From 136f2f7046dfed18fde0b5f9933ddfafc1518ef5 Mon Sep 17 00:00:00 2001 From: Shea Levy Date: Fri, 13 Sep 2013 16:55:33 -0400 Subject: [PATCH] Add the ExprBuiltin Expr type to the AST Certain desugaring schemes may require the parser to use some builtin function to do some of the work (e.g. currently `throw` is used to lazily cause an error if a `<>`-style path is not in the search path) Unfortunately, these names are not reserved keywords, so an expression that uses such a syntactic sugar will not see the expected behavior (see tests/lang/eval-okay-redefine-builtin.nix for an example). This adds the ExprBuiltin AST type, which when evaluated uses the value from the rootmost variable scope (which of course is initialized internally and can't shadow any of the builtins). Signed-off-by: Shea Levy --- src/libexpr/eval.cc | 11 +++++++++++ src/libexpr/nixexpr.cc | 9 +++++++++ src/libexpr/nixexpr.hh | 7 +++++++ src/libexpr/parser.y | 18 +++++++++--------- tests/lang/eval-okay-redefine-builtin.exp | 1 + tests/lang/eval-okay-redefine-builtin.nix | 3 +++ 6 files changed, 40 insertions(+), 9 deletions(-) create mode 100644 tests/lang/eval-okay-redefine-builtin.exp create mode 100644 tests/lang/eval-okay-redefine-builtin.nix diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index 3db4bb66f4..538325601b 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -908,6 +908,17 @@ void ExprOpNot::eval(EvalState & state, Env & env, Value & v) } +void ExprBuiltin::eval(EvalState & state, Env & env, Value & v) +{ + // Not a hot path at all, but would be nice to access state.baseEnv directly + Env *baseEnv = &env; + while (baseEnv->up) baseEnv = baseEnv->up; + Bindings::iterator binding = baseEnv->values[0]->attrs->find(name); + assert(binding != baseEnv->values[0]->attrs->end()); + v = *binding->value; +} + + void ExprOpEq::eval(EvalState & state, Env & env, Value & v) { Value v1; e1->eval(state, env, v1); diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc index f4b4295e29..c7ac967968 100644 --- a/src/libexpr/nixexpr.cc +++ b/src/libexpr/nixexpr.cc @@ -121,6 +121,11 @@ void ExprOpNot::show(std::ostream & str) str << "! " << *e; } +void ExprBuiltin::show(std::ostream & str) +{ + str << "builtins." << name; +} + void ExprConcatStrings::show(std::ostream & str) { bool first = true; @@ -314,6 +319,10 @@ void ExprOpNot::bindVars(const StaticEnv & env) e->bindVars(env); } +void ExprBuiltin::bindVars(const StaticEnv & env) +{ +} + void ExprConcatStrings::bindVars(const StaticEnv & env) { foreach (vector::iterator, i, *es) diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh index 61eb81fab1..2ae2e2e96f 100644 --- a/src/libexpr/nixexpr.hh +++ b/src/libexpr/nixexpr.hh @@ -248,6 +248,13 @@ struct ExprOpNot : Expr COMMON_METHODS }; +struct ExprBuiltin : Expr +{ + Symbol name; + ExprBuiltin(Symbol name) : name(name) { }; + COMMON_METHODS +}; + #define MakeBinOp(name, s) \ struct Expr##name : Expr \ { \ diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y index 7699cf502b..d30882ac84 100644 --- a/src/libexpr/parser.y +++ b/src/libexpr/parser.y @@ -311,13 +311,13 @@ expr_if expr_op : '!' expr_op %prec NOT { $$ = new ExprOpNot($2); } -| '-' expr_op %prec NEGATE { $$ = new ExprApp(new ExprApp(new ExprVar(noPos, data->symbols.create("__sub")), new ExprInt(0)), $2); } +| '-' expr_op %prec NEGATE { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("sub")), new ExprInt(0)), $2); } | expr_op EQ expr_op { $$ = new ExprOpEq($1, $3); } | expr_op NEQ expr_op { $$ = new ExprOpNEq($1, $3); } - | expr_op '<' expr_op { $$ = new ExprApp(new ExprApp(new ExprVar(noPos, data->symbols.create("__lessThan")), $1), $3); } - | expr_op LEQ expr_op { $$ = new ExprOpNot(new ExprApp(new ExprApp(new ExprVar(noPos, data->symbols.create("__lessThan")), $3), $1)); } - | expr_op '>' expr_op { $$ = new ExprApp(new ExprApp(new ExprVar(noPos, data->symbols.create("__lessThan")), $3), $1); } - | expr_op GEQ expr_op { $$ = new ExprOpNot(new ExprApp(new ExprApp(new ExprVar(noPos, data->symbols.create("__lessThan")), $1), $3)); } + | expr_op '<' expr_op { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("lessThan")), $1), $3); } + | expr_op LEQ expr_op { $$ = new ExprOpNot(new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("lessThan")), $3), $1)); } + | expr_op '>' expr_op { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("lessThan")), $3), $1); } + | expr_op GEQ expr_op { $$ = new ExprOpNot(new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("lessThan")), $1), $3)); } | expr_op AND expr_op { $$ = new ExprOpAnd($1, $3); } | expr_op OR expr_op { $$ = new ExprOpOr($1, $3); } | expr_op IMPL expr_op { $$ = new ExprOpImpl($1, $3); } @@ -329,9 +329,9 @@ expr_op l->push_back($3); $$ = new ExprConcatStrings(false, l); } - | expr_op '-' expr_op { $$ = new ExprApp(new ExprApp(new ExprVar(noPos, data->symbols.create("__sub")), $1), $3); } - | expr_op '*' expr_op { $$ = new ExprApp(new ExprApp(new ExprVar(noPos, data->symbols.create("__mul")), $1), $3); } - | expr_op '/' expr_op { $$ = new ExprApp(new ExprApp(new ExprVar(noPos, data->symbols.create("__div")), $1), $3); } + | expr_op '-' expr_op { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("sub")), $1), $3); } + | expr_op '*' expr_op { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("mul")), $1), $3); } + | expr_op '/' expr_op { $$ = new ExprApp(new ExprApp(new ExprBuiltin(data->symbols.create("div")), $1), $3); } | expr_op CONCAT expr_op { $$ = new ExprOpConcatLists($1, $3); } | expr_app ; @@ -381,7 +381,7 @@ expr_simple ‘throw’. */ $$ = path2 == "" ? (Expr * ) new ExprApp( - new ExprVar(noPos, data->symbols.create("throw")), + new ExprBuiltin(data->symbols.create("throw")), new ExprString(data->symbols.create( (format("file `%1%' was not found in the Nix search path (add it using $NIX_PATH or -I)") % path).str()))) : (Expr * ) new ExprPath(path2); diff --git a/tests/lang/eval-okay-redefine-builtin.exp b/tests/lang/eval-okay-redefine-builtin.exp new file mode 100644 index 0000000000..c508d5366f --- /dev/null +++ b/tests/lang/eval-okay-redefine-builtin.exp @@ -0,0 +1 @@ +false diff --git a/tests/lang/eval-okay-redefine-builtin.nix b/tests/lang/eval-okay-redefine-builtin.nix new file mode 100644 index 0000000000..df9fc3f37d --- /dev/null +++ b/tests/lang/eval-okay-redefine-builtin.nix @@ -0,0 +1,3 @@ +let + throw = abort "Error!"; +in (builtins.tryEval ).success