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interval_set.go
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/
interval_set.go
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// Copyright (c) 2012-2022 The ANTLR Project. All rights reserved.
// Use of this file is governed by the BSD 3-clause license that
// can be found in the LICENSE.txt file in the project root.
package antlr
import (
"strconv"
"strings"
)
type Interval struct {
Start int
Stop int
}
// NewInterval creates a new interval with the given start and stop values.
func NewInterval(start, stop int) Interval {
return Interval{
Start: start,
Stop: stop,
}
}
// Contains returns true if the given item is contained within the interval.
func (i Interval) Contains(item int) bool {
return item >= i.Start && item < i.Stop
}
// String generates a string representation of the interval.
func (i Interval) String() string {
if i.Start == i.Stop-1 {
return strconv.Itoa(i.Start)
}
return strconv.Itoa(i.Start) + ".." + strconv.Itoa(i.Stop-1)
}
// Length returns the length of the interval.
func (i Interval) Length() int {
return i.Stop - i.Start
}
// IntervalSet represents a collection of [Intervals], which may be read-only.
type IntervalSet struct {
intervals []Interval
readOnly bool
}
// NewIntervalSet creates a new empty, writable, interval set.
func NewIntervalSet() *IntervalSet {
i := new(IntervalSet)
i.intervals = nil
i.readOnly = false
return i
}
func (i *IntervalSet) Equals(other *IntervalSet) bool {
if len(i.intervals) != len(other.intervals) {
return false
}
for k, v := range i.intervals {
if v.Start != other.intervals[k].Start || v.Stop != other.intervals[k].Stop {
return false
}
}
return true
}
func (i *IntervalSet) first() int {
if len(i.intervals) == 0 {
return TokenInvalidType
}
return i.intervals[0].Start
}
func (i *IntervalSet) addOne(v int) {
i.addInterval(NewInterval(v, v+1))
}
func (i *IntervalSet) addRange(l, h int) {
i.addInterval(NewInterval(l, h+1))
}
func (i *IntervalSet) addInterval(v Interval) {
if i.intervals == nil {
i.intervals = make([]Interval, 0)
i.intervals = append(i.intervals, v)
} else {
// find insert pos
for k, interval := range i.intervals {
// distinct range -> insert
if v.Stop < interval.Start {
i.intervals = append(i.intervals[0:k], append([]Interval{v}, i.intervals[k:]...)...)
return
} else if v.Stop == interval.Start {
i.intervals[k].Start = v.Start
return
} else if v.Start <= interval.Stop {
i.intervals[k] = NewInterval(intMin(interval.Start, v.Start), intMax(interval.Stop, v.Stop))
// if not applying to end, merge potential overlaps
if k < len(i.intervals)-1 {
l := i.intervals[k]
r := i.intervals[k+1]
// if r contained in l
if l.Stop >= r.Stop {
i.intervals = append(i.intervals[0:k+1], i.intervals[k+2:]...)
} else if l.Stop >= r.Start { // partial overlap
i.intervals[k] = NewInterval(l.Start, r.Stop)
i.intervals = append(i.intervals[0:k+1], i.intervals[k+2:]...)
}
}
return
}
}
// greater than any exiting
i.intervals = append(i.intervals, v)
}
}
func (i *IntervalSet) addSet(other *IntervalSet) *IntervalSet {
if other.intervals != nil {
for k := 0; k < len(other.intervals); k++ {
i2 := other.intervals[k]
i.addInterval(NewInterval(i2.Start, i2.Stop))
}
}
return i
}
func (i *IntervalSet) complement(start int, stop int) *IntervalSet {
result := NewIntervalSet()
result.addInterval(NewInterval(start, stop+1))
for j := 0; j < len(i.intervals); j++ {
result.removeRange(i.intervals[j])
}
return result
}
func (i *IntervalSet) contains(item int) bool {
if i.intervals == nil {
return false
}
for k := 0; k < len(i.intervals); k++ {
if i.intervals[k].Contains(item) {
return true
}
}
return false
}
func (i *IntervalSet) length() int {
iLen := 0
for _, v := range i.intervals {
iLen += v.Length()
}
return iLen
}
func (i *IntervalSet) removeRange(v Interval) {
if v.Start == v.Stop-1 {
i.removeOne(v.Start)
} else if i.intervals != nil {
k := 0
for n := 0; n < len(i.intervals); n++ {
ni := i.intervals[k]
// intervals are ordered
if v.Stop <= ni.Start {
return
} else if v.Start > ni.Start && v.Stop < ni.Stop {
i.intervals[k] = NewInterval(ni.Start, v.Start)
x := NewInterval(v.Stop, ni.Stop)
// i.intervals.splice(k, 0, x)
i.intervals = append(i.intervals[0:k], append([]Interval{x}, i.intervals[k:]...)...)
