lower-level replace(...) hooks in latest Julia (#21)

* lower-level replace(...) hooks in latest Julia

* multiple replacements require julia 1.7

Author: stevengj

src/util.jl

@@ -36,49 +36,64 @@ function Base.chomp(s::StringViewAndSub)
     end
 end
 
-Base.replace(str::DenseStringViewAndSub, pat_repl::Pair{<:AbstractChar}; count::Integer=typemax(Int)) =
-    replace(str, isequal(first(pat_repl)) => last(pat_repl); count=count)
 
-Base.replace(str::DenseStringViewAndSub, pat_repl::Pair{<:Union{Tuple{Vararg{AbstractChar}},
-                                            AbstractVector{<:AbstractChar},Set{<:AbstractChar}}};
-        count::Integer=typemax(Int)) =
-    replace(str, in(first(pat_repl)) => last(pat_repl), count=count)
+# support replace via JuliaLang/julia#48625
+if isdefined(Base, :_replace_)
+    Base.replace(io::IO, s::DenseStringViewAndSub, pat_f::Pair...; count=typemax(Int)) =
+        Base._replace_(io, s, pat_f, Int(count))
 
-import Base: _pat_replacer, _free_pat_replacer
-
-function Base.replace(str::DenseStringViewAndSub, pat_repl::Pair; count::Integer=typemax(Int))
-    pattern, repl = pat_repl
-    count == 0 && return str
-    count < 0 && throw(DomainError(count, "`count` must be non-negative."))
-    n = 1
-    e = lastindex(str)
-    i = a = firstindex(str)
-    pattern = _pat_replacer(pattern)
-    r = something(findnext(pattern,str,i), 0)
-    j, k = first(r), last(r)
-    if j == 0
-        _free_pat_replacer(pattern)
-        return str
+    function Base.replace(s::DenseStringViewAndSub, pat_f::Pair...; count=typemax(Int))
+        # don't simply call Base._replace_(s, pat_f, Int(count)),
+        # to avoid type-instability for empty-replacements case: always return String
+        # (remove when #50424 is merged)
+        buf = IOBuffer(sizehint=floor(Int, 1.2sizeof(s)))
+        return String(take!(replace(buf, s, pat_f...; count=count)))
     end
-    out = IOBuffer(sizehint=floor(Int, 1.2sizeof(str)))
-    while j != 0
-        if i == a || i <= k
-            GC.@preserve str unsafe_write(out, pointer(str, i), UInt(j-i))
-            Base._replace(out, repl, str, r, pattern)
+else
+    Base.replace(str::DenseStringViewAndSub, pat_repl::Pair{<:AbstractChar}; count::Integer=typemax(Int)) =
+        replace(str, isequal(first(pat_repl)) => last(pat_repl); count=count)
+
+    Base.replace(str::DenseStringViewAndSub, pat_repl::Pair{<:Union{Tuple{Vararg{AbstractChar}},
+                                                AbstractVector{<:AbstractChar},Set{<:AbstractChar}}};
+            count::Integer=typemax(Int)) =
+        replace(str, in(first(pat_repl)) => last(pat_repl), count=count)
+
+    import Base: _pat_replacer, _free_pat_replacer
+
+    function Base.replace(str::DenseStringViewAndSub, pat_repl::Pair; count::Integer=typemax(Int))
+        pattern, repl = pat_repl
+        count == 0 && return str
+        count < 0 && throw(DomainError(count, "`count` must be non-negative."))
+        n = 1
+        e = lastindex(str)
+        i = a = firstindex(str)
+        pattern = _pat_replacer(pattern)
+        r = something(findnext(pattern,str,i), 0)
+        j, k = first(r), last(r)
+        if j == 0
+            _free_pat_replacer(pattern)
+            return str
         end
-        if k < j
-            i = j
-            j > e && break
-            k = nextind(str, j)
-        else
-            i = k = nextind(str, k)
+        out = IOBuffer(sizehint=floor(Int, 1.2sizeof(str)))
+        while j != 0
+            if i == a || i <= k
+                GC.@preserve str unsafe_write(out, pointer(str, i), UInt(j-i))
+                Base._replace(out, repl, str, r, pattern)
+            end
+            if k < j
+                i = j
+                j > e && break
+                k = nextind(str, j)
+            else
+                i = k = nextind(str, k)
+            end
+            r = something(findnext(pattern,str,k), 0)
+            r === 0:-1 || n == count && break
+            j, k = first(r), last(r)
+            n += 1
         end
-        r = something(findnext(pattern,str,k), 0)
-        r === 0:-1 || n == count && break
-        j, k = first(r), last(r)
-        n += 1
+        _free_pat_replacer(pattern)
+        write(out, SubString(str,i))
+        String(take!(out))
     end
-    _free_pat_replacer(pattern)
-    write(out, SubString(str,i))
-    String(take!(out))
 end

test/runtests.jl

@@ -140,6 +140,16 @@ end
     end
 end
 
+@testset "replace" begin
+    @test replace(StringView(b"abcd"), r"[bc]?" => "^") == "^a^^d^"
+    @test replace(StringView(b"a"), 'a' => typeof) == "Char"
+    @test replace(StringView(b"The foxes."), r"fox(es)?" => s"bus\1") == "The buses."
+    if VERSION ≥ v"1.7" # for multiple replacements
+        @test replace(StringView(b"foobarbaz"), "oo" => "zz", "ar" => "zz", "z" => "m") == "fzzbzzbam"
+        @test replace(StringView(b"foobar"), 'o' => '0', "" => "") == "f00bar"
+    end
+end
+
 @testset "miscellaneous" begin
     @test cmp("foobar","bar") == cmp(s,"bar") == -cmp("bar",s) == cmp(s,StringView("bar"))
     @test s == StringView("foobar") == "foobar" == s == "foobar" != StringView("bar")