Introduce AbstractPos

This makes the position object used in exceptions abstract, with a
method getSource() to get the source code of the file in which the
error originated. This is needed for lazy trees because source files
don't necessarily exist in the filesystem, and we don't want to make
libutil depend on the InputAccessor type in libfetcher.

1 files changed, 15 insertions, 24 deletions

diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index fbf865719..ea4e0bfb0 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -34,11 +34,6 @@ namespace nix {
         Path basePath;
         PosTable::Origin origin;
         std::optional<ErrorInfo> error;
-        ParseData(EvalState & state, PosTable::Origin origin)
-            : state(state)
-            , symbols(state.symbols)
-            , origin(std::move(origin))
-            { };
     };
 
     struct ParserFormals {
@@ -649,24 +644,20 @@ formal
 namespace nix {
 
 
-Expr * EvalState::parse(char * text, size_t length, FileOrigin origin,
-    const PathView path, const PathView basePath, std::shared_ptr<StaticEnv> & staticEnv)
+Expr * EvalState::parse(
+    char * text,
+    size_t length,
+    Pos::Origin origin,
+    Path basePath,
+    std::shared_ptr<StaticEnv> & staticEnv)
 {
     yyscan_t scanner;
-    std::string file;
-    switch (origin) {
-        case foFile:
-            file = path;
-            break;
-        case foStdin:
-        case foString:
-            file = text;
-            break;
-        default:
-            assert(false);
-    }
-    ParseData data(*this, {file, origin});
-    data.basePath = basePath;
+    ParseData data {
+        .state = *this,
+        .symbols = symbols,
+        .basePath = std::move(basePath),
+        .origin = {origin},
+    };
 
     yylex_init(&scanner);
     yy_scan_buffer(text, length, scanner);
@@ -718,14 +709,14 @@ Expr * EvalState::parseExprFromFile(const Path & path, std::shared_ptr<StaticEnv
     auto buffer = readFile(path);
     // readFile should have left some extra space for terminators
     buffer.append("\0\0", 2);
-    return parse(buffer.data(), buffer.size(), foFile, path, dirOf(path), staticEnv);
+    return parse(buffer.data(), buffer.size(), path, dirOf(path), staticEnv);
 }
 
 
 Expr * EvalState::parseExprFromString(std::string s, const Path & basePath, std::shared_ptr<StaticEnv> & staticEnv)
 {
     s.append("\0\0", 2);
-    return parse(s.data(), s.size(), foString, "", basePath, staticEnv);
+    return parse(s.data(), s.size(), Pos::string_tag(), basePath, staticEnv);
 }
 
 
@@ -741,7 +732,7 @@ Expr * EvalState::parseStdin()
     auto buffer = drainFD(0);
     // drainFD should have left some extra space for terminators
     buffer.append("\0\0", 2);
-    return parse(buffer.data(), buffer.size(), foStdin, "", absPath("."), staticBaseEnv);
+    return parse(buffer.data(), buffer.size(), Pos::stdin_tag(), absPath("."), staticBaseEnv);
 }