[Libguestfs] [PATCH v3 4/6] mllib: modify nsplit to take optional noempty and count arguments

[Tomáš Golembiovský]

Added two new optional arguments to nsplit:

* noempty: if set to false empty elements are not stored in the returned
  list. The default is to keep the empty elements

* count: specifies how many splits to perform; negative count
  (the default) means do as many splits as possible

Signed-off-by: Tomáš Golembiovský <tgolembi at redhat.com>
---
 mllib/common_utils.ml  | 12 +++++++++---
 mllib/common_utils.mli | 12 ++++++++++--
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/mllib/common_utils.ml b/mllib/common_utils.ml
index 78618f5..2d373f9 100644
--- a/mllib/common_utils.ml
+++ b/mllib/common_utils.ml
@@ -92,15 +92,21 @@ module String = struct
         s' ^ s2 ^ replace s'' s1 s2
       )
 
-    let rec nsplit sep str =
+    let rec nsplit ?(noempty = true) ?(count = -1) sep str =
       let len = length str in
       let seplen = length sep in
       let i = find str sep in
-      if i = -1 then [str]
+      if i = -1 || count = 0 then [str]
       else (
         let s' = sub str 0 i in
         let s'' = sub str (i+seplen) (len-i-seplen) in
-        s' :: nsplit sep s''
+        let elem, count =
+          if s' = "" && noempty then
+            [], count
+          else
+            [s'], if count > 0 then count-1 else count
+        in
+        elem @ nsplit ~noempty:noempty ~count:count sep s''
       )
 
     let split sep str =
diff --git a/mllib/common_utils.mli b/mllib/common_utils.mli
index ad43345..bcd459d 100644
--- a/mllib/common_utils.mli
+++ b/mllib/common_utils.mli
@@ -64,9 +64,17 @@ module String : sig
     val replace : string -> string -> string -> string
     (** [replace str s1 s2] replaces all instances of [s1] appearing in
         [str] with [s2]. *)
-    val nsplit : string -> string -> string list
+    val nsplit : ?noempty:bool -> ?count:int -> string -> string -> string list
     (** [nsplit sep str] splits [str] into multiple strings at each
-        separator [sep]. *)
+        separator [sep].
+
+        If [noempty] is set to true empty elements are not included in the
+        list. By default empty elements are kept.
+
+        If [count] is specified it says how many splits to perform. I.e. the
+        returned array will have at most [count]+1 elements. Negative [count]
+        (the default) means do as many splits as possible.
+        *)
     val split : string -> string -> string * string
     (** [split sep str] splits [str] at the first occurrence of the
         separator [sep], returning the part before and the part after.
-- 
2.10.2