cgen: optionals

vlib/v/ast/ast.v

@@ -247,6 +247,7 @@ pub mut:
 	typ         table.Type
 	is_mut      bool
 	is_static   bool
+	is_optional bool
 }
 
 pub type IdentInfo = IdentFn | IdentVar

vlib/v/checker/checker.v

@@ -733,6 +733,7 @@ pub fn (c mut Checker) ident(ident mut ast.Ident) table.Type {
 			ident.kind = .variable
 			ident.info = ast.IdentVar{
 				typ: typ
+				is_optional: table.type_is_optional(typ)
 			}
 			return typ
 		}

vlib/v/gen/cgen.v

@@ -51,7 +51,7 @@ pub fn (g mut Gen) init() {
 }
 
 // V type to C type
-pub fn (g &Gen) typ(t table.Type) string {
+pub fn (g mut Gen) typ(t table.Type) string {
 	nr_muls := table.type_nr_muls(t)
 	sym := g.table.get_type_symbol(t)
 	mut styp := sym.name.replace_each(['.', '__'])
@@ -65,6 +65,10 @@ pub fn (g &Gen) typ(t table.Type) string {
 		// TODO perf and other C structs
 		styp = 'struct stat'
 	}
+	if table.type_is_optional(t) {
+		styp = 'Option_' + styp
+		g.definitions.writeln('typedef Option $styp;')
+	}
 	return styp
 }
 
@@ -264,26 +268,7 @@ fn (g mut Gen) stmt(node ast.Stmt) {
 		}
 		ast.Import {}
 		ast.Return {
-			g.write('return')
-			// multiple returns
-			if it.exprs.len > 1 {
-				styp := g.typ(g.fn_decl.return_type)
-				g.write(' ($styp){')
-				for i, expr in it.exprs {
-					g.write('.arg$i=')
-					g.expr(expr)
-					if i < it.exprs.len - 1 {
-						g.write(',')
-					}
-				}
-				g.write('}')
-			}
-			// normal return
-			else if it.exprs.len == 1 {
-				g.write(' ')
-				g.expr(it.exprs[0])
-			}
-			g.writeln(';')
+			g.return_statement(it)
 		}
 		ast.StructDecl {
 			name := it.name.replace('.', '__')
@@ -621,13 +606,7 @@ fn (g mut Gen) expr(node ast.Expr) {
 			g.write(it.val)
 		}
 		ast.Ident {
-			name := it.name.replace('.', '__')
-			if name.starts_with('C__') {
-				g.write(name[3..])
-			}
-			else {
-				g.write(name)
-			}
+			g.ident(it)
 		}
 		ast.IfExpr {
 			// If expression? Assign the value to a temp var.
@@ -798,7 +777,7 @@ fn (g mut Gen) expr(node ast.Expr) {
 			g.write(')')
 		}
 		ast.None {
-			g.write('0')
+			g.write('opt_none()')
 		}
 		ast.ParExpr {
 			g.write('(')
@@ -965,6 +944,27 @@ fn (g mut Gen) infix_expr(node ast.InfixExpr) {
 	}
 }
 
+fn (g mut Gen) ident(node ast.Ident) {
+	name := node.name.replace('.', '__')
+	if name.starts_with('C__') {
+		g.write(name[3..])
+	}
+	else {
+		// TODO `is`
+		match node.info {
+			ast.IdentVar {
+				if it.is_optional {
+					styp := g.typ(it.typ)[7..] // Option_int => int TODO perf?
+					g.write('(*($styp*)${name}.data)')
+					return
+				}
+			}
+			else {}
+	}
+		g.write(name)
+	}
+}
+
 fn (g mut Gen) index_expr(node ast.IndexExpr) {
 	// TODO else doesn't work with sum types
 	mut is_range := false
@@ -1041,6 +1041,51 @@ fn (g mut Gen) index_expr(node ast.IndexExpr) {
 	}
 }
 
+fn (g mut Gen) return_statement(it ast.Return) {
+	g.write('return')
+	// multiple returns
+	if it.exprs.len > 1 {
+		styp := g.typ(g.fn_decl.return_type)
+		g.write(' ($styp){')
+		for i, expr in it.exprs {
+			g.write('.arg$i=')
+			g.expr(expr)
+			if i < it.exprs.len - 1 {
+				g.write(',')
+			}
+		}
+		g.write('}')
+	}
+	// normal return
+	else if it.exprs.len == 1 {
+		g.write(' ')
+		// `return opt_ok(expr)` for functions that expect an optional
+		if table.type_is_optional(g.fn_decl.return_type) {
+			mut is_none := false
+			mut is_error := false
+			match it.exprs[0] {
+				ast.None {
+					is_none = true
+				}
+				ast.CallExpr {
+					is_error = true // TODO check name 'error'
+				}
+				else {}
+	}
+			if !is_none && !is_error {
+				g.write('opt_ok(')
+				g.expr(it.exprs[0])
+				styp := g.typ(g.fn_decl.return_type)[7..] // remove 'Option_'
+				g.writeln(', sizeof($styp));')
+				return
+			}
+			// g.write('/*OPTIONAL*/')
+		}
+		g.expr(it.exprs[0])
+	}
+	g.writeln(';')
+}
+
 fn (g mut Gen) const_decl(node ast.ConstDecl) {
 	for i, field in node.fields {
 		name := field.name.replace('.', '__')

vlib/v/table/atype_symbols.v

@@ -1,5 +0,0 @@
-// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
-// Use of this source code is governed by an MIT license
-// that can be found in the LICENSE file.
-module table
-

vlib/v/table/modules.v

@@ -1,18 +0,0 @@
-module table
-
-import os
-
-// Once we have a module format we can read from module file instead
-// this is not optimal
-pub fn (table &Table) qualify_module(mod string, file_path string) string {
-	for m in table.imports {
-		if m.contains('.') && m.contains(mod) {
-			m_parts := m.split('.')
-			m_path := m_parts.join(os.path_separator)
-			if mod == m_parts[m_parts.len - 1] && file_path.contains(m_path) {
-				return m
-			}
-		}
-	}
-	return mod
-}

vlib/v/table/table.v

@@ -5,6 +5,7 @@ module table
 
 import (
 	strings
+	os
 )
 
 pub struct Table {
@@ -494,3 +495,18 @@ pub fn (t &Table) check(got, expected Type) bool {
 	}
 	return true
 }
+
+// Once we have a module format we can read from module file instead
+// this is not optimal
+pub fn (table &Table) qualify_module(mod string, file_path string) string {
+	for m in table.imports {
+		if m.contains('.') && m.contains(mod) {
+			m_parts := m.split('.')
+			m_path := m_parts.join(os.path_separator)
+			if mod == m_parts[m_parts.len - 1] && file_path.contains(m_path) {
+				return m
+			}
+		}
+	}
+	return mod
+}