1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
|
// 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
Context Context
}
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), p.Context)
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
}
|
