1 files changed, 112 insertions, 0 deletions
diff --git a/src/libutil/position.cc b/src/libutil/position.cc
new file mode 100644
index 000000000..b39a5a1d4
--- /dev/null
+++ b/src/libutil/position.cc
@@ -0,0 +1,112 @@
+#include "position.hh"
+
+namespace nix {
+
+Pos::Pos(const Pos * other)
+{
+    if (!other) {
+        return;
+    }
+    line = other->line;
+    column = other->column;
+    origin = std::move(other->origin);
+}
+
+Pos::operator std::shared_ptr<Pos>() const
+{
+    return std::make_shared<Pos>(&*this);
+}
+
+bool Pos::operator<(const Pos &rhs) const
+{
+    return std::forward_as_tuple(line, column, origin)
+        < std::forward_as_tuple(rhs.line, rhs.column, rhs.origin);
+}
+
+std::optional<LinesOfCode> Pos::getCodeLines() const
+{
+    if (line == 0)
+        return std::nullopt;
+
+    if (auto source = getSource()) {
+
+        std::istringstream iss(*source);
+        // count the newlines.
+        int count = 0;
+        std::string curLine;
+        int pl = line - 1;
+
+        LinesOfCode loc;
+
+        do {
+            std::getline(iss, curLine);
+            ++count;
+            if (count < pl)
+                ;
+            else if (count == pl) {
+                loc.prevLineOfCode = curLine;
+            } else if (count == pl + 1) {
+                loc.errLineOfCode = curLine;
+            } else if (count == pl + 2) {
+                loc.nextLineOfCode = curLine;
+                break;
+            }
+
+            if (!iss.good())
+                break;
+        } while (true);
+
+        return loc;
+    }
+
+    return std::nullopt;
+}
+
+
+std::optional<std::string> Pos::getSource() const
+{
+    return std::visit(overloaded {
+        [](const std::monostate &) -> std::optional<std::string> {
+            return std::nullopt;
+        },
+        [](const Pos::Stdin & s) -> std::optional<std::string> {
+            // Get rid of the null terminators added by the parser.
+            return std::string(s.source->c_str());
+        },
+        [](const Pos::String & s) -> std::optional<std::string> {
+            // Get rid of the null terminators added by the parser.
+            return std::string(s.source->c_str());
+        },
+        [](const SourcePath & path) -> std::optional<std::string> {
+            try {
+                return path.readFile();
+            } catch (Error &) {
+                return std::nullopt;
+            }
+        }
+    }, origin);
+}
+
+void Pos::print(std::ostream & out, bool showOrigin) const
+{
+    if (showOrigin) {
+        std::visit(overloaded {
+            [&](const std::monostate &) { out << "«none»"; },
+            [&](const Pos::Stdin &) { out << "«stdin»"; },
+            [&](const Pos::String & s) { out << "«string»"; },
+            [&](const SourcePath & path) { out << path; }
+        }, origin);
+        out << ":";
+    }
+    out << line;
+    if (column > 0)
+        out << ":" << column;
+}
+
+std::ostream & operator<<(std::ostream & str, const Pos & pos)
+{
+    pos.print(str, true);
+    return str;
+}
+
+}