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parser.go
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parser.go
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// Code generated by gocc; DO NOT EDIT.
// This file is dual licensed under CC0 and The Gonum License.
//
// Copyright ©2017 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//
// Copyright ©2017 Robin Eklind.
// This file is made available under a Creative Commons CC0 1.0
// Universal Public Domain Dedication.
package parser
import (
"fmt"
"strings"
parseError "gonum.org/v1/gonum/graph/formats/dot/internal/errors"
"gonum.org/v1/gonum/graph/formats/dot/internal/token"
)
const (
numProductions = 55
numStates = 87
numSymbols = 50
)
// Stack
type stack struct {
state []int
attrib []Attrib
}
const iNITIAL_STACK_SIZE = 100
func newStack() *stack {
return &stack{
state: make([]int, 0, iNITIAL_STACK_SIZE),
attrib: make([]Attrib, 0, iNITIAL_STACK_SIZE),
}
}
func (s *stack) reset() {
s.state = s.state[:0]
s.attrib = s.attrib[:0]
}
func (s *stack) push(state int, a Attrib) {
s.state = append(s.state, state)
s.attrib = append(s.attrib, a)
}
func (s *stack) top() int {
return s.state[len(s.state)-1]
}
func (s *stack) peek(pos int) int {
return s.state[pos]
}
func (s *stack) topIndex() int {
return len(s.state) - 1
}
func (s *stack) popN(items int) []Attrib {
lo, hi := len(s.state)-items, len(s.state)
attrib := s.attrib[lo:hi]
s.state = s.state[:lo]
s.attrib = s.attrib[:lo]
return attrib
}
func (s *stack) String() string {
w := new(strings.Builder)
fmt.Fprintf(w, "stack:\n")
for i, st := range s.state {
fmt.Fprintf(w, "\t%d: %d , ", i, st)
if s.attrib[i] == nil {
fmt.Fprintf(w, "nil")
} else {
switch attr := s.attrib[i].(type) {
case *token.Token:
fmt.Fprintf(w, "%s", attr.Lit)
default:
fmt.Fprintf(w, "%v", attr)
}
}
fmt.Fprintf(w, "\n")
}
return w.String()
}
// Parser
type Parser struct {
stack *stack
nextToken *token.Token
pos int
}
type Scanner interface {
Scan() (tok *token.Token)
}
func NewParser() *Parser {
p := &Parser{stack: newStack()}
p.Reset()
return p
}
func (p *Parser) Reset() {
p.stack.reset()
p.stack.push(0, nil)
}
func (p *Parser) Error(err error, scanner Scanner) (recovered bool, errorAttrib *parseError.Error) {
errorAttrib = &parseError.Error{
Err: err,
ErrorToken: p.nextToken,
ErrorSymbols: p.popNonRecoveryStates(),
ExpectedTokens: make([]string, 0, 8),
}
for t, action := range actionTab[p.stack.top()].actions {
if action != nil {
errorAttrib.ExpectedTokens = append(errorAttrib.ExpectedTokens, token.TokMap.Id(token.Type(t)))
}
}
if action := actionTab[p.stack.top()].actions[token.TokMap.Type("error")]; action != nil {
p.stack.push(int(action.(shift)), errorAttrib) // action can only be shift
} else {
return
}
if action := actionTab[p.stack.top()].actions[p.nextToken.Type]; action != nil {
recovered = true
}
for !recovered && p.nextToken.Type != token.EOF {
p.nextToken = scanner.Scan()
if action := actionTab[p.stack.top()].actions[p.nextToken.Type]; action != nil {
recovered = true
}
}
return
}
func (p *Parser) popNonRecoveryStates() (removedAttribs []parseError.ErrorSymbol) {
if rs, ok := p.firstRecoveryState(); ok {
errorSymbols := p.stack.popN(p.stack.topIndex() - rs)
removedAttribs = make([]parseError.ErrorSymbol, len(errorSymbols))
for i, e := range errorSymbols {
removedAttribs[i] = e
}
} else {
removedAttribs = []parseError.ErrorSymbol{}
}
return
}
// recoveryState points to the highest state on the stack, which can recover
func (p *Parser) firstRecoveryState() (recoveryState int, canRecover bool) {
recoveryState, canRecover = p.stack.topIndex(), actionTab[p.stack.top()].canRecover
for recoveryState > 0 && !canRecover {
recoveryState--
canRecover = actionTab[p.stack.peek(recoveryState)].canRecover
}
return
}
func (p *Parser) newError(err error) error {
e := &parseError.Error{
Err: err,
StackTop: p.stack.top(),
ErrorToken: p.nextToken,
}
actRow := actionTab[p.stack.top()]
for i, t := range actRow.actions {
if t != nil {
e.ExpectedTokens = append(e.ExpectedTokens, token.TokMap.Id(token.Type(i)))
}
}
return e
}
func (p *Parser) Parse(scanner Scanner) (res interface{}, err error) {
p.Reset()
p.nextToken = scanner.Scan()
for acc := false; !acc; {
action := actionTab[p.stack.top()].actions[p.nextToken.Type]
if action == nil {
if recovered, errAttrib := p.Error(nil, scanner); !recovered {
p.nextToken = errAttrib.ErrorToken
return nil, p.newError(nil)
}
if action = actionTab[p.stack.top()].actions[p.nextToken.Type]; action == nil {
panic("Error recovery led to invalid action")
}
}
switch act := action.(type) {
case accept:
res = p.stack.popN(1)[0]
acc = true
case shift:
p.stack.push(int(act), p.nextToken)
p.nextToken = scanner.Scan()
case reduce:
prod := productionsTable[int(act)]
attrib, err := prod.ReduceFunc(p.stack.popN(prod.NumSymbols))
if err != nil {
return nil, p.newError(err)
} else {
p.stack.push(gotoTab[p.stack.top()][prod.NTType], attrib)
}
default:
panic("unknown action: " + action.String())
}
}
return res, nil
}