Fuzzy matching instead of startsWith for filtering

Experimental, subject to change

dsymbol/dub.json

@@ -7,6 +7,7 @@
 	"targetType": "library",
 	"dependencies": {
 		"libdparse": ">=0.20.0 <1.0.0",
-		"emsi_containers": "~>0.9.0"
+		"emsi_containers": "~>0.9.0",
+		"fuzzymatch": "~>1.0"
 	}
 }

dsymbol/src/dsymbol/ufcs.d

@@ -231,12 +231,12 @@ private DSymbol*[] getUFCSSymbolsForDotCompletion(const(DSymbol)* symbolType, Sc
     // local appender
     FilteredAppender!((DSymbol* a) =>
             a.isCallableWithArg(symbolType)
-            && toUpper(a.name.data).startsWith(toUpper(partial)),
+            && prettyFuzzyMatch(a.name.data, partial),
         DSymbol*[]) localAppender;
     // global appender
     FilteredAppender!((DSymbol* a) =>
             a.isCallableWithArg(symbolType, true)
-            && toUpper(a.name.data).startsWith(toUpper(partial)),
+            && prettyFuzzyMatch(a.name.data, partial),
         DSymbol*[]) globalAppender;
 
     getUFCSSymbols(localAppender, globalAppender, completionScope, cursorPosition);

dsymbol/src/dsymbol/utils.d

@@ -153,3 +153,19 @@ unittest
 	i = skipParenReverseBefore(t, i, tok!")", tok!"(");
 	assert(i == 1);
 }
+
+/// Checks if `doesThis` roughly starts with `matchThis`, case-insensitive
+bool prettyFuzzyMatch(scope const(char)[] doesThis, scope const(char)[] matchThis) @safe pure nothrow @nogc
+{
+	import fuzzymatch;
+
+	if (!matchThis.length)
+		return true;
+
+	// return false if identifier starts with _, but search doesn't or vice-versa
+	if (doesThis.length && (doesThis[0] == '_' && matchThis[0] != '_'
+		|| doesThis[0] != '_' && matchThis[0] == '_'))
+		return false;
+
+	return fuzzyMatchesString(doesThis, matchThis);
+}

dub.selections.json

@@ -3,6 +3,7 @@
 	"versions": {
 		"dsymbol": "0.14.1",
 		"emsi_containers": "0.9.0",
+		"fuzzymatch": "1.0.0",
 		"libdparse": "0.22.0",
 		"msgpack-d": "1.0.4",
 		"stdx-allocator": "2.77.5"

src/dcd/server/autocomplete/complete.d

@@ -188,7 +188,6 @@ AutocompleteResponse dotCompletion(T)(T beforeTokens, const(Token)[] tokenArray,
 		{
 			partial = t.text[0 .. cursorPosition - t.index];
 			// issue 442 - prevent `partial` to start in the middle of a MBC
-			// since later there's a non-nothrow call to `toUpper`
 			import std.utf : validate, UTFException;
 			try validate(partial);
 			catch (UTFException)
@@ -513,7 +512,7 @@ void setCompletions(T)(ref AutocompleteResponse response,
 		foreach (sym; s.opSlice())
 		{
 			if (sym.name !is null && sym.name.length > 0 && isPublicCompletionKind(sym.kind)
-				&& (p is null ? true : toUpper(sym.name.data).startsWith(toUpper(p)))
+				&& prettyFuzzyMatch(sym.name.data, p)
 				&& !r.completions.canFind!(a => a.identifier == sym.name)
 				&& sym.name[0] != '*'
 				&& mightBeRelevantInCompletionScope(sym, completionScope))
@@ -531,7 +530,7 @@ void setCompletions(T)(ref AutocompleteResponse response,
 	{
 		auto currentSymbols = completionScope.getSymbolsInCursorScope(cursorPosition);
 		foreach (s; currentSymbols.filter!(a => isPublicCompletionKind(a.kind)
-				&& toUpper(a.name.data).startsWith(toUpper(partial))
+				&& prettyFuzzyMatch(a.name.data, partial)
 				&& mightBeRelevantInCompletionScope(a, completionScope)))
 		{
 			response.completions ~= makeSymbolCompletionInfo(s, s.kind);
@@ -549,8 +548,7 @@ void setCompletions(T)(ref AutocompleteResponse response,
 				&& a.kind != CompletionKind.importSymbol
 				&& a.kind != CompletionKind.dummy
 				&& a.symbolFile == "stdin"
-				&& (partial !is null && toUpper(a.name.data).startsWith(toUpper(partial))
+				&& prettyFuzzyMatch(a.name.data, partial)
-					|| partial is null)
 				&& mightBeRelevantInCompletionScope(a, completionScope)))
 		{
 			response.completions ~= makeSymbolCompletionInfo(s, s.kind);

tests/tc021/expected.txt

@@ -3,3 +3,6 @@ idouble	k
 ifloat	k
 int	k
 ireal	k
+string	l
+uint	k
+void	k

tests/tc029/expected1.txt

@@ -6,3 +6,6 @@ cfloat	k
 char	k
 complicatedLess	l
 creal	k
+dchar	k
+ucent	k
+wchar	k

tests/tc051/expected.txt

@@ -1,3 +1,5 @@
 identifiers
 Foo	s
+cfloat	k
 float	k
+ifloat	k

tests/tc_accesschain_type/expected.txt

@@ -1,2 +1,7 @@
 identifiers
+alignof	k
 foo	f
+mangleof	k
+sizeof	k
+stringof	k
+tupleof	k

tests/tc_complete_kw/expected3.txt

@@ -1,2 +1,3 @@
 identifiers
+init	k
 internal	v

tests/tc_extended_ditto/expected1.txt

@@ -1,3 +1,6 @@
 identifiers
+cfloat	k				cfloat
+float	k				float
 foo	f	void foo()	stdin 26	my documentation	void
 foo	f	void foo(int i)	stdin 49	my documentation	void
+ifloat	k				ifloat