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|
package compiler
import (
"fmt"
"sort"
"strings"
)
type symbolPosition uint8
const (
symbolPositionNil = symbolPosition(0)
symbolPositionMaskSymbol = uint8(0x00) // 0000 0000
symbolPositionMaskEndMark = uint8(0x80) // 1000 0000
symbolPositionMaskValue = uint8(0x7f) // 0111 1111
)
func newSymbolPosition(n uint8, endMark bool) symbolPosition {
if endMark {
return symbolPosition(n | symbolPositionMaskEndMark)
}
return symbolPosition(n | symbolPositionMaskSymbol)
}
func (p symbolPosition) String() string {
if p.isEndMark() {
return fmt.Sprintf("end#%v", uint8(p)&symbolPositionMaskValue)
}
return fmt.Sprintf("sym#%v", uint8(p)&symbolPositionMaskValue)
}
func (p symbolPosition) isEndMark() bool {
if uint8(p)&symbolPositionMaskEndMark > 1 {
return true
}
return false
}
func (p symbolPosition) describe() (uint8, bool) {
v := uint8(p) & symbolPositionMaskValue
if p.isEndMark() {
return v, true
}
return v, false
}
type symbolPositionSet map[symbolPosition]struct{}
func newSymbolPositionSet() symbolPositionSet {
return map[symbolPosition]struct{}{}
}
func (s symbolPositionSet) String() string {
if len(s) <= 0 {
return "{}"
}
ps := s.sort()
var b strings.Builder
fmt.Fprintf(&b, "{")
for i, p := range ps {
if i <= 0 {
fmt.Fprintf(&b, "%v", p)
continue
}
fmt.Fprintf(&b, ", %v", p)
}
fmt.Fprintf(&b, "}")
return b.String()
}
func (s symbolPositionSet) add(pos symbolPosition) symbolPositionSet {
s[pos] = struct{}{}
return s
}
func (s symbolPositionSet) merge(t symbolPositionSet) symbolPositionSet {
for p := range t {
s.add(p)
}
return s
}
func (s symbolPositionSet) intersect(set symbolPositionSet) symbolPositionSet {
in := newSymbolPositionSet()
for p1 := range s {
for p2 := range set {
if p1 != p2 {
continue
}
in.add(p1)
}
}
return in
}
func (s symbolPositionSet) hash() string {
if len(s) <= 0 {
return ""
}
sorted := s.sort()
var b strings.Builder
fmt.Fprintf(&b, "%v", sorted[0])
for _, p := range sorted[1:] {
fmt.Fprintf(&b, ":%v", p)
}
return b.String()
}
func (s symbolPositionSet) sort() []symbolPosition {
sorted := []symbolPosition{}
for p := range s {
sorted = append(sorted, p)
}
sort.Slice(sorted, func(i, j int) bool {
return sorted[i] < sorted[j]
})
return sorted
}
type astNode interface {
fmt.Stringer
children() (astNode, astNode)
nullable() bool
first() symbolPositionSet
last() symbolPositionSet
}
type symbolNode struct {
token *token
value byte
pos symbolPosition
}
func newSymbolNode(tok *token, value byte, pos symbolPosition) *symbolNode {
return &symbolNode{
token: tok,
value: value,
pos: pos,
}
}
func (n *symbolNode) String() string {
return fmt.Sprintf("{type: char, char: %v, int: %v, pos: %v}", string(n.token.char), n.token.char, n.pos)
}
func (n *symbolNode) children() (astNode, astNode) {
return nil, nil
}
func (n *symbolNode) nullable() bool {
return false
}
func (n *symbolNode) first() symbolPositionSet {
s := newSymbolPositionSet()
s.add(n.pos)
return s
}
func (n *symbolNode) last() symbolPositionSet {
s := newSymbolPositionSet()
s.add(n.pos)
return s
}
type endMarkerNode struct {
id int
pos symbolPosition
}
func newEndMarkerNode(id int, pos symbolPosition) *endMarkerNode {
return &endMarkerNode{
id: id,
pos: pos,
}
}
func (n *endMarkerNode) String() string {
