Accept docstrings with last line not fully indented

When trimming indent, the last line, if only containing
whitespaces does not need to match the indent, so that
this indentation style works:

    -docstring %{
        indented string
    }

1 files changed, 19 insertions, 24 deletions

diff --git a/src/string_utils.cc b/src/string_utils.cc
index 348526e9..a87d4cc3 100644
--- a/src/string_utils.cc
+++ b/src/string_utils.cc
@@ -23,31 +23,25 @@ String trim_indent(StringView str)
 {
     if (str.empty())
         return {};
-    else if (str[0_byte] != '\n')
-        return trim_whitespaces(str).str();
 
-    str = str.substr(1_byte);
-    const CharCount docstring_length = str.char_length();
-
-    CharCount level_indent = 0;
-    while (level_indent < docstring_length
-           and is_horizontal_blank(str[level_indent]))
-        level_indent++;
-
-    if (level_indent >= docstring_length or not level_indent)
-        return trim_whitespaces(str).str();
-
-    const auto str_indent = str.substr(0, level_indent);
-    auto s = str | split<StringView>('\n') | transform([&](auto&& line) {
-        if (line.empty())
-            return line;
-        else if (not prefix_match(line, str_indent))
-            throw runtime_error("inconsistent indentation in the string");
-
-        return line.substr(str_indent.char_length());
-    });
-
-    return trim_whitespaces(join(s, '\n', false)).str();
+    if (str[0_byte] == '\n')
+        str = str.substr(1_byte);
+    while (not str.empty() and is_blank(str.back()))
+        str = str.substr(0, str.length() - 1);
+
+    utf8::iterator it{str.begin(), str};
+    while (it != str.end() and is_horizontal_blank(*it))
+        it++;
+
+    const StringView indent{str.begin(), it.base()};
+    return accumulate(str | split_after<StringView>('\n') | transform([&](auto&& line) {
+            if (line == "\n")
+                return line;
+            else if (not prefix_match(line, indent))
+                throw runtime_error("inconsistent indentation in the string");
+
+            return line.substr(indent.length());
+        }), String{}, [](String& s, StringView l) -> decltype(auto) { return s += l; });
 }
 
 String escape(StringView str, StringView characters, char escape)
@@ -414,6 +408,7 @@ UnitTest test_string{[]()
     kak_assert(trim_indent("\nno-indent") == "no-indent");
     kak_assert(trim_indent("\n  indent\n  indent") == "indent\nindent");
     kak_assert(trim_indent("\n  indent\n    indent") == "indent\n  indent");
+    kak_assert(trim_indent("\n  indent\n  indent\n   ") == "indent\nindent");
 
     kak_expect_throw(runtime_error, trim_indent("\n  indent\nno-indent"));