fix: improve parsing of assign statements

Handle assign statements in parseAssign function. Detect multi-assign
by the presence of comma in the right hand side tokens.
The case of swap is not handled yet.

3 files changed, 31 insertions, 3 deletions

diff --git a/interp/interpreter_test.go b/interp/interpreter_test.go
index adb550b..27b7dd8 100644
--- a/interp/interpreter_test.go
+++ b/interp/interpreter_test.go
@@ -72,8 +72,9 @@ func TestExpr(t *testing.T) {
 
 func TestAssign(t *testing.T) {
 	run(t, []etest{
-		{src: "var a int = 1; a", res: "1"},       // #00
-		{src: "var a, b int = 1, 2; b", res: "2"}, // #01
+		{src: "var a int = 1; a", res: "1"},             // #00
+		{src: "var a, b int = 1, 2; b", res: "2"},       // #01
+		{src: "var a, b int; a, b = 1, 2; b", res: "2"}, // #02
 	})
 }
 
diff --git a/parser/parse.go b/parser/parse.go
index e72e16e..f42193a 100644
--- a/parser/parse.go
+++ b/parser/parse.go
@@ -145,15 +145,41 @@ func (p *Parser) parseStmt(in Tokens) (out Tokens, err error) {
 	case lang.Var:
 		return p.parseVar(in)
 	case lang.Ident:
-		if len(in) == 2 && in[1].Tok == lang.Colon {
+		if in.Index(lang.Colon) == 1 {
 			return p.parseLabel(in)
 		}
+		if i := in.Index(lang.Assign); i > 0 {
+			return p.parseAssign(in, i)
+		}
 		fallthrough
 	default:
 		return p.parseExpr(in, "")
 	}
 }
 
+func (p *Parser) parseAssign(in Tokens, aindex int) (out Tokens, err error) {
+	rhs := in[aindex+1:].Split(lang.Comma)
+	lr := len(rhs)
+	if lr == 1 {
+		return p.parseExpr(in, "")
+	}
+	lhs := in[:aindex].Split(lang.Comma)
+	for i, e := range rhs {
+		toks, err := p.parseExpr(lhs[i], "")
+		if err != nil {
+			return out, err
+		}
+		out = append(out, toks...)
+		toks, err = p.parseExpr(e, "")
+		if err != nil {
+			return out, err
+		}
+		out = append(out, toks...)
+		out = append(out, newAssign(in[aindex].Pos))
+	}
+	return out, err
+}
+
 func (p *Parser) parseBreak(in Tokens) (out Tokens, err error) {
 	var label string
 	switch len(in) {
diff --git a/parser/tokens.go b/parser/tokens.go
index 7a241f3..b8f462f 100644
--- a/parser/tokens.go
+++ b/parser/tokens.go
@@ -94,3 +94,4 @@ func newInt(i, pos int) Token                         { return newToken(lang.Int
 func newColon(pos int) Token                          { return newToken(lang.Colon, "", pos) }
 func newLen(i, pos int) Token                         { return newToken(lang.Len, "", pos, i) }
 func newSlice(pos int) Token                          { return newToken(lang.Slice, "", pos) }
+func newAssign(pos int) Token                         { return newToken(lang.Assign, "", pos) }