace sourcemeta::core {
/// DOES NOT define expansion. So this is an opinionated non-standard adaptation
/// of URI Template for path routing purposes
class SOURCEMETA_CORE_URITEMPLATE_EXPORT URITemplateRouter {
friend class URITemplateRouterView;

public:
/// A handler identifier 0 means "no handler"
using Identifier = std::uint16_t;
Expand Down Expand Up @@ -86,6 +88,11 @@ class SOURCEMETA_CORE_URITEMPLATE_EXPORT URITemplateRouter {
const Identifier context = 0,
const std::span<const Argument> arguments = {}) -> void;

/// Register a fallback context and arguments to be returned when matching
/// a path that does not correspond to any registered route
auto otherwise(const Identifier context,
const std::span<const Argument> arguments = {}) -> void;

/// Match a path against the router. Note the callback might fire for
/// initial matches even though the entire match might still fail
[[nodiscard]] auto match(const std::string_view path,
Expand All @@ -111,6 +118,7 @@ class SOURCEMETA_CORE_URITEMPLATE_EXPORT URITemplateRouter {

private:
Node root_;
Node otherwise_;
std::string base_path_;
std::vector<std::pair<Identifier, std::vector<Argument>>> arguments_;
std::size_t size_{0};
Expand Down
54 changes: 46 additions & 8 deletions src/core/uritemplate/uritemplate_router.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,17 @@ inline auto extract_segment(const char *start, const char *end)
return {start, static_cast<std::size_t>(position - start)};
}

inline auto finalize_match(const Node &otherwise,
const URITemplateRouter::Identifier identifier,
const URITemplateRouter::Identifier context)
-> std::pair<URITemplateRouter::Identifier, URITemplateRouter::Identifier> {
if (identifier == 0) {
return {URITemplateRouter::Identifier{0}, otherwise.context};
}

return {identifier, context};
}

} // namespace

URITemplateRouter::URITemplateRouter(const std::string_view base_path)
Expand All @@ -113,6 +124,28 @@ auto URITemplateRouter::size() const noexcept -> std::size_t {
return this->size_;
}

auto URITemplateRouter::otherwise(const Identifier context,
const std::span<const Argument> arguments)
-> void {
this->otherwise_.context = context;

const auto existing = std::ranges::find_if(
this->arguments_, [](const auto &entry) { return entry.first == 0; });
if (existing == this->arguments_.end()) {
if (!arguments.empty()) {
this->arguments_.emplace_back(
Identifier{0},
std::vector<Argument>{arguments.begin(), arguments.end()});
}
} else {
if (arguments.empty()) {
this->arguments_.erase(existing);
} else {
existing->second.assign(arguments.begin(), arguments.end());
}
}
}

auto URITemplateRouter::add(const std::string_view uri_template,
const Identifier identifier,
const Identifier context,
Expand Down Expand Up @@ -361,14 +394,16 @@ auto URITemplateRouter::match(const std::string_view path,
const Callback &callback) const
-> std::pair<Identifier, Identifier> {
if (path.empty()) {
return {this->root_.identifier, this->root_.context};
return finalize_match(this->otherwise_, this->root_.identifier,
this->root_.context);
}

if (path.size() == 1 && path[0] == '/') {
if (auto *child = find_literal_child(this->root_.literals, "")) {
return {child->identifier, child->context};
return finalize_match(this->otherwise_, child->identifier,
child->context);
}
return {};
return finalize_match(this->otherwise_, 0, 0);
}

const Node *current = nullptr;
Expand Down Expand Up @@ -396,7 +431,7 @@ auto URITemplateRouter::match(const std::string_view path,

// Empty segment (from double slash or trailing slash) doesn't match
if (segment.empty()) {
return {};
return finalize_match(this->otherwise_, 0, 0);
}

if (auto *literal_match = find_literal_child(*literal_children, segment)) {
Expand All @@ -409,14 +444,15 @@ auto URITemplateRouter::match(const std::string_view path,
segment_start, static_cast<std::size_t>(path_end - segment_start)};
callback(static_cast<URITemplateRouter::Index>(variable_index),
(*variable_child)->value, remaining);
return {(*variable_child)->identifier, (*variable_child)->context};
return finalize_match(this->otherwise_, (*variable_child)->identifier,
(*variable_child)->context);
}
callback(static_cast<URITemplateRouter::Index>(variable_index),
(*variable_child)->value, segment);
++variable_index;
current = variable_child->get();
} else {
return {};
return finalize_match(this->otherwise_, 0, 0);
}

literal_children = &current->literals;
Expand All @@ -431,8 +467,10 @@ auto URITemplateRouter::match(const std::string_view path,
++position;
}

return current ? std::pair{current->identifier, current->context}
: std::pair{this->root_.identifier, this->root_.context};
return current ? finalize_match(this->otherwise_, current->identifier,
current->context)
: finalize_match(this->otherwise_, this->root_.identifier,
this->root_.context);
}

} // namespace sourcemeta::core
54 changes: 38 additions & 16 deletions src/core/uritemplate/uritemplate_router_view.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -8,14 +8,15 @@
#include <queue> // std::queue
#include <string> // std::string
#include <unordered_map> // std::unordered_map
#include <utility> // std::pair
#include <vector> // std::vector

namespace sourcemeta::core {

namespace {

constexpr std::uint32_t ROUTER_MAGIC = 0x52544552; // "RTER"
constexpr std::uint32_t ROUTER_VERSION = 4;
constexpr std::uint32_t ROUTER_VERSION = 5;
constexpr std::uint32_t NO_CHILD = std::numeric_limits<std::uint32_t>::max();

// Type tags for argument value serialization
Expand All @@ -31,6 +32,7 @@ struct RouterHeader {
std::uint32_t arguments_offset;
std::uint32_t base_path_offset;
std::uint32_t base_path_length;
std::uint32_t otherwise_context;
};

struct ArgumentEntryHeader {
Expand All @@ -52,6 +54,18 @@ struct alignas(8) SerializedNode {
std::array<std::uint8_t, 6> padding2;
};

inline auto
finalize_match(const URITemplateRouter::Identifier otherwise_context,
const URITemplateRouter::Identifier identifier,
const URITemplateRouter::Identifier context)
-> std::pair<URITemplateRouter::Identifier, URITemplateRouter::Identifier> {
if (identifier == 0) {
return {URITemplateRouter::Identifier{0}, otherwise_context};
}

return {identifier, context};
}

// Binary search for a literal child matching the given segment
inline auto binary_search_literal_children(
const SerializedNode *nodes, const char *string_table,
Expand Down Expand Up @@ -258,6 +272,7 @@ auto URITemplateRouterView::save(const URITemplateRouter &router,
header.string_table_offset + string_table.size());
header.base_path_offset = base_path_string_offset;
header.base_path_length = static_cast<std::uint32_t>(base_path_value.size());
header.otherwise_context = router.otherwise_.context;

std::ofstream file(path, std::ios::binary);
if (!file) {
Expand Down Expand Up @@ -333,10 +348,13 @@ auto URITemplateRouterView::match(
return {};
}

const auto otherwise_context =
static_cast<URITemplateRouter::Identifier>(header->otherwise_context);

if (header->node_count == 0 ||
header->node_count > (this->data_.size() - sizeof(RouterHeader)) /
sizeof(SerializedNode)) {
return {};
return finalize_match(otherwise_context, 0, 0);
}

const auto *nodes = reinterpret_cast<const SerializedNode *>(
Expand All @@ -346,12 +364,12 @@ auto URITemplateRouterView::match(
const auto expected_string_table_offset = sizeof(RouterHeader) + nodes_size;
if (header->string_table_offset < expected_string_table_offset ||
header->string_table_offset > this->data_.size()) {
return {};
return finalize_match(otherwise_context, 0, 0);
}

if (header->arguments_offset < header->string_table_offset ||
header->arguments_offset > this->data_.size()) {
return {};
return finalize_match(otherwise_context, 0, 0);
}

const auto *string_table = reinterpret_cast<const char *>(
Expand All @@ -361,29 +379,31 @@ auto URITemplateRouterView::match(

// Empty path matches empty template
if (path.empty()) {
return {nodes[0].identifier, nodes[0].context};
return finalize_match(otherwise_context, nodes[0].identifier,
nodes[0].context);
}

// Root path "/" is stored as an empty literal segment
if (path.size() == 1 && path[0] == '/') {
const auto &root = nodes[0];
if (root.first_literal_child == NO_CHILD) {
return {};
return finalize_match(otherwise_context, 0, 0);
}

if (root.first_literal_child >= header->node_count ||
root.literal_child_count >
header->node_count - root.first_literal_child) {
return {};
return finalize_match(otherwise_context, 0, 0);
}

const auto match = binary_search_literal_children(
nodes, string_table, string_table_size, root.first_literal_child,
root.literal_child_count, "", 0);
if (match == NO_CHILD) {
return {};
return finalize_match(otherwise_context, 0, 0);
}
return {nodes[match].identifier, nodes[match].context};
return finalize_match(otherwise_context, nodes[match].identifier,
nodes[match].context);
}

// Walk the trie, matching each path segment
Expand All @@ -410,7 +430,7 @@ auto URITemplateRouterView::match(

// Empty segment (from double slash or trailing slash) doesn't match
if (segment_length == 0) {
return {};
return finalize_match(otherwise_context, 0, 0);
}

const auto &node = nodes[current_node];
Expand All @@ -420,7 +440,7 @@ auto URITemplateRouterView::match(
if (node.first_literal_child != NO_CHILD) {
if (node.first_literal_child >= node_count ||
node.literal_child_count > node_count - node.first_literal_child) {
return {};
return finalize_match(otherwise_context, 0, 0);
}

const auto literal_match = binary_search_literal_children(
Expand All @@ -441,15 +461,15 @@ auto URITemplateRouterView::match(
if (node.variable_child >= node_count ||
variable_index >
std::numeric_limits<URITemplateRouter::Index>::max()) {
return {};
return finalize_match(otherwise_context, 0, 0);
}

const auto &variable_node = nodes[node.variable_child];

if (variable_node.string_offset > string_table_size ||
variable_node.string_length >
string_table_size - variable_node.string_offset) {
return {};
return finalize_match(otherwise_context, 0, 0);
}

// Check if this is an expansion (catch-all)
Expand All @@ -460,7 +480,8 @@ auto URITemplateRouterView::match(
{string_table + variable_node.string_offset,
variable_node.string_length},
{segment_start, remaining_length});
return {variable_node.identifier, variable_node.context};
return finalize_match(otherwise_context, variable_node.identifier,
variable_node.context);
}

// Regular variable - match single segment
Expand All @@ -478,10 +499,11 @@ auto URITemplateRouterView::match(
}

// No match
return {};
return finalize_match(otherwise_context, 0, 0);
}

return {nodes[current_node].identifier, nodes[current_node].context};
return finalize_match(otherwise_context, nodes[current_node].identifier,
nodes[current_node].context);
}

auto URITemplateRouterView::arguments(
Expand Down
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