Improve expression handling and add parentheses support

expr.go

@@ -8,33 +8,14 @@ import (
 )
 
 func (t *Template) evalExpr(expr ast.Expr, local map[string]any) (any, error) {
-	val, err := t.getValue(expr.Segment, local)
+	val, err := t.getValue(expr.First, local)
 	if err != nil {
 		return nil, err
 	}
 	a := reflect.ValueOf(val)
 
 	for _, exprB := range expr.Rest {
-		val, err := t.getValue(exprB.Segment, local)
-		if err != nil {
-			return nil, err
-		}
-		b := reflect.ValueOf(val)
-		a = reflect.ValueOf(t.performOp(a, b, exprB.Logical))
-	}
-
-	return a.Interface(), nil
-}
-
-func (t *Template) evalExprSegment(expr ast.ExprSegment, local map[string]any) (any, error) {
-	val, err := t.getValue(expr.Value, local)
-	if err != nil {
-		return nil, err
-	}
-	a := reflect.ValueOf(val)
-
-	for _, exprB := range expr.Rest {
-		val, err := t.getValue(exprB.Value, local)
+		val, err := t.getValue(exprB.First, local)
 		if err != nil {
 			return nil, err
 		}

for_tag.go

@@ -17,15 +17,15 @@ func (ft forTag) Run(tc *TagContext, block, args []ast.Node) error {
 		return ErrForTagInvalidArgs
 	}
 
-	var expr ast.ExprSegment
+	var expr ast.Expr
 	if len(args) == 1 {
-		expr2, ok := args[0].(ast.ExprSegment)
+		expr2, ok := args[0].(ast.Expr)
 		if !ok {
 			return ErrForTagInvalidArgs
 		}
 		expr = expr2
 	} else if len(args) == 2 {
-		expr2, ok := args[1].(ast.ExprSegment)
+		expr2, ok := args[1].(ast.Expr)
 		if !ok {
 			return ErrForTagInvalidArgs
 		}
@@ -44,7 +44,7 @@ func (ft forTag) Run(tc *TagContext, block, args []ast.Node) error {
 
 	}
 
-	varName, ok := unwrap(expr.Value).(ast.Ident)
+	varName, ok := unwrap(expr.First).(ast.Ident)
 	if !ok {
 		return ErrForTagInvalidArgs
 	}

go.mod

@@ -1,3 +1,5 @@
 module go.elara.ws/salix
 
 go 1.21.2
+
+require github.com/davecgh/go-spew v1.1.1

go.sum

@@ -0,0 +1,2 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=

internal/ast/ast.go

@@ -63,8 +63,8 @@ type Value struct {
 }
 
 type Expr struct {
-	Segment  Node
-	Logical  Logical
+	First    Node
+	Operator Operator
 	Rest     []Expr
 	Position Position
 }
@@ -73,17 +73,6 @@ func (e Expr) Pos() Position {
 	return e.Position
 }
 
-type ExprSegment struct {
-	Value    Node
-	Operator Operator
-	Rest     []ExprSegment
-	Position Position
-}
-
-func (es ExprSegment) Pos() Position {
-	return es.Position
-}
-
 type FuncCall struct {
 	Name     Ident
 	Params   []Node

internal/parser/salix.peg

@@ -28,6 +28,25 @@ func getPos(c *current) ast.Position {
     }
 }
 
+func toExpr(c *current, first, rest any) ast.Node {
+    restSlice := toAnySlice(rest)
+    if len(restSlice) == 0 {
+        return first.(ast.Node)
+    }
+    
+    out := ast.Expr{First: first.(ast.Node), Position: getPos(c)}
+    for _, restValue := range restSlice {
+        valueSlice := toAnySlice(restValue)
+        out.Rest = append(out.Rest, ast.Expr{
+            Operator: valueSlice[1].(ast.Operator),
+            First:  valueSlice[3].(ast.Node),
+            Position: valueSlice[3].(ast.Node).Pos(),
+        })
+    }
+    
+    return out
+}
+
 }
 
 Root = items:(Tag / ExprTag / EndTag / Text)* {
@@ -55,54 +74,32 @@ EndTag = "#!" name:Ident {
     }, nil
 }
 
-ExprTag = "#(" item:Item ')' {
+ExprTag = "#(" item:Expr ')' {
     return ast.ExprTag{
         Value:    item.(ast.Node),
         Position: getPos(c),
     }, nil
 }
 
