From b5a1544bf8964e142cbc68a894dfb6643395eb09 Mon Sep 17 00:00:00 2001
From: Tanel Liiv <204019+dkull@users.noreply.github.com>
Date: Wed, 6 May 2020 21:09:29 +0300
Subject: [PATCH] parser: allow re-assigning fns to variables

---
 vlib/v/checker/checker.v    |  46 ++++++-----
 vlib/v/gen/cgen.v           |  22 +++++-
 vlib/v/tests/fn_high_test.v | 147 ++++++++++++++++++++++++++++++++++++
 vlib/v/tests/fn_test.v      | 101 -------------------------
 4 files changed, 196 insertions(+), 120 deletions(-)
 create mode 100644 vlib/v/tests/fn_high_test.v

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 8314eb2e9e..24d5ac909c 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1728,6 +1728,11 @@ pub fn (mut c Checker) ident(ident mut ast.Ident) table.Type {
 		info := ident.info as ast.IdentFn
 		return info.typ
 	} else if ident.kind == .unresolved {
+		// prepend mod to look for fn call or const
+		mut name := ident.name
+		if !name.contains('.') && ident.mod !in ['builtin', 'main'] {
+			name = '${ident.mod}.$ident.name'
+		}
 		// first use
 		start_scope := c.file.scope.innermost(ident.pos.pos)
 		if obj := start_scope.find(ident.name) {
@@ -1737,27 +1742,34 @@ pub fn (mut c Checker) ident(ident mut ast.Ident) table.Type {
 					if typ == 0 {
 						typ = c.expr(it.expr)
 					}
-					is_optional := typ.flag_is(.optional)
-					ident.kind = .variable
-					ident.info = ast.IdentVar{
-						typ: typ
-						is_optional: is_optional
+					sym := c.table.get_type_symbol(typ)
+					if sym.info is table.FnType {
+						// anon/local fn assigned to new variable uses this
+						info := sym.info as table.FnType
+						fn_type := table.new_type(c.table.find_or_register_fn_type(info.func, true, true))
+						ident.kind = .function
+						ident.info = ast.IdentFn{
+							typ: fn_type
+						}
+						return fn_type
+					} else {
+						is_optional := typ.flag_is(.optional)
+						ident.kind = .variable
+						ident.info = ast.IdentVar{
+							typ: typ
+							is_optional: is_optional
+						}
+						it.typ = typ
+						// unwrap optional (`println(x)`)
+						if is_optional {
+							return typ.set_flag(.unset)
+						}
+						return typ
 					}
-					it.typ = typ
-					// unwrap optional (`println(x)`)
-					if is_optional {
-						return typ.set_flag(.unset)
-					}
-					return typ
 				}
 				else {}
 			}
 		}
-		// prepend mod to look for fn call or const
-		mut name := ident.name
-		if !name.contains('.') && ident.mod !in ['builtin', 'main'] {
-			name = '${ident.mod}.$ident.name'
-		}
 		if obj := c.file.global_scope.find(name) {
 			match obj {
 				ast.GlobalDecl {
@@ -1783,7 +1795,7 @@ pub fn (mut c Checker) ident(ident mut ast.Ident) table.Type {
 				else {}
 			}
 		}
-		// Function object (not a call), e.g. `onclick(my_click)`
+		// Non-anon-function object (not a call), e.g. `onclick(my_click)`
 		if func := c.table.find_fn(name) {
 			fn_type := table.new_type(c.table.find_or_register_fn_type(func, false, true))
 			ident.name = name
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 0dc0d26bf7..0062f9ad00 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -367,7 +367,8 @@ typedef struct {
