From 0a623a10c7e89a80b6dc74445a0ae6240f65723e Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 13 Jul 2011 12:19:57 +0000 Subject: [PATCH] * Allow a default value in attribute selection by writing x.y.z or default (as originally proposed in https://mail.cs.uu.nl/pipermail/nix-dev/2009-September/002989.html). For instance, an expression like stdenv.lib.attrByPath ["features" "ckSched"] false args can now be written as args.features.ckSched or false --- doc/manual/release-notes.xml | 4 ++++ misc/emacs/nix-mode.el | 2 +- src/libexpr/eval.cc | 19 +++++++++++------ src/libexpr/lexer.l | 1 + src/libexpr/nixexpr.cc | 2 ++ src/libexpr/nixexpr.hh | 6 +++--- src/libexpr/parser.y | 36 ++++++++++++++++++++++----------- tests/lang/eval-okay-attrs5.exp | 1 + tests/lang/eval-okay-attrs5.nix | 21 +++++++++++++++++++ 9 files changed, 70 insertions(+), 22 deletions(-) create mode 100644 tests/lang/eval-okay-attrs5.exp create mode 100644 tests/lang/eval-okay-attrs5.nix diff --git a/doc/manual/release-notes.xml b/doc/manual/release-notes.xml index 0c29cae90..cf025aaf5 100644 --- a/doc/manual/release-notes.xml +++ b/doc/manual/release-notes.xml @@ -32,6 +32,10 @@ --max-silent-time is ineffective. + + TODO: “or” keyword. + + diff --git a/misc/emacs/nix-mode.el b/misc/emacs/nix-mode.el index 22e735b89..306d478bd 100644 --- a/misc/emacs/nix-mode.el +++ b/misc/emacs/nix-mode.el @@ -67,7 +67,7 @@ The hook `nix-mode-hook' is run when Nix mode is started. (defvar nix-keywords '("\\" "\\" "\\" "\\" "\\" - "\\" "\\" "\\" "\\" + "\\" "\\" "\\" "\\" "\\" ("\\" . font-lock-builtin-face) ("\\" . font-lock-builtin-face) ("\\" . font-lock-builtin-face) diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index 4d3a369aa..acf5d7a8a 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -632,7 +632,6 @@ void ExprVar::eval(EvalState & state, Env & env, Value & v) unsigned long nrLookups = 0; -unsigned long nrLookupSize = 0; void ExprSelect::eval(EvalState & state, Env & env, Value & v) { @@ -646,11 +645,20 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v) foreach (AttrPath::const_iterator, i, attrPath) { nrLookups++; - state.forceAttrs(*vAttrs); - nrLookupSize += vAttrs->attrs->size(); Bindings::iterator j; - if ((j = vAttrs->attrs->find(*i)) == vAttrs->attrs->end()) - throwEvalError("attribute `%1%' missing", showAttrPath(attrPath)); + if (def) { + state.forceValue(*vAttrs); + if (vAttrs->type != tAttrs || + (j = vAttrs->attrs->find(*i)) == vAttrs->attrs->end()) + { + state.eval(env, def, v); + return; + } + } else { + state.forceAttrs(*vAttrs); + if ((j = vAttrs->attrs->find(*i)) == vAttrs->attrs->end()) + throwEvalError("attribute `%1%' missing", showAttrPath(attrPath)); + } vAttrs = j->value; pos = j->pos; } @@ -1270,7 +1278,6 @@ void EvalState::printStats() printMsg(v, format(" number of thunks: %1%") % nrThunks); printMsg(v, format(" number of thunks avoided: %1%") % nrAvoided); printMsg(v, format(" number of attr lookups: %1%") % nrLookups); - printMsg(v, format(" attr lookup size: %1%") % nrLookupSize); } diff --git a/src/libexpr/lexer.l b/src/libexpr/lexer.l index 5b27e2582..330c2bd54 100644 --- a/src/libexpr/lexer.l +++ b/src/libexpr/lexer.l @@ -96,6 +96,7 @@ let { return LET; } in { return IN; } rec { return REC; } inherit { return INHERIT; } +or { return OR_KW; } \.\.\. { return ELLIPSIS; } \=\= { return EQ; } diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc index 2632d9f3f..c52a41391 100644 --- a/src/libexpr/nixexpr.cc +++ b/src/libexpr/nixexpr.cc @@ -44,6 +44,7 @@ void ExprVar::show(std::ostream & str) void ExprSelect::show(std::ostream & str) { str << "(" << *e << ")." << showAttrPath(attrPath); + if (def) str << " or " << *def; } void ExprOpHasAttr::show(std::ostream & str) @@ -211,6 +212,7 @@ void ExprVar::bindVars(const StaticEnv & env) void ExprSelect::bindVars(const StaticEnv & env) { e->bindVars(env); + if (def) def->bindVars(env); } void ExprOpHasAttr::bindVars(const StaticEnv & env) diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh index 725e30c6f..166289b29 100644 --- a/src/libexpr/nixexpr.hh +++ b/src/libexpr/nixexpr.hh @@ -121,10 +121,10 @@ struct ExprVar : Expr struct ExprSelect : Expr { - Expr * e; + Expr * e, * def; AttrPath attrPath; - ExprSelect(Expr * e, const AttrPath & attrPath) : e(e), attrPath(attrPath) { }; - ExprSelect(Expr * e, const Symbol & name) : e(e) { attrPath.push_back(name); }; + ExprSelect(Expr * e, const AttrPath & attrPath, Expr * def) : e(e), def(def), attrPath(attrPath) { }; + ExprSelect(Expr * e, const Symbol & name) : e(e), def(0) { attrPath.push_back(name); }; COMMON_METHODS }; diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y index 49bd7bfa5..ec194a516 100644 --- a/src/libexpr/parser.y +++ b/src/libexpr/parser.y @@ -237,7 +237,7 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err char * id; // !!! -> Symbol char * path; char * uri; - std::vector * ids; + std::vector * attrNames; std::vector * string_parts; } @@ -247,14 +247,15 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err %type binds %type formals %type formal -%type ids attrpath +%type attrs attrpath %type string_parts ind_string_parts +%type attr %token ID ATTRPATH %token STR IND_STR %token INT %token PATH %token URI -%token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL +%token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL OR_KW %token DOLLAR_CURLY /* == ${ */ %token IND_STRING_OPEN IND_STRING_CLOSE %token ELLIPSIS @@ -326,7 +327,13 @@ expr_app expr_select : expr_simple '.' attrpath - { $$ = new ExprSelect($1, *$3); } + { $$ = new ExprSelect($1, *$3, 0); } + | expr_simple '.' attrpath OR_KW expr_select + { $$ = new ExprSelect($1, *$3, $5); } + | /* Backwards compatibility: because Nixpkgs has a rarely used + function named ‘or’, allow stuff like ‘map or [...]’. */ + expr_simple OR_KW + { $$ = new ExprApp($1, new ExprVar(data->symbols.create("or"))); } | expr_simple { $$ = $1; } ; @@ -370,7 +377,7 @@ ind_string_parts binds : binds attrpath '=' expr ';' { $$ = $1; addAttr($$, *$2, $4, makeCurPos(@2, data)); } - | binds INHERIT ids ';' + | binds INHERIT attrs ';' { $$ = $1; foreach (AttrPath::iterator, i, *$3) { if ($$->attrs.find(*i) != $$->attrs.end()) @@ -379,26 +386,31 @@ binds $$->attrs[*i] = ExprAttrs::AttrDef(*i, pos); } } - | binds INHERIT '(' expr ')' ids ';' + | binds INHERIT '(' expr ')' attrs ';' { $$ = $1; /* !!! Should ensure sharing of the expression in $4. */ foreach (vector::iterator, i, *$6) { if ($$->attrs.find(*i) != $$->attrs.end()) dupAttr(*i, makeCurPos(@6, data), $$->attrs[*i].pos); $$->attrs[*i] = ExprAttrs::AttrDef(new ExprSelect($4, *i), makeCurPos(@6, data)); - }} - + } + } | { $$ = new ExprAttrs; } ; -ids - : ids ID { $$ = $1; $1->push_back(data->symbols.create($2)); /* !!! dangerous */ } +attrs + : attrs attr { $$ = $1; $1->push_back(data->symbols.create($2)); /* !!! dangerous */ } | { $$ = new vector; } ; attrpath - : attrpath '.' ID { $$ = $1; $1->push_back(data->symbols.create($3)); } - | ID { $$ = new vector; $$->push_back(data->symbols.create($1)); } + : attrpath '.' attr { $$ = $1; $1->push_back(data->symbols.create($3)); } + | attr { $$ = new vector; $$->push_back(data->symbols.create($1)); } + ; + +attr + : ID { $$ = $1; } + | OR_KW { $$ = "or"; } ; expr_list diff --git a/tests/lang/eval-okay-attrs5.exp b/tests/lang/eval-okay-attrs5.exp new file mode 100644 index 000000000..ce0430d78 --- /dev/null +++ b/tests/lang/eval-okay-attrs5.exp @@ -0,0 +1 @@ +[ 123 "foo" 456 456 "foo" "xyzzy" "xyzzy" true ] diff --git a/tests/lang/eval-okay-attrs5.nix b/tests/lang/eval-okay-attrs5.nix new file mode 100644 index 000000000..e77ee7a1c --- /dev/null +++ b/tests/lang/eval-okay-attrs5.nix @@ -0,0 +1,21 @@ +with import ./lib.nix; + +let + + as = { x.y.z = 123; a.b.c = 456; }; + + bs = { foo.bar = "foo"; }; + + or = x: y: x || y; + +in + [ as.x.y.z + as.foo or "foo" + as.x.y.bla or as.a.b.c + as.a.b.c or as.x.y.z + as.x.y.bla or bs.foo.bar or "xyzzy" + as.x.y.bla or bs.bar.foo or "xyzzy" + 123.bla or null.foo or "xyzzy" + # Backwards compatibility test. + (fold or [] [true false false]) + ]