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package ast
import (
"fmt"
"unsafe"
"github.com/pelletier/go-toml/v2/internal/danger"
)
// Iterator starts uninitialized, you need to call Next() first.
//
// For example:
//
// it := n.Children()
// for it.Next() {
// it.Node()
// }
type Iterator struct {
started bool
node *Node
}
// Next moves the iterator forward and returns true if points to a
// node, false otherwise.
func (c *Iterator) Next() bool {
if !c.started {
c.started = true
} else if c.node.Valid() {
c.node = c.node.Next()
}
return c.node.Valid()
}
// IsLast returns true if the current node of the iterator is the last
// one. Subsequent call to Next() will return false.
func (c *Iterator) IsLast() bool {
return c.node.next == 0
}
// Node returns a copy of the node pointed at by the iterator.
func (c *Iterator) Node() *Node {
return c.node
}
// Root contains a full AST.
//
// It is immutable once constructed with Builder.
type Root struct {
nodes []Node
}
// Iterator over the top level nodes.
func (r *Root) Iterator() Iterator {
it := Iterator{}
if len(r.nodes) > 0 {
it.node = &r.nodes[0]
}
return it
}
func (r *Root) at(idx Reference) *Node {
return &r.nodes[idx]
}
// Arrays have one child per element in the array. InlineTables have
// one child per key-value pair in the table. KeyValues have at least
// two children. The first one is the value. The rest make a
// potentially dotted key. Table and Array table have one child per
// element of the key they represent (same as KeyValue, but without
// the last node being the value).
type Node struct {
Kind Kind
Raw Range // Raw bytes from the input.
Data []byte // Node value (either allocated or referencing the input).
// References to other nodes, as offsets in the backing array
// from this node. References can go backward, so those can be
// negative.
next int // 0 if last element
child int // 0 if no child
}
type Range struct {
Offset uint32
Length uint32
}
// Next returns a copy of the next node, or an invalid Node if there
// is no next node.
func (n *Node) Next() *Node {
if n.next == 0 {
return nil
}
ptr := unsafe.Pointer(n)
size := unsafe.Sizeof(Node{})
return (*Node)(danger.Stride(ptr, size, n.next))
}
// Child returns a copy of the first child node of this node. Other
// children can be accessed calling Next on the first child. Returns
// an invalid Node if there is none.
func (n *Node) Child() *Node {
if n.child == 0 {
return nil
}
ptr := unsafe.Pointer(n)
size := unsafe.Sizeof(Node{})
return (*Node)(danger.Stride(ptr, size, n.child))
}
// Valid returns true if the node's kind is set (not to Invalid).
func (n *Node) Valid() bool {
return n != nil
}
// Key returns the child nodes making the Key on a supported
// node. Panics otherwise. They are guaranteed to be all be of the
// Kind Key. A simple key would return just one element.
func (n *Node) Key() Iterator {
switch n.Kind {
case KeyValue:
value := n.Child()
if !value.Valid() {
panic(fmt.Errorf("KeyValue should have at least two children"))
}
return Iterator{node: value.Next()}
case Table, ArrayTable:
return Iterator{node: n.Child()}
default:
panic(fmt.Errorf("Key() is not supported on a %s", n.Kind))
}
}
// Value returns a pointer to the value node of a KeyValue.
// Guaranteed to be non-nil. Panics if not called on a KeyValue node,
// or if the Children are malformed.
func (n *Node) Value() *Node {
return n.Child()
}
// Children returns an iterator over a node's children.
func (n *Node) Children() Iterator {
return Iterator{node: n.Child()}
}
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