From bd49977feb360bdee5452b81ec6bb0270981b43c Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Fri, 28 Jun 2019 12:41:09 +0200
Subject: [PATCH] fix single file programs without `fn main` and REPL (allow
 imports, function definitions, consts, etc)

---
 compiler/fn.v          |  2 +-
 compiler/main.v        |  9 ++++-----
 compiler/parser.v      | 38 +++++++++++++++++++++-----------------
 compiler/table.v       |  7 +++----
 examples/hello_world.v |  3 ++-
 5 files changed, 31 insertions(+), 28 deletions(-)

diff --git a/compiler/fn.v b/compiler/fn.v
index da86dc7dae..22e1ad27e0 100644
--- a/compiler/fn.v
+++ b/compiler/fn.v
@@ -84,8 +84,8 @@ fn (f mut Fn) register_var(v Var) {
 	}
 	else {
 		f.local_vars[f.var_idx] = new_var
-		f.var_idx++
 	}
+	f.var_idx++
 }
 
 // vlib header file?
diff --git a/compiler/main.v b/compiler/main.v
index 22d0de8c7d..c787725313 100644
--- a/compiler/main.v
+++ b/compiler/main.v
@@ -343,7 +343,7 @@ string _STR_TMP(const char *fmt, ...) {
 		if !c.table.main_exists() && !c.is_test {
 			// It can be skipped in single file programs
 			if c.is_script {
-				println('Generating main()...')
+				//println('Generating main()...')
 				cgen.genln('int main() { $cgen.fn_main; return 0; }')
 			}
 			else {
@@ -372,14 +372,14 @@ string _STR_TMP(const char *fmt, ...) {
 		cgen.genln('return 1; }')
 	}
 	cgen.save()
-	c.log('flags=')
 	if c.is_verbose {
+		c.log('flags=')
 		println(c.table.flags)
 	}
 	c.cc()
 	if c.is_test || c.is_run {
 		if true || c.is_verbose {
-			println('============running $c.out_name==============================')
+			println('============ running $c.out_name ============') 
 		}
 		mut cmd := if c.out_name.starts_with('/') {
 			c.out_name
@@ -866,10 +866,9 @@ fn run_repl() []string {
 		// but don't add this print call to the `lines` array,
 		// so that it doesn't get called during the next print.
 		if line.starts_with('print') {
-			// TODO remove this once files without main compile correctly
 			void_line := line.substr(line.index('(') + 1, line.len - 1)
 			lines << void_line
-			source_code := 'fn main(){' + lines.join('\n') + '\n' + line + '}'
+			source_code := lines.join('\n') + '\n' + line 
 			os.write_file(file, source_code)
 			mut v := new_v( ['v', '-repl', file])
 			v.compile()
diff --git a/compiler/parser.v b/compiler/parser.v
index 8ec039c664..ec959e72fa 100644
--- a/compiler/parser.v
+++ b/compiler/parser.v
@@ -77,6 +77,7 @@ mut:
 
 const (
 	EmptyFn = &Fn { }
+	MainFn= &Fn{name:'main'} 
 )
 