-Item = Ternary / Expr
+Expr = Ternary / LogicalExpr
 
-Expr = first:ExprSegment rest:(_ Logical _ ExprSegment)* {
-    restSlice := toAnySlice(rest)
-    if len(restSlice) == 0 {
-        return first, nil
-    }
-    
-    out := ast.Expr{Segment: first.(ast.Node), Position: getPos(c)}
-    for _, restValue := range restSlice {
-        valueSlice := toAnySlice(restValue)
-        out.Rest = append(out.Rest, ast.Expr{
-            Logical:  valueSlice[1].(ast.Logical),
-            Segment:  valueSlice[3].(ast.Node),
-            Position: valueSlice[3].(ast.Node).Pos(),
-        })
-    }
-    
-    return out, nil
+LogicalExpr = _ first:ComparisonExpr rest:(_ LogicalOp _ ComparisonExpr)* _ {
+    return toExpr(c, first, rest), nil
 }
 
-ExprSegment = first:Value rest:(_ Operator _ Value)* {
-    restSlice := toAnySlice(rest)
-    if len(restSlice) == 0 {
-        return first, nil
-    }
-    
-    out := ast.ExprSegment{Value: first.(ast.Node), Position: getPos(c)}
-    for _, restValue := range restSlice {
-        valueSlice := toAnySlice(restValue)
-        out.Rest = append(out.Rest, ast.ExprSegment{
-            Operator: valueSlice[1].(ast.Operator),
-            Value:    valueSlice[3].(ast.Node),
-            Position: valueSlice[3].(ast.Node).Pos(),
-        })
-    }
-    
-    return out, nil
+ComparisonExpr = _ first:ArithmeticExpr rest:(_ ComparisonOp _ ArithmeticExpr)* _ {
+    return toExpr(c, first, rest), nil
 }
 
-ParamList = '(' params:(Item ( ',' _ Item )* )? ')' {
+ArithmeticExpr = _ first:Value rest:(_ ArithmeticOp _ Value)* _ {
+    return toExpr(c, first, rest), nil
+}
+
+ParenExpr = '(' expr:Expr ')' {
+    return expr, nil
+}
+
+ParamList = '(' params:(Expr ( ',' _ Expr )* )? ')' {
     paramSlice := toAnySlice(params)
     if len(paramSlice) == 0 {
         return []ast.Node{}, nil
@@ -116,7 +113,7 @@ ParamList = '(' params:(Item ( ',' _ Item )* )? ')' {
     return out, nil
 }
 
-Value = not:"!"? node:(MethodCall / FieldAccess / Index / String / RawString / Float / Integer / Bool / FuncCall / VariableOr / Ident) {
+Value = not:"!"? node:(MethodCall / FieldAccess / Index / String / RawString / Float / Integer / Bool / FuncCall / VariableOr / Ident / ParenExpr) {
     return ast.Value{
         Node: node.(ast.Node),
         Not:  not != nil,
@@ -218,15 +215,22 @@ Bool = ("true"i / "false"i) {
     }, err
 }
 
-Operator = ("==" / "<=" / ">=" / "in"i / '<' / '>' / '+' / '-' / '/' / '*') {
+LogicalOp = ("||" / "&&") {
     return ast.Operator{
         Value:    string(c.text),
         Position: getPos(c),
     }, nil
 }
 
-Logical = ("&&" / "||") {
-    return ast.Logical{
+ComparisonOp = ("==" / "<=" / ">=" / '<' / '>' / "in"i) {
+    return ast.Operator{
+        Value:    string(c.text),
+        Position: getPos(c),
+    }, nil
+}
+
+ArithmeticOp = ('+' / '-' / '/' / '*' / '%') {
+    return ast.Operator{
         Value:    string(c.text),
         Position: getPos(c),
     }, nil

salix.go

@@ -206,8 +206,6 @@ func (t *Template) getValue(node ast.Node, local map[string]any) (any, error) {
 		return node.Value, nil
 	case ast.Expr:
 		return t.evalExpr(node, local)
-	case ast.ExprSegment:
-		return t.evalExprSegment(node, local)
 	case ast.FuncCall:
 		return t.execFuncCall(node, local)
 	case ast.Index: