strings: Implement join_string_set() as bif

Haven't measured speed, but this is probably faster than
the cat() and string invocations.

scripts/base/utils/strings.zeek

@@ -9,29 +9,6 @@ function is_string_binary(s: string): bool
 	return |gsub(s, /[\x00-\x7f]/, "")| * 100 / |s| >= 25;
 	}
 
-## Join a set of strings together, with elements delimited by a constant string.
-##
-## ss: a set of strings to join.
-##
-## j: the string used to join set elements.
-##
-## Returns: a string composed of all elements of the set, delimited by the
-##          joining string.
-function join_string_set(ss: set[string], j: string): string
-	{
-	local output="";
-	local i=0;
-	for ( s in ss )
-		{
-		if ( i > 0 )
-			output = cat(output, j);
-
-		output = cat(output, s);
-		++i;
-		}
-	return output;
-	}
-
 ## Given a string, returns an escaped version.
 ##
 ## s: a string to escape.

src/strings.bif

@@ -127,6 +127,65 @@ function join_string_vec%(vec: string_vec, sep: string%): string
 	return zeek::make_intrusive<zeek::StringVal>(s);
 	%}
 
+## Joins all values in the given set of strings with a separator placed
+## between each element.
+##
+## ss: The :zeek:type:`string_set` (``set[string]``).
+##
+## sep: The separator to place between each element.
+##
+## Returns: The concatenation of all elements in *s*, with *sep* placed
+##          between each element.
+##
+## .. zeek:see:: cat cat_sep string_cat
+##              fmt
+##              join_string_vec
+function join_string_set%(ss: string_set, sep: string%): string
+	%{
+	ODesc d;
+	d.SetStyle(RAW_STYLE);
+
+	if ( ! ss->GetType()->IsSet () )
+		{
+		zeek::emit_builtin_error("join_string_set() requires a string set argument");
+		return val_mgr->EmptyString();
+		}
+
+	// Not sure we need to protect from this
+	const auto& it = ss->GetType()->AsTableType()->GetIndexTypes();
+	if ( it.size() != 1  || it[0]->Tag() != TYPE_STRING )
+		{
+		zeek::emit_builtin_error("join_string_set() requires a string set argument");
+		return val_mgr->EmptyString();
+		}
+
+	int i = 0;
+	TableVal* tv = ss->AsTableVal();
+	const PDict<TableEntryVal>* loop_vals = tv->AsTable();
+
+	if ( ! loop_vals->Length() )
+		return val_mgr->EmptyString();
+
+	for ( const auto& iter : *loop_vals )
+		{
+		if ( i > 0 )
+			d.AddN(reinterpret_cast<const char*>(sep->Bytes()), sep->Len());
+
+		// Not sure this is fast - I guess we don't have access to the
+		// values used for the keys directly anymore.
+		auto k = iter.GetHashKey();
+		auto ind_lv = tv->RecreateIndex(*k);
+		ind_lv->Describe(&d);
+
+		++i;
+		}
+
+	zeek::String* str = new zeek::String(1, d.TakeBytes(), d.Len());
+	str->SetUseFreeToDelete(true);
+
+	return zeek::make_intrusive<zeek::StringVal>(str);
+	%}
+
 ## Returns an edited version of a string that applies a special
 ## "backspace character" (usually ``\x08`` for backspace or ``\x7f`` for DEL).
 ## For example, ``edit("hello there", "e")`` returns ``"llo t"``.

testing/btest/Baseline/bifs.join_string/out

@@ -4,3 +4,7 @@ thisisanothertest
 Test
 ...hi..there
 this\x00is\x00another\x00test
+ (empty)
+one
+two, one, three
+twoone

testing/btest/Baseline/scripts.base.utils.strings/output

@@ -3,8 +3,6 @@
 '\xff\xff\xff\x00' IS considered binary
 '\x00\x00\xff\x00' IS considered binary
 '\x00\x00\x00\x00' is NOT considered binary
-two, one, three
-one
 hell\o w\orl\d
 \\hello world\\
 hello world

testing/btest/bifs/join_string.zeek

@@ -19,4 +19,10 @@ event zeek_init()
 	print join_string_vec(d, "-");
 	print join_string_vec(e, ".");
 	print join_string_vec(c, "\x00");
+
+	local empty_set: set[string] = set();
+	print fmt("%s (empty)", join_string_set(empty_set, ", "));
+	print join_string_set(set("one"), ", ");
+	print join_string_set(set("one", "two", "three"), ", ");
+	print join_string_set(set("one", "two"), "");
 	}

testing/btest/scripts/base/utils/strings.test

@@ -16,9 +16,6 @@ test_binary_string("\xFF\xFF\xFF\x00");
 test_binary_string("\x00\x00\xFF\x00");
 test_binary_string("\x00\x00\x00\x00");
 
-print join_string_set(set("one", "two", "three"), ", ");
-print join_string_set(set("one"), ", ");
-
 print string_escape("hello world", "od");
 print string_escape("\\hello world\\", "");