Move /src to /subprojects

This will facilitate breaking up Nix into multiple packages for each
component with Meson.

subprojects/libutil/url.cc

@@ -0,0 +1,198 @@
+#include "url.hh"
+#include "url-parts.hh"
+#include "util.hh"
+#include "split.hh"
+#include "canon-path.hh"
+
+namespace nix {
+
+std::regex refRegex(refRegexS, std::regex::ECMAScript);
+std::regex badGitRefRegex(badGitRefRegexS, std::regex::ECMAScript);
+std::regex revRegex(revRegexS, std::regex::ECMAScript);
+
+ParsedURL parseURL(const std::string & url)
+{
+    static std::regex uriRegex(
+        "((" + schemeNameRegex + "):"
+        + "(?:(?://(" + authorityRegex + ")(" + absPathRegex + "))|(/?" + pathRegex + ")))"
+        + "(?:\\?(" + queryRegex + "))?"
+        + "(?:#(" + fragmentRegex + "))?",
+        std::regex::ECMAScript);
+
+    std::smatch match;
+
+    if (std::regex_match(url, match, uriRegex)) {
+        auto & base = match[1];
+        std::string scheme = match[2];
+        auto authority = match[3].matched
+            ? std::optional<std::string>(match[3]) : std::nullopt;
+        std::string path = match[4].matched ? match[4] : match[5];
+        auto & query = match[6];
+        auto & fragment = match[7];
+
+        auto transportIsFile = parseUrlScheme(scheme).transport == "file";
+
+        if (authority && *authority != "" && transportIsFile)
+            throw BadURL("file:// URL '%s' has unexpected authority '%s'",
+                url, *authority);
+
+        if (transportIsFile && path.empty())
+            path = "/";
+
+        return ParsedURL{
+            .url = url,
+            .base = base,
+            .scheme = scheme,
+            .authority = authority,
+            .path = percentDecode(path),
+            .query = decodeQuery(query),
+            .fragment = percentDecode(std::string(fragment))
+        };
+    }
+
+    else
+        throw BadURL("'%s' is not a valid URL", url);
+}
+
+std::string percentDecode(std::string_view in)
+{
+    std::string decoded;
+    for (size_t i = 0; i < in.size(); ) {
+        if (in[i] == '%') {
+            if (i + 2 >= in.size())
+                throw BadURL("invalid URI parameter '%s'", in);
+            try {
+                decoded += std::stoul(std::string(in, i + 1, 2), 0, 16);
+                i += 3;
+            } catch (...) {
+                throw BadURL("invalid URI parameter '%s'", in);
+            }
+        } else
+            decoded += in[i++];
+    }
+    return decoded;
+}
+
+std::map<std::string, std::string> decodeQuery(const std::string & query)
+{
+    std::map<std::string, std::string> result;
+
+    for (auto s : tokenizeString<Strings>(query, "&")) {
+        auto e = s.find('=');
+        if (e == std::string::npos) {
+            warn("dubious URI query '%s' is missing equal sign '%s', ignoring", s, "=");
+            continue;
+        }
+
+        result.emplace(
+            s.substr(0, e),
+            percentDecode(std::string_view(s).substr(e + 1)));
+    }
+
+    return result;
+}
+
+const static std::string allowedInQuery = ":@/?";
+const static std::string allowedInPath = ":@/";
+
+std::string percentEncode(std::string_view s, std::string_view keep)
+{
+    std::string res;
+    for (auto & c : s)
+        // unreserved + keep
+        if ((c >= 'a' && c <= 'z')
+            || (c >= 'A' && c <= 'Z')
+            || (c >= '0' && c <= '9')
+            || strchr("-._~", c)
+            || keep.find(c) != std::string::npos)
+            res += c;
+        else
+            res += fmt("%%%02X", c & 0xFF);
+    return res;
+}
+
+std::string encodeQuery(const std::map<std::string, std::string> & ss)
+{
+    std::string res;
+    bool first = true;
+    for (auto & [name, value] : ss) {
+        if (!first) res += '&';
+        first = false;
+        res += percentEncode(name, allowedInQuery);
+        res += '=';
+        res += percentEncode(value, allowedInQuery);
+    }
+    return res;
+}
+
+std::string ParsedURL::to_string() const
+{
+    return
+        scheme
+        + ":"
+        + (authority ? "//" + *authority : "")
+        + percentEncode(path, allowedInPath)
+        + (query.empty() ? "" : "?" + encodeQuery(query))
+        + (fragment.empty() ? "" : "#" + percentEncode(fragment));
+}
+
+bool ParsedURL::operator ==(const ParsedURL & other) const noexcept
+{
+    return
+        scheme == other.scheme
+        && authority == other.authority
+        && path == other.path
+        && query == other.query
+        && fragment == other.fragment;
+}
+
+ParsedURL ParsedURL::canonicalise()
+{
+    ParsedURL res(*this);
+    res.path = CanonPath(res.path).abs();
+    return res;
+}
+
+/**
+ * Parse a URL scheme of the form '(applicationScheme\+)?transportScheme'
+ * into a tuple '(applicationScheme, transportScheme)'
+ *
+ * > parseUrlScheme("http") == ParsedUrlScheme{ {}, "http"}
+ * > parseUrlScheme("tarball+http") == ParsedUrlScheme{ {"tarball"}, "http"}
+ */
+ParsedUrlScheme parseUrlScheme(std::string_view scheme)
+{
+    auto application = splitPrefixTo(scheme, '+');
+    auto transport = scheme;
+    return ParsedUrlScheme {
+        .application = application,
+        .transport = transport,
+    };
+}
+
+std::string fixGitURL(const std::string & url)
+{
+    std::regex scpRegex("([^/]*)@(.*):(.*)");
+    if (!hasPrefix(url, "/") && std::regex_match(url, scpRegex))
+        return std::regex_replace(url, scpRegex, "ssh://$1@$2/$3");
+    if (hasPrefix(url, "file:"))
+        return url;
+    if (url.find("://") == std::string::npos) {
+        return (ParsedURL {
+            .scheme = "file",
+            .authority = "",
+            .path = url
+        }).to_string();
+    }
+    return url;
+}
+
+// https://www.rfc-editor.org/rfc/rfc3986#section-3.1
+bool isValidSchemeName(std::string_view s)
+{
+    static std::regex regex(schemeNameRegex, std::regex::ECMAScript);
+
+    return std::regex_match(s.begin(), s.end(), regex, std::regex_constants::match_default);
+}
+
+}