nixpkgs/lib/debug.nix
Profpatsch a7fdd10bf3 lib/debug: deprecate & modernize showVal
The code is re-implemented in terms of `generators.toPretty`, but is strictly
less general than `traceValSeqN`, so we deprecate it.
2018-04-27 18:59:39 +02:00

131 lines
5.2 KiB
Nix

{ lib }:
let
inherit (builtins) trace attrNamesToStr isAttrs isList isInt
isString isBool head substring attrNames;
inherit (lib) all id mapAttrsFlatten elem isFunction;
in
rec {
inherit (builtins) addErrorContext;
addErrorContextToAttrs = lib.mapAttrs (a: v: lib.addErrorContext "while evaluating ${a}" v);
traceIf = p: msg: x: if p then trace msg x else x;
traceValFn = f: x: trace (f x) x;
traceVal = traceValFn id;
traceXMLVal = x: trace (builtins.toXML x) x;
traceXMLValMarked = str: x: trace (str + builtins.toXML x) x;
# strict trace functions (traced structure is fully evaluated and printed)
/* `builtins.trace`, but the value is `builtins.deepSeq`ed first. */
traceSeq = x: y: trace (builtins.deepSeq x x) y;
/* Like `traceSeq`, but only down to depth n.
* This is very useful because lots of `traceSeq` usages
* lead to an infinite recursion.
*/
traceSeqN = depth: x: y: with lib;
let snip = v: if isList v then noQuotes "[]" v
else if isAttrs v then noQuotes "{}" v
else v;
noQuotes = str: v: { __pretty = const str; val = v; };
modify = n: fn: v: if (n == 0) then fn v
else if isList v then map (modify (n - 1) fn) v
else if isAttrs v then mapAttrs
(const (modify (n - 1) fn)) v
else v;
in trace (generators.toPretty { allowPrettyValues = true; }
(modify depth snip x)) y;
/* `traceSeq`, but the same value is traced and returned */
traceValSeqFn = f: v: traceVal f (builtins.deepSeq v v);
traceValSeq = traceValSeqFn id;
/* `traceValSeq` but with fixed depth */
traceValSeqNFn = f: depth: v: traceSeqN depth (f v) v;
traceValSeqN = traceValSeqNFn id;
# this can help debug your code as well - designed to not produce thousands of lines
traceShowVal = x: trace (showVal x) x;
traceShowValMarked = str: x: trace (str + showVal x) x;
attrNamesToStr = a: lib.concatStringsSep "; " (map (x: "${x}=") (attrNames a));
showVal = with lib;
trace ( "Warning: `showVal` is deprecated "
+ "and will be removed in the next release, "
+ "please use `traceSeqN`" )
(let
modify = v:
let pr = f: { __pretty = f; val = v; };
in if isDerivation v then pr
(drv: "<δ:${drv.name}:${concatStringsSep ","
(attrNames drv)}>")
else if [] == v then pr (const "[]")
else if isList v then pr (l: "[ ${go (head l)}, ]")
else if isAttrs v then pr
(a: "{ ${ concatStringsSep ", " (attrNames a)} }")
else v;
go = x: generators.toPretty
{ allowPrettyValues = true; }
(modify x);
in go);
# trace the arguments passed to function and its result
# maybe rewrite these functions in a traceCallXml like style. Then one function is enough
traceCall = n: f: a: let t = n2: x: traceShowValMarked "${n} ${n2}:" x; in t "result" (f (t "arg 1" a));
traceCall2 = n: f: a: b: let t = n2: x: traceShowValMarked "${n} ${n2}:" x; in t "result" (f (t "arg 1" a) (t "arg 2" b));
traceCall3 = n: f: a: b: c: let t = n2: x: traceShowValMarked "${n} ${n2}:" x; in t "result" (f (t "arg 1" a) (t "arg 2" b) (t "arg 3" c));
# FIXME: rename this?
traceValIfNot = c: x:
if c x then true else trace (showVal x) false;
/* Evaluate a set of tests. A test is an attribute set {expr,
expected}, denoting an expression and its expected result. The
result is a list of failed tests, each represented as {name,
expected, actual}, denoting the attribute name of the failing
test and its expected and actual results. Used for regression
testing of the functions in lib; see tests.nix for an example.
Only tests having names starting with "test" are run.
Add attr { tests = ["testName"]; } to run these test only
*/
runTests = tests: lib.concatLists (lib.attrValues (lib.mapAttrs (name: test:
let testsToRun = if tests ? tests then tests.tests else [];
in if (substring 0 4 name == "test" || elem name testsToRun)
&& ((testsToRun == []) || elem name tests.tests)
&& (test.expr != test.expected)
then [ { inherit name; expected = test.expected; result = test.expr; } ]
else [] ) tests));
# create a test assuming that list elements are true
# usage: { testX = allTrue [ true ]; }
testAllTrue = expr: { inherit expr; expected = map (x: true) expr; };
# example: (traceCallXml "myfun" id 3) will output something like
# calling myfun arg 1: 3 result: 3
# this forces deep evaluation of all arguments and the result!
# note: if result doesn't evaluate you'll get no trace at all (FIXME)
# args should be printed in any case
traceCallXml = a:
if !isInt a then
traceCallXml 1 "calling ${a}\n"
else
let nr = a;
in (str: expr:
if isFunction expr then
(arg:
traceCallXml (builtins.add 1 nr) "${str}\n arg ${builtins.toString nr} is \n ${builtins.toXML (builtins.seq arg arg)}" (expr arg)
)
else
let r = builtins.seq expr expr;
in trace "${str}\n result:\n${builtins.toXML r}" r
);
}