From 193bd5c2d574df45d15559554d5ee34caf999ffd Mon Sep 17 00:00:00 2001
From: MrLetsplay <mr@cringe-studios.com>
Date: Sat, 23 Mar 2024 14:10:53 +0100
Subject: [PATCH] Simplify expression parsing

---
 parser.go | 105 ++++++------------------------------------------------
 1 file changed, 11 insertions(+), 94 deletions(-)

diff --git a/parser.go b/parser.go
index e644059..ed57dde 100644
--- a/parser.go
+++ b/parser.go
@@ -487,8 +487,8 @@ func (p *Parser) tryUnaryExpression() (*Expression, error) {
 	return nil, nil
 }
 
-func (p *Parser) tryMultiplicativeExpression() (*Expression, error) {
-	left, err := p.tryUnaryExpression()
+func (p *Parser) tryBinaryExpression0(opFunc func() (*Expression, error), operators ...Operator) (*Expression, error) {
+	left, err := opFunc()
 	if err != nil {
 		return nil, err
 	}
@@ -498,7 +498,7 @@ func (p *Parser) tryMultiplicativeExpression() (*Expression, error) {
 	}
 
 	for {
-		op, err := p.tryOperator(Operator_Multiply, Operator_Divide, Operator_Modulo)
+		op, err := p.tryOperator(operators...)
 		if err != nil {
 			return nil, err
 		}
@@ -507,7 +507,7 @@ func (p *Parser) tryMultiplicativeExpression() (*Expression, error) {
 			return left, nil
 		}
 
-		right, err := p.tryUnaryExpression()
+		right, err := opFunc()
 		if err != nil {
 			return nil, err
 		}
@@ -520,103 +520,20 @@ func (p *Parser) tryMultiplicativeExpression() (*Expression, error) {
 	}
 }
 
+func (p *Parser) tryMultiplicativeExpression() (*Expression, error) {
+	return p.tryBinaryExpression0(p.tryUnaryExpression, Operator_Multiply, Operator_Divide, Operator_Modulo)
+}
+
 func (p *Parser) tryAdditiveExpression() (*Expression, error) {
-	left, err := p.tryMultiplicativeExpression()
-	if err != nil {
-		return nil, err
-	}
-
-	if left == nil {
-		return nil, nil
-	}
-
-	for {
-		op, err := p.tryOperator(Operator_Plus, Operator_Minus)
-		if err != nil {
-			return nil, err
-		}
-
-		if op == nil {
-			return left, nil
-		}
-
-		right, err := p.tryMultiplicativeExpression()
-		if err != nil {
-			return nil, err
-		}
-
-		if right == nil {
-			return nil, p.error("expected expression")
-		}
-
-		left = &Expression{Type: Expression_Binary, Value: BinaryExpression{Operation: getArithmeticOperation(*op), Left: *left, Right: *right}, Position: left.Position}
-	}
+	return p.tryBinaryExpression0(p.tryMultiplicativeExpression, Operator_Plus, Operator_Minus)
 }
 
 func (p *Parser) tryRelationalExpression() (*Expression, error) {
-	left, err := p.tryAdditiveExpression()
-	if err != nil {
-		return nil, err
-	}
-
-	if left == nil {
-		return nil, nil
-	}
-
-	for {
-		op, err := p.tryOperator(Operator_Less, Operator_Greater, Operator_LessEquals, Operator_GreaterEquals)
-		if err != nil {
-			return nil, err
-		}
-
-		if op == nil {
-			return left, nil
-		}
-
-		right, err := p.tryAdditiveExpression()
-		if err != nil {
-			return nil, err
-		}
-
-		if right == nil {
-			return nil, p.error("expected expression")
-		}
-
-		left = &Expression{Type: Expression_Binary, Value: BinaryExpression{Operation: getArithmeticOperation(*op), Left: *left, Right: *right}, Position: left.Position}
-	}
+	return p.tryBinaryExpression0(p.tryAdditiveExpression, Operator_Less, Operator_Greater, Operator_LessEquals, Operator_GreaterEquals)
 }
 
 func (p *Parser) tryEqualityExpression() (*Expression, error) {
-	left, err := p.tryRelationalExpression()
-	if err != nil {
-		return nil, err
-	}
-
-	if left == nil {
-		return nil, nil
-	}
-
-	for {
-		op, err := p.tryOperator(Operator_EqualsEquals, Operator_NotEquals)
-		if err != nil {
-			return nil, err
-		}
-
-		if op == nil {
-			return left, nil
-		}
-
-		right, err := p.tryRelationalExpression()
-		if err != nil {
-			return nil, err
-		}
-
-		if right == nil {
-			return nil, p.error("expected expression")
-		}
-
-		left = &Expression{Type: Expression_Binary, Value: BinaryExpression{Operation: getArithmeticOperation(*op), Left: *left, Right: *right}, Position: left.Position}
-	}
+	return p.tryBinaryExpression0(p.tryRelationalExpression, Operator_EqualsEquals, Operator_NotEquals)
 }
 
 func (p *Parser) tryBinaryExpression() (*Expression, error) {