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node.go
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node.go
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// Copyright (C) 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package lingo
import "fmt"
// Record is an entry in a Records list that holds a parse result along with its scan stream bounds.
type Record struct {
Start int
End int
Object interface{}
}
// Records is a list of Record objects that represent the ordered sequence of parse results.
type Records []Record
// Node is the form used when Records are reconstituted into a
type Node struct {
Start int
End int
Object interface{}
Parent *Node
Children []*Node
}
// ToCST converts from a record list to a node span tree.
func (r Records) ToCST() *Node {
root := &Node{
Start: 0,
End: len(r),
}
active := root
for _, entry := range r {
for entry.Start >= active.End && active.Parent != nil {
active = active.Parent
}
child := &Node{
Start: entry.Start,
End: entry.End,
Object: entry.Object,
Parent: active,
}
active.Children = append(active.Children, child)
active = child
}
return root
}
// Format implements fmt.Formatter to print the full record list.
func (r Records) Format(f fmt.State, _ rune) {
for _, entry := range r {
fmt.Fprint(f, entry.Object)
}
}
// Format implements fmt.Formatter to print the leaf nodes in depth first order.
func (n *Node) Format(f fmt.State, _ rune) {
if len(n.Children) > 0 {
for _, child := range n.Children {
fmt.Fprint(f, child)
}
} else if n.Object != nil {
fmt.Fprint(f, n.Object)
}
}