gen: basic initial work on the Go backend

cmd/tools/builders/golang_builder.v

@@ -0,0 +1,7 @@
+module main
+
+import v.builder.golangbuilder
+
+fn main() {
+	golangbuilder.start()
+}

cmd/v/v.v

@@ -176,5 +176,9 @@ fn rebuild(prefs &pref.Preferences) {
 		.interpret {
 			util.launch_tool(prefs.is_verbose, 'builders/interpret_builder', os.args[1..])
 		}
+		.golang {
+			println('using Go WIP backend...')
+			util.launch_tool(prefs.is_verbose, 'builders/golang_builder', os.args[1..])
+		}
 	}
 }

vlib/v/builder/golangbuilder/golangbuilder.v

@@ -0,0 +1,41 @@
+module golangbuilder
+
+import os
+import v.pref
+import v.util
+import v.builder
+import v.gen.golang
+
+pub fn start() {
+	mut args_and_flags := util.join_env_vflags_and_os_args()[1..]
+	prefs, _ := pref.parse_args([], args_and_flags)
+	builder.compile('build', prefs, compile_golang)
+}
+
+pub fn compile_golang(mut b builder.Builder) {
+	// v.files << v.v_files_from_dir(os.join_path(v.pref.vlib_path,'builtin','bare'))
+	files := [b.pref.path]
+	b.set_module_lookup_paths()
+	build_golang(mut b, files, b.pref.out_name)
+}
+
+pub fn build_golang(mut b builder.Builder, v_files []string, out_file string) {
+	if b.pref.os == .windows {
+		if !b.pref.is_shared && b.pref.build_mode != .build_module
+			&& !b.pref.out_name.ends_with('.exe') {
+			b.pref.out_name += '.exe'
+		}
+	}
+	mut nvf := []string{}
+	for vf in v_files {
+		if os.is_dir(vf) {
+			nvf << b.v_files_from_dir(vf)
+		} else {
+			nvf << vf
+		}
+	}
+	b.front_and_middle_stages(nvf) or { return }
+	util.timing_start('Golang GEN')
+	b.stats_lines, b.stats_bytes = golang.gen(b.parsed_files, b.table, out_file, b.pref)
+	util.timing_measure('Golang GEN')
+}

vlib/v/checker/checker.v

@@ -1765,12 +1765,12 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 	if c.ct_cond_stack.len > 0 {
 		node.ct_conds = c.ct_cond_stack.clone()
 	}
-	if c.pref.backend.is_js() {
-		if !c.file.path.ends_with('.js.v') {
-			c.error('hash statements are only allowed in backend specific files such "x.js.v"',
+	if c.pref.backend.is_js() || c.pref.backend == .golang {
+		if !c.file.path.ends_with('.js.v') && !c.file.path.ends_with('.go.v') {
+			c.error('hash statements are only allowed in backend specific files such "x.js.v" and "x.go.v"',
 				node.pos)
 		}
-		if c.mod == 'main' {
+		if c.mod == 'main' && c.pref.backend != .golang {
 			c.error('hash statements are not allowed in the main module. Place them in a separate module.',
 				node.pos)
 		}

vlib/v/gen/golang/align.v

@@ -0,0 +1,59 @@
+// Copyright (c) 2019-2022 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 golang
+
+import v.mathutil
+
+const struct_field_align_threshold = 8
+
+struct AlignInfo {
+mut:
+	line_nr      int
+	max_len      int
+	max_type_len int
+}
+
+/*
+[params]
+struct AddInfoConfig {
+	use_threshold bool
+}
+
+fn (mut infos []AlignInfo) add_new_info(len int, type_len int, line int) {
+	infos << AlignInfo{
+		line_nr: line
+		max_len: len
+		max_type_len: type_len
+	}
+}
+
+[direct_array_access]
+fn (mut infos []AlignInfo) add_info(len int, type_len int, line int, cfg AddInfoConfig) {
+	if infos.len == 0 {
+		infos.add_new_info(len, type_len, line)
+		return
+	}
+	i := infos.len - 1
+	if line - infos[i].line_nr > 1 {
+		infos.add_new_info(len, type_len, line)
+		return
+	}
+	if cfg.use_threshold {
+		len_diff := mathutil.abs(infos[i].max_len - len) +
+			mathutil.abs(infos[i].max_type_len - type_len)
+
+		if len_diff >= fmt.struct_field_align_threshold {
+			infos.add_new_info(len, type_len, line)
+			return
+		}
+	}
+	infos[i].line_nr = line
+	if len > infos[i].max_len {
+		infos[i].max_len = len
+	}
+	if type_len > infos[i].max_type_len {
+		infos[i].max_type_len = type_len
+	}
+}
+*/

