auto complete else after if blocks

(and else if!)

woah, technology

Author: WebFreak001

source/workspaced/com/snippets/generator.d

@@ -242,7 +242,8 @@ void map()
 enum StackStorageScope(string val) = "if (done) return; auto __" ~ val
 	~ "_scope = " ~ val ~ "; scope (exit) if (!done) " ~ val ~ " = __" ~ val ~ "_scope;";
 enum SnippetLevelWrapper(SnippetLevel level) = "if (done) return; pushLevel("
-	~ level.stringof ~ ", dec); scope (exit) popLevel(dec);";
+	~ level.stringof ~ ", dec); scope (exit) popLevel(dec); "
+	~ "if (!dec.tokens.length || dec.tokens[0].index <= position) lastStatement = null;";
 enum FullSnippetLevelWrapper(SnippetLevel level) = SnippetLevelWrapper!level ~ " super.visit(dec);";
 
 class SnippetInfoGenerator : ASTVisitor
@@ -286,6 +287,13 @@ class SnippetInfoGenerator : ASTVisitor
 		super.visit(dec);
 	}
 
+	override void visit(const DeclarationOrStatement dec)
+	{
+		super.visit(dec);
+		if (!dec.tokens.length || dec.tokens[0].index <= position)
+			lastStatement = cast()dec;
+	}
+
 	static foreach (T; AliasSeq!(Arguments, ExpressionNode))
 		override void visit(const T dec)
 		{
@@ -363,6 +371,7 @@ class SnippetInfoGenerator : ASTVisitor
 
 	bool done;
 	VariableUsage[] variableStack;
+	DeclarationOrStatement lastStatement;
 	size_t position, current;
 	SnippetInfo ret;
 }

source/workspaced/com/snippets/package.d

@@ -73,9 +73,16 @@ class SnippetsComponent : ComponentWrapper
 		// nudge in next token if position is not exactly on the start of it
 		if (loc < tokens.length && tokens[loc].index < position)
 			loc++;
+		// determine info from before start of identifier (so you can start typing something and it still finds a snippet scope)
+		if (loc > 0 && loc < tokens.length && tokens[loc].type == tok!"identifier" && tokens[loc].index >= position)
+			loc--;
+
+		int contextIndex;
+		if (loc >= 0 && loc < tokens.length)
+			contextIndex = cast(int) tokens[loc].index;
 
 		if (loc == 0 || loc == tokens.length)
-			return SnippetInfo([SnippetLevel.global]);
+			return SnippetInfo(contextIndex, [SnippetLevel.global]);
 
 		auto leading = tokens[0 .. loc];
 
@@ -93,9 +100,9 @@ class SnippetsComponent : ComponentWrapper
 				// needs to be modified to check the exact trivia token instead
 				// of the associated token with it.
 				if (last.text[0 .. len].startsWith("///", "/++", "/**"))
-					return SnippetInfo([SnippetLevel.docComment]);
+					return SnippetInfo(contextIndex, [SnippetLevel.docComment]);
 				else if (len >= 2)
-					return SnippetInfo([SnippetLevel.comment]);
+					return SnippetInfo(contextIndex, [SnippetLevel.comment]);
 				else
 					break;
 			case tok!"dstringLiteral":
@@ -109,15 +116,15 @@ class SnippetsComponent : ComponentWrapper
 				// quote character
 				// TODO: properly check if this is an unescaped escape
 				if (textSoFar.endsWith('\\', last.text[0]))
-					return SnippetInfo([SnippetLevel.strings, SnippetLevel.other]);
+					return SnippetInfo(contextIndex, [SnippetLevel.strings, SnippetLevel.other]);
 				else
-					return SnippetInfo([SnippetLevel.strings]);
+					return SnippetInfo(contextIndex, [SnippetLevel.strings]);
 			case tok!"(":
 				if (leading.length >= 2)
 				{
 					auto beforeLast = leading[$ - 2];
 					if (beforeLast.type.among(tok!"__traits", tok!"version", tok!"debug"))
-						return SnippetInfo([SnippetLevel.other]);
+						return SnippetInfo(contextIndex, [SnippetLevel.other]);
 				}
 				break;
 			default:
@@ -133,13 +140,13 @@ class SnippetsComponent : ComponentWrapper
 			// test for tokens semicolon closed statements where we should abort to avoid incomplete syntax
 			if (t.type.among!(tok!"import", tok!"module"))
 			{
-				return SnippetInfo([SnippetLevel.global, SnippetLevel.other]);
+				return SnippetInfo(contextIndex, [SnippetLevel.global, SnippetLevel.other]);
 			}
 			else if (t.type.among!(tok!"=", tok!"+", tok!"-", tok!"*", tok!"/",
 					tok!"%", tok!"^^", tok!"&", tok!"|", tok!"^", tok!"<<",
 					tok!">>", tok!">>>", tok!"~", tok!"in"))
 			{
-				return SnippetInfo([SnippetLevel.global, SnippetLevel.value]);
+				return SnippetInfo(contextIndex, [SnippetLevel.global, SnippetLevel.value]);
 			}
 		}
 