return
} else if v.Start <= ni.Start && v.Stop >= ni.Stop {
// i.intervals.splice(k, 1)
i.intervals = append(i.intervals[0:k], i.intervals[k+1:]...)
k = k - 1 // need another pass
} else if v.Start < ni.Stop {
i.intervals[k] = NewInterval(ni.Start, v.Start)
} else if v.Stop < ni.Stop {
i.intervals[k] = NewInterval(v.Stop, ni.Stop)
}
k++
}
}
}
func (i *IntervalSet) removeOne(v int) {
if i.intervals != nil {
for k := 0; k < len(i.intervals); k++ {
ki := i.intervals[k]
// intervals i ordered
if v < ki.Start {
return
} else if v == ki.Start && v == ki.Stop-1 {
// i.intervals.splice(k, 1)
i.intervals = append(i.intervals[0:k], i.intervals[k+1:]...)
return
} else if v == ki.Start {
i.intervals[k] = NewInterval(ki.Start+1, ki.Stop)
return
} else if v == ki.Stop-1 {
i.intervals[k] = NewInterval(ki.Start, ki.Stop-1)
return
} else if v < ki.Stop-1 {
x := NewInterval(ki.Start, v)
ki.Start = v + 1
// i.intervals.splice(k, 0, x)
i.intervals = append(i.intervals[0:k], append([]Interval{x}, i.intervals[k:]...)...)
return
}
}
}
}
func (i *IntervalSet) String() string {
return i.StringVerbose(nil, nil, false)
}
func (i *IntervalSet) StringVerbose(literalNames []string, symbolicNames []string, elemsAreChar bool) string {
if i.intervals == nil {
return "{}"
} else if literalNames != nil || symbolicNames != nil {
return i.toTokenString(literalNames, symbolicNames)
} else if elemsAreChar {
return i.toCharString()
}
return i.toIndexString()
}
func (i *IntervalSet) GetIntervals() []Interval {
return i.intervals
}
func (i *IntervalSet) toCharString() string {
names := make([]string, len(i.intervals))
var sb strings.Builder
for j := 0; j < len(i.intervals); j++ {
v := i.intervals[j]
if v.Stop == v.Start+1 {
if v.Start == TokenEOF {
names = append(names, "<EOF>")
} else {
sb.WriteByte('\'')
sb.WriteRune(rune(v.Start))
sb.WriteByte('\'')
names = append(names, sb.String())
sb.Reset()
}
} else {
sb.WriteByte('\'')
sb.WriteRune(rune(v.Start))
sb.WriteString("'..'")
sb.WriteRune(rune(v.Stop - 1))
sb.WriteByte('\'')
names = append(names, sb.String())
sb.Reset()
}
}
if len(names) > 1 {
return "{" + strings.Join(names, ", ") + "}"
}
return names[0]
}
func (i *IntervalSet) toIndexString() string {
names := make([]string, 0)
for j := 0; j < len(i.intervals); j++ {
v := i.intervals[j]
if v.Stop == v.Start+1 {
if v.Start == TokenEOF {
names = append(names, "<EOF>")
} else {
names = append(names, strconv.Itoa(v.Start))
}
} else {
names = append(names, strconv.Itoa(v.Start)+".."+strconv.Itoa(v.Stop-1))
}
}
if len(names) > 1 {
return "{" + strings.Join(names, ", ") + "}"
}
return names[0]
}
func (i *IntervalSet) toTokenString(literalNames []string, symbolicNames []string) string {
names := make([]string, 0)
for _, v := range i.intervals {
for j := v.Start; j < v.Stop; j++ {
names = append(names, i.elementName(literalNames, symbolicNames, j))
}
}
if len(names) > 1 {
return "{" + strings.Join(names, ", ") + "}"
}
return names[0]
}
func (i *IntervalSet) elementName(literalNames []string, symbolicNames []string, a int) string {
if a == TokenEOF {
return "<EOF>"
} else if a == TokenEpsilon {
return "<EPSILON>"
} else {
if a < len(literalNames) && literalNames[a] != "" {
return literalNames[a]
}
return symbolicNames[a]
}
}