return fmt.Sprintf("{type: end, pos: %v}", n.pos)
}
func (n *endMarkerNode) children() (astNode, astNode) {
return nil, nil
}
func (n *endMarkerNode) nullable() bool {
return false
}
func (n *endMarkerNode) first() symbolPositionSet {
s := newSymbolPositionSet()
s.add(n.pos)
return s
}
func (n *endMarkerNode) last() symbolPositionSet {
s := newSymbolPositionSet()
s.add(n.pos)
return s
}
type concatNode struct {
left astNode
right astNode
}
func newConcatNode(left, right astNode) *concatNode {
return &concatNode{
left: left,
right: right,
}
}
func (n *concatNode) String() string {
return fmt.Sprintf("{type: concat}")
}
func (n *concatNode) children() (astNode, astNode) {
return n.left, n.right
}
func (n *concatNode) nullable() bool {
return n.left.nullable() && n.right.nullable()
}
func (n *concatNode) first() symbolPositionSet {
s := newSymbolPositionSet()
s.merge(n.left.first())
if n.left.nullable() {
s.merge(n.right.first())
}
return s
}
func (n *concatNode) last() symbolPositionSet {
s := newSymbolPositionSet()
s.merge(n.right.last())
return s
}
type altNode struct {
left astNode
right astNode
}
func newAltNode(left, right astNode) *altNode {
return &altNode{
left: left,
right: right,
}
}
func (n *altNode) String() string {
return fmt.Sprintf("{type: alt}")
}
func (n *altNode) children() (astNode, astNode) {
return n.left, n.right
}
func (n *altNode) nullable() bool {
return n.left.nullable() || n.right.nullable()
}
func (n *altNode) first() symbolPositionSet {
s := newSymbolPositionSet()
s.merge(n.left.first())
s.merge(n.right.first())
return s
}
func (n *altNode) last() symbolPositionSet {
s := newSymbolPositionSet()
s.merge(n.left.last())
s.merge(n.right.last())
return s
}
type repeatNode struct {
left astNode
}
func newRepeatNode(left astNode) *repeatNode {
return &repeatNode{
left: left,
}
}
func (n *repeatNode) String() string {
return fmt.Sprintf("{type: repeat}")
}
func (n *repeatNode) children() (astNode, astNode) {
return n.left, nil
}
func (n *repeatNode) nullable() bool {
return true
}
func (n *repeatNode) first() symbolPositionSet {
s := newSymbolPositionSet()
s.merge(n.left.first())
return s
}
func (n *repeatNode) last() symbolPositionSet {
s := newSymbolPositionSet()
s.merge(n.left.last())
return s
}
type followTable map[symbolPosition]symbolPositionSet
func genFollowTable(root astNode) followTable {
follow := followTable{}
calcFollow(follow, root)
return follow
}
func calcFollow(follow followTable, ast astNode) {
if ast == nil {
return
}
left, right := ast.children()
calcFollow(follow, left)
calcFollow(follow, right)
switch n := ast.(type) {
case *concatNode:
l, r := n.children()
for _, p := range l.last().sort() {
if _, ok := follow[p]; !ok {
follow[p] = newSymbolPositionSet()
}
follow[p].merge(r.first())
}
case *repeatNode:
for _, p := range n.last().sort() {
if _, ok := follow[p]; !ok {
follow[p] = newSymbolPositionSet()
}
follow[p].merge(n.first())
}
}
}
func positionSymbols(node astNode, n uint8) uint8 {
if node == nil {
return n
}
l, r := node.children()
p := n
p = positionSymbols(l, p)
p = positionSymbols(r, p)
switch n := node.(type) {
case *symbolNode:
n.pos = newSymbolPosition(p, false)
p++
case *endMarkerNode:
n.pos = newSymbolPosition(p, true)
p++
}
return p
}
|
