Move /src to /subprojects

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

subprojects/libutil/util.hh

@@ -0,0 +1,361 @@
+#pragma once
+///@file
+
+#include "types.hh"
+#include "error.hh"
+#include "logging.hh"
+
+
+#include <functional>
+#include <map>
+#include <sstream>
+#include <optional>
+
+#include "strings.hh"
+
+namespace nix {
+
+void initLibUtil();
+
+/**
+ * Convert a list of strings to a null-terminated vector of `char
+ * *`s. The result must not be accessed beyond the lifetime of the
+ * list of strings.
+ */
+std::vector<char *> stringsToCharPtrs(const Strings & ss);
+
+
+MakeError(FormatError, Error);
+
+
+template<class... Parts>
+auto concatStrings(Parts &&... parts)
+    -> std::enable_if_t<(... && std::is_convertible_v<Parts, std::string_view>), std::string>
+{
+    std::string_view views[sizeof...(parts)] = {parts...};
+    return concatStringsSep({}, views);
+}
+
+
+/**
+ * Add quotes around a collection of strings.
+ */
+template<class C> Strings quoteStrings(const C & c)
+{
+    Strings res;
+    for (auto & s : c)
+        res.push_back("'" + s + "'");
+    return res;
+}
+
+/**
+ * Remove trailing whitespace from a string.
+ *
+ * \todo return std::string_view.
+ */
+std::string chomp(std::string_view s);
+
+
+/**
+ * Remove whitespace from the start and end of a string.
+ */
+std::string trim(std::string_view s, std::string_view whitespace = " \n\r\t");
+
+
+/**
+ * Replace all occurrences of a string inside another string.
+ */
+std::string replaceStrings(
+    std::string s,
+    std::string_view from,
+    std::string_view to);
+
+
+std::string rewriteStrings(std::string s, const StringMap & rewrites);
+
+
+/**
+ * Parse a string into an integer.
+ */
+template<class N>
+std::optional<N> string2Int(const std::string_view s);
+
+/**
+ * Like string2Int(), but support an optional suffix 'K', 'M', 'G' or
+ * 'T' denoting a binary unit prefix.
+ */
+template<class N>
+N string2IntWithUnitPrefix(std::string_view s)
+{
+    uint64_t multiplier = 1;
+    if (!s.empty()) {
+        char u = std::toupper(*s.rbegin());
+        if (std::isalpha(u)) {
+            if (u == 'K') multiplier = 1ULL << 10;
+            else if (u == 'M') multiplier = 1ULL << 20;
+            else if (u == 'G') multiplier = 1ULL << 30;
+            else if (u == 'T') multiplier = 1ULL << 40;
+            else throw UsageError("invalid unit specifier '%1%'", u);
+            s.remove_suffix(1);
+        }
+    }
+    if (auto n = string2Int<N>(s))
+        return *n * multiplier;
+    throw UsageError("'%s' is not an integer", s);
+}
+
+/**
+ * Pretty-print a byte value, e.g. 12433615056 is rendered as `11.6
+ * GiB`. If `align` is set, the number will be right-justified by
+ * padding with spaces on the left.
+ */
+std::string renderSize(uint64_t value, bool align = false);
+
+/**
+ * Parse a string into a float.
+ */
+template<class N>
+std::optional<N> string2Float(const std::string_view s);
+
+
+/**
+ * Convert a little-endian integer to host order.
+ */
+template<typename T>
+T readLittleEndian(unsigned char * p)
+{
+    T x = 0;
+    for (size_t i = 0; i < sizeof(x); ++i, ++p) {
+        x |= ((T) *p) << (i * 8);
+    }
+    return x;
+}
+
+
+/**
+ * @return true iff `s` starts with `prefix`.
+ */
+bool hasPrefix(std::string_view s, std::string_view prefix);
+
+
+/**
+ * @return true iff `s` ends in `suffix`.
+ */
+bool hasSuffix(std::string_view s, std::string_view suffix);
+
+
+/**
+ * Convert a string to lower case.
+ */
+std::string toLower(std::string s);
+
+
+/**
+ * Escape a string as a shell word.
+ */
+std::string shellEscape(const std::string_view s);
+
+
+/**
+ * Exception handling in destructors: print an error message, then
+ * ignore the exception.
+ *
+ * If you're not in a destructor, you usually want to use `ignoreExceptionExceptInterrupt()`.
+ *
+ * This function might also be used in callbacks whose caller may not handle exceptions,
+ * but ideally we propagate the exception using an exception_ptr in such cases.
+ * See e.g. `PackBuilderContext`
+ */
+void ignoreExceptionInDestructor(Verbosity lvl = lvlError);
+
+/**
+ * Not destructor-safe.
+ * Print an error message, then ignore the exception.
+ * If the exception is an `Interrupted` exception, rethrow it.
+ *
+ * This may be used in a few places where Interrupt can't happen, but that's ok.
+ */
+void ignoreExceptionExceptInterrupt(Verbosity lvl = lvlError);
