zclsyntax: parsing of the two unary operators

zcl/zclsyntax/expression_ops.go

@@ -90,3 +90,27 @@ func (e *BinaryOpExpr) Range() zcl.Range {
 func (e *BinaryOpExpr) StartRange() zcl.Range {
 	return e.LHS.StartRange()
 }
+
+type UnaryOpExpr struct {
+	Op  Operation
+	Val Expression
+
+	SrcRange    zcl.Range
+	SymbolRange zcl.Range
+}
+
+func (e *UnaryOpExpr) walkChildNodes(w internalWalkFunc) {
+	e.Val = w(e.Val).(Expression)
+}
+
+func (e *UnaryOpExpr) Value(ctx *zcl.EvalContext) (cty.Value, zcl.Diagnostics) {
+	panic("UnaryOpExpr.Value not yet implemented")
+}
+
+func (e *UnaryOpExpr) Range() zcl.Range {
+	return e.SrcRange
+}
+
+func (e *UnaryOpExpr) StartRange() zcl.Range {
+	return e.SymbolRange
+}

zcl/zclsyntax/expression_vars.go

@@ -26,3 +26,7 @@ func (e *LiteralValueExpr) Variables() []zcl.Traversal {
 func (e *ScopeTraversalExpr) Variables() []zcl.Traversal {
 	return Variables(e)
 }
+
+func (e *UnaryOpExpr) Variables() []zcl.Traversal {
+	return Variables(e)
+}

zcl/zclsyntax/parser.go

@@ -485,6 +485,37 @@ func (p *parser) parseExpressionTerm() (Expression, zcl.Diagnostics) {
 			}, nil
 		}
 
+	case TokenMinus:
+		tok := p.Read() // eat minus token
+
+		// Important to use parseExpressionTerm rather than parseExpression
+		// here, otherwise we can capture a following binary expression into
+		// our negation.
+		// e.g. -46+5 should parse as (-46)+5, not -(46+5)
+		operand, diags := p.parseExpressionTerm()
+		return &UnaryOpExpr{
+			Op:  OpNegate,
+			Val: operand,
+
+			SrcRange:    zcl.RangeBetween(tok.Range, operand.Range()),
+			SymbolRange: tok.Range,
+		}, diags
+
+	case TokenBang:
+		tok := p.Read() // eat bang token
+
+		// Important to use parseExpressionTerm rather than parseExpression
+		// here, otherwise we can capture a following binary expression into
+		// our negation.
+		operand, diags := p.parseExpressionTerm()
+		return &UnaryOpExpr{
+			Op:  OpLogicalNot,
+			Val: operand,
+
+			SrcRange:    zcl.RangeBetween(tok.Range, operand.Range()),
+			SymbolRange: tok.Range,
+		}, diags
+
 	default:
 		var diags zcl.Diagnostics
 		if !p.recovery {