Make RegexMatch iterable

don't forget to pass the state
add length and eltype to RegexMatch
Fix missing enumerate
=update news for RegexMatch iterating

fix typo in news

Co-authored-by: Curtis Vogt <curtis.vogt@gmail.com>

remove example of possible use from NEWS.md

Remove stray at-test

NEWS.md

@@ -46,6 +46,7 @@ Standard library changes
 * `escape_string` can now receive a collection of characters in the keyword
   `keep` that are to be kept as they are. ([#38597]).
 * `getindex` can now be used on `NamedTuple`s with multiple values ([#38878])
+* `RegexMatch` now iterate to give their captures. ([#34355]).
 
 #### Package Manager
 

base/regex.jl

@@ -155,13 +155,13 @@ function show(io::IO, m::RegexMatch)
     idx_to_capture_name = PCRE.capture_names(m.regex.regex)
     if !isempty(m.captures)
         print(io, ", ")
-        for i = 1:length(m.captures)
+        for (i, capture) in enumerate(m)
             # If the capture group is named, show the name.
             # Otherwise show its index.
             capture_name = get(idx_to_capture_name, i, i)
             print(io, capture_name, "=")
-            show(io, m.captures[i])
-            if i < length(m.captures)
+            show(io, capture)
+            if i < length(m)
                 print(io, ", ")
             end
         end
@@ -185,6 +185,10 @@ function haskey(m::RegexMatch, name::Symbol)
 end
 haskey(m::RegexMatch, name::AbstractString) = haskey(m, Symbol(name))
 
+iterate(m::RegexMatch, args...) = iterate(m.captures, args...)
+length(m::RegexMatch) = length(m.captures)
+eltype(m::RegexMatch) = eltype(m.captures)
+
 function occursin(r::Regex, s::AbstractString; offset::Integer=0)
     compile(r)
     return PCRE.exec_r(r.regex, String(s), offset, r.match_options)

test/regex.jl

@@ -166,6 +166,24 @@
         @test r"this|that"^2 == r"(?:this|that){2}"
     end
 
+    @testset "iterate" begin
+        m = match(r"(.) test (.+)", "a test 123")
+        @test first(m) == "a"
+        @test collect(m) == ["a", "123"]
+        for (i, capture) in enumerate(m)
+            i == 1 && @test capture == "a"
+            i == 2 && @test capture == "123"
+        end
+    end
+
+    @testset "Destructuring dispatch" begin
+        handle(::Nothing) = "not found"
+        handle((capture,)::RegexMatch) = "found $capture"
+
+        @test handle(match(r"a (\d)", "xyz")) == "not found"
+        @test handle(match(r"a (\d)", "a 1")) == "found 1"
+    end
+
     # Test that PCRE throws the correct kind of error
     # TODO: Uncomment this once the corresponding change has propagated to CI
     #@test_throws ErrorException Base.PCRE.info(C_NULL, Base.PCRE.INFO_NAMECOUNT, UInt32)