vlib/v/gen/golang/attrs.v

@@ -0,0 +1,64 @@
+// Copyright (c) 2019-2022 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 golang
+
+import v.ast
+
+pub fn (mut f Gen) attrs(attrs []ast.Attr) {
+	mut sorted_attrs := attrs.clone()
+	// Sort the attributes. The ones with arguments come first
+	sorted_attrs.sort_with_compare(fn (a &ast.Attr, b &ast.Attr) int {
+		d := b.arg.len - a.arg.len
+		return if d != 0 { d } else { compare_strings(b.arg, a.arg) }
+	})
+	for i, attr in sorted_attrs {
+		if attr.arg.len == 0 {
+			f.single_line_attrs(sorted_attrs[i..])
+			break
+		}
+		f.writeln('[$attr]')
+	}
+}
+
+[params]
+pub struct AttrsOptions {
+	inline bool
+}
+
+pub fn (mut f Gen) single_line_attrs(attrs []ast.Attr, options AttrsOptions) {
+	if attrs.len == 0 {
+		return
+	}
+	mut sorted_attrs := attrs.clone()
+	sorted_attrs.sort(a.name < b.name)
+	if options.inline {
+		f.write(' ')
+	}
+	f.write('[')
+	for i, attr in sorted_attrs {
+		if i > 0 {
+			f.write('; ')
+		}
+		f.write('$attr')
+	}
+	f.write(']')
+	if !options.inline {
+		f.writeln('')
+	}
+}
+
+fn inline_attrs_len(attrs []ast.Attr) int {
+	if attrs.len == 0 {
+		return 0
+	}
+	mut n := 2 // ' ['.len
+	for i, attr in attrs {
+		if i > 0 {
+			n += 2 // '; '.len
+		}
+		n += '$attr'.len
+	}
+	n++ // ']'.len
+	return n
+}

vlib/v/gen/golang/comments.v

@@ -0,0 +1,142 @@
+// Copyright (c) 2019-2022 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 golang
+
+import v.ast
+
+pub enum CommentsLevel {
+	keep
+	indent
+}
+
+// CommentsOptions defines the way comments are going to be written
+// - has_nl: adds an newline at the end of a list of comments
+// - inline: line comments will be on the same line as the last statement
+// - level:  either .keep (don't indent), or .indent (increment indentation)
+// - iembed: a /* ... */ block comment used inside expressions; // comments the whole line
+// - prev_line: the line number of the previous token to save linebreaks
+[minify; params]
+pub struct CommentsOptions {
+	has_nl    bool = true
+	inline    bool
+	level     CommentsLevel
+	iembed    bool
+	prev_line int = -1
+}
+
+pub fn (mut f Gen) comment(node ast.Comment, options CommentsOptions) {
+	// Shebang in .vsh files
+	if node.text.starts_with('#!') {
+		f.writeln(node.text)
+		return
+	}
+	if options.level == .indent {
+		f.indent++
+	}
+	if options.iembed {
+		x := node.text.trim_left('\x01').trim_space()
+		if x.contains('\n') {
+			f.writeln('/*')
+			f.writeln(x)
+			f.write('*/')
+		} else {
+			f.write('/* $x */')
+		}
+	} else if !node.text.contains('\n') {
+		is_separate_line := !options.inline || node.text.starts_with('\x01')
+		mut s := node.text.trim_left('\x01').trim_right(' ')
+		mut out_s := '//'
+		if s != '' {
+			if is_char_alphanumeric(s[0]) {
+				out_s += ' '
+			}
+			out_s += s
+		}
+		if !is_separate_line && f.indent > 0 {
+			f.remove_new_line() // delete the generated \n
+			f.write(' ')
+		}
+		f.write(out_s)
+	} else {
+		lines := node.text.trim_space().split_into_lines()
+		start_break := is_char_alphanumeric(node.text[0]) || node.text[0].is_space()
+		end_break := is_char_alphanumeric(node.text.trim('\t').bytes().last())
+			|| node.text.bytes().last().is_space()
+		f.write('/*')
+		if start_break {
+			f.writeln('')
+		}
+		for line in lines {
+			f.writeln(line.trim_right(' '))
+			f.empty_line = false
+		}
+		if end_break {
+			f.empty_line = true
+		} else {
+			f.remove_new_line()
+		}
+		f.write('*/')
+	}
+	if options.level == .indent {
+		f.indent--
+	}
+}
+
+pub fn (mut f Gen) comments(comments []ast.Comment, options CommentsOptions) {
+	mut prev_line := options.prev_line
+	for i, c in comments {
+		if options.prev_line > -1 && ((c.pos.line_nr > prev_line && f.out.last_n(1) != '\n')
+			|| (c.pos.line_nr > prev_line + 1 && f.out.last_n(2) != '\n\n')) {
+			f.writeln('')
+		}
+		if !f.out.last_n(1)[0].is_space() {
+			f.write(' ')
+		}
+		f.comment(c, options)
+		if !options.iembed && (i < comments.len - 1 || options.has_nl) {
+			f.writeln('')
+		}
+		prev_line = c.pos.last_line
+	}
+}
+
+pub fn (mut f Gen) comments_before_field(comments []ast.Comment) {
+	// They behave the same as comments after the last field. This alias is just for clarity.
+	f.comments_after_last_field(comments)
+}
+
+pub fn (mut f Gen) comments_after_last_field(comments []ast.Comment) {
+	for comment in comments {
+		f.indent++
+		f.empty_line = true
+		f.comment(comment, inline: true)
+		f.writeln('')
+		f.indent--
+	}
+}
+
+pub fn (mut f Gen) import_comments(comments []ast.Comment, options CommentsOptions) {
+	if comments.len == 0 {
+		return
+	}
+	if options.inline {
+		f.remove_new_line(imports_buffer: true)
+	}
+	for c in comments {
+		ctext := c.text.trim_left('\x01')
+		if ctext == '' {
+			continue
+		}
+		mut out_s := if options.inline { ' ' } else { '' } + '//'
+		if is_char_alphanumeric(ctext[0]) {
+			out_s += ' '
+		}
+		out_s += ctext
+		f.out_imports.writeln(out_s)
+	}
+}
+
+fn is_char_alphanumeric(c u8) bool {
+	return c.is_letter() || c.is_digit()
+}

vlib/v/gen/golang/struct.v

@@ -0,0 +1,283 @@
+// Copyright (c) 2019-2022 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 golang
+
+import strings
+import v.ast
+import v.mathutil as mu
+
+pub fn (mut f Gen) struct_decl(node ast.StructDecl) {
+	f.attrs(node.attrs)
+	f.write('type ')
+	if node.is_pub {
+		f.write('pub ')
+	}
+	f.write_language_prefix(node.language)
+	name := node.name.after('.') // strip prepended module
+	f.write(name)
+	if node.is_union {
+		f.write('union ')
+	} else {
+		f.write(' struct ')
+	}
+	f.write_generic_types(node.generic_types)
+	if node.fields.len == 0 && node.embeds.len == 0 && node.pos.line_nr == node.pos.last_line {
+		f.writeln(' {}')
+		return
+	}
+	mut field_aligns := []AlignInfo{}
+	mut comment_aligns := []AlignInfo{}
+	mut default_expr_aligns := []AlignInfo{}
+	mut field_types := []string{cap: node.fields.len}
+	for i, field in node.fields {
+		ft := f.no_cur_mod(f.table.type_to_str_using_aliases(field.typ, f.mod2alias))
+		field_types << ft
+		attrs_len := inline_attrs_len(field.attrs)
+		end_pos := field.pos.pos + field.pos.len
+		mut comments_len := 0 // Length of comments between field name and type
+		// field_aligns.add_info(comments_len + field.name.len, ft.len, field.pos.line_nr)
+		if field.has_default_expr {
+			// default_expr_aligns.add_info(attrs_len, field_types[i].len, field.pos.line_nr,
+			// use_threshold: true)
+		}
+	}
+	f.writeln(' {')
+	for embed in node.embeds {
+		f.mark_types_import_as_used(embed.typ)
+		styp := f.table.type_to_str_using_aliases(embed.typ, f.mod2alias)
+
+		pre_comments := embed.comments.filter(it.pos.pos < embed.pos.pos)
+		comments := embed.comments[pre_comments.len..]
+
+		f.comments_before_field(pre_comments)
+		if comments.len == 0 {
+			f.writeln('\t$styp')
+		} else {
+			f.write('\t$styp')
+			f.comments(comments, level: .indent)
+		}
+	}
+	mut field_align_i := 0
+	mut comment_align_i := 0
+	mut default_expr_align_i := 0
+	mut inc_indent := false // for correct indents with multi line default exprs
+	for i, field in node.fields {
+		if i == node.mut_pos {
+			f.writeln('mut:')
+		} else if i == node.pub_pos {
+			f.writeln('pub:')
+		} else if i == node.pub_mut_pos {
+			f.writeln('pub mut:')
+		} else if i == node.global_pos {
+			f.writeln('__global:')
+		} else if i == node.module_pos {
+			f.writeln('module:')
+		} else if i > 0 {
+			// keep one empty line between fields (exclude one after mut:, pub:, ...)
+			mut before_last_line := node.fields[i - 1].pos.line_nr
+			if node.fields[i - 1].comments.len > 0 {
+				before_last_line = mu.max(before_last_line, node.fields[i - 1].comments.last().pos.last_line)
+			}
+			if node.fields[i - 1].has_default_expr {
+				before_last_line = mu.max(before_last_line, node.fields[i - 1].default_expr.pos().last_line)
+			}
+
+			mut next_first_line := field.pos.line_nr
+			if field.comments.len > 0 {
+				next_first_line = mu.min(next_first_line, field.comments[0].pos.line_nr)
+			}
+			if next_first_line - before_last_line > 1 {
+				f.writeln('')
+			}
+		}
+		end_pos := field.pos.pos + field.pos.len
+		before_comments := field.comments.filter(it.pos.pos < field.pos.pos)
+		between_comments := field.comments[before_comments.len..].filter(it.pos.pos < end_pos)
+		after_type_comments := field.comments[(before_comments.len + between_comments.len)..]
+		// Handle comments before the field
+		f.comments_before_field(before_comments)
+		volatile_prefix := if field.is_volatile { 'volatile ' } else { '' }
+		f.write('\t$volatile_prefix$field.name ')
+		// Handle comments between field name and type
+		before_len := f.line_len
+		f.comments(between_comments, iembed: true, has_nl: false)
+		comments_len := f.line_len - before_len
+		// mut field_align := field_aligns[field_align_i]
+		// if field_align.line_nr < field.pos.line_nr {
+		// field_align_i++
+		// field_align = field_aligns[field_align_i]
+		//}
+		// f.write(strings.repeat(` `, field_align.max_len - field.name.len - comments_len))
+		f.write(field_types[i])
+		f.mark_types_import_as_used(field.typ)
+		attrs_len := inline_attrs_len(field.attrs)
+		has_attrs := field.attrs.len > 0
+		if has_attrs {
+			// f.write(strings.repeat(` `, field_align.max_type_len - field_types[i].len))
+			f.single_line_attrs(field.attrs, inline: true)
+		}
+		if field.has_default_expr {
+			mut align := default_expr_aligns[default_expr_align_i]
