parser: fix to multi-expr

vlib/v/parser/parser.v

@@ -448,7 +448,7 @@ pub fn (mut p Parser) stmt() ast.Stmt {
 				return p.assign_stmt()
 			} else if p.peek_tok.kind == .comma {
 				// `a, b ...`
-				return p.parse_comma_separated()
+				return p.parse_multi_expr()
 			} else if p.peek_tok.kind == .colon {
 				// `label:`
 				name := p.check_name()
@@ -462,11 +462,7 @@ pub fn (mut p Parser) stmt() ast.Stmt {
 				[.rcbr, .eof] {
 				p.error_with_pos('`$p.tok.lit` evaluated but not used', p.tok.position())
 			}
-			epos := p.tok.position()
-			return ast.ExprStmt{
-				expr: p.expr(0)
-				pos: epos
-			}
+			return p.parse_multi_expr()
 		}
 		.comment {
 			return p.comment()
@@ -527,8 +523,9 @@ pub fn (mut p Parser) stmt() ast.Stmt {
 			p.error_with_pos('const can only be defined at the top level (outside of functions)',
 				p.tok.position())
 		}
+		// literals, 'if', etc. in here
 		else {
-			return p.parse_comma_separated()
+			return p.parse_multi_expr()
 		}
 	}
 }
@@ -644,39 +641,47 @@ pub fn (mut p Parser) warn_with_pos(s string, pos token.Position) {
 	}
 }
 
-fn (mut p Parser) parse_comma_separated() ast.Stmt {
+fn (mut p Parser) parse_multi_expr() ast.Stmt {
 	// in here might be 1) multi-expr 2) multi-assign
 	// 1, a, c ... }       // multi-expression
 	// a, mut b ... :=/=   // multi-assign
 	// collect things upto hard boundaries
 	mut collected := []ast.Expr{}
-	mut op := p.tok.kind
-	for op !in [.rcbr, .decl_assign, .assign] {
-		if op == .name {
-			collected << p.name_expr()
-		} else {
-			collected << p.expr(0)
-		}
+	for {
+		collected << p.expr(0)
 		if p.tok.kind == .comma {
 			p.next()
 		} else {
 			break
 		}
-		op = p.tok.kind
 	}
-	is_assignment := p.tok.kind in [.decl_assign, .assign]
-	if is_assignment {
+	// TODO: Try to merge assign_expr and assign_stmt
+	if p.tok.kind == .decl_assign || (p.tok.kind == .assign && collected.len > 1) {
 		mut idents := []ast.Ident{}
 		for c in collected {
 			idents << c as ast.Ident
 		}
 		return p.partial_assign_stmt(idents)
+	} else if p.tok.kind.is_assign() {
+		epos := p.tok.position()
+		if collected.len == 1 {
+			return ast.ExprStmt {
+				expr: p.assign_expr(collected[0])
+				pos: epos
+			}
+		} else {
+			return ast.ExprStmt {
+				expr: p.assign_expr(ast.ConcatExpr{
+					vals: collected
+				})
+				pos: epos
+			}
+		}
 	} else {
 		if collected.len == 1 {
-			epos := p.tok.position()
 			return ast.ExprStmt{
 				expr: collected[0]
-				pos: epos
+				pos: p.tok.position()
 			}
 		}
 		return ast.ExprStmt{

vlib/v/parser/pratt.v

@@ -138,7 +138,7 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 	}
 	// Infix
 	for precedence < p.tok.precedence() {
-		if p.tok.kind.is_assign() {
+		if p.tok.kind.is_assign() && !p.is_stmt_ident {
 			node = p.assign_expr(node)
 		} else if p.tok.kind == .dot {
 			node = p.dot_expr(node)

vlib/v/tests/complex_assign_test.v

@@ -7,25 +7,7 @@ fn multireturner(n int, s string) (int, string) {
 	return n + 1, s
 }
 
