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nixpkgs/lib/generators.nix
Graham Christensen 152c63c9ff
Convert libs to a fixed-point
This does break the API of being able to import any lib file and get
its libs, however I'm not sure people did this.

I made this while exploring being able to swap out docFn with a stub
in #2305, to avoid functor performance problems. I don't know if that
is going to move forward (or if it is a problem or not,) but after
doing all this work figured I'd put it up anyway :)

Two notable advantages to this approach:

1. when a lib inherits another lib's functions, it doesn't
   automatically get put in to the scope of lib
2. when a lib implements a new obscure functions, it doesn't
   automatically get put in to the scope of lib

Using the test script (later in this commit) I got the following diff
on the API:

  + diff master fixed-lib
  11764a11765,11766
  > .types.defaultFunctor
  > .types.defaultTypeMerge
  11774a11777,11778
  > .types.isOptionType
  > .types.isType
  11781a11786
  > .types.mkOptionType
  11788a11794
  > .types.setType
  11795a11802
  > .types.types

This means that this commit _adds_ to the API, however I can't find a
way to fix these last remaining discrepancies. At least none are
_removed_.

Test script (run with nix-repl in the PATH):

  #!/bin/sh

  set -eux

  repl() {
      suff=${1:-}
      echo "(import ./lib)$suff" \
          | nix-repl 2>&1
  }

  attrs_to_check() {
      repl "${1:-}" \
          | tr ';'  $'\n' \
          | grep "\.\.\." \
          | cut -d' ' -f2 \
          | sed -e "s/^/${1:-}./" \
          | sort
  }

  summ() {
      repl "${1:-}" \
          | tr ' ' $'\n' \
          | sort \
          | uniq
  }

  deep_summ() {
      suff="${1:-}"
      depth="${2:-4}"
      depth=$((depth - 1))
      summ "$suff"

      for attr in $(attrs_to_check "$suff" | grep -v "types.types"); do
          if [ $depth -eq 0 ]; then
              summ "$attr" | sed -e "s/^/$attr./"
          else
              deep_summ "$attr" "$depth" | sed -e "s/^/$attr./"
          fi
      done
  }

  (
      cd nixpkgs

      #git add .
      #git commit -m "Auto-commit, sorry" || true
      git checkout fixed-lib
      deep_summ > ../fixed-lib
      git checkout master
      deep_summ > ../master
  )

  if diff master fixed-lib; then
      echo "SHALLOW MATCH!"
  fi

  (
      cd nixpkgs
      git checkout fixed-lib
      repl .types
  )
2017-09-16 21:36:43 -04:00

132 lines
4.1 KiB
Nix

/* Functions that generate widespread file
* formats from nix data structures.
*
* They all follow a similar interface:
* generator { config-attrs } data
*
* Tests can be found in ./tests.nix
* Documentation in the manual, #sec-generators
*/
{ lib }:
with (lib).trivial;
let
libStr = lib.strings;
libAttr = lib.attrsets;
flipMapAttrs = flip libAttr.mapAttrs;
in
rec {
/* Generate a line of key k and value v, separated by
* character sep. If sep appears in k, it is escaped.
* Helper for synaxes with different separators.
*
* mkKeyValueDefault ":" "f:oo" "bar"
* > "f\:oo:bar"
*/
mkKeyValueDefault = sep: k: v:
"${libStr.escape [sep] k}${sep}${toString v}";
/* Generate a key-value-style config file from an attrset.
*
* mkKeyValue is the same as in toINI.
*/
toKeyValue = {
mkKeyValue ? mkKeyValueDefault "="
}: attrs:
let mkLine = k: v: mkKeyValue k v + "\n";
in libStr.concatStrings (libAttr.mapAttrsToList mkLine attrs);
/* Generate an INI-style config file from an
* attrset of sections to an attrset of key-value pairs.
*
* generators.toINI {} {
* foo = { hi = "${pkgs.hello}"; ciao = "bar"; };
* baz = { "also, integers" = 42; };
* }
*
*> [baz]
*> also, integers=42
*>
*> [foo]
*> ciao=bar
*> hi=/nix/store/y93qql1p5ggfnaqjjqhxcw0vqw95rlz0-hello-2.10
*
* The mk* configuration attributes can generically change
* the way sections and key-value strings are generated.
*
* For more examples see the test cases in ./tests.nix.
*/
toINI = {
# apply transformations (e.g. escapes) to section names
mkSectionName ? (name: libStr.escape [ "[" "]" ] name),
# format a setting line from key and value
mkKeyValue ? mkKeyValueDefault "="
}: attrsOfAttrs:
let
# map function to string for each key val
mapAttrsToStringsSep = sep: mapFn: attrs:
libStr.concatStringsSep sep
(libAttr.mapAttrsToList mapFn attrs);
mkSection = sectName: sectValues: ''
[${mkSectionName sectName}]
'' + toKeyValue { inherit mkKeyValue; } sectValues;
in
# map input to ini sections
mapAttrsToStringsSep "\n" mkSection attrsOfAttrs;
/* Generates JSON from an arbitrary (non-function) value.
* For more information see the documentation of the builtin.
*/
toJSON = {}: builtins.toJSON;
/* YAML has been a strict superset of JSON since 1.2, so we
* use toJSON. Before it only had a few differences referring
* to implicit typing rules, so it should work with older
* parsers as well.
*/
toYAML = {}@args: toJSON args;
/* Pretty print a value, akin to `builtins.trace`.
* Should probably be a builtin as well.
*/
toPretty = {
/* If this option is true, attrsets like { __pretty = fn; val = ; }
will use fn to convert val to a pretty printed representation.
(This means fn is type Val -> String.) */
allowPrettyValues ? false
}@args: v: with builtins;
if isInt v then toString v
else if isBool v then (if v == true then "true" else "false")
else if isString v then "\"" + v + "\""
else if null == v then "null"
else if isFunction v then
let fna = functionArgs v;
showFnas = concatStringsSep "," (libAttr.mapAttrsToList
(name: hasDefVal: if hasDefVal then "(${name})" else name)
fna);
in if fna == {} then "<λ>"
else "<λ:{${showFnas}}>"
else if isList v then "[ "
+ libStr.concatMapStringsSep " " (toPretty args) v
+ " ]"
else if isAttrs v then
# apply pretty values if allowed
if attrNames v == [ "__pretty" "val" ] && allowPrettyValues
then v.__pretty v.val
# TODO: there is probably a better representation?
else if v ? type && v.type == "derivation" then "<δ>"
else "{ "
+ libStr.concatStringsSep " " (libAttr.mapAttrsToList
(name: value:
"${toPretty args name} = ${toPretty args value};") v)
+ " }"
else "toPretty: should never happen (v = ${v})";
}