primop functions listToAttrs (+test), __isAttrs, __trace added
new configuration style proposal in lib/default-unstable.nix
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		|  | @ -296,6 +296,17 @@ static Expr prim_getEnv(EvalState & state, const ATermVector & args) | |||
|     return makeStr(getEnv(name)); | ||||
| } | ||||
| 
 | ||||
| /* for debugging purposes. print the first arg on stdout (perhaps stderr should be used?)
 | ||||
|  * and return the second | ||||
|  */ | ||||
| static Expr prim_trace(EvalState & state, const ATermVector & args) | ||||
| { | ||||
|     //string str = evalStringNoCtx(state, args[0]);
 | ||||
| 
 | ||||
|     Expr a = evalExpr(state, args[0]); | ||||
|     printf("traced value: %s\n", atPrint(a).c_str()); | ||||
|     return evalExpr(state, args[1]); | ||||
| } | ||||
| 
 | ||||
| static Expr prim_relativise(EvalState & state, const ATermVector & args) | ||||
| { | ||||
|  | @ -744,6 +755,39 @@ static Expr prim_hasAttr(EvalState & state, const ATermVector & args) | |||
| } | ||||
| 
 | ||||
| 
 | ||||
| /* takes 
 | ||||
|  * param: list of { attr="attr"; value=value }  | ||||
|  * returns an attribute set | ||||
|  * */ | ||||
| static Expr prim_listToAttrs(EvalState & state, const ATermVector & args) | ||||
| { | ||||
|   try { | ||||
|     ATermMap res = ATermMap(); | ||||
| 
 | ||||
|     ATermList list; | ||||
|     list = evalList(state, args[0]); | ||||
|     for (ATermIterator i(list); i; ++i){ | ||||
|       // *i should now contain a pointer to the list item expression
 | ||||
|       ATermList attrs; | ||||
|       Expr evaledExpr = evalExpr(state, *i); | ||||
|       if (matchAttrs(evaledExpr, attrs)){ | ||||
|         Expr e = evalExpr(state, makeSelect(evaledExpr, toATerm("attr"))); | ||||
|         string attr = evalStringNoCtx(state,e); | ||||
|         ATerm value; | ||||
|         Expr r = makeSelect(evaledExpr, toATerm("value")); | ||||
|         res.set(toATerm(attr), makeAttrRHS(r, makeNoPos())); | ||||
|       } | ||||
|       else { | ||||
|         throw EvalError(format("passed list item is a %s (value: %s). Set { attr=\"name\"; value=nix expr; } expected.") % showType(evaledExpr) % showValue(evaledExpr));  | ||||
|       } | ||||
|     } // for
 | ||||
|     return makeAttrs(res); | ||||
|   } catch (Error & e) { | ||||
|     e.addPrefix(format("while calling listToAttrs ")); | ||||
|     throw; | ||||
|   } | ||||
| } | ||||
| 
 | ||||
| static Expr prim_removeAttrs(EvalState & state, const ATermVector & args) | ||||
| { | ||||
|     ATermMap attrs; | ||||
|  | @ -758,6 +802,12 @@ static Expr prim_removeAttrs(EvalState & state, const ATermVector & args) | |||
|     return makeAttrs(attrs); | ||||
| } | ||||
| 
 | ||||
| /* Determine whether the argument is a list. */ | ||||
| static Expr prim_isAttrs(EvalState & state, const ATermVector & args) | ||||
| { | ||||
|     ATermList list; | ||||
|     return makeBool(matchAttrs(evalExpr(state, args[0]), list)); | ||||
| } | ||||
| 
 | ||||
| /*************************************************************
 | ||||
|  * Lists | ||||
|  | @ -901,6 +951,7 @@ void EvalState::addPrimOps() | |||
|     addPrimOp("abort", 1, prim_abort); | ||||
|     addPrimOp("throw", 1, prim_throw); | ||||
|     addPrimOp("__getEnv", 1, prim_getEnv); | ||||
|     addPrimOp("__trace", 2, prim_trace); | ||||
| 
 | ||||
|     addPrimOp("relativise", 2, prim_relativise); | ||||
| 
 | ||||
|  | @ -923,7 +974,9 @@ void EvalState::addPrimOps() | |||
|     addPrimOp("__attrNames", 1, prim_attrNames); | ||||
|     addPrimOp("__getAttr", 2, prim_getAttr); | ||||
|     addPrimOp("__hasAttr", 2, prim_hasAttr); | ||||
|     addPrimOp("__isAttrs", 1, prim_isAttrs); | ||||
|     addPrimOp("removeAttrs", 2, prim_removeAttrs); | ||||
|     addPrimOp("__listToAttrs", 1, prim_listToAttrs); | ||||
| 
 | ||||
|     // Lists
 | ||||
|     addPrimOp("__isList", 1, prim_isList); | ||||
|  |  | |||
							
								
								
									
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								tests/lang/eval-okay-listToAttrs.nix
									
										
									
									
									
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								tests/lang/eval-okay-listToAttrs.nix
									
										
									
									
									
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							|  | @ -0,0 +1,8 @@ | |||
| # this test shows how to use listToAttrs and that evaluation is still lazy (throw isn't called) | ||||
| let  | ||||
|   asi = attr: value : { inherit attr value; }; | ||||
|   list = [ ( asi "a" "A" ) ( asi "b" "B" ) ]; | ||||
|   a = builtins.listToAttrs list; | ||||
|   b = builtins.listToAttrs ( list ++ list ); | ||||
|   r = builtins.listToAttrs [ (asi "result" [ a b ]) ( asi "throw" (throw "this should not be thrown")) ]; | ||||
| in r.result | ||||
							
								
								
									
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								tests/lang/eval-okay-listToAttrs.out
									
										
									
									
									
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								tests/lang/eval-okay-listToAttrs.out
									
										
									
									
									
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							|  | @ -0,0 +1 @@ | |||
| List([Attrs([Bind("a",Str("A",[]),NoPos),Bind("b",Str("B",[]),NoPos)]),Attrs([Bind("a",Str("A",[]),NoPos),Bind("b",Str("B",[]),NoPos)])]) | ||||
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