Add .editorconfig reading support. #122

src/dfmt/editorconfig.d

@@ -0,0 +1,167 @@
+module dfmt.editorconfig;
+import std.regex : ctRegex;
+
+private auto headerRe = ctRegex!(`^\s*\[([^\n]+)\]\s*(:?#.*)?$`);
+private auto propertyRe = ctRegex!(`^\s*([\w_]+)\s*=\s*([\w_]+)\s*[#;]?.*$`);
+private auto commentRe = ctRegex!(`^\s*[#;].*$`);
+
+enum OptionalBoolean : ubyte
+{
+	unspecified = 3,
+	t = 1,
+	f = 0
+}
+
+enum IndentStyle : ubyte
+{
+	unspecified,
+	tab,
+	space
+}
+
+enum EOL : ubyte
+{
+	unspecified,
+	lf,
+	cr,
+	crlf
+}
+
+mixin template StandardEditorConfigFields()
+{
+	string pattern;
+	OptionalBoolean root;
+	EOL end_of_line;
+	OptionalBoolean insert_final_newline;
+	string charset;
+	IndentStyle indent_style;
+	int indent_size = -1;
+	int tab_width = -1;
+	OptionalBoolean trim_trailing_whitespace;
+	int max_line_length = -1;
+
+	void merge(ref const typeof(this) other, const string fileName)
+	{
+		import std.path : globMatch;
+		import std.traits : FieldNameTuple;
+
+		if (other.pattern is null || !fileName.globMatch(other.pattern))
+			return;
+		foreach (N; FieldNameTuple!(typeof(this)))
+		{
+			alias T = typeof(mixin(N));
+			const otherN = mixin("other." ~ N);
+			auto thisN = &mixin("this." ~ N);
+			static if (N == "pattern")
+				continue;
+			else static if (is (T == enum))
+				*thisN = otherN != T.unspecified ? otherN : *thisN;
+			else static if (is (T == int))
+				*thisN = otherN != -1 ? otherN : *thisN;
+			else static if (is (T == string))
+				*thisN = otherN !is null ? otherN : *thisN;
+			else
+				static assert(false);
+		}
+	}
+}
+
+/**
+ * Params:
+ *     path = the path to the file
+ * Returns:
+ *     The configuration for the file at the given path
+ */
+EC getConfigFor(EC)(string path)
+{
+	import std.stdio : File;
+	import std.regex : regex, match;
+	import std.path : globMatch, dirName, baseName, pathSplitter, buildPath;
+	import std.algorithm : reverse, map, filter, each;
+	import std.array : array;
+
+	EC result;
+	EC[][] configs;
+	string dir = dirName(path);
+	immutable string fileName = baseName(path);
+	string[] pathParts = cast(string[]) pathSplitter(dir).array();
+	for (size_t i = pathParts.length; i > 1; i--)
+	{
+		EC[] sections = parseConfig!EC(buildPath(pathParts[0 .. i]));
+		if (sections.length)
+			configs ~= sections;
+		if (!sections.map!(a => a.root).filter!(a => a == OptionalBoolean.t).empty)
+			break;
+	}
+	reverse(configs);
+	configs.each!(a => a.each!(b => result.merge(b, fileName)))();
+	return result;
+}
+
+private EC[] parseConfig(EC)(string dir)
+{
+	import std.stdio : File;
+	import std.file : exists;
+	import std.path : buildPath;
+	import std.regex : matchAll;
+	import std.traits : FieldNameTuple;
+	import std.conv : to;
+	import std.uni : toLower;
+
+	EC section;
+	EC[] sections;
+	immutable string path = buildPath(dir, ".editorconfig");
+	if (!exists(path))
+		return sections;
+
+	File f = File(path);
+	foreach (line; f.byLineCopy())
+	{
+		auto headerMatch = line.matchAll(headerRe);
+		if (headerMatch)
+		{
+			sections ~= section;
+			section = EC.init;
+			auto c = headerMatch.captures;
+			c.popFront();
+			section.pattern = c.front();
+		}
+		else
+		{
+			auto propertyMatch = line.matchAll(propertyRe);
+			if (propertyMatch)
+			{
+				auto c = propertyMatch.captures;
+				c.popFront();
+				immutable string propertyName = c.front();
+				c.popFront();
+				immutable string propertyValue = toLower(c.front());
+				foreach (F; FieldNameTuple!EC)
+				{
+					enum configDot = "section." ~ F;
+					alias FieldType = typeof(mixin(configDot));
+					if (F == propertyName)
+					{
+						static if (is(FieldType == OptionalBoolean))
+							mixin(configDot) = propertyValue == "true" ? OptionalBoolean.t
+								: OptionalBoolean.f;
+						else
+									mixin(configDot) = to!(FieldType)(propertyValue);
+					}
+				}
+			}
+		}
+	}
+	sections ~= section;
+	return sections;
+}
+
+version (editorconfig_main) void main()
+{
+	import std.stdio : writeln;
+
+	static struct EditorConfig { mixin StandardEditorConfigFields; }
+
+	auto c = getConfigFor!EditorConfig("/home/brian/src/aias/src/dummy.d");
+	writeln(c);
+}