-fn test_assign_multireturn_expression() {
-	a, b := if true {
-		multireturner(13, 'awesome')
-	} else {
-		multireturner(-1, 'notawesome')
-	}
-	assert a == 14
-	assert b == 'awesome'
-
-	c, d := if false {
-		multireturner(-1, 'notawesome')
-	} else if true {
-		multireturner(17, 'awesomer')
-	} else {
-		multireturner(-1, 'notawesome')
-	}
-	assert c == 18
-	assert d == 'awesomer'
-
+fn test_assign_multi_expr_func() {
 	e, f := if false {
 		multireturner(-1, 'notawesome')
 	} else if false {
@@ -43,63 +25,84 @@ fn test_assign_multireturn_expression() {
 	}
 	assert g == 1
 	assert h == 'good'
+}
 
-	i, j := match true {
-		false { multireturner(100, 'bad') }
-		else { multireturner(0, 'good') }
-	}
-	assert i == 1
-	assert j == 'good'
-
-	k, l, m := if true {
-		1, 'awesome', [13]
-	} else {
-		0, 'bad', [0]
-	}
-	assert k == 1
-	assert l == 'awesome'
-	assert m == [13]
-
-	n, o, p := if false {
-		1, 'awesome', [13]
-	} else {
-		0, 'bad', [0]
-	}
-	assert n == 0
-	assert o == 'bad'
-	assert p == [0]
-
-	mut var1 := 17
-	var2 := 'awesome'
-	q, r, s := if true {
-		1 + var1, var2, [13]
-	} else {
-		0, 'bad', [0]
-	}
-	assert q == 18
-	assert r == 'awesome'
-	assert s == [13]
-
+fn test_assign_multi_expr() {
+	// helpers
 	val1 := 1
-	val2 := 0
-	t, u, v := if true {
+	val2 := 2
+
+	// simple case for match
+	a,b,c := match false {
+		true { 1,2,3 }
+		false { 4,5,6 }
+		else { 7,8,9 }
+	}
+	assert a == 4
+	assert b == 5
+	assert c == 6
+
+	// test with first value `literal`
+	d, e, f := if true {
+		1, 'awesome', [13]
+	} else {
+		0, 'bad', [0]
+	}
+	assert d == 1
+	assert e == 'awesome'
+	assert f == [13]
+
+	// test with first value `literal expr` and statement
+	awesome := 'awesome'
+	g, h, i := if true {
+		1 + val1, awesome, [13]
+	} else {
+		0, 'bad', [0]
+	}
+	assert g == 2
+	assert h == 'awesome'
+	assert i == [13]
+
+	// test with first value `.name`
+	j, k, l := if true {
 		val1, 'awesome', [13]
 	} else {
 		val2, 'bad', [0]
 	}
-	assert t == val1
-	assert u == 'awesome'
-	assert v == [13]
+	assert j == 1
+	assert k == 'awesome'
+	assert l == [13]
 
-	val3 := Object { name: 'foo', value: 19 }
-	x, y, z := if true {
-		1 + 1, 'awe' + 'some', { val3 | name: 'bar' }
+	// test with first value name and peek != .comma
+	m, n, o := if true {
+		val1 + 1, val1, val1
+	} else {
+		val2, val2, val2
+	}
+	assert m == val1 + 1
+	assert n == val1
+	assert o == val1
+
+	// test practical complex expressions
+	val3 := Object { name: 'initial', value: 19 }
+	mut q, mut r, mut s := if true {
+		1 + 1, 'awe' + 'some', { val3 | name: 'ok' }
 	} else {
 		0, '0', Object {}
 	}
-	assert x == 2
-	assert y == 'awesome'
-	assert z.name == 'bar'
-	assert z.value == 19
+	assert q == 2
+	assert r == 'awesome'
+	assert s.name == 'ok'
+	assert s.value == 19
 
+	// test assign to existing variables
+	q, r, s = if false {
+		0, '0', Object {}
+	} else {
+		5, '55', { val3 | value: 555 }
+	}
+	assert q == 5
+	assert r == '55'
+	assert s.value == 555
+	assert s.name == 'initial'
 }