From 5fd5e558ae7f46ac6a4fe6cba829f651c1081d2e Mon Sep 17 00:00:00 2001
From: joe-conigliaro <joe@vlang.io>
Date: Wed, 8 Jul 2020 01:10:39 +1000
Subject: [PATCH] parser/checker/gen: anon fn direct call with args

---
 vlib/v/ast/ast.v            |  4 +++-
 vlib/v/checker/checker.v    | 16 +++++++++++-----
 vlib/v/fmt/fmt.v            |  3 ---
 vlib/v/gen/cgen.v           | 18 ++++++------------
 vlib/v/gen/fn.v             |  5 +++++
 vlib/v/parser/fn.v          |  7 -------
 vlib/v/parser/pratt.v       | 16 ++++++++++++++++
 vlib/v/tests/fn_high_test.v | 11 +++++++++++
 8 files changed, 52 insertions(+), 28 deletions(-)

diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index aa33c3fb34..5ec7cb3bf7 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -213,7 +213,6 @@ pub:
 pub struct AnonFn {
 pub:
 	decl      FnDecl
-	is_called bool
 pub mut:
 	typ       table.Type
 }
@@ -896,6 +895,9 @@ pub fn (expr Expr) is_blank_ident() bool {
 pub fn (expr Expr) position() token.Position {
 	// all uncommented have to be implemented
 	match mut expr {
+		AnonFn {
+			return expr.decl.pos
+		}
 		ArrayInit {
 			return expr.pos
 		}
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 894a777e5d..e7477e94ac 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1014,6 +1014,16 @@ pub fn (mut c Checker) call_fn(mut call_expr ast.CallExpr) table.Type {
 	mut f := table.Fn{}
 	mut found := false
 	mut found_in_args := false
+	// anon fn direct call
+	if call_expr.left is ast.AnonFn {
+		// it was set to anon for checker errors, clear for gen
+		call_expr.name = ''
+		c.expr(call_expr.left)
+		anon_fn := call_expr.left as ast.AnonFn
+		anon_fn_sym := c.table.get_type_symbol(anon_fn.typ)
+		f = (anon_fn_sym.info as table.FnType).func
+		found = true
+	}
 	// try prefix with current module as it would have never gotten prefixed
 	if !fn_name.contains('.') && call_expr.mod !in ['builtin'] {
 		name_prefixed := '${call_expr.mod}.$fn_name'
@@ -2072,11 +2082,7 @@ pub fn (mut c Checker) expr(node ast.Expr) table.Type {
 			c.cur_fn = &node.decl
 			c.stmts(node.decl.stmts)
 			c.cur_fn = keep_fn
-			return if node.is_called {
-				node.decl.return_type
-			} else {
-				node.typ
-			}
+			return node.typ
 		}
 		ast.ArrayInit {
 			return c.array_init(mut node)
diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index 68163157f1..2ac33269ae 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -701,9 +701,6 @@ pub fn (mut f Fmt) expr(node ast.Expr) {
 	match node {
 		ast.AnonFn {
 			f.fn_decl(node.decl)
-			if node.is_called {
-				f.write('()')
-			}
 		}
 		ast.ArrayInit {
 			f.array_init(node)
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index d9d4c0eaf8..41ec308163 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -1210,18 +1210,12 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 					g.write('{')
 				}
 				ret_styp := g.typ(val.decl.return_type)
-				if val.is_called {
-					g.write('$ret_styp $ident.name = ')
-					g.expr(*val)
-					g.write('()')
-				} else {
-					g.write('$ret_styp (*$ident.name) (')
-					def_pos := g.definitions.len
-					g.fn_args(val.decl.args, val.decl.is_variadic)
-					g.definitions.go_back(g.definitions.len - def_pos)
-					g.write(') = ')
-					g.expr(*val)
-				}
+				g.write('$ret_styp (*$ident.name) (')
+				def_pos := g.definitions.len
+				g.fn_args(val.decl.args, val.decl.is_variadic)
+				g.definitions.go_back(g.definitions.len - def_pos)
+				g.write(') = ')
+				g.expr(*val)
 				g.writeln(';')
 				if blank_assign {
 					g.write('}')
diff --git a/vlib/v/gen/fn.v b/vlib/v/gen/fn.v
index 0adee441e4..539ac9da76 100644
--- a/vlib/v/gen/fn.v
+++ b/vlib/v/gen/fn.v
@@ -241,6 +241,11 @@ fn (mut g Gen) fn_args(args []table.Arg, is_variadic bool) ([]string, []string)
 }
 
 fn (mut g Gen) call_expr(node ast.CallExpr) {
+	// NOTE: everything could be done this way
+	// see my comment in parser near anon_fn
+	if node.left is ast.AnonFn {
+		g.expr(node.left)
+	}
 	if node.should_be_skipped {
 		return
 	}
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index 76f34fb840..c0fc44c91f 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -355,12 +355,6 @@ fn (mut p Parser) anon_fn() ast.AnonFn {
 		return_type: return_type
 	}
 	name := 'anon_${p.tok.pos}_$func.signature()'
-	mut is_called := false
-	if p.tok.kind == .lpar {
-		is_called = true
-		p.check(.lpar)
-		p.check(.rpar)
-	}
 	func.name = name
 	idx := p.table.find_or_register_fn_type(p.mod, func, true, false)
 	typ := table.new_type(idx)
@@ -379,7 +373,6 @@ fn (mut p Parser) anon_fn() ast.AnonFn {
 			pos: pos
 			file: p.file_name
 		}
-		is_called: is_called
 		typ: typ
 	}
 }
diff --git a/vlib/v/parser/pratt.v b/vlib/v/parser/pratt.v
index e5bdb1208d..b4bb18028d 100644
--- a/vlib/v/parser/pratt.v
+++ b/vlib/v/parser/pratt.v
@@ -166,6 +166,22 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 		.key_fn {
 			// Anonymous function
 			node = p.anon_fn()
+			// its a call
+			// NOTE: this could be moved to just before the pratt loop
+			// then anything can be a call, eg. `index[2]()` or `stuct.field()`
+			// but this would take a bit of modification
+			if p.tok.kind == .lpar {
+				p.next()
+				pos := p.tok.position()
+				args := p.call_args()
+				p.check(.rpar)
+				node = ast.CallExpr{
+					name: 'anon'
+					left: node
+					args: args
+					pos: pos
+				}
+			}
 			return node
 		}
 		else {
diff --git a/vlib/v/tests/fn_high_test.v b/vlib/v/tests/fn_high_test.v
index 0cbdb4db80..ac06b9f826 100644
--- a/vlib/v/tests/fn_high_test.v
+++ b/vlib/v/tests/fn_high_test.v
@@ -101,6 +101,17 @@ fn test_anon_fn() {
 	})
 }
 
+fn test_anon_fn_direct_call() {
+	fn(name string) {
+		println('hello $name')
+	}('from anon')
+	
+	b := fn(n int) int {
+		return 11+n
+	}(100)
+	assert b == 111
+}
+
 //
 // Test assigning functions (IdentFn)
 //