From d07953b0f0d6823274931a3fba278bc610caccb3 Mon Sep 17 00:00:00 2001
From: joe-conigliaro <joe-conigliaro@users.noreply.github.com>
Date: Tue, 31 Dec 2019 01:06:56 +1100
Subject: [PATCH] v: fix postfix unary `++`  `--` operators & some cleanup

---
 vlib/v/gen/cgen.v      |  2 +-
 vlib/v/gen/tests/1.c   |  1 +
 vlib/v/gen/tests/1.vv  |  1 +
 vlib/v/parser/parser.v | 45 +++++++++++++++++++++++-------------------
 vlib/v/token/token.v   | 34 +++++++++++++++++++++----------
 5 files changed, 52 insertions(+), 31 deletions(-)

diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 0de87a4407..4569881157 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -111,7 +111,7 @@ fn (g mut Gen) expr(node ast.Expr) {
 		}
 		ast.UnaryExpr {
 			g.expr(it.left)
-			g.write(' $it.op ')
+			g.write(it.op.str())
 		}
 		ast.StringLiteral {
 			g.write('tos3("$it.val")')
diff --git a/vlib/v/gen/tests/1.c b/vlib/v/gen/tests/1.c
index 2d3020b2b4..f2f9a0d061 100644
--- a/vlib/v/gen/tests/1.c
+++ b/vlib/v/gen/tests/1.c
@@ -1,4 +1,5 @@
 int main() {
 int a = 10;
+a++;
 return 0;
 }
diff --git a/vlib/v/gen/tests/1.vv b/vlib/v/gen/tests/1.vv
index 2b684716cb..29ae4d536b 100644
--- a/vlib/v/gen/tests/1.vv
+++ b/vlib/v/gen/tests/1.vv
@@ -1,3 +1,4 @@
 fn main() {
 	a := 10
+	a++
 }
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index 1f3b38087c..8e6317fe02 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -28,8 +28,7 @@ pub fn parse_stmt(text string, table &table.Table) ast.Stmt {
 		scanner: s
 		table: table
 	}
-	p.next()
-	p.next()
+	p.read_first_token()
 	return p.stmt()
 }
 
@@ -304,13 +303,10 @@ pub fn (p mut Parser) expr(rbp int) (ast.Expr,types.Type) {
 			p.check(.rpar)
 		}
 		else {
-			p.next()
 			if p.tok.is_unary() {
 				expr,_ := p.expr(token.highest_prec)
 				node = ast.UnaryExpr{
-					// left: p.expr(token.highest_prec)
 					left: expr
-					op: p.tok.kind
 				}
 			}
 			else {
@@ -323,7 +319,7 @@ pub fn (p mut Parser) expr(rbp int) (ast.Expr,types.Type) {
 		prev_tok := p.tok
 		p.next()
 		mut t2 := types.Type{}
-		// left denotation (infix)
+		// left denotation (infix / postfix)
 		if prev_tok.is_right_assoc() {
 			mut expr := ast.Expr{}
 			expr,t2 = p.expr(prev_tok.precedence() - 1)
@@ -334,24 +330,33 @@ pub fn (p mut Parser) expr(rbp int) (ast.Expr,types.Type) {
 			}
 			// println(t2.name + 'OOO')
 			if !types.check(&typ, &t2) {
+				println('tok: $prev_tok.str()')
 				p.error('cannot convert `$t2.name` to `$typ.name`')
 			}
 		}
 		else if prev_tok.is_left_assoc() {
-			mut expr := ast.Expr{}
-			expr,t2 = p.expr(prev_tok.precedence())
-			op := prev_tok.kind
-			if op in [.gt, .lt, .ge, .le] {
-				typ = types.bool_type
-			}
-			else {
-				typ = t2
-			}
-			// println(t2.name + '222')
-			node = ast.BinaryExpr{
-				left: node
-				op: prev_tok.kind
-				right: expr
+			// postfix (`++` | `--`)
+			if prev_tok.kind in [.inc, .dec] {
+				node = ast.UnaryExpr{
+					left: node
+					op: prev_tok.kind
+				}
+			} else {
+				mut expr := ast.Expr{}
+				expr,t2 = p.expr(prev_tok.precedence())
+				op := prev_tok.kind
+				if prev_tok.is_relational() {
+					typ = types.bool_type
+				}
+				else {
+					typ = t2 
+				}
+				// println(t2.name + '222')
+				node = ast.BinaryExpr{
+					left: node
+					op: prev_tok.kind
+					right: expr
+				}	
 			}
 		}
 	}
diff --git a/vlib/v/token/token.v b/vlib/v/token/token.v
index 440b12ddc2..db39a2dea1 100644
--- a/vlib/v/token/token.v
+++ b/vlib/v/token/token.v
@@ -306,30 +306,34 @@ pub fn (t Token) str() string {
 // Representation of highest and lowest precedence
 pub const (
 	lowest_prec = 0
-	highest_prec = 7
+	highest_prec = 8
 )
 // Precedence returns a tokens precedence if defined, otherwise lowest_prec
 pub fn (tok Token) precedence() int {
 	match tok.kind {
+		// `++` | `--`
+		.inc, .dec {
+			return 7
+		}
 		// `*` |  `/` | `%` | `<<` | `>>` | `&`
 		.mul, .div, .left_shift, .righ_shift, .amp {
-			return 7
+			return 6
 		}
 		// `+` |  `-` |  `|` | `^`
 		.plus, .minus, .pipe, .xor {
-			return 6
+			return 5
 		}
 		// `==` | `!=` | `<` | `<=` | `>` | `>=`
 		.eq, .ne, .lt, .le, .gt, .ge {
-			return 5
+			return 4
 		}
 		// `&&`
 		.and {
-			return 4
+			return 3
 		}
 		// `||`
 		.logical_or {
-			return 3
+			return 2
 		}
 		// /.plus_assign {
 		// /return 2
@@ -358,10 +362,14 @@ pub fn (tok Token) is_unary() bool {
 pub fn (tok Token) is_left_assoc() bool {
 	return tok.kind in [
 	// .number,
+	//  `++` | `--`
+	.inc, .dec,
 	// `*` | `/` | `%`
 	.mul, .div, .mod,
-	// `^` | `||` | `&` < > <= >=
-	.xor, .logical_or, .and, .gt, .lt, .le, .ge,
+	// `^` | `||` | `&`
+	.xor, .logical_or, .and,
+	// `<` | `<=` | `>` | `>=`
+	.lt, .le, .gt, .ge,
 	// `,`
 	.comma]
 }
@@ -369,8 +377,8 @@ pub fn (tok Token) is_left_assoc() bool {
 // is_right_assoc returns true if the token is right associative
 pub fn (tok Token) is_right_assoc() bool {
 	return tok.kind in [
-	// `+` | `-` | `!` | `++` | `--`
-	.plus, .minus, .not, .inc, .dec,
+	// `+` | `-` | `!`
+	.plus, .minus, .not,
 	// `=` | `+=` | `-=` | `*=` | `/=`
 	.assign, .plus_assign, .minus_assign, .mult_assign, .div_assign,
 	// `%=` | `>>=` | `<<=`
@@ -378,3 +386,9 @@ pub fn (tok Token) is_right_assoc() bool {
 	// `&=` | `^=` | `|=`
 	.and_assign, .xor_assign, .or_assign]
 }
+
+pub fn (tok Token) is_relational() bool {
+	return tok.kind in [
+	// `<` | `<=` | `>` | `>=`
+	.lt, .le, .gt, .ge]
+}