 				sym := g.table.get_type_symbol(func.return_type)
 				is_multi := sym.kind == .multi_return
 				is_fn_sig := func.name == ''
-				if !info.has_decl && (!info.is_anon || is_fn_sig) && !is_multi {
+				not_anon := !info.is_anon
+				if !info.has_decl && !is_multi && (not_anon || is_fn_sig) {
 					fn_name := if func.is_c {
 						func.name.replace('.', '__')
 					} else if info.is_anon {
@@ -890,8 +891,8 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 					or_stmts = it.or_block.stmts
 					return_type = it.return_type
 				}
+				// TODO: no buffer fiddling
 				ast.AnonFn {
-					// TODO: no buffer fiddling
 					if blank_assign {
 						g.write('{')
 					}
@@ -908,6 +909,23 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 					}
 					continue
 				}
+				ast.Ident {
+					if it.info is ast.IdentFn {
+						thing := it.info as ast.IdentFn
+						sym := g.table.get_type_symbol(thing.typ)
+						info := sym.info as table.FnType
+						func := info.func
+						ret_styp := g.typ(func.return_type)
+						g.write('$ret_styp (*$ident.name) (')
+						def_pos := g.definitions.len
+						g.fn_args(func.args, func.is_variadic)
+						g.definitions.go_back(g.definitions.len - def_pos)
+						g.write(') = ')
+						g.expr(*it)
+						g.writeln(';')
+						continue
+					}
+				}
 				else {}
 			}
 			gen_or := is_call && return_type.flag_is(.optional)
diff --git a/vlib/v/tests/fn_high_test.v b/vlib/v/tests/fn_high_test.v
new file mode 100644
index 0000000000..e60c230c6e
--- /dev/null
+++ b/vlib/v/tests/fn_high_test.v
@@ -0,0 +1,147 @@
+// helper
+fn sqr(x int) int {
+	return x * x
+}
+
+fn high_fn(f fn(int) int) {
+	x := f(111)
+	println('x == $x')
+}
+
+fn high_fn_no_ret(f fn(int)) {
+	f(111)
+}
+
+fn high_fn_array(f fn(a []int) []int) {
+
+}
+
+fn high_fn_multi_return(a int, b fn (c []int, d []string) ([]int, []string)) {
+
+}
+
+fn high_fn_return_single_anon() (fn(int)f32) {
+	_ := 1
+	correct := fn(n int)f32 {
+		return n * n
+	}
+	return correct
+}
+fn high_fn_return_multi_anons() (fn(int)f32, fn(int)string) {
+	// parsing trap
+	_ := fn(n int)byte {
+		return 0x00
+	}
+	correct_second := fn(n int)string {
+		return '$n'
+	}
+	correct_first := fn(n int)f32 {
+		return n * n
+	}
+	// parsing trap
+	_ := fn(n int)[]int {
+		return [n]
+	}
+	return correct_first, correct_second
+}
+fn high_fn_return_named_fn() (fn(int)int) {
+	return sqr
+}
+fn test_high_fn_ret_anons() {
+	param := 13
+	func_sqr1 := high_fn_return_single_anon()
+	assert func_sqr1(param) == param * param
+
+	func_sqr2, func_repr := high_fn_return_multi_anons()
+	assert func_sqr2(param) == (param * param)
+	assert func_repr(param) == '$param'
+
+	top_lvl_sqr := high_fn_return_named_fn()
+	assert top_lvl_sqr(param) == param * param
+}
+
+fn high_fn_applier(arg int, func fn(a int)string) string {
+	return func(arg)
+}
+fn test_high_fn_applier() {
+	arg := 13
+	expect := '$arg $arg'
+	func := fn (arg int) string {
+		return '$arg $arg'
+	}
+	assert expect == high_fn_applier(arg, func)
+}
+
+fn test_fns() {
+	// no asserts for now, just test function declarations above
+	high_fn(sqr)
+}
+
+fn test_anon_fn() {
+	f1 := fn(a int){
+		println('hello from f1')
+	}
+	f1(1)
+
+	f2 := fn(a int) int {
+		println('hello from f2')
+		return 10
+	}
+	f2res := f2(1)
+	println('f2res == $f2res')
+	// TODO/FIXME: assert bug? uncomment to see
+	// assert f2res == 10
+
+	high_fn(fn (x int) int {
+		return x + 1
+	})
+
+	high_fn_no_ret(fn (x int) {
+		println('hello $x')
+	})
+}
+
+//
+// Test assigning functions (IdentFn)
+//
+
+fn simple_fn1() int {
+	return 1
+}
+
+fn simple_fn2(n f32) (int, string) {
+	return 1 + n, "fish"
+}
+
+fn test_assigning_fns() {
+	func1 := simple_fn1
+	assert func1() == 1
+
+	func2 := simple_fn2
+	res2_1, res2_2 := func2(13.0)
+	assert res2_1 == 14.0
+	assert res2_2 == "fish"
+
+	anon_func1 := fn(s string)int {
+		return s.len
+	}
+	func3 := anon_func1
+	res3 := func3("fish")
+	assert res3 == 4
+}
+
+//
+// End assigning functions (IdentFn)
+//
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/vlib/v/tests/fn_test.v b/vlib/v/tests/fn_test.v
index 1ee3ea0b2e..d1312e5a2f 100644
--- a/vlib/v/tests/fn_test.v
+++ b/vlib/v/tests/fn_test.v
@@ -111,107 +111,6 @@ fn test_mut_ptr() {
 	assert buf[0] == 77
 }
 
-fn high_fn(f fn(int) int) {
-	x := f(111)
-	println('x == $x')
-}
-
-fn high_fn_no_ret(f fn(int)) {
-	f(111)
-}
-
-fn high_fn_array(f fn(a []int) []int) {
-
-}
-
-fn high_fn_multi_return(a int, b fn (c []int, d []string) ([]int, []string)) {
-
-}
-
-fn high_fn_return_single_anon() (fn(int)f32) {
-	_ := 1
-	correct := fn(n int)f32 {
-		return n * n
-	}
-	return correct
-}
-fn high_fn_return_multi_anons() (fn(int)f32, fn(int)string) {
-	// parsing trap
-	_ := fn(n int)byte {
-		return 0x00
-	}
-	correct_second := fn(n int)string {
-		return '$n'
-	}
-	correct_first := fn(n int)f32 {
-		return n * n
-	}
-	// parsing trap
-	_ := fn(n int)[]int {
-		return [n]
-	}
-	return correct_first, correct_second
-}
-fn high_fn_return_named_fn() (fn(int)int) {
-	return sqr
-}
-fn test_high_fn_ret_anons() {
-	param := 13
-	func_sqr1 := high_fn_return_single_anon()
-	assert func_sqr1(param) == param * param
-
-	func_sqr2, func_repr := high_fn_return_multi_anons()
-	assert func_sqr2(param) == (param * param)
-	assert func_repr(param) == '$param'
-
-	top_lvl_sqr := high_fn_return_named_fn()
-	assert top_lvl_sqr(param) == param * param
-}
-
-fn high_fn_applier(arg int, func fn(a int)string) string {
-	return func(arg)
-}
-fn test_high_fn_applier() {
-	arg := 13
-	expect := '$arg $arg'
-	func := fn (arg int) string {
-		return '$arg $arg'
-	}
-	assert expect == high_fn_applier(arg, func)
-}
-
-fn sqr(x int) int {
-	return x * x
-}
-
-fn test_fns() {
-	// no asserts for now, just test function declarations above
-	high_fn(sqr)
-}
-
-fn test_anon_fn() {
-	f1 := fn(a int){
-		println('hello from f1')
-	}
-	f1(1)
-
-	f2 := fn(a int) int {
-		println('hello from f2')
-		return 10
-	}
-	f2res := f2(1)
-	println('f2res == $f2res')
-	// TODO/FIXME: assert bug? uncomment to see
-	// assert f2res == 10
-
-	high_fn(fn (x int) int {
-		return x + 1
-	})
-
-	high_fn_no_ret(fn (x int) {
-		println('hello $x')
-	})
-}
 
 fn assert_in_bool_fn(v int) bool {
 	assert v < 3