Merge commit staging+systemd into closure-size

Many non-conflict problems weren't (fully) resolved in this commit yet.

lib/strings.nix

@@ -8,11 +8,15 @@ in
 
 rec {
 
-  inherit (builtins) stringLength substring head tail isString;
+  inherit (builtins) stringLength substring head tail isString replaceStrings;
 
 
   # Concatenate a list of strings.
-  concatStrings = lib.fold (x: y: x + y) "";
+  concatStrings =
+    if builtins ? concatStringsSep then
+      builtins.concatStringsSep ""
+    else
+      lib.foldl' (x: y: x + y) "";
 
 
   # Map a function over a list and concatenate the resulting strings.
@@ -25,14 +29,13 @@ rec {
   intersperse = separator: list:
     if list == [] || length list == 1
     then list
-    else [(head list) separator]
-         ++ (intersperse separator (tail list));
+    else tail (lib.concatMap (x: [separator x]) list);
 
 
   # Concatenate a list of strings with a separator between each element, e.g.
   # concatStringsSep " " ["foo" "bar" "xyzzy"] == "foo bar xyzzy"
-  concatStringsSep = separator: list:
-    concatStrings (intersperse separator list);
+  concatStringsSep = builtins.concatStringsSep or (separator: list:
+    concatStrings (intersperse separator list));
 
   concatMapStringsSep = sep: f: list: concatStringsSep sep (map f list);
   concatImapStringsSep = sep: f: list: concatStringsSep sep (lib.imap f list);
@@ -63,13 +66,13 @@ rec {
 
   # Determine whether a string has given prefix/suffix.
   hasPrefix = pref: str:
-    eqStrings (substring 0 (stringLength pref) str) pref;
+    substring 0 (stringLength pref) str == pref;
   hasSuffix = suff: str:
     let
       lenStr = stringLength str;
       lenSuff = stringLength suff;
     in lenStr >= lenSuff &&
-       eqStrings (substring (lenStr - lenSuff) lenStr str) suff;
+       substring (lenStr - lenSuff) lenStr str == suff;
 
 
   # Convert a string to a list of characters (i.e. singleton strings).
@@ -78,63 +81,57 @@ rec {
   # will likely be horribly inefficient; Nix is not a general purpose
   # programming language.  Complex string manipulations should, if
   # appropriate, be done in a derivation.
-  stringToCharacters = s: let l = stringLength s; in
-    if l == 0
-    then []
-    else map (p: substring p 1 s) (lib.range 0 (l - 1));
+  stringToCharacters = s:
+    map (p: substring p 1 s) (lib.range 0 (stringLength s - 1));
 
 
-  # Manipulate a string charcater by character and replace them by strings
-  # before concatenating the results.
+  # Manipulate a string charactter by character and replace them by
+  # strings before concatenating the results.
   stringAsChars = f: s:
     concatStrings (
       map f (stringToCharacters s)
     );
 
 
-  # same as vim escape function.
-  # Each character contained in list is prefixed by "\"
-  escape = list : string :
-    stringAsChars (c: if lib.elem c list then "\\${c}" else c) string;
+  # Escape occurrence of the elements of ‘list’ in ‘string’ by
+  # prefixing it with a backslash. For example, ‘escape ["(" ")"]
+  # "(foo)"’ returns the string ‘\(foo\)’.
+  escape = list: replaceChars list (map (c: "\\${c}") list);
 
 
-  # still ugly slow. But more correct now
-  # [] for zsh
+  # Escape all characters that have special meaning in the Bourne shell.
   escapeShellArg = lib.escape (stringToCharacters "\\ ';$`()|<>\t*[]");
 
 
-  # replace characters by their substitutes.  This function is equivalent to
-  # the `tr' command except that one character can be replace by multiple
-  # ones.  e.g.,
-  # replaceChars ["<" ">"] ["&lt;" "&gt;"] "<foo>" returns "&lt;foo&gt;".
-  replaceChars = del: new: s:
+  # Obsolete - use replaceStrings instead.
+  replaceChars = builtins.replaceStrings or (
+    del: new: s:
     let
+      substList = lib.zipLists del new;
       subst = c:
-        (lib.fold
-          (sub: res: if sub.fst == c then sub else res)
-          {fst = c; snd = c;} (lib.zipLists del new)
-        ).snd;
+        let found = lib.findFirst (sub: sub.fst == c) null substList; in
+        if found == null then
+          c
+        else
+          found.snd;
     in
-      stringAsChars subst s;
+      stringAsChars subst s);
 
 
-  # Case conversion utilities
+  # Case conversion utilities.
   lowerChars = stringToCharacters "abcdefghijklmnopqrstuvwxyz";
   upperChars = stringToCharacters "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
   toLower = replaceChars upperChars lowerChars;
   toUpper = replaceChars lowerChars upperChars;
 
-  # Appends string context from another string
+
+  # Appends string context from another string.
   addContextFrom = a: b: substring 0 0 a + b;
 
-  # Compares strings not requiring context equality
-  # Obviously, a workaround but works on all Nix versions
-  eqStrings = a: b: addContextFrom b a == addContextFrom a b;
 
-
-  # Cut a string with a separator and produces a list of strings which were
-  # separated by this separator. e.g.,
-  # `splitString "." "foo.bar.baz"' returns ["foo" "bar" "baz"].
+  # Cut a string with a separator and produces a list of strings which
+  # were separated by this separator; e.g., `splitString "."
+  # "foo.bar.baz"' returns ["foo" "bar" "baz"].
   splitString = _sep: _s:
     let
       sep = addContextFrom _s _sep;
@@ -177,7 +174,7 @@ rec {
       sufLen = stringLength suf;
       sLen = stringLength s;
     in
-      if sufLen <= sLen && eqStrings suf (substring (sLen - sufLen) sufLen s) then
+      if sufLen <= sLen && suf == substring (sLen - sufLen) sufLen s then
         substring 0 (sLen - sufLen) s
       else
         s;
@@ -196,21 +193,22 @@ rec {
 
 
   # Extract name with version from URL. Ask for separator which is
-  # supposed to start extension
-  nameFromURL = url: sep: let
-    components = splitString "/" url;
-    filename = lib.last components;
-    name = builtins.head (splitString sep filename);
-  in
-  assert ! eqStrings name filename;
-  name;
+  # supposed to start extension.
+  nameFromURL = url: sep:
+    let
+      components = splitString "/" url;
+      filename = lib.last components;
+      name = builtins.head (splitString sep filename);
+    in assert name !=  filename; name;
 
 
   # Create an --{enable,disable}-<feat> string that can be passed to
   # standard GNU Autoconf scripts.
   enableFeature = enable: feat: "--${if enable then "enable" else "disable"}-${feat}";
 
-  # Create a fixed width string with additional prefix to match required width
+
+  # Create a fixed width string with additional prefix to match
+  # required width.
   fixedWidthString = width: filler: str:
     let
       strw = lib.stringLength str;
@@ -219,6 +217,12 @@ rec {
       assert strw <= width;
       if strw == width then str else filler + fixedWidthString reqWidth filler str;
 
-  # Format a number adding leading zeroes up to fixed width
+
+  # Format a number adding leading zeroes up to fixed width.
   fixedWidthNumber = width: n: fixedWidthString width "0" (toString n);
+
+
+  # Check whether a value is a store path.
+  isStorePath = x: builtins.substring 0 1 (toString x) == "/" && dirOf (builtins.toPath x) == builtins.storeDir;
+
 }