parser: anonymous functions (part 1)

vlib/v/ast/ast.v

@@ -10,7 +10,7 @@ import (
 
 pub type TypeDecl = AliasTypeDecl | SumTypeDecl | FnTypeDecl
 
-pub type Expr = InfixExpr | IfExpr | StringLiteral | IntegerLiteral | CharLiteral | FloatLiteral | Ident | CallExpr | BoolLiteral | StructInit | ArrayInit | SelectorExpr | PostfixExpr | AssignExpr | PrefixExpr | IndexExpr | RangeExpr | MatchExpr | CastExpr | EnumVal | Assoc | SizeOf | None | MapInit | IfGuardExpr | ParExpr | OrExpr | ConcatExpr | Type | AsCast | TypeOf | StringInterLiteral
+pub type Expr = InfixExpr | IfExpr | StringLiteral | IntegerLiteral | CharLiteral | FloatLiteral | Ident | CallExpr | BoolLiteral | StructInit | ArrayInit | SelectorExpr | PostfixExpr | AssignExpr | PrefixExpr | IndexExpr | RangeExpr | MatchExpr | CastExpr | EnumVal | Assoc | SizeOf | None | MapInit | IfGuardExpr | ParExpr | OrExpr | ConcatExpr | Type | AsCast | TypeOf | StringInterLiteral | AnonFn
 
 pub type Stmt = GlobalDecl | FnDecl | Return | Module | Import | ExprStmt | ForStmt | StructDecl | ForCStmt | ForInStmt | CompIf | ConstDecl | Attr | BranchStmt | HashStmt | AssignStmt | EnumDecl | TypeDecl | DeferStmt | GotoLabel | GotoStmt | Comment | AssertStmt | UnsafeStmt | GoStmt | Block | InterfaceDecl
 
@@ -184,6 +184,13 @@ pub:
 	alias string
 }
 
+pub struct AnonFn {
+pub:
+	decl FnDecl
+mut:
+	typ table.Type
+}
+
 pub struct FnDecl {
 pub:
 	name          string
@@ -193,11 +200,12 @@ pub:
 	is_deprecated bool
 	is_pub        bool
 	is_variadic   bool
+	is_anon       bool
 	receiver      Field
 	is_method     bool
 	rec_mut       bool // is receiver mutable
 	is_c          bool
-	is_js		  bool
+	is_js         bool
 	no_body       bool // just a definition `fn C.malloc()`
 	is_builtin    bool // this function is defined in builtin/strconv
 	pos           token.Position

vlib/v/checker/checker.v

@@ -1198,6 +1198,9 @@ pub fn (c mut Checker) expr(node ast.Expr) table.Type {
 			it.expr_type = c.expr(it.expr)
 			return table.string_type
 		}
+		ast.AnonFn {
+			return it.typ
+		}
 		else {
 			tnode := typeof(node)
 			if tnode != 'unknown v.ast.Expr' {

vlib/v/gen/cgen.v

@@ -248,8 +248,14 @@ pub fn (var g Gen) write_typedef_types() {
 			.function {
 				info := typ.info as table.FnType
 				func := info.func
-				if !info.has_decl && !info.is_anon {
-					fn_name := if func.is_c { func.name.replace('.', '__') } else { c_name(func.name) }
+				if !info.has_decl {
+					fn_name := if func.is_c { 
+						func.name.replace('.', '__') 
+					} else if info.is_anon {
+						typ.name
+					} else { 
+						c_name(func.name) 
+					}
 					g.definitions.write('typedef ${g.typ(func.return_type)} (*$fn_name)(')
 					for i, arg in func.args {
 						g.definitions.write(g.typ(arg.typ))
@@ -1085,6 +1091,33 @@ fn (var g Gen) expr(node ast.Expr) {
 		ast.TypeOf {
 			g.typeof_expr(it)
 		}
+		ast.AnonFn {
+			sym := g.table.get_type_symbol(it.typ)
+			func := it.decl
+
+			// TODO: Fix hack and write function implementation directly to definitions
+			pos := g.out.len
+			type_name := g.typ(func.return_type)
+			g.write('$type_name ${sym.name}_impl(')
+			g.fn_args(func.args, func.is_variadic)
+			g.writeln(') {')
+			g.stmts(func.stmts)
+			if g.autofree {
+				g.free_scope_vars(func.pos.pos - 1)
+			}
+			if g.defer_stmts.len > 0 {
+				g.write_defer_stmts()
+			}
+			g.out.writeln('}')
+			g.defer_stmts = []
+			g.fn_decl = 0
+
+			fn_body := g.out.after(pos)
+			g.definitions.write(fn_body)
+			g.out.go_back(fn_body.len)
+
+			g.out.write('&${sym.name}_impl')
+		}
 		else {
 			// #printf("node=%d\n", node.typ);
 			println(term.red('cgen.expr(): bad node ' + typeof(node)))

vlib/v/parser/fn.v

@@ -234,6 +234,58 @@ fn (var p Parser) fn_decl() ast.FnDecl {
 	}
 }
 
+fn (var p Parser) anon_fn() ast.AnonFn {
+	pos := p.tok.position()
+	p.open_scope()
+	p.check(.key_fn)
+
+	// TODO generics
+
+	args, is_variadic := p.fn_args()
+	for arg in args {
+		p.scope.register(arg.name, ast.Var{
+			name: arg.name
+			typ: arg.typ
+		})
+	}
+
+	var return_type := table.void_type
+	if p.tok.kind.is_start_of_type() {
+		return_type = p.parse_type()
+	}
+
+	var stmts := []ast.Stmt
+	no_body := p.tok.kind != .lcbr
+	if p.tok.kind == .lcbr {
+		stmts = p.parse_block()
+	}
+	p.close_scope()
+
+	func := table.Fn{
+		args: args
+		is_variadic: is_variadic
+		return_type: return_type
+	}
+	idx := p.table.find_or_register_fn_type(func, false)
+	typ := table.new_type(idx)
+	name := p.table.get_type_name(typ)
+
+	return ast.AnonFn{
+		decl: ast.FnDecl{
+			name: name
+			stmts: stmts
+			return_type: return_type
+			args: args
+			is_variadic: is_variadic
+			is_method: false
+			is_anon: true
+			no_body: no_body
+			pos: pos
+		}
+		typ: typ
+	}
+}
+
 fn (var p Parser) fn_args() ([]table.Arg, bool) {
 	p.check(.lpar)
 	var args := []table.Arg