/
strings.go
81 lines (67 loc) · 1.99 KB
/
strings.go
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// Copyright 2017 Istio Authors
//
// 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 il
const (
// allocSize is the allocation size when extending the string table.
allocSize = 512
nullString = "<<DEADBEEF>>"
)
// StringTable is a table that maps uint32 ids to strings and allows efficient storage of strings in IL.
type StringTable struct {
stringToID map[string]uint32
idToString []string
nextID uint32
}
// newStringTable creates a new StringTable.
func newStringTable() *StringTable {
t := &StringTable{
stringToID: make(map[string]uint32),
idToString: make([]string, allocSize),
nextID: 0,
}
t.Add(nullString)
return t
}
// Add adds the given string to the table, if it doesn't exit, and returns its id.
func (t *StringTable) Add(s string) uint32 {
id, exists := t.stringToID[s]
if !exists {
id = t.nextID
t.nextID++
if len(t.idToString) <= int(id) {
tmp := make([]string, len(t.idToString)+allocSize)
copy(tmp, t.idToString)
t.idToString = tmp
}
t.stringToID[s] = id
t.idToString[id] = s
}
return id
}
// TryGetID returns the id of the given string if it exists, or returns 0.
func (t *StringTable) TryGetID(s string) uint32 {
id, exists := t.stringToID[s]
if !exists {
return 0
}
return id
}
// GetString returns the string with the given id, or empty string.
func (t *StringTable) GetString(id uint32) string {
return t.idToString[id]
}
// Size returns the number of entries in the table.
func (t *StringTable) Size() int {
return int(t.nextID)
}