lib/generators: toPretty

`toPretty` implements a pretty printer for nix values.
This commit is contained in:
Profpatsch 2017-06-06 22:41:22 +02:00
parent dd3f2e648a
commit b1ffe5e4c0
2 changed files with 62 additions and 0 deletions

View file

@ -90,4 +90,36 @@ rec {
* parsers as well.
*/
toYAML = {}@args: toJSON args;
# TODO we need some kind of pattern matching sometimes
/* Pretty print a value, akin to `builtins.trace`.
* Should probably be a builtin as well.
*/
toPretty = {
/* If this option is true, attrsets like { __pretty = fn; val = ; }
will use fn to convert val to a pretty printed representation.
(This means fn is type Val -> String.) */
allowPrettyValues ? false
}@args: v: with builtins;
if isInt v then toString v
else if isBool v then (if v == true then "true" else "false")
else if isString v then "\"" + v + "\""
else if null == v then "null"
else if isFunction v then "<λ>"
else if isList v then "[ "
+ libStr.concatMapStringsSep " " (toPretty args) v
+ " ]"
else if isAttrs v then
# apply pretty values if allowed
if attrNames v == [ "__pretty" "val" ] && allowPrettyValues
then v.__pretty v.val
# TODO: there is probably a better representation?
else if v ? type && v.type == "derivation" then "<δ>"
else "{ "
+ libStr.concatStringsSep " " (libAttr.mapAttrsToList
(name: value:
"${toPretty args name} = ${toPretty args value};") v)
+ " }"
else "toPretty: should never happen (v = ${v})";
}

View file

@ -285,6 +285,36 @@ runTests {
expected = builtins.toJSON val;
};
testToPretty = {
expr = mapAttrs (const (generators.toPretty {})) rec {
int = 42;
bool = true;
string = "fnord";
null_ = null;
function = x: x;
list = [ 3 4 function [ false ] ];
attrs = { foo = null; "foo bar" = "baz"; };
drv = derivation { name = "test"; system = builtins.currentSystem; };
};
expected = rec {
int = "42";
bool = "true";
string = "\"fnord\"";
null_ = "null";
function = "<λ>";
list = "[ 3 4 ${function} [ false ] ]";
attrs = "{ \"foo\" = null; \"foo bar\" = \"baz\"; }";
drv = "<δ>";
};
};
testToPrettyAllowPrettyValues = {
expr = generators.toPretty { allowPrettyValues = true; }
{ __pretty = v: "«" + v + "»"; val = "foo"; };
expected = "«foo»";
};
# MISC
testOverridableDelayableArgsTest = {