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nodes.go
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nodes.go
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// Copyright 2013 Rodrigo Moraes. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package bantam
import (
"bytes"
"fmt"
)
// Node is the basic interface for expression nodes.
type Node interface {
String() string
}
// ----------------------------------------------------------------------------
// AssignNode represents an assignment expression like "a = b".
type AssignNode struct {
Name string
Right Node
}
func NewAssignNode(name string, right Node) *AssignNode {
return &AssignNode{Name: name, Right: right}
}
func (n *AssignNode) String() string {
return fmt.Sprintf("(%s = %s)", n.Name, n.Right)
}
// ----------------------------------------------------------------------------
// BinaryNode represents a binary arithmetic expression like "a + b".
type BinaryNode struct {
Left Node
Operator TokenType
Right Node
}
func NewBinaryNode(left Node, operator TokenType, right Node) *BinaryNode {
return &BinaryNode{Left: left, Operator: operator, Right: right}
}
func (n *BinaryNode) String() string {
return fmt.Sprintf("(%s %s %s)", n.Left, n.Operator, n.Right)
}
// ----------------------------------------------------------------------------
// FunctionNode represents a function call like "a(b, c, d)".
type FunctionNode struct {
Function Node
Args *ListNode
}
func NewFunctionNode(function Node, args *ListNode) *FunctionNode {
return &FunctionNode{Function: function, Args: args}
}
func (n *FunctionNode) String() string {
b := new(bytes.Buffer)
for k, v := range n.Args.Nodes {
fmt.Fprint(b, v)
if k < len(n.Args.Nodes)-1 {
b.WriteString(", ")
}
}
return fmt.Sprintf("%s(%s)", n.Function, b)
}
// ----------------------------------------------------------------------------
// ListNode holds a sequence of nodes.
type ListNode struct {
Nodes []Node // The element nodes in lexical order.
}
func NewListNode() *ListNode {
return &ListNode{}
}
func (n *ListNode) Append(node Node) {
n.Nodes = append(n.Nodes, node)
}
func (n *ListNode) String() string {
b := new(bytes.Buffer)
for _, v := range n.Nodes {
fmt.Fprint(b, v)
}
return b.String()
}
func listNode(n Node) *ListNode {
list, ok := n.(*ListNode)
if !ok {
list = &ListNode{}
list.Append(n)
}
return list
}
// ----------------------------------------------------------------------------
// NameNode represents a simple variable name expression like "abc".
type NameNode struct {
Name string
}
func NewNameNode(name string) *NameNode {
return &NameNode{Name: name}
}
func (n *NameNode) String() string {
return n.Name
}
// ----------------------------------------------------------------------------
// TernaryNode represents a ternary expression like "a ? b : c".
type TernaryNode struct {
Condition Node
List *ListNode
ElseList *ListNode
}
func NewTernaryNode(condition Node, list, elseList *ListNode) *TernaryNode {
return &TernaryNode{Condition: condition, List: list, ElseList: elseList}
}
func (n *TernaryNode) String() string {
return fmt.Sprintf("(%s ? %s : %s)", n.Condition, n.List, n.ElseList)
}
// ----------------------------------------------------------------------------
// UnaryNode represents a prefix unary arithmetic expression like "!a" or "-b".
type UnaryNode struct {
Operator TokenType
Right Node
}
func NewUnaryNode(operator TokenType, right Node) *UnaryNode {
return &UnaryNode{Operator: operator, Right: right}
}
func (n *UnaryNode) String() string {
return fmt.Sprintf("(%s%s)", n.Operator, n.Right)
}
// ----------------------------------------------------------------------------
// UnaryPostfixNode represents a postfix unary arithmetic expression like "a++".
type UnaryPostfixNode struct {
Left Node
Operator TokenType
}
func NewUnaryPostfixNode(left Node, operator TokenType) *UnaryPostfixNode {
return &UnaryPostfixNode{Left: left, Operator: operator}
}
func (n *UnaryPostfixNode) String() string {
return fmt.Sprintf("(%s%s)", n.Left, n.Operator)
}