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symbols.go
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symbols.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 semantic
import (
"fmt"
"sort"
)
// Symbols is an object with named members and no other functionality.
type Symbols struct {
sorted bool
entries byName
}
// AddNamed inserts a named node into the symbol space.
func (s *Symbols) AddNamed(entry NamedNode) {
s.entries = append(s.entries, namedEntry{name: entry.Name(), node: entry})
s.sorted = false
}
// Add inserts a node into the symbol space with the specified name.
func (s *Symbols) Add(name string, entry Node) {
s.entries = append(s.entries, namedEntry{name: name, node: entry})
s.sorted = false
}
func (s *Symbols) Visit(visitor func(string, Node)) {
s.sort()
for _, e := range s.entries {
visitor(e.name, e.node)
}
}
func (s *Symbols) Find(name string) (Node, error) {
i := s.find(name)
if i >= len(s.entries) || s.entries[i].name != name {
return nil, nil
}
match := s.entries[i].node
if i+1 < len(s.entries) && s.entries[i+1].name == name {
return match, fmt.Errorf("Ambiguous match")
}
return match, nil
}
func (s *Symbols) FindAll(name string) []Node {
i := s.find(name)
result := []Node{}
for ; i < len(s.entries) && s.entries[i].name == name; i++ {
result = append(result, s.entries[i].node)
}
return result
}
func (s *Symbols) find(name string) int {
s.sort()
return sort.Search(len(s.entries), func(i int) bool { return s.entries[i].name >= name })
}
func (s *Symbols) sort() {
if !s.sorted {
//we use a stable sort for deterministic iteration order
sort.Stable(s.entries)
s.sorted = true
}
}
type namedEntry struct {
name string
node Node
}
type byName []namedEntry
func (a byName) Len() int { return len(a) }
func (a byName) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
func (a byName) Less(i, j int) bool { return a[i].name < a[j].name }