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text/template: add an unexported method to Node

Protects the package a little against undesirable clients.

R=golang-dev, bradfitz, rsc
CC=golang-dev
https://golang.org/cl/6624054
This commit is contained in:
Rob Pike 2012-10-07 07:15:11 +11:00
parent bbccfddb84
commit 421b75c0db

View File

@ -13,7 +13,9 @@ import (
"strings"
)
// A node is an element in the parse tree. The interface is trivial.
// A Node is an element in the parse tree. The interface is trivial.
// The interface contains an unexported method so that only
// types local to this package can satisfy it.
type Node interface {
Type() NodeType
String() string
@ -22,6 +24,8 @@ type Node interface {
// CopyXxx methods that return *XxxNode.
Copy() Node
Position() Pos // byte position of start of node in full original input string
// Make sure only functions in this package can create Nodes.
unexported()
}
// NodeType identifies the type of a parse tree node.
@ -35,6 +39,11 @@ func (p Pos) Position() Pos {
return p
}
// unexported keeps Node implementations local to the package.
// All implementations embed Pos, so this takes care of it.
func (Pos) unexported() {
}
// Type returns itself and provides an easy default implementation
// for embedding in a Node. Embedded in all non-trivial Nodes.
func (t NodeType) Type() NodeType {