allow predicate functions to lstrip etc.

base/strings/util.jl

@@ -137,13 +137,15 @@ end
 const _default_delims = [' ','\t','\n','\v','\f','\r']
 
 """
-    lstrip(s::AbstractString[, chars::Chars])
+    lstrip(str::AbstractString[, chars])
 
-Return `s` with any leading whitespace and delimiters removed.
-The default delimiters to remove are `' '`, `\\t`, `\\n`, `\\v`,
-`\\f`, and `\\r`.
-If `chars` (a character, or vector or set of characters) is provided,
-instead remove characters contained in it.
+Remove leading characters from `str`.
+
+The default behaviour is to remove leading whitespace and delimiters: see
+[`isspace`](@ref) for precise details.
+
+The optional `chars` argument specifies which characters to remove: it can be a single character,
+vector or set of characters, or a predicate function.
 
 # Examples
 ```jldoctest
@@ -154,22 +156,25 @@ julia> lstrip(a)
 "March"
 ```
 """
-function lstrip(s::AbstractString, chars::Chars=_default_delims)
+function lstrip(s::AbstractString, f=isspace)
     e = lastindex(s)
     for (i, c) in pairs(s)
-        !(c in chars) && return SubString(s, i, e)
+        !f(c) && return SubString(s, i, e)
     end
     SubString(s, e+1, e)
 end
+lstrip(s::AbstractString, chars::Chars) = lstrip(s, in(chars))
 
 """
-    rstrip(s::AbstractString[, chars::Chars])
+    rstrip(str::AbstractString[, chars])
+
+Remove trailing characters from `str`.
 
-Return `s` with any trailing whitespace and delimiters removed.
-The default delimiters to remove are `' '`, `\\t`, `\\n`, `\\v`,
-`\\f`, and `\\r`.
-If `chars` (a character, or vector or set of characters) is provided,
-instead remove characters contained in it.
+The default behaviour is to remove leading whitespace and delimiters: see
+[`isspace`](@ref) for precise details.
+
+The optional `chars` argument specifies which characters to remove: it can be a single character,
+vector or set of characters, or a predicate function.
 
 # Examples
 ```jldoctest
@@ -180,19 +185,24 @@ julia> rstrip(a)
 "March"
 ```
 """
-function rstrip(s::AbstractString, chars::Chars=_default_delims)
+function rstrip(s::AbstractString, f=isspace)
     for (i, c) in Iterators.reverse(pairs(s))
-        c in chars || return SubString(s, 1, i)
+        f(c) in chars || return SubString(s, 1, i)
     end
     SubString(s, 1, 0)
 end
+rstrip(s, chars::Chars) = rstrip(s, in(chars))
 
 """
-    strip(s::AbstractString, [chars::Chars])
+    strip(str::AbstractString, [chars])
+
+Remove leading and trailing characters from `str`.
+
+The default behaviour is to remove leading whitespace and delimiters: see
+[`isspace`](@ref) for precise details.
 
-Return `s` with any leading and trailing whitespace removed.
-If `chars` (a character, or vector or set of characters) is provided,
-instead remove characters contained in it.
+The optional `chars` argument specifies which characters to remove: it can be a single character,
+vector or set of characters, or a predicate function.
 
 # Examples
 ```jldoctest
@@ -201,7 +211,7 @@ julia> strip("{3, 5}\\n", ['{', '}', '\\n'])
 ```
 """
 strip(s::AbstractString) = lstrip(rstrip(s))
-strip(s::AbstractString, chars::Chars) = lstrip(rstrip(s, chars), chars)
+strip(s::AbstractString, chars) = lstrip(rstrip(s, chars), chars)
 
 ## string padding functions ##
 

test/strings/util.jl

@@ -50,6 +50,7 @@ end
     @test strip("  ") == ""
     @test strip("   ") == ""
     @test strip("\t  hi   \n") == "hi"
+    @test strip(" \u2009 hi \u2009 ") == "hi"
     @test strip("foobarfoo", ['f','o']) == "bar"
     @test strip("foobarfoo", ('f','o')) == "bar"