+			if align.line_nr < field.pos.line_nr {
+				default_expr_align_i++
+				align = default_expr_aligns[default_expr_align_i]
+			}
+			pad_len := align.max_len - attrs_len + align.max_type_len - field_types[i].len
+			f.write(strings.repeat(` `, pad_len))
+			f.write(' = ')
+			if !expr_is_single_line(field.default_expr) {
+				f.indent++
+				inc_indent = true
+			}
+			f.expr(field.default_expr)
+			if inc_indent {
+				f.indent--
+				inc_indent = false
+			}
+		}
+		// Handle comments after field type
+		if after_type_comments.len > 0 {
+			if after_type_comments[0].pos.line_nr > field.pos.line_nr {
+				f.writeln('')
+			} else {
+				if !field.has_default_expr {
+					mut align := comment_aligns[comment_align_i]
+					if align.line_nr < field.pos.line_nr {
+						comment_align_i++
+						align = comment_aligns[comment_align_i]
+					}
+					pad_len := align.max_len - attrs_len + align.max_type_len - field_types[i].len
+					f.write(strings.repeat(` `, pad_len))
+				}
+				f.write(' ')
+			}
+			f.comments(after_type_comments, level: .indent)
+		} else {
+			f.writeln('')
+		}
+	}
+	f.comments_after_last_field(node.end_comments)
+	f.writeln('}\n')
+}
+
+pub fn (mut f Gen) struct_init(node ast.StructInit) {
+	struct_init_save := f.is_struct_init
+	f.is_struct_init = true
+	defer {
+		f.is_struct_init = struct_init_save
+	}
+
+	type_sym := f.table.sym(node.typ)
+	// f.write('<old name: $type_sym.name>')
+	mut name := type_sym.name
+	if !name.starts_with('C.') && !name.starts_with('JS.') {
+		name = f.no_cur_mod(f.short_module(type_sym.name)) // TODO f.type_to_str?
+	}
+	if name == 'void' {
+		name = ''
+	}
+	if node.fields.len == 0 && !node.has_update_expr {
+		// `Foo{}` on one line if there are no fields or comments
+		if node.pre_comments.len == 0 {
+			f.write('$name{}')
+		} else {
+			f.writeln('$name{')
+			f.comments(node.pre_comments, inline: true, has_nl: true, level: .indent)
+			f.write('}')
+		}
+		f.mark_import_as_used(name)
+	} else if node.is_short {
+		// `Foo{1,2,3}` (short syntax )
+		f.write('$name{')
+		f.mark_import_as_used(name)
+		if node.has_update_expr {
+			f.write('...')
+			f.expr(node.update_expr)
+			f.write(', ')
+		}
+		for i, field in node.fields {
+			f.expr(field.expr)
+			if i < node.fields.len - 1 {
+				f.write(', ')
+			}
+		}
+		f.write('}')
+	} else {
+		use_short_args := f.use_short_fn_args && !node.has_update_expr
+		f.use_short_fn_args = false
+		mut single_line_fields := f.single_line_fields
+		f.single_line_fields = false
+		if node.pos.line_nr < node.pos.last_line || node.pre_comments.len > 0 {
+			single_line_fields = false
+		}
+		if !use_short_args {
+			f.write('$name{')
+			f.mark_import_as_used(name)
+			if single_line_fields {
+				f.write(' ')
+			}
+		}
+		fields_start := f.out.len
+		fields_loop: for {
+			if !single_line_fields {
+				if use_short_args && f.out[f.out.len - 1] == ` ` {
+					//           v Remove space at tail of line
+					// f(a, b, c, \n
+					//     f1: 0\n
+					//     f2: 1\n
+					// )
+					f.out.go_back(1)
+				}
+				f.writeln('')
+				f.indent++
+			}
+			f.comments(node.pre_comments, inline: true, has_nl: true, level: .keep)
+			if node.has_update_expr {
+				f.write('...')
+				f.expr(node.update_expr)
+				if single_line_fields {
+					if node.fields.len > 0 {
+						f.write(', ')
+					}
+				} else {
+					f.writeln('')
+				}
+				f.comments(node.update_expr_comments, inline: true, has_nl: true, level: .keep)
+			}
+			for i, field in node.fields {
+				f.write('$field.name: ')
+				f.expr(field.expr)
+				f.comments(field.comments, inline: true, has_nl: false, level: .indent)
+				if single_line_fields {
+					if i < node.fields.len - 1 {
+						f.write(', ')
+					}
+				} else {
+					f.writeln('')
+				}
+				f.comments(field.next_comments, inline: false, has_nl: true, level: .keep)
+				if single_line_fields && (field.comments.len > 0
+					|| field.next_comments.len > 0
+					|| !expr_is_single_line(field.expr)
+					|| f.line_len > max_len.last()) {
+					single_line_fields = false
+					f.out.go_back_to(fields_start)
+					f.line_len = fields_start
+					f.remove_new_line()
+					continue fields_loop
+				}
+			}
+			break
+		}
+		if !single_line_fields {
+			f.indent--
+		}
+		if !use_short_args {
+			if single_line_fields {
+				f.write(' ')
+			}
+			f.write('}')
+		}
+	}
+}

