fmt: force break in front of long unbreakable parts, avoid very small sub-expressions

vlib/v/fmt/fmt.v

@@ -13,7 +13,7 @@ const (
 		'\t\t\t\t\t\t\t\t'
 	]
 	// when to break a line dependant on penalty
-	max_len = [0, 30, 85, 95, 100]
+	max_len = [0, 35, 85, 93, 100]
 )
 
 pub struct Fmt {
@@ -150,7 +150,7 @@ fn (mut f Fmt) adjust_complete_line() {
 			mut sub_expr_end_idx := f.penalties.len
 			// search for next position with low penalty and same precedence to form subexpression
 			for j in i..f.penalties.len {
-				if f.penalties[j] <= 1 && f.precedences[j] == precedence {
+				if f.penalties[j] <= 1 && f.precedences[j] == precedence && len_sub_expr >= max_len[1] {
 					sub_expr_end_idx = j
 					break
 				} else if f.precedences[j] < precedence {
@@ -164,7 +164,7 @@ fn (mut f Fmt) adjust_complete_line() {
 			// if subexpression would fit in single line adjust penalties to actually do so
 			if len_sub_expr <= max_len[max_len.len-1] {
 				for j in i..sub_expr_end_idx {
-						f.penalties[j] = max_len.len-1
+					f.penalties[j] = max_len.len-1
 				}
 				if i > 0 {
 					f.penalties[i-1] = 0
@@ -174,6 +174,10 @@ fn (mut f Fmt) adjust_complete_line() {
 				}
 			}
 		}
+		// emergency fallback: decrease penalty in front of long unbreakable parts 
+		if i > 0 && buf.len > max_len[3] - max_len[1] && f.penalties[i-1] > 0 {
+			f.penalties[i-1] = if buf.len >= max_len[2] { 0 } else { 1 }
+		}
 	}
 }
 

vlib/v/fmt/tests/consts_expected.vv

@@ -10,8 +10,8 @@ const (
 	eulers              = 2.7182
 	supported_platforms = ['windows', 'mac', 'macos', 'darwin', 'linux', 'freebsd', 'openbsd',
 		'netbsd', 'dragonfly', 'android', 'js', 'solaris', 'haiku', 'linux_or_macos']
-	one_line_supported  = ['windows', 'mac', 'macos', 'darwin', 'linux', 'freebsd', 'openbsd', 'netbsd',
+	one_line_supported  = ['windows', 'mac', 'macos', 'darwin', 'linux', 'freebsd', 'openbsd',
-		'dragonfly', 'android', 'js', 'solaris', 'haiku', 'linux_or_macos']
+		'netbsd', 'dragonfly', 'android', 'js', 'solaris', 'haiku', 'linux_or_macos']
 	another_const       = ['a', 'b', 'c', 'd', 'e', 'f']
 )
 

vlib/v/fmt/tests/expressions_expected.vv

@@ -50,6 +50,13 @@ fn main() {
 	s := []string{}
 	s << '	`$v_str`'
 	println(s)
+	println('this is quite a long string' +
+		' that is followd by an even longer part that should go to another line')
+	if (a == b && b > r) ||
+		(d > r) || (a < b) || (b < d && a + b > r) ||
+		(a + b + d >= 0 && r < 0) || (a > b && d - r < b) {
+		println('ok')
+	}
 }
 
 fn gen_str_for_multi_return(mut g gen.Gen, info table.MultiReturn, styp, str_fn_name string) {

vlib/v/fmt/tests/expressions_input.vv

@@ -60,6 +60,10 @@ fn main() {
 	s := []string{}
 	s << '	`$v_str`'
 	println(s)
+	println('this is quite a long string' + ' that is followd by an even longer part that should go to another line')
+	if (a == b && b > r) || (d > r) || (a < b) || (b< d && a+b > r) || (a+b+d >= 0 && r < 0) || (a > b && d-r < b) {
+		println('ok')
+	}
 }
 
 fn gen_str_for_multi_return(mut g gen.Gen,