+
+
+
+/**
+ * Tree formatting.
+ */
+constexpr char treeConn[] = "├───";
+constexpr char treeLast[] = "└───";
+constexpr char treeLine[] = "│   ";
+constexpr char treeNull[] = "    ";
+
+
+/**
+ * Encode arbitrary bytes as Base64.
+ */
+std::string base64Encode(std::string_view s);
+
+/**
+ * Decode arbitrary bytes to Base64.
+ */
+std::string base64Decode(std::string_view s);
+
+
+/**
+ * Remove common leading whitespace from the lines in the string
+ * 's'. For example, if every line is indented by at least 3 spaces,
+ * then we remove 3 spaces from the start of every line.
+ */
+std::string stripIndentation(std::string_view s);
+
+
+/**
+ * Get the prefix of 's' up to and excluding the next line break (LF
+ * optionally preceded by CR), and the remainder following the line
+ * break.
+ */
+std::pair<std::string_view, std::string_view> getLine(std::string_view s);
+
+
+/**
+ * Get a value for the specified key from an associate container.
+ */
+template <class T>
+const typename T::mapped_type * get(const T & map, const typename T::key_type & key)
+{
+    auto i = map.find(key);
+    if (i == map.end()) return nullptr;
+    return &i->second;
+}
+
+template <class T>
+typename T::mapped_type * get(T & map, const typename T::key_type & key)
+{
+    auto i = map.find(key);
+    if (i == map.end()) return nullptr;
+    return &i->second;
+}
+
+/**
+ * Get a value for the specified key from an associate container, or a default value if the key isn't present.
+ */
+template <class T>
+const typename T::mapped_type & getOr(T & map,
+    const typename T::key_type & key,
+    const typename T::mapped_type & defaultValue)
+{
+    auto i = map.find(key);
+    if (i == map.end()) return defaultValue;
+    return i->second;
+}
+
+/**
+ * Remove and return the first item from a container.
+ */
+template <class T>
+std::optional<typename T::value_type> remove_begin(T & c)
+{
+    auto i = c.begin();
+    if (i == c.end()) return {};
+    auto v = std::move(*i);
+    c.erase(i);
+    return v;
+}
+
+
+/**
+ * Remove and return the first item from a container.
+ */
+template <class T>
+std::optional<typename T::value_type> pop(T & c)
+{
+    if (c.empty()) return {};
+    auto v = std::move(c.front());
+    c.pop();
+    return v;
+}
+
+
+template<typename T>
+class Callback;
+
+
+/**
+ * A RAII helper that increments a counter on construction and
+ * decrements it on destruction.
+ */
+template<typename T>
+struct MaintainCount
+{
+    T & counter;
+    long delta;
+    MaintainCount(T & counter, long delta = 1) : counter(counter), delta(delta) { counter += delta; }
+    ~MaintainCount() { counter -= delta; }
+};
+
+
+/**
+ * A Rust/Python-like enumerate() iterator adapter.
+ *
+ * Borrowed from http://reedbeta.com/blog/python-like-enumerate-in-cpp17.
+ */
+template <typename T,
+          typename TIter = decltype(std::begin(std::declval<T>())),
+          typename = decltype(std::end(std::declval<T>()))>
+constexpr auto enumerate(T && iterable)
+{
+    struct iterator
+    {
+        size_t i;
+        TIter iter;
+        constexpr bool operator != (const iterator & other) const { return iter != other.iter; }
+        constexpr void operator ++ () { ++i; ++iter; }
+        constexpr auto operator * () const { return std::tie(i, *iter); }
+    };
+
+    struct iterable_wrapper
+    {
+        T iterable;
+        constexpr auto begin() { return iterator{ 0, std::begin(iterable) }; }
+        constexpr auto end() { return iterator{ 0, std::end(iterable) }; }
+    };
+
+    return iterable_wrapper{ std::forward<T>(iterable) };
+}
+
+
+/**
+ * C++17 std::visit boilerplate
+ */
+template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
+template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
+
+
+std::string showBytes(uint64_t bytes);
+
+
+/**
+ * Provide an addition operator between strings and string_views
+ * inexplicably omitted from the standard library.
+ */
+inline std::string operator + (const std::string & s1, std::string_view s2)
+{
+    auto s = s1;
+    s.append(s2);
+    return s;
+}
+
+inline std::string operator + (std::string && s, std::string_view s2)
+{
+    s.append(s2);
+    return std::move(s);
+}
+
+inline std::string operator + (std::string_view s1, const char * s2)
+{
+    std::string s;
+    s.reserve(s1.size() + strlen(s2));
+    s.append(s1);
+    s.append(s2);
+    return s;
+}
+
+}