 fn (c mut V) new_parser(path string, run Pass) Parser {
@@ -225,7 +226,7 @@ fn (p mut Parser) parse() {
 				g += p.cgen.end_tmp()
 			}
 			// p.genln('; // global')
-			g += ('; // global')
+			g += '; // global' 
 			p.cgen.consts << g
 		case EOF:
 			p.log('end of parse()')
@@ -238,25 +239,29 @@ fn (p mut Parser) parse() {
 		default:
 			// no `fn main`, add this "global" statement to cgen.fn_main
 			if p.is_script && !p.is_test {
-				if p.cur_fn.scope_level == 0 {
-					// p.cur_fn.scope_level++
-				}
-				// println('is script')
-				p.print_tok()
+				// cur_fn is empty since there was no fn main declared
+				// we need to set it to save and find variables 
+				if p.first_run() {
+					if p.cur_fn.name == '' {
+						p.cur_fn = MainFn 
+					} 
+					return 
+				} 
+				if p.cur_fn.name == '' {
+					p.cur_fn = MainFn 
+				} 
 				start := p.cgen.lines.len
 				p.statement(true)
+				p.genln('') 
 				end := p.cgen.lines.len
 				lines := p.cgen.lines.slice(start, end)
-				// p.cgen.fn_main << p.cgen.prev_line
-				// println('fn line:')
-				// println(p.cgen.fn_main + lines.join('\n'))
+				//mut line := p.cgen.fn_main + lines.join('\n') 
+				//line = line.trim_space() 
 				p.cgen.fn_main = p.cgen.fn_main + lines.join('\n')
 				p.cgen.cur_line = ''
 				for i := start; i < end; i++ {
-					// p.cgen.lines[p.cgen.lines.len - 1] = ''
 					p.cgen.lines[i] = ''
 				}
-				// exit('')
 			}
 			else {
 				p.error('unexpected token `${p.strtok()}`')
@@ -664,13 +669,14 @@ fn (p mut Parser) error(s string) {
 	p.cgen.save()
 	// V git pull hint
 	cur_path := os.getwd()
-	if p.file_path.contains('v/compiler') || cur_path.contains('v/compiler') {
+	if !p.is_repl && ( p.file_path.contains('v/compiler') || cur_path.contains('v/compiler') ){
 		println('\n=========================')
 		println('It looks like you are building V. It is being frequently updated every day.') 
 		println('If you didn\'t modify the compiler\'s code, most likely there was a change that ')
 		println('lead to this error.')
-		println('\nTry to run `git pull && make clean && make`, that will most likely fix it.')
-		println('\nIf this doesn\'t help, re-install V from source or download a precompiled' + ' binary from\nhttps://vlang.io.')
+		println('\nRun `git pull && make`, that will most likely fix it.')
+		//println('\nIf this doesn\'t help, re-install V from source or download a precompiled' + ' binary from\nhttps://vlang.io.')
+		println('\nIf this doesn\'t help, please create a GitHub issue.')
 		println('=========================\n')
 	}
 	// p.scanner.debug_tokens()
@@ -1349,9 +1355,7 @@ fn (p mut Parser) name_expr() string {
 	// Function (not method btw, methods are handled in dot())
 	f := p.table.find_fn(name)
 	if f.name == '' {
-		println(p.cur_fn.name)
-		println(p.cur_fn.args.len)
-		// if !p.first_run() && !p.translated {
+		// We are in a second pass, that means this function was not defined, throw an error. 
 		if !p.first_run() {
 			// println('name_expr():')
 			// If orig_name is a pkg, then printing undefined: `pkg` tells us nothing
diff --git a/compiler/table.v b/compiler/table.v
index 1b70b6a384..d067c91f09 100644
--- a/compiler/table.v
+++ b/compiler/table.v
@@ -210,7 +210,7 @@ fn (table &Table) known_type(typ string) bool {
 	return false
 }
 
-// TODO PERF O(N) this slows down the comiler a lot!
+// TODO PERF O(N) this slows down the compiler a lot!
 fn (t &Table) find_fn(name string) Fn {
 	for f in t.fns {
 		if f.name == name {
@@ -220,7 +220,7 @@ fn (t &Table) find_fn(name string) Fn {
 	return Fn{}
 }
 
-// TODO PERF O(N) this slows down the comiler a lot!
+// TODO PERF O(N) this slows down the compiler a lot! 
 fn (t &Table) known_fn(name string) bool {
 	for f in t.fns {
 		if f.name == name {
@@ -249,10 +249,9 @@ fn (t mut Table) register_type(typ string) {
 	// if t.types.filter( _.name == typ.name).len > 0 {
 	// return
 	// }
-	datyp := Type {
+	t.types << Type {
 		name: typ
 	}
-	t.types << datyp
 }
 
 fn (p mut Parser) register_type_with_parent(strtyp, parent string) {
diff --git a/examples/hello_world.v b/examples/hello_world.v
index fb964162bb..bdb69bc160 100644
--- a/examples/hello_world.v
+++ b/examples/hello_world.v
@@ -1 +1,2 @@
-println('Hello, World!')
+println('Hello, World!') 
+