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docs(3p/nix/libexpr): Add comment on ExprSelect

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This commit is contained in:
Vincent Ambo 2020-05-23 16:01:52 +01:00
parent bca0e34859
commit 39e72c27f1
1 changed files with 8 additions and 1 deletions
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9
third_party/nix/src/libexpr/nixexpr.hh vendored
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@ -147,6 +147,13 @@ struct ExprVar : Expr {
Value* maybeThunk(EvalState& state, Env& env); Value* maybeThunk(EvalState& state, Env& env);
}; };
// [tazjin] I *think* that this struct describes the syntactic
// construct for "selecting" something out of an attribute set, e.g.
// `a.b.c` => ExprSelect{"b", "c"}.
//
// Each path element has got a pointer to an expression, which seems
// to be the thing preceding its period, but afaict that is only set
// for the first one in a path.
struct ExprSelect : Expr { struct ExprSelect : Expr {
Pos pos; Pos pos;
Expr *e, *def; Expr *e, *def;
@ -200,7 +207,7 @@ struct ExprList : Expr {
struct Formal { struct Formal {
Symbol name; Symbol name;
Expr* def; // def = default, not definition Expr* def; // def = default, not definition
Formal(const Symbol& name, Expr* def) : name(name), def(def){}; Formal(const Symbol& name, Expr* def) : name(name), def(def){};
}; };