@@ -149,6 +156,7 @@ class SnippetsComponent : ComponentWrapper
 		//trace("determineSnippetInfo at ", position);
 
 		scope gen = new SnippetInfoGenerator(position);
+		gen.value.contextTokenIndex = contextIndex;
 		gen.variableStack.reserve(64);
 		gen.visit(parsed);
 
@@ -165,6 +173,34 @@ class SnippetsComponent : ComponentWrapper
 			}
 		}
 
+		if (gen.lastStatement)
+		{
+			import dparse.ast;
+
+			LastStatementInfo info;
+			auto nodeType = gen.lastStatement.findDeepestNonBlockNode;
+			if (gen.lastStatement.tokens.length)
+				info.location = cast(int) nodeType.tokens[0].index;
+			info.type = typeid(nodeType).name;
+			auto lastDot = info.type.lastIndexOf('.');
+			if (lastDot != -1)
+				info.type = info.type[lastDot + 1 .. $];
+			if (auto ifStmt = cast(IfStatement)nodeType)
+			{
+				auto elseStmt = getIfElse(ifStmt);
+				if (cast(IfStatement)elseStmt)
+					info.ifHasElse = false;
+				else
+					info.ifHasElse = elseStmt !is null;
+			}
+			else if (auto ifStmt = cast(ConditionalDeclaration)nodeType)
+				info.ifHasElse = ifStmt.hasElse;
+			// if (auto ifStmt = cast(ConditionalStatement)nodeType)
+			// 	info.ifHasElse = !!getIfElse(ifStmt);
+
+			gen.value.lastStatement = info;
+		}
+
 		return gen.value;
 	}
 
@@ -540,10 +576,15 @@ struct SnippetLoopScope
 ///
 struct SnippetInfo
 {
+	/// Index in code which token was used to determine this snippet info.
+	int contextTokenIndex;
 	/// Levels this snippet location has gone through, latest one being the last
 	SnippetLevel[] stack = [SnippetLevel.global];
 	/// Information about snippets using loop context
 	SnippetLoopScope loopScope;
+	/// Information about the last parsable statement before the cursor. May be
+	/// `LastStatementInfo.init` at start of function or block.
+	LastStatementInfo lastStatement;
 
 	/// Current snippet scope level of the location
 	SnippetLevel level() const @property
@@ -552,6 +593,19 @@ struct SnippetInfo
 	}
 }
 
+struct LastStatementInfo
+{
+	/// The libdparse class name (typeid) of the last parsable statement before
+	/// the cursor, stripped of module name.
+	string type;
+	/// If type is set, this is the start location in bytes where
+	/// the first token was.
+	int location;
+	/// True if the type is (`IfStatement`, `ConditionalDeclaration` or
+	/// `ConditionalStatement`) and has a final `else` block defined.
+	bool ifHasElse;
+}
+
 /// A list of snippets resolved at a given position.
 struct SnippetList
 {

source/workspaced/com/snippets/smart.d

@@ -1,18 +1,23 @@
 module workspaced.com.snippets.smart;
 
+// debug = SnippetScope;
+
 import workspaced.api;
 import workspaced.com.snippets;
 
+import std.algorithm;
 import std.conv;
+import std.string;
 