vlib/v/gen/golang/tests/simple.vv

@@ -0,0 +1,43 @@
+module main
+
+#import "fmt"
+
+//fn println(x any){
+fn println(x string){
+#fmt.Println(x)
+}
+
+struct Foo {
+	x int
+	s string
+}
+
+fn is_prime(x int) bool {
+	for i := 2; i <= x/2; i++ {
+		if x % i == 0 {
+			return false
+		}
+	}
+
+	return true
+}
+
+fn main() {
+	x := 10
+	if x % 2 == 0 {
+		println('even')
+	}
+	//println(x.str())
+	println('hello world!')
+	
+	foo := Foo{}
+	q := foo.x
+	_ = q
+	w := q>2 && 3<q
+	_ = w
+
+	numbers := [1,2,3]
+	for number in numbers {
+		_ = number
+	}
+}

vlib/v/gen/golang/tests/simple.vv.out

@@ -0,0 +1,2 @@
+even
+hello world!

vlib/v/pref/pref.v

@@ -51,6 +51,7 @@ pub enum Backend {
 	js_freestanding // The JavaScript freestanding backend
 	native // The Native backend
 	interpret // Interpret the ast
+	golang // Go backend
 }
 
 pub fn (b Backend) is_js() bool {
@@ -921,6 +922,7 @@ pub fn backend_from_string(s string) ?Backend {
 	match s {
 		'c' { return .c }
 		'js' { return .js_node }
+		'go' { return .golang }
 		'js_node' { return .js_node }
 		'js_browser' { return .js_browser }
 		'js_freestanding' { return .js_freestanding }