 class SmartSnippetProvider : SnippetProvider
 {
 	Future!(Snippet[]) provideSnippets(scope const WorkspaceD.Instance instance,
 			scope const(char)[] file, scope const(char)[] code, int position, const SnippetInfo info)
 	{
+		Snippet[] res;
+
 		if (info.loopScope.supported)
 		{
-			Snippet[] res;
 			if (info.loopScope.numItems > 1)
 			{
 				res ~= ndForeach(info.loopScope.numItems, info.loopScope.iterator);
@@ -29,10 +34,50 @@ class SmartSnippetProvider : SnippetProvider
 				res ~= simpleForeach(info.loopScope.iterator, info.loopScope.type);
 				res ~= stringIterators();
 			}
-			return typeof(return).fromResult(res);
 		}
-		else
-			return typeof(return).fromResult(null);
+
+		if (info.lastStatement.type == "IfStatement"
+			&& !info.lastStatement.ifHasElse)
+		{
+			int ifIndex = info.contextTokenIndex == 0 ? position : info.contextTokenIndex;
+			auto hasBraces = code[0 .. max(min(ifIndex, $), 0)].stripRight.endsWith("}");
+			Snippet snp;
+			snp.providerId = typeid(this).name;
+			snp.id = "else";
+			snp.title = "else";
+			snp.shortcut = "else";
+			snp.documentation = "else block";
+			if (hasBraces)
+			{
+				snp.plain = "else {\n\t\n}";
+				snp.snippet = "else {\n\t$0\n}";
+			}
+			else
+			{
+				snp.plain = "else\n\t";
+				snp.snippet = "else\n\t$0";
+			}
+			snp.unformatted = true;
+			snp.resolved = true;
+			res ~= snp;
+		}
+
+		debug (SnippetScope)
+		{
+			import painlessjson : toJSON;
+
+			Snippet ret;
+			ret.providerId = typeid(this).name;
+			ret.id = "workspaced-snippet-debug";
+			ret.title = "[DEBUG] Snippet";
+			ret.shortcut = "__debug_snippet";
+			ret.plain = ret.snippet = info.toJSON.toPrettyString;
+			ret.unformatted = true;
+			ret.resolved = true;
+			res ~= ret;
+		}
+
+		return typeof(return).fromResult(res.length ? res : null);
 	}
 
 	Future!Snippet resolveSnippet(scope const WorkspaceD.Instance instance,

source/workspaced/dparseext.d

@@ -301,3 +301,82 @@ string evaluateExpressionString(const Token token)
 		return null;
 	}
 }
+
+/// Finds the deepest non-null node of any BaseNode. (like visiting the tree)
+/// Aborts on types that contain `DeclarationOrStatement` or `Declaration[]`
+/// fields.
+/// Useful for getting the IfStatement out of a DeclarationOrStatement without
+/// traversing its children.
+BaseNode findDeepestNonBlockNode(T : BaseNode)(T ast)
+{
+	static assert(!is(T == BaseNode), "Passed in a BaseNode, that's probably not what you wanted to do (pass in the most specific type you have)");
+	bool nonProcess = false;
+	foreach (member; ast.tupleof)
+	{
+		static if (is(typeof(member) : DeclarationOrStatement)
+			|| is(typeof(member) : Declaration[]))
+		{
+			nonProcess = true;
+		}
+	}
+
+	if (nonProcess)
+		return ast;
+
+	foreach (member; ast.tupleof)
+	{
+		static if (is(typeof(member) : BaseNode))
+		{
+			if (member !is null)
+			{
+				return findDeepestNonBlockNode(member);
+			}
+		}
+	}
+	return ast;
+}
+
+/// Gets the final `else` block of an if. Will return a node of type
+/// `IfStatement` if it's an `else if` block. Returns null if there is no single
+/// else statement.
+BaseNode getIfElse(IfStatement ifStmt)
+{
+	if (!ifStmt.elseStatement)
+		return null;
+
+	while (true)
+	{
+		auto elseStmt = ifStmt.elseStatement;
+		if (!elseStmt)
+			return ifStmt;
+
+		auto stmtInElse = elseStmt.findDeepestNonBlockNode;
+		assert(stmtInElse !is elseStmt);
+
+		if (cast(IfStatement)stmtInElse)
+			ifStmt = cast(IfStatement)stmtInElse;
+		else
+			return stmtInElse;
+	}
+}
+
+unittest
+{
+	StringCache stringCache = StringCache(StringCache.defaultBucketCount);
+	RollbackAllocator rba;
+	IfStatement parseIfStmt(string code)
+	{
+		const(Token)[] tokens = getTokensForParser(cast(ubyte[])code, LexerConfig.init, &stringCache);
+		auto parser = new Parser();
+		parser.tokens = tokens;
+		parser.allocator = &rba;
+		return parser.parseIfStatement();
+	}
+
+	alias p = parseIfStmt;
+	assert(getIfElse(p("if (x) {}")) is null);
+	assert(getIfElse(p("if (x) {} else if (y) {}")) !is null);
+	assert(cast(IfStatement)getIfElse(p("if (x) {} else if (y) {}")) !is null, typeid(getIfElse(p("if (x) {} else if (y) {}"))).name);
+	assert(getIfElse(p("if (x) {} else if (y) {} else {}")) !is null);
+	assert(cast(IfStatement)getIfElse(p("if (x) {} else if (y) {} else {